Impact of the ~ 2400 yr solar cycle on climate and human societies

*by Javier

The role of solar variability on climate change, despite having a very long scientific tradition, is currently downplayed as a climatic factor within the most popular hypothesis for climate change.

As the root of this neglect lie two fundamental problems. Solar variability is quite small (about 0.1% of total irradiation), and there is no generally accepted mechanism by which the solar variability signal could be amplified by the climate system.

While progress is being made to solve these problems, there is a growing number of scientific paleoclimatology articles published every year that defend a significant role for solar variability in paleoclimate change. The explanation for this contradiction is that evidence always trumps theory, and there is very solid evidence that periods of low solar activity in the past, identified by a higher rate of cosmogenic isotopes production, have a high degree of correlation with periods of climate deterioration manifested as lower temperatures and precipitation changes.

Frequency analysis of solar variability during the Holocene identifies several cycles (McCracken et al., 2013), with the most important being the 11.4-yr Schwabe cycle, the 87-yr Gleissberg cycle, the 208-yr de Vries cycle, the ~ 1000-yr Eddy cycle, and the ~ 2400-yr cycle. Even longer cycles can be identified from 10-Berilium (10Be) records in ice cores, like a 9600-yr cycle (Sánchez-Sesma, 2015). Comparison of climate and solar variability records leads to the important observation that the length of the cycle correlates with the amplitude of the climate effect observed and in general the longer the cycle the more profound effect it appears to have on climate.

For an analysis of solar cycles during the Holocene you can read “Periodicities in solar variability and climate change: A simple model”

For this article I am going to concentrate mainly on the ~ 2400-yr cycle during the Holocene and on its effects both on climate and people. It is important to highlight two things. First, that solar variability, even if an important factor affecting climate change is neither the main one, nor the only one. Temperatures on Earth appear to depend mainly on orbital changes, firstly obliquity, but also precession and eccentricity, and oceanic cycles, and volcanic activity also play an important role at times, and therefore solar variability alone does not explain climate changes. The second is that solar cycles are irregular in nature. The Schwabe cycle is a good example. Although described as an 11-yr cycle it can be anywhere from 8 to 15 years. Also its amplitude is very variable, and during the Maunder minimum between 1620 and 1700 AD even became inconspicuous. Other solar cycles also manifest this irregularity both in periodicity and amplitude, and similarly the ~ 1000-yr Eddy cycle was inconspicuous between 4500 and 1500 yr BP (years before 1950).

The ~ 2400-yr Bray cycle

This cycle was identified by J. Roger Bray in 1968 from a consilience of geophysical, biological, and glaciological evidence contrasted with solar activity reconstructed from sunspot naked eye observations and aurora records. This proposed solar cycle was later confirmed by Sonnet and Damon by spectral analysis of the 14C record when it became available in the late 80’s and named Hallstattzei (later Hallstatt) for a late Bronze-early Iron cultural transition in an Austrian archeological site during the cycle’s previous to last minimum, 2800 years ago. However the name breaks the tradition of naming solar cycles after their discoverer, and refers to a cultural change at a specific time and location, and so I propose the name to be changed to the Bray cycle.

The average length of this cycle has not been very clearly determined due to its irregularity and the difficulty from separating its signal from the ~ 1000-yr Eddy cycle. It was originally described by J. R. Bray as a ~ 2500-yr cycle, and values as low as ~ 2200 years have been published. My own estimate based on known occurrences of its lows during the entire Holocene is around 2450 years, quite similar to Bray’s estimate 50 years ago.

figure-1

Figure 1. Variation in 14C after removal of the long-term trend. An oscillation of the ~ 2400-year Bray cycle is superposed on the data to indicate times when periods of very low solar activity would be expected to occur (arrows). As with every solar cycle, there is some variability in the spacing that complicates mathematical analysis. Adapted to show correct cycle length from Clilverd et al., 2003.

The ~ 2400-yr cycle in solar activity could be a lower harmonic of the ~ 9600-yr cycle found by Sánchez-Sesma (2015) in 10Be records for the past 135 kyr. Alternatively the ~ 9600-yr cycle could be the result of a constructive interference between the ~ 1000-yr and ~ 2400-yr cycles.

We do not know what causes a ~ 2400-yr cycle in solar variability. Scientists are divided between those that propose solar internal causes, and those that defend a “planetary hypothesis” where the giant planets in the Solar System would cause these cycles by affecting the movements on the Sun around the Baricenter of the Solar System, either through changes in planetary torque (Abreu et al., 2012), or through changes in solar inertial motion (Charvátová & Hejda, 2014).

Ivanka Charvátová’s hypothesis is specially relevant to this article since she finds a 2402 year cycle in changes in solar inertial motion, a period in close agreement with the ~ 2400-yr cycle in solar variability.n essence periods of high solar activity would coincide with planetary and solar configurations in an equilibrated figure known as the trefoil, while periods of low solar activity would be associated with disordered configurations (Charvátová & Hejda, 2014). An obstacle to the acceptance of the planetary hypothesis is that several massive exoplanets have been discovered at orbits around their star much closer than Jupiter without causing a measurable effect on the star’s activity.

Whatever its cause, the observed effect of the ~ 2400-yr Bray cycle is to result in long grand solar minima (GSM) or clusters of GSM at its lows. According to Usoskin et al., 2007:

“the occurrence of grand minima depicts a weak (marginally significant) quasi-periodicity of 2000–2400 years, which is a well-known period in 14C data… no clear periodicities are observed in the occurrence of grand maxima.”

This fits well with the observation that unlike the last glacial period, during the Holocene after it reaches its Hypsithermal or Climatic Optimum there are no warming events, just cooling events followed by recovery, and thus a warming period cannot be separated from the previous cold event without losing context. According to this view, a low in the Bray cycle would increase the probability of a long GSM or a cluster of GSM that would reduce temperatures and cause changes in precipitation patterns bringing about a general worsening of the climate for a few centuries. The end of the low would bring about a return to normal solar activity with a natural increase in temperatures that can also take a few centuries.

The climatic effect of the GSM caused by the lows in the Bray cycle appears to register mainly as a significant reduction in winter temperatures with a smaller effect on summer temperatures, and profound changes in precipitation patterns, usually registered in the best studied North Atlantic region as a very significant increase in precipitations. The combination usually leads to cold winters, increased snow, glacier re-advance, and spring flooding. The effect on human societies can be postulated as higher frequency of food crises, population decrease, increased migration, increased violence, and higher chance of civilization regression or failure. It is so common that new civilizations emerge after climatic crises that some archaeologists have developed the theory that climate caused environmental stress is an engine to societal change (Weninger et al., 2009; Roberts et al., 2011).

Let’s now review what has happened to the planet and people at the lows of the Bray cycle during the Holocene. These have taken place around the following dates (kyr BP. indicates thousands of years before 1950):

B1. 0.4 kyr BP. Little Ice Age (LIA)
B2. 2.8 kyr BP. Sub-Boreal/Sub-Atlantic Minimum
B3. 5.2 kyr BP. Mid-Holocene Transition. Ötzi buried in ice. Start of Neoglacial period
B4. 7.7 kyr BP. Boreal/Atlantic transition and precipitation change
B5. 10.3 kyr BP. Early Holocene Boreal Oscillation
B6. 12.8 kyr BP. Younger Dryas cooling onset

figure-2

Figure 2. Holocene climate reconstruction. Major palinological subdivisions of the Holocene (names on top) match a 2450-yr regular spacing (grey arches on top). (a) The global temperature reconstruction (black curve; Marcott et al., 2013 by the differencing method with proxy published dates) has been rescaled in temperature anomaly to match biological, glaciological, and marine sedimentary evidence, resulting in the Holocene Climate Optimum being about 1.2°K warmer than LIA (See Appendix). (b) The general temperature trend of the Holocene follows the Earth’s axis obliquity (purple), and significant downside deviations generally match the lows of the ~ 2400-year Bray cycle of solar activity (grey bands labelled B-1 to B-5). (c) Significant negative climate deviations manifest also in global glacier advances (blue bars; Mayewski et al., 2004) and (d) strong increases in iceberg detrital discharges (red curve, inverted; Bond et al., 2001) that generally agree well with the lows in the ~ 2400-year Bray cycle and ~ 1000-year Eddy cycle (not shown) of solar activity.

The 10.3 kyr event. The Boreal Oscillation.

The fifth low in the Bray cycle at about 10.3 kyr BP coincides with the GSM known as Boreal 1 and the climate worsening named Boreal Oscillation. The planet was at that time still warming towards the Holocene Hypsithermal, due to increasing obliquity and northern latitudinal summer insolation and the event appears to not have been a major trend inversion, but a relatively brief cold and wet period for the areas we have the best evidence.

The 10.3 kyr event and its associated Boreal 1 GSM coincide with Bond event 7 of increased iceberg discharge in the North Atlantic (Bond et al., 2001; figure 2), and with the highest concentration of non-sea salt potassium deposition in the Greenland GISP2 ice core for the Holocene (figure 3e). The presence of non-sea salt potassium in Greenland is associated to the expansion of the Siberian High pressure system that brings polar temperatures over a wide area in the northern hemisphere (Mayewski et al., 2004).

The precise dating of the potassium increase around 10250 BP allows to estimate the duration of the Bray cycle. Since the Spører minimum takes place around 450 BP, that gives an average duration of around 2450 years.

The 10.3 kyr event has been studied mainly by Björk et al. (2001) and attributed to decreased solar forcing. The event is recorded at proxies from multiple sites in the Northern Hemisphere, like Norwegian sea surface temperatures (SST) that show a drop of >2°C both in winter and summer that lasted less than 200 years. This Norwegian sea cooling coincides with harsher conditions in the Faroe Islands lacustrine records that show a decrease in birch pollen and increase in grass and herb pollen. German pines show at the time a tree-ring width minimum and the Santa Barbara basin shows a cold related peak of oxygenation. Greenland and Tibetan ice cores display a d 18O isotope minimum (Björk et al., 2001, and references within). The increase in precipitation in the North Atlantic-European region is supported by the increase in lake levels in west-central Europe and central Italy (Magny et al., 2007; figure 3c), and the increased iceberg discharge (Bond et al., 2001). Glacier readvances took place in Norway (the Erdalen event; Dahl et al., 2002) and Tibet (Seong et al., 2009).

figure-3

Figure 3. Climate change in the Early Holocene. Upper panel shows the correlation between solar activity and cold phases reflected by highstands of mid-European lake levels (c). Higher indicates wetter. Periods of lower solar activity coincide with periods of higher production of the cosmogenic radionuclides 10Be (a) and 14C (b). Source: Magny et al., 2007. Bottom panel (d) d 18O speleothem (‰, inverted) from Qunf Cave (Southern Oman), a proxy for the strength of the Indian monsoon (as represented, weaker towards bottom). (e) GISP2 non-sea salt [K+] (ppb, inverted), a proxy for Siberian High polar conditions. (f) Relative abundance (%, inverted) of the cold-water dinocyst Spiniferites elongatus in the Aegean sea core SL21. Lower indicates colder. Source: Marino et al., 2009. The position of the two lows for the ~ 2400-yr Bray cycle in this period at 10.3 and 7.7 kyr BP is indicated by the two violet bars.

In the Aegean sea, the increase in abundance of the cold-water dinocyst species Spiniferites elongatus indicates a strong biological response to the climatic deterioration and lower SST in the Eastern Mediterranean during the 10.3 kyr event (Marino et al., 2009; figure 3f). Within dating uncertainties a coincident dryer period for the Indian monsoon can be postulated based on an increase in d 18O speleothem in the Qunf cave of Oman (Marino et al., 2009; figure 3d).

The climatic deterioration described must have had an impact on the prehistoric societies, but then most of the world was populated by hunter-gatherer cultures. In the Fertile Crescent, humans were in a pre- or proto-agricultural state, with increased population densities. At the time of the 10.3 kyr event Göbekli Tepe was being constructed, and Jericho, one of the oldest cities in the world was the first city known to have built a wall, dated precisely at 10.3 kyr BP. The proposed roles for the first city wall fit what we would expect from a climatic deterioration: defensive role against raiders in search of stored food, or protective role against flooding, as mud deposits indicate it had become more common.

Whatever the reason, the walls of Jericho do not appear to have spared the city from the societal changes usually associated to bad climatic conditions. For over 700 years Jericho inhabitants were part of the Pre-Pottery Neolithic A (PPNA) culture, a strange culture characterized for living with their dead (home burials) and construction of the first granaries. The 10.3 kyr event marks the end of PPNA in Jericho (Weninberg et al., 2009; figure 4). There is a gap of about 200 years in radiocarbon dates that suggests a hiatus or strong reduction in construction and habitation and afterwards Jericho’s inhabitants belong to the PPNB culture that has Anatolian influence, which suggest northern immigration, and is characterized by domesticated sheep, and a different more advanced flint toolkit. The PPNB culture disappears at the 8.2 kyr event, a climate pessimum that does not belong to the ~ 2400-yr Bray cycle.

figure-4

Figure 4. Cultural shift at Jericho coinciding with the 10.3 kyr event. Radiocarbon Data from Jericho arranged according to cultural period (Top: Pre-Pottery Neolithic B, PPNB; Middle: PPNA; Lower: Combined PPNA and PPNB), in comparison to (lower graph): Gaussian smoothed (200 yr) and high-resolution GISP2 potassium (non-sea salt [K+]; ppb) ion proxy for the Siberian High. The calibrated 14C-age distribution (radiocarbon periodization) gives reason to assume a hiatus between PPNA and PPNB. Source: Weninger et al., 2009.

The 7.7 kyr event. The Boreal/Atlantic transition.

The low in the Bray cycle at about 7.7 kyr BP coincides with a cluster of four GSM known as Jericho 0 to 3 and a long period of climate worsening between 7.8 and 7.0 kyr BP. The planet had reached maximum North polar insolation over a millennia before but the melting of the ice sheets was completed at about this time so general conditions were still within the Holocene Hypsithermal. The 7.7 kyr event marks a climatic change in Holocene conditions in northern Europe from the warm relatively dry Boreal period to the warm more humid Atlantic period, reflected in a vegetation change in high northern latitudes with a significant arboreal species expansion.

The 7.7 kyr event coincides with Bond event 5a of increased iceberg discharge in the North Atlantic (Bond et al., 2001; figure 2). It is not however a very strong minimum in the ~ 2400-yr Bray cycle and it is completely overshadowed by the strength of the close 8.2 kyr event, the most profound cooling in the Holocene, that does not belong to the Bray series. Due to that, although detected in most proxy series for climate change, it is seldom studied.

As with any Bray low, it is characterized both by winter cooling reflected in Greenland and the Aegean Sea, and an increase in precipitations in the North Atlantic-European region (figures 3c & 5). A detailed study of the hydrology of the Rhone Valley of France during this time by Berger et al. (2016) shows that, very much like the LIA, this long period of climate deterioration can be subdivided into three subperiods (A, B, and C in figure 5): two cold and wet sub-periods separated by a warm and drier interval. During the cold-humid periods the Citelle river changed to a braided fluvial style, greatly increasing the liquid flow and sediment discharges. This fluvial changes coincide with increased hydrological activity elsewhere in Europe, lower temperatures in the Greenland ice core GISP2 and glacier advances in the Alps (Berger et al., 2016; figure 5).

figure-5

Figure 5. Hydrological and climate indicators during the 6.5-8.5 kyr BP. Hydrological analysis defines seven phases at Lalo site (Rhone valley, France). Four of them correspond to periods of soil formation (pedogenesis), meandering entrenched Citelle river, and normal sediment discharge. Three periods at 8.2, 7.7, and 7.2 kyr BP show braided Citelle river flow, and enhanced flux and sediment discharges. They coincide with periods of low or decreasing temperatures in Greenland, reduced solar activity, increased hydrology elsewhere in Europe and Alps glacier advances. The blue bands correspond to colder periods in the Greenland ice sheet and alpine areas and to moister signals in western/central hydrosystems, defining the known 8.2, 7.7, and 7.2 kyr events. A, B and C letters indicate the tripartite climate division of the 7.7-7.1 period. Source: Berger et al., 2016.

Solar activity cycle timing indicates that the cold 7.7 kyr event belongs to the ~ 2400-yr Bray cycle, while the 7.2 kyr event belongs to the ~ 1000-yr Eddy cycle. The Eddy cycle is modulated by a longer cycle resulting in very strong lows (both in solar activity and climate worsening) during the early Holocene at 11.2, 10.2, 9.2, 8.2, 7.2, 6.2 and 5.2 kyr BP, followed by subdued lows at 4.3, and 2.3 kyr BP, and again increasingly stronger lows at 1.3 and 0.3 kyr BP. Every two ~ 2400-yr Bray cycle lows, nearly five Eddy cycles have taken place and both Bray and Eddy cycle lows fall close enough to produce a longer significantly colder period. This has happened not only at the LIA (0.4 kyr event), but also at the Mid-Holocene transition (5.2 kyr event), and at the Boreal Oscillation 1 (10.3 kyr event).

7.7 kyr ago the agro-pastoral system was being introduced in Central and Southern Europe by two routes: One in Central Europe following the river valleys originating in the Hungarian region of the Danube, by a culture known as the Linear Pottery Culture or LBK, and the other in Southern Europe following a maritime route from the costs of Greece all the way to the Iberian peninsula by the Cardium Pottery Culture. Both group of farmers descended directly from Neolithic people that established in the Aegean from the Fertile Crescent during the 8.2 kyr event.

The effect on human societies in Central Europe of the cold and wet periods that coincide with periods of reduced solar activity is to reduce the length of the growing season for plants, reducing the output of both natural ecosystems and agro-pastoral systems, resulting in food shortages and food crises. Suddenly the population cannot be sustained. Malnourishment often comes accompanied by plagues. Before increased mortality can reduce the population naturally, some societies resort to emigration and the destination places, also experimenting food shortages, are usually subjected to increased violence in the ensuing fight for resources. It is the Four Horsemen scenario. Archeologists are increasingly aware that the pattern of advances of farming in Europe follows stages that coincide within dating uncertainties with periods of climate deterioration often coincident with periods of reduced solar activity. Agro-pastoral societies appear to have expanded faster during periods of climate worsening, pushed by human overshooting conditions caused by climate crises.

During the 8.2 kyr event, the worse climate event of the Holocene produced by the coincidence of several solar and non-solar causes, farmers from the Levant and Southern Anatolia moved to the shores of the Aegean Sea and expanded into the Balkans. This event marked a significant population decline in the hunter-gatherer societies of Europe (Shennan et al., 2013), probably facilitating the invasion. At around 7.7 kyr BP, when the climate deteriorates again, arises the LBK culture that flourishes and expands into hunter-gatherer areas during the 7.7-7.0 kyr period, substituting the human populations that lived in Central Europe (figure 6c, d, & e). According to Dubouloz (2008), the LBK culture was well adapted to cold, wet periods through construction of robust buildings, placement of villages in tertiary drainage networks, well away from flood risk areas, the importance of cattle-herding, a marked reduction of the Balkan early Neolithic range of cultivated plants, and the practice of autumn sowing in intensively cultivated plots.

figure-6

Figure 6. The effect of 8th millennium BP climate changes on human societies of Central Europe. (a) Solar activity reconstruction by Steinhilber et al., 2012 (in black) shows the cluster of Jericho 0-3 grand solar minima. (b) Bi-decadal Greenland GISP2 temperatures (2-period averaged, in red) highlights a general correspondence between low solar activity and climate cooling during the two periods marked by light blue bands, that correspond also to the same periods in figure 5. (c) Dubouloz, 2008 Linear Pottery LBK culture demographic analysis (blue lines) shows demographic peaks coincident with temperature valleys just at the time of the major dispersal periods of LBK (blue boxes). (e) Shennan et al., 2013 analysis of Central/West Europe population (in purple) shows that the population decline of the 8.2 kyr event did not recover until the arrival of the LBK agro-pastoral culture, and that this population increase took place during the cold 7.7 and 7.2 events, when LBK was expanding. (d) The agro-pastoral expansion was at the expense of the hunter-gatherer population that did not get diluted but disappeared, according to genetic mitochondrial DNA studies (Brandt et al., 2013).

Dubouloz (2008), and Gronenborn et al. (2013), show that LBK expansion follows a climatic rhythm (figures 6c & 7). LBK forms during the increasingly colder 7.7 kyr event and initiates its dispersal around 7.5 kyr BP at the peak of cold conditions. During the period of warmer drier climate that followed the 7.7 kyr event LBK consolidates a wide territory. The next period of dispersal initiates again at the next cold period around 7.3 kyr BP when LBK crosses the Rhine into Alsace and present time Dutch area. It is 200 years later during another cold period around 7.1 Kyr BP when LBK experiments its last dispersal into the Seine basin. Demographic analysis of LBK habitation (Dubouloz, 2008) indicates that periods of dispersal coincide not only with cold, wet, periods but also with periods of maximal population (figure 6c dark blue lines), suggesting that the difficult conditions that gave the LBK its edge over other human groups, also caused the hardship and population decline that usually instigates climate migration. The arrival of better climate conditions after 7.0 kyr BP probably rendered the harsh climate adaptations of LBK disadvantageous and the culture quickly disorganized, losing its vast circulation networks of raw materials, and disappeared.

figure-7

Figure 7. Geographical and temporal expansion phases of Linear Pottery Culture (LBK), according to Gronenborn et al., 2008. Expansion phases coincide with periods of cooling in Greenland, and in fact the entire LBK culture appears to encompass the long period of climate worsening between 7700 and 6900 yr BP, known as the Cerin phase in the Alpine region and defined by some authors as a Little Ice Age within the Holocene Climatic Optimum.

The expansion of the agro-pastoral system in Europe marked the end of the hunter-gatherers. Analysis of mitochondrial DNA (mtDNA) frequencies in Central Europe human remains shows that hunter-gatherers mtDNA alleles essentially vanished during the 7.7 kyr event with the arrival of the LBK early Neolithic mtDNA alleles (Brandt et al., 2013; figure 6d). This mtDNA genetic shift and population substitution takes place even as the general population of Western/Central Europe experiments a great population boom due to the arrival of the agro-pastoral societies (Shennan et al., 2013; figure 6e). That the two biggest increases in population in Western/Central Europe take place during the 7.7 and 7.2 kyr events further confirms the expansion of the agro-pastoral system in Central Europe during periods of climate worsening, and lends support to similar expansions elsewhere, like the Aegean expansion during the 8.2 kyr event.

The 5.2 kyr event. The Mid-Holocene Transition and the start of the Neoglacial period.

During the fifth millennium BC (~ 7000-6000 yr BP), the climate of the Atlantic period was in general warm, humid, and stable, constituting ideal conditions for Neolithic farming. In the following millennium, however, the entire climate system of the planet changed, driven by orbital changes in precession and producing a reduction in solar forcing while the oceanic/atmospheric forcing increased in importance. Since 10 kyr BP northern summer insolation has been reducing and southern winter insolation increasing. The balance between northern and southern insolation determines the position of the Inter-Tropical Convergence Zone (ITCZ), a low pressure belt around the planet that organizes the wind patterns, separating the hemispheres and determining the location of the monsoons. The southward displacement of the ITCZ and the changes in insolation during the fourth millennium BC completely altered the planet’s climate, putting an end to the Holocene Climatic Optimum in what is called the Mid-Holocene Transition, setting the path for the colder, dryer world of the Neoglacial Period (figure 8). Between its most notorious effects, the southward displacement of the African monsoon brought an end to the African humid period causing the desertification of the Sahara.

figure-8

Figure 8. Timing of global glacier fluctuations during the Holocene. Horizontal dark blue bars indicate times of glacier advance; vertical light blue bars are periods of glacier advance based on the global data set. The main periods of the Holocene are indicated. Position of the ~ 2400-yr Bray solar cycle lows are indicated as B1-B5. Timing of glacier advances indicates a progressive cooling of the Holocene. Source: J. Koch & J.J. Clague. 2006.

Within this context of climate instability and increasingly difficult conditions takes place the next low in the Bray cycle between 5.6 and 5.2 kyr BP, coinciding with Bond event 4 of increased iceberg discharge in the North Atlantic (Bond et al., 2001; figure 2). A cluster of three GSM known as Sumerian 1 to 3 are responsible for the reduced solar activity of this low (figure 9a).

GISP2 temperature proxy points to an important but not extraordinary cooling centered at around 5400 BP, but other climate proxies do show exceptional climate for this period. Sea and non-sea salts in GISP2 have been used to reconstruct the polar atmospheric circulation (O’Brien et al., 1995; inverted in figure 9d). The estimated orthogonal function (EOF) that represents the fluxes of these salts displays its highest values respect its baseline of the entire Holocene (figure 9d), indicating very strong high latitude winds and a great polar vortex expansion that could have brought a very cold period over the northern hemisphere while reducing the cold near the pole. Further confirmation for an extraordinary atmospheric circulation at the time of the Bray 3 cycle low comes from Iceland, where Jackson et al. (2005) detected the strongest winds and associated cooling of the entire Holocene in eolic loess deposits between 5600-5100 BP (figure 9e). Both polar circulation changes and Icelandic wind intensity proxies also match very well other known periods of strong climate deteriorations, including all of the Bray cycle lows. The final extinction of the mammoth at its St. Paul island (Alaska) refuge has been dated with precision at 5550 BP, coinciding with the beginning of this climatic deterioration, and attributed to climate change (Graham et al., 2016; figure 9c).

figure-9

Figure 9. Climate indicators of the 5.2 kyr event. From top to bottom: (a) Solar activity reconstruction by Steinhilber et al., 2012 (in black) shows the cluster of Sumerian 1-3 grand solar minima. (b) Bi-decadal Greenland GISP2 temperatures (2-period averaged, in red) displays a significant cooling centered at 5400 BP. (c) Orange box is mammoth extinction at 5550 ± 100 BP at St. Paul Island (Alaska; Graham et al., 2016). (d) Polar Circulation Index determined by sea and non-sea salt fluxes from GISP2 ice core by O’Brien et al., 1995 (inverted, in blue) manifests at this period one of its biggest departures from baseline (blue straight line) of the entire Holocene. (e) Iceland wind strength determined by eolic loess deposit size by Jackson et al., 2005 (inverted, in green) displays the highest values of the entire 8000-years series at this time. (f) Arboreal/non-arboreal pollen ratio (in magenta) in the Austrian Alps highlights periods of forest retraction (below the baseline) due to colder and wetter climate (this proxy and next in Magny et al., 2006, and references within). (g) Black boxes represent periods of Mid-European higher lake levels. (h) Turquoise box is the Alpine glacier advance period known as Rotmoos II in Austria and Piora oscillation in Switzerland. Blue bands highlight periods of climate deterioration.

In Central Europe, pollen analysis in Alpine Austria shows a retraction of warmer loving arboreal species versus cold-resistant grasses and shrubs in three periods coincident with the three GSM, while increasing precipitation reflects in three corresponding periods of higher lake levels (Magny et al., 2006 and references within; figure 9f & g). At the same time glacier advances are recorded in several parts of the world (figure 2), and in the Alpine region this glacier advance receives the names of Rotmoos II, or Piora oscillation (figure 9h).

The 5.2 kyr event was demonstrated to have been a global phenomenon by Lonnie Thompson (2006) through a variety of records that show that at 5200 BP a strong and sudden cooling took place all over the world. Those records include simultaneous freezing of organic remains at glaciers in Tyrol, Peru, and Western Canada, at the same time the Kilimanjaro ice cores display a sudden and profound cooling. The transition from wet to dry conditions is recorded by changes in the water balance in many African lakes and the driest excursion recorded at the Soreq Cave speleothem. Concurrently, global atmospheric CH4 concentrations recorded in both Greenland and Antarctica stopped decreasing and started to increase for the rest of the Holocene. Dendrochronological records from Irish and Lancashire oaks extending back to 7000 BP exhibit some of their most narrow rings during the decade-long 5145 BP (3195 BC) event (Thompson et al., 2006 and references within).

In Mesopotamia the Uruk culture started to develop around 6000-5800 BP as a response to an increasingly arid period as attested by several Near East proxies (Soreq Cave, Lake Van, and Gulf of Oman), and flourished based on a system of high yield cereal irrigation, efficient canal transportation, and slavery and forced labor. Uruk culture first developed mass production and writing. By 5500 BP Uruk had become the first city-state and started to expand through “colony” settlements founded across the dry-farming portions of the Near East. A short but very arid period at around 5200 BP coincides with the abrupt collapse of the Uruk colony system, as the colonies in the North and smaller settlements in the South are abandoned, and formerly cultivated areas are turned into pastures with the changes of river courses (Brooks, 2012). The 5200 BP arid event in the Near East is also reflected in the abrupt cessation of precipitations over the Nile river delta. At that time an Early Bronze culture was flourishing in Egypt based on a very high population density at the Nile Valley boosted by climate refugees from the Sahara aridification over the previous centuries. The sudden 5200 BP dry period must have increased competition over resources resulting in widespread violence that ended with the subjugation of the Lower (Northern) Nile by the Upper Nile and the unification of Egypt under the first pharaoh at that date (Brooks, 2012).

The difficult climatic conditions through the 5.2 kyr event constituted an authentic disaster for Neolithic farmers in Central Europe. There is a widespread record of settlement abandonment at the Late Neolithic/Chalcolithic-Early Bronze transition, as attested by lake dwellings at France and Switzerland (Arbogast et al., 2006; figure 10b), and the almost complete absence of radiocarbon dates for a period of four centuries in Bulgaria (Weninger et al., 2009; figure 10c). At the same time and with an eerie similarity to the solar activity record, the population of West/Central Europe crashed, revealing the true extent of one of the most difficult periods for humankind (Shennan et al., 2013; figure 10e). The population fell so hard that it is believed that diseases must have played an important role in bringing down the debilitated Neolithic farmers. About this time, at 5800 BP the pneumonic plague (Yersinia pestis) is believed to have emerged for the first time between the Kurgan nomadic herders of the Pontic steppe.

figure-10

Figure 10. The effect of 6th millennium BP climate changes on human societies of Central Europe. From top to bottom: (a) Solar activity reconstruction by Steinhilber et al., 2012 (in black) shows the cluster of Sumerian 1-3 grand solar minima. (b) Number of Neolithic lake villages (in red) in an area comprising East France and West Switzerland by Arbogast et al., 2006. (c) Cultural shift in Northern Greek area (Bulgaria) from Chalcolithic (Copper Age) to Early Bronze based on radiocarbon data (black boxes) from Weninger et al., 2009. The calibrated 14C-age distribution (radiocarbon periodization, in blue) supports a hiatus during the 5.2 kyr event. (d) The burial dating of Ötzi, the Tyrolean iceman (orange box). (e) Shennan et al., 2013 analysis of Central/West Europe population (in purple) reveals a catastrophic decline coincident with the climatic deterioration, with no recovery until the following millennia. (f) The population decline was accompanied by a shift in mtDNA frequencies (Brandt et al., 2013) that supports a recovery of the descendents of the Paleolithic hunter-gatherer population. (g) Turquoise box corresponds to the Globular Amphora Culture, the first Indo-European culture in Central Europe. Blue columns correspond to the same periods of climatic deterioration as in figure 9.

The decline of the Neolithic farmers of Central Europe allowed a return of the Western European hunter-gatherers as attested by the re-appearance of their genetic signature in areas where they had previously disappeared (Brandt et al., 2013; figure 10f). It was the prelude to the second major invasion and last big population turnover of the Holocene in Europe. Starting around 5350 BP the first nomadic herders from the steppes invaded Central Europe establishing the Globular amphora culture (figure 10g), probably pushed by the climate pessimum conditions and taking advantage of the weak state of Neolithic farmers. A few centuries later came the great invasion by the Battle Axe people (Corded Ware culture). The Indo-European nomads had domesticated the horse, developed the war chariot, acquired the bronze culture and had a patriarchal war-like culture. The Late-Neolithic farmers did not stand a chance, and according to genetics the third known major genetic shift in Europe took place, being the first the Neanderthals substitution by Paleolithic hunter-gatherers and the second the replacement of the hunter-gatherers by Neolithic farmers.

Ötzi, the iceman from Tyrol, was a Neolithic farmer closely related to the LBK people that lived in this violent times and met a violent final (figure 10d). Whether he was killed by other waning Neolithic farmers, by resurging hunter-gatherers now pastoralists, or by invading Indo-European nomadic herders is not possible to know. But as he fled his enemies uphill only to be buried in ice for over 5000 years, he was a testimony of both the changing climate of the Mid-Holocene Transition and its devastating effect on human societies.

The 2.8 kyr event. The Sub-Boreal/Sub-Atlantic Minimum.

The second low in the Bray cycle at about 2.8 kyr BP coincides with the Homer grand solar minimum that took place right after one of the worst climate-induced human catastrophes known to history. This crisis that took place around 3160 BP (1210 BC) has been convincingly linked to a severe drought that affected the Black Sea area and the Eastern Mediterranean in what probably constituted a global climatic event known as the 3.2 kyr event. The drought is likely to have triggered a massive migration by land and sea of the people that lived North and West of the Black Sea and the Balkans. They are collectively known by historians as the Sea Peoples. They destroyed everything in their way bringing about the Late Bronze Age collapse. In a period of less than 50 years the Hittite Empire and the Mycenaean Kingdoms of Greece were destroyed while the New Kingdom of Egypt was brought to its knees by the combined effect of the climatic crisis and the invaders. Every city between Pylos in the Peloponnese and Ashkelon in Gaza was destroyed, including the famous Troy at the Dardanelles, most of them never to be rebuilt. The Late Bronze Age collapse was so destructive that nothing similar has taken place later. The Fall of the Roman Empire pales in comparison. The palace cultures were substituted by small villages and writing was lost in most areas. Greece entered the Greek Dark Ages and Egypt the Third Intermediate Period.

The 3.2 kyr event with its two centuries long megadrought in the Eastern Mediterranean was not associated with a reduction in solar activity nor did it display the climate signature of a solar event. Given the date it is probable that it coincided with a low in the ~1500 year oceanic cycle that also occurred around 1700 years ago at the end of the Roman Warm Period and during the LIA.

The 2.8 kyr event and its associated Homer GSM coincide with Bond event 2a of increased iceberg discharge in the North Atlantic (Bond et al., 2001; figure 2), and with an abrupt climate change from relatively warm and continental to cooler and wetter conditions that marks the transition of the Sub-Boreal to the Sub-Atlantic period. This transition is reflected by an abrupt change in moss species in raised bogs of Northwest Europe at this time (van Geel et al., 1998).

The event started with a 50 year reduction in solar activity and temperatures around 2950 yr BP (figure 11a, b), that brought much needed precipitations to the Eastern Mediterranean, briefly interrupting the drought and allowing a temporary recovery of agriculture in the region (Kaniewski et al., 2013, figure 11f, g). After a return to dry warmer conditions for another century, the Homer minimum started at 2800 yr BP coinciding with an abrupt descent in land and sea surface temperatures (figure 11a, b, c). In Europe the event is very well described as a change to colder, wetter conditions from Northwestern Europe to the Eastern Mediterranean (van Geel et al., 1998; figure 11f). In South America, glacier advances, peat changes, vegetation changes, and sediments, indicate also an abrupt transition to colder, wetter conditions dated at 2750 BP. North America was also affected by a general climate change around 3000-2600 BP towards cooler temperatures and increased precipitation. Increased flooding in the Mississippi basin and an hyperactive storm period in the Gulf coast are dated at that time. Pollen and sediment organic contents in Central Asia support also a coincidental increase in precipitation. Lake Pupuke (New Zealand) isotopic levels indicate a 400 year marked increase in precipitations starting at 2800 BP.

figure-11

Figure 11. Climate indicators of the 2.8 kyr event. From top to bottom: (a) Solar activity reconstruction by Steinhilber et al., 2012 (in black) shows the Homer grand solar minimum. (b) Northern Hemisphere temperature reconstruction by Kobashi et al., 2013 (in red) displays a significant cooling centered at 2700 BP. (c) Iceland summer sea surface temperature diatom-based reconstruction by Jiang et al., 2015 (in blue) displays a similar simultaneous cooling. (d) Asian summer monsoon proxy from Dongge Cave stalagmite DA oxygen isotope ratio (in green) suggests a weakening of the monsoon starting about 2950 BP and reaching its lowest values at 2750 BP. (e) Tree pollen percentage (in brown) in Cameroon indicates the biggest Central African forest retraction in the entire Holocene starting at about 2800 BP (Maley & Brenac, 1998). (f) Pollen-derived proxy of moisture availability (in purple) at Gibala-Tell Tweini, a city in the ancient Ugarit Kingdom, Northwest Syria, plotted as Principal Components Analysis scores, and (g) pollen-derived proxy of agriculture showing the percentage of pollen coming from cultivated species (in orange) at the same location (Kaniewski et al., 2013) indicating that humid periods at this time in the Eastern Mediterranean coincided with periods of reduced solar activity. (h) White boxes show historic periods in the Eastern Mediterranean. Light blue bands highlight colder and wetter periods that correspond to the 2.8 kyr event. Light orange bar indicates the dry period that constituted the 3.2 kyr event.

While in mid-latitude areas of North America, South America, Europe, Central Asia and Australasia there was an important increase in precipitations, analysis of the Dongge Cave stalagmite DA in China shows one of the biggest reductions in oxygen isotopes ratio of the entire series (Wang et al., 2005; figure 11d), indicative of an important weakening of the summer monsoon and an increase in aridity in South Asia. This prominent weakening of the Asian summer monsoon coincided with what has been described as the “dramatic forest decline” in Central Africa (Maley & Brenac, 1998; figure 11e), the biggest forest reduction in the area for the entire Holocene, of which the forests of Central Africa are still recovering 2000 years later. A possible weakening of the West African monsoon is the likely cause, and although drier conditions started at around 3150 BP, it was around 2750 BP that the forests initiated a marked decline accompanied by expansion of grasses and very dry conditions as attested by the complete drying of several lakes such as lake Sinnda in the Niary valley (Congo). The forest cover opened up and fragmented, and enclosed savannas appeared.

In Europe the 2.8 kyr event separates the Late Bronze Age from the Early Iron Age. The impact of this climatic crisis is somewhat diluted by the previous dramatic crisis of the 3.2 kyr dry event from which there had been no recovery. In fact the increase in precipitations, despite the cooling, was very beneficial for agriculture in drier areas (figure 11f, g) and probably was a significant factor contributing to the end of the Greek Dark Ages (figure 11h). In wet marginal areas however the change had a negative impact. In West Friesland (Netherlands), the Late Bronze settlement phase came to an end coincident with rising water tables as houses started to be built on artificial mounds. The rising water and bog expansion caused a loss of agricultural land forcing the migration of the population to coastal salt marshes, richer in food resources, that also started to appear around 2700 BP (van Geel et al., 1998). The end of habitation in West Friesland is also coincident with the end of Late Bronze lakeside village construction in Central Europe for half a millennium from 2.8 kyr BP. In Central and Western Europe the Late Bronze Urnfield culture gave way to the Early Iron Hallstatt culture that expanded during the 8th century BC (2750-2650 BP), amid the dramatic changes in flora and fauna that accompanied the 2.8 kyr event.

In North America the abrupt climate change at 2.8 BP also separates two cultural periods in the Mississippi basin, supporting the theory that abrupt climate change is a motor for cultural change. The Archaic hunter-gatherer period reached an end in the 3000-2600 BP, marked by a hiatus of several hundred years in riverside settlements, suggesting an abandonment of frequently flooded areas, after which the new settlements belong to the Woodland period, characterized by widespread use of pottery and domesticated plants (Kidder, 2006). Meanwhile in Central Africa the opening of the forest allowed the migration of Bantu speaking, metal working people into areas that are now completely forested.

In the Central Asian steppes the increase in precipitations at 2800 BP brought the Scythians into preeminence. They were semi-nomadic herders of the Eastern Iranian language group from the Tuva region at the intersect of Russia, Mongolia, China, and Kazakhstan. With the wetter climate the steppes expanded and could support huge herds of horses, sheep, and goats. The Scythians abandoned any trace of settlement and became nomadic riders. They are credited with developing mounted warfare using composite bows. By 2700 BP they invaded the Northern Black Sea and the Caucasus pushing the Cimmerians southward into conflict with the Assyrians. The Scythians would continue expanding their territory up to Thrace and Eastern Europe, and played a leading role in the destruction of the Assyrian Empire. To the Greeks they were the prototype of savage barbarians, as they were very war-like and practiced human sacrifices. They were also their main providers of slaves from selling their captives. They inspired two well known Greek myths, the centaurs from their riding combat skills, and the amazons because their women also fought, as one in three women was buried with weapons and many sustained war wounds.

figure-12

Figure 12. The steppe migration climatic hypothesis. From top to bottom: North Atlantic stacked percentage of ice-rafted debris (a, in red), indicative of iceberg activity (Bond et al., 2001). The main peaks have been labeled with their accepted numbers. Pollen-derived aridity index (b, inverted, in green) from a Central Mongolian lake (Fowell et al., 2003). Light orange bars indicate drought periods. Light blue bars mark millennial humidity maxima. Arrows indicate downward trends in humidity from millennial maxima. Main historic migration events are indicated by boxes, and they took place after humidity maxima within an increasing aridity context. Notice that the Bond events pattern does not correspond to the humidity pattern at the Central Asian steppes, however big changes in humidity tend to coincide with Bond events. Background picture: Scythian king and warriors, drawn after figures on an electrum cup from the Kul’Oba kurgan burial.

In the perpetual conflict between nomads and settlers, climate change appears to have played an essential role in setting the stage for numerous conflicts. From the invasion of Central Europe during the 7.7 kyr event by LBK agro-pastoralists, to the Sea Peoples invasion at the 3.2 kyr event, and the periodical invasions of Eurasia from steppe nomads, we find evidence of climate change creating conditions that resulted in migration as a response, and conflict as a consequence. The productivity of the steppes is very dependent on precipitations and the nomads and their herds cannot rely on stored food during bad years. When analyzing precipitations in Central Asia we find a common pattern for nomadic invasions. They don’t take place during arid periods, but following a maximum in humidity (figure 12b), suggesting that the increase in precipitations, like in the 2.8 kyr event, brings the nomad population and their herds to a maximum, and from that point, any decrease in precipitations, even if not pronounced (figure 12b arrows), places the population in overshooting. The result is a high number of steppe nomads migrating to adjacent areas where easy conquests stimulate further advances, pushing other groups into migration. This pattern is detected not only in the case of the Scythians, but also with the Huns in the 2nd century AD, the Turkic peoples in the 11th century and the Mongols in the 13th century (figure 12b). I have termed this pattern the steppe migration climatic mechanism. A similar pattern is observed with lemmings, that don’t mass migrate during bad years that keep the population in check, but after good years that push the population up creating overshooting conditions.

The 0.4 kyr event. The Little Ice Age.

The first low in the Bray cycle at about 0.4 kyr BP coincides with the Wolff/Spører/Maunder/Dalton cluster of GSM that took place during the coldest period of the Holocene that is generally known as the LIA. Due to have taken place during modern historic times, it is also the most well studied and known cold period.

The LIA coincides with Bond event 0 of increased iceberg discharge in the North Atlantic (Bond et al., 2001; figure 2). Different authors choose a different start for the LIA, since the climate started to deteriorate progressively from its previous warm period at about 1150 AD, but did not become significantly colder than the previous four hundred years until after 1250 AD, becoming a serious problem for human societies of the time after 1300 AD. Other authors however wait until after 1500 AD, when a relatively warm interlude in the 15th century ended. I place the start of the LIA at 1258 AD, a year after the Rinjani eruption (Lombok, Indonesia), the strongest since writing was invented. As with other lows in the Bray cycle, in the LIA there is a pattern of colder phases recognizable in many climate proxies that in general matches quite well the pattern of solar activity (figure 13a). Some temperature reconstructions (Christiansen & Ljunqvist, 2012; figure 13b) show good agreement with solar activity except for starting the initial cooling before solar activity declined with the Wolf minimum and showing a very cold period before the Maunder minimum. This general pattern of four cold phases for the LIA can be defended on the basis of decreasing Mediterranean sea surface temperatures (Versteegh et al., 2007; figure 13c), increased Iceland sea ice (Massé et al., 2008; figure 13d), glacier advances in the Alps (Holzhauser et al., 2008; figure 13e) and Venezuela (Polissar et al., 2006; figure 13f), and increased North Atlantic deposition of ice-rafted debris (Bond et al., 2001). Alpine glaciers do not show an advance during the Spører minimum, and this requires some explanation. Unlike during most GSM, the LIA GSM do not show a pattern of increased Central European precipitations, and during the Spører minimum Central Europe experienced a very dry period (Büntgen et al., 2010; figure 13g). It has been reported that in England due to the fields not been covered in snow during severe winters around 1458 AD the seeds in the field were killed by the cold resulting in several years of poor crops and famine (figure 14e, g, h). The reduction in precipitations would have prevented glacier advances in the region (but not in Venezuela) and might have reduced the growth of Iceland sea ice that was lesser during the Spører minimum that at other minima during the LIA (figure 13d).

figure-13

Figure 13. Climate indicators of the 0.4 kyr event. From top to bottom: (a) Solar activity reconstruction by Steinhilber et al., 2012 (in black) shows the Wolf, Spører, Maunder, and Dalton grand solar minima. (b) Northern Hemisphere temperature reconstruction by Christiansen & Ljungqvist, 2012 (in red) displaying a pattern that generally matches solar activity. (c) Mediterranean sea surface temperature proxy record (in brown) also displays four cooling periods (Versteegh et al., 2007). (d) A biomarker sea ice proxy from Iceland (in medium blue) agrees well with the sea surface temperature (Massé et al., 2008). (e) Glacier retreat in km from maximum extent in the Alps (in dark blue) does not show glacier advances during the Spører minimum (Holzhauser et al., 2005), while (f) Venezuelan glaciers (in purple) show glacier advances at every minima (Polissar et al., 2006). (g) Precipitation in Central Europe (in green) measured from German oak rings (Büntgen et al., 2010) showing a period of very low precipitation during the Spører minimum (light orange box). Blue bars highlight the four periods of climatic deterioration within the LIA as determined by the climate proxies.

Why would there have been dry conditions in West/Central Europe during the Spører minimum, when we have seen a general pattern of increased precipitations in this region during previous GSM? A possible explanation comes from the ~1500 yr oceanic cycle that based on evidence not presented here appears to have had a low around 400 BP. 2,800 years before (two periods), at around 3200 BP, another dry period brought about the Late Bronze Age collapse, and 1,400 years before (one period), at around 1800 BP, the Roman Empire suffered the Third Century Crisis at a time of poor harvests form their North African and Iberian granaries that greatly contributed to produce the crisis.

The Dalton minimum, that is also unusual in some climatic aspects, including precipitations in Central Europe and glacier advances in Venezuela (figure 13f, g), has the same problem as planet/dwarf planet Pluto. Whether it qualifies as a GSM or not is a matter of opinion as it was both brief and barely showed the required reduction in solar activity. Had the Dalton minimum taken place farther from us and isolated it would probably not have been considered a GSM. To make matters worse, most of the climatic effects during the Dalton minimum are of clear volcanic origin.

Why was the LIA so cold? There was a confluence of causes that made the LIA the coldest period in the Holocene. To start, the Holocene has been cooling since the Climatic Optimum due to an accelerating reduction in obliquity (figure 2), so the LIA started from a lower temperature than previous Bray events. In addition the LIA has been a very long cold event (600 years), longer than similar periods during the Holocene, and its cooling phase was also longer and therefore more profound. The probable reason that the LIA was so long is the coincidence of the lows from three long climate cycles, the ~ 2400-yr Bray solar cycle at around 400 BP, the ~ 1500-yr oceanic cycle also at around 400 BP, and the ~ 1000-yr Eddy solar cycle at around 300 BP, and significant volcanic activity both at its beginning from 1150 AD, and at its end at 1815-1840 AD. The third reason that the LIA was so cold was a very significant contribution from very high volcanic activity during this period.

While volcanic activity during the past 2000 years does not correlate with solar activity, the concentration of strong eruptions during the LIA is so high that it has been proposed that the LIA was mainly due to a volcanic effect on climate. Available evidence however indicates that this is not the case. Moberg et al. (2005) Northern Hemisphere temperature reconstruction has very good yearly resolution and allows to investigate this issue (figure 14b). Very strong isolated volcanic eruptions like the 536 and 540 AD eruptions or the 1453 and 1458 AD eruptions (one of them the Kuwae eruption in Vanuatu) have a very clear effect on temperatures that last 1 to 2 decades at most (figure 14 blue bars), while clusters of eruptions, like around 1257 and 1815, can reduce temperatures for about 4-5 decades. But in every case, after the effect of the volcanic aerosol ends, temperatures recover (figure 14 orange bars), and the general temperature trends continue, whether they were going up or down. It is clear therefore that even though volcanism contributed to the cold and misery of the LIA, and can explain why the cooling at the Wolf and Maunder minima started before there was a significant reduction in solar activity (figure 15a, b, c), it cannot have been the driving factor behind the LIA.

figure-14

Figure 14. The effect of volcanic forcing on temperatures. (a) Reconstruction of the time and aerosol forcing of major volcanic eruptions from sulfate levels in Greenland and Antarctic ice cores (Sigl et al., 2015) for the past 2000 years. (b) Multi-proxy temperature reconstruction (Moberg et al., 2005) AD 1-1979 (grey line) with a 10 year moving average (black line) and its >80-yr slow component (red line). Light blue columns indicate the temperature reduction after the four biggest volcanic eruptions. Orange columns indicate the temperature recovery after the temperature effect of volcanic eruptions ended.

The effect on human societies of the climate deterioration brought about by the LIA is better known, and the case of the Vikings in Greenland has been brought up often. However it was almost the entire population of the planet who suffered the situation. Data for grain production in England shows that yield per acre decreased following a similar pattern to Northern Hemisphere temperatures (figure 15c, e), probably reflecting the shortening of the season. Back to back and even three in a row (highly unusual) years of bad crops took place on this period (figure 15 vertical grey lines) causing a marked increase in wheat prices (figure 15d, inverted) and major famines. The first one at 1315-17 was the worst, affecting most of Northern and Central Europe and initiating the Crisis of the 14th Century. Climatic factors also determined the increase in contact between rodents and humans in Central Asia, giving rise to the bubonic plague, a different manifestation of the plague that had a near 100% mortality. The plague reached Europe in 1347 and in six years killed over one third of the population in the Black Death pandemic. The population decline was so large (figure 15f), that subsequent crop failures had less effect on people’s famine and wheat prices even one century later, like the bad crops of 1459-61. The plague became recurrent in Europe being always present somewhere in the continent until 1750, and causing major epidemics periodically. The spread to other countries of the Hundred Year War between England, France and Burgundy through the Free Companies of mercenary bandits, the start of the peasants revolts, and the Western Schism in the Church completed the Crisis of the 14th Century, that manifested as a complete failure of the institutions to cope with climate-related natural disasters that were seen then as acts of God.

figure-15

Figure 15. The effect of LIA climate changes on human societies of Europe. From top to bottom: (a) Solar activity reconstruction by Steinhilber et al., 2012 (in black), shows the Wolf, Spører, Maunder, and Dalton grand solar minima. (b) Volcanic activity reconstruction by Sigl et al., 2015, (in magenta), with dates for the three major eruptions. (c) Northern Hemisphere temperature reconstruction (in red), by Christiansen & Ljungqvist, 2012. (d) Wheat price in Dutch guilders per 100 kg (Lamb, 1995; inverted, in blue), for France (continuous), England (dashed) and Germany (dotted). (e) Three main crops of grain net yield per acre in England, with annual data in pink, and long term trend in brown (Campbell & Ó Gráda, 2011). (f) Northern Hemisphere population growth in % (Zhang et al., 2010; in orange). (g) Northern Hemisphere famine index in events per decade (Zhang et al., 2010; in green). (h) Major famine events (green boxes) and major epidemic and pandemic events (brown boxes). Main historical periods of crisis are shown in boxes at the bottom. Grey vertical lines link multiyear crop failures in (e) with major famines in (h). Light blue boxes are periods of climate deterioration defined in figure 13.

The 15th century was a period of recovery and Renaissance in Europe, despite the severe impact of what is believed to have been the coldest decade of the millennium according to both climate and historic reconstructions, the 1430s during the Spører minimum. However one can never underestimate the capacity of humans to make a difficult situation worse, and so while Japan was developing successful strategies to cope with the challenges that the LIA posed on food production, most of Europe and a great part of the world was again engulfed by man-made crises at the time of the Maunder cold period. The General Crisis of the 17th Century was again a period when the Four Horsemen of Apocalypse rode unchallenged, as the world saw the biggest number, and duration of wars, and war casualties in recorded history to that time. Climatic factors contributed to the general worsening, and glaciers advanced destroying farms, houses, and villages. Climate worsening, together with peasants revolts and war destruction, produced a record number of major famines and accompanying epidemics, to the point of producing a collapse in population growth (figure 15f, g, h). It was a period that coincided with major political upheaval, including frequent government replacements and even state failures. One of the biggest countries in Europe, the Polish-Lithuanian Confederation, completely disappeared, together with one third of its population. The Seven Ill Years of Scotland in the 1690s, were caused by a major famine event in Northern Europe that killed half of the population in Finland and 15% in Scotland, and were decisive for its union to England.

The 18th century was again a period of recovery, after which the climatic deterioration and social problems returned. The inability of the Old Regime to respond to the frequent crises was the cause of the French Revolution when bad crops due to a drought in 1788, and resulting high food prices in 1789 affected again the population of France. The French Revolutionary Wars, followed by the Napoleonic Wars engulfed Europe once more.

However the European farmers from the second half of the 18th century had learned to cope with the challenging climatic conditions through a series of adaptations that constituted the Agricultural Revolution, which in turn helped drive the Industrial Revolution. The final disappearance of the plague from Europe around 1750 was followed however by the appearance of the recurrent cholera pandemics of the 19th century. By 1850 the LIA had been left behind and much better climatic conditions have accompanied human societies since then.

Climatic effects of grand solar minima.

The considerable amount of climate information about the climatic effects of GSM essentially points to an atmospheric effect. The observed phenomenology is usually:

– Increased precipitation in mid and high-latitudes
– Decreased precipitation in tropical and subtropical areas
– Weakening of tropical monsoons.
– Increase in mid and high-latitude wind strength
– Increase in polar circulation
– General cooling
– Sea surface cooling
– Glacier advances
– Increased iceberg activity

These effects are consistent with an expansion of the polar cells, a southward displacement of the polar jet, an equatorial shift of the Ferrel cell and subtropical jet, and a similar displacement of the descending parts of the Hadley Cells that contract. The resulting change in wind patterns would be responsible for the alterations in precipitations and temperatures. These atmospheric changes were described by Joanna Haigh in her landmark 1996 article “The impact of solar variability on climate” where she described the changes found in a general circulation model when simulating changes in solar irradiance and stratospheric ozone. Since then Haigh’s hypothesis has received support not only from paleoclimatology, as seen here, but also from meteorological data reanalysis. The hypothesis states that solar variability affects climate through a bottom up mechanism from surface changes in irradiation coupled to a top down mechanism from stratospheric UV and ozone changes, being the second one the main in terms of effect.

Although changes in oceanic circulation have been implicated by some authors in the climatic changes of the Bray cycle cold events, the global nature of these suggests that oceanic changes, although potentially very important, are probably of secondary nature, induced by atmospheric changes in wind patterns.

Analysis of Holocene climate shows a long term cooling trend punctuated by cold events (figure 2; see also Appendix). For the past seven thousand years, every millennia has been colder on average than the previous one, driven by orbital changes. Obliquity is now decreasing at its fastest rate in 40,000 years and Northern summer insolation is at its minimum value in 20,000 years, an orbital configuration that supports a continuation of the multi-millennial cooling trend. Within this background, the Holocene, since reaching the Climate Optimum, does not display warming events, as any significant multi-centennial warming period is preceded by a similarly significant multi-centennial cooling period, and the Current Warming Period is no exception, as it is preceded by the LIA.

Comparing the Holocene major cold events that include the lows in the Bray cycle at 0.4, 2.8, and 5.2 kyr, plus the major 8.2 kyr event (figure 16) shows that both cooling and posterior warming can last from 2 to 4 centuries. Given that solar activity usually returns quite quickly to normal levels after a SGM, the slow recovery in temperatures suggests that the atmospheric reorganization induced by the changes in solar activity is a slow process, and since the entire event usually takes over half a millennia, the climate seems to settle in a different configuration, as the orbital conditions have changed, and this could be the reason why the lows in the Bray cycle broadly mark the separation between the different climatic periods of the palynological Blytt-Sernander series (Boreal, Atlantic, Sub-Boreal, Sub-Atlantic periods).

figure-16

Figure 16. Global temperature reconstruction during major Holocene cooling events (blue curves; Marcott et al., 2013 by the differencing method with proxy published dates) has been rescaled in temperature anomaly to match biological, glaciological, and marine sedimentary evidence (see Appendix). Black curve instrumental temperature anomaly data from HadCRUT4.

There is paleoclimatological evidence that a poleward atmospheric expansion of the Hadley and Ferrel cells, and associated wind regimes, including the Southern Westerly Winds strengthening and southern displacement associated with persistently positive phases of the Southern Annular Mode (Antarctic Oscillation) has been taking place, as assessed in the Patagonia (Chile), for over 100 years (Moreno et al., 2014). The expansion of the Hadley cells, that is usually attributed to ozone depletion, has been measured since 1979 at about 1-2° in latitude. The continuation of the Hadley cells expansion is an indication that natural recovery from the LIA has not ended, since it is believed that greenhouse gases contribute little to this phenomenon (Allen et al., 2012) and it seems to have been taking place for over 100 years.

To the natural warming caused by the post-LIA recovery we have added the anthropogenic warming. Nowhere is the anthropogenic effect more noticeable than in the status of the cryosphere. Globally glaciers have retreated to a point last seen around 5000 years ago, during the Mid-Holocene Transition at the start of the Neoglacial period. That is the reason why organic remains like Ötzi, the iceman from Tyrol, from 5200 BP are being uncovered. It is possible that the cryosphere is particularly sensitive to greenhouse gas warming, since water vapor content is very low when the air is very cold. Nevertheless we cannot rule out that global average temperatures are approaching values that took place during the 5.2 kyr event as figure 16 suggests.

Future projections

The closest orbital analogue for the Holocene or Marine Isotope Stage 1 (MIS 1) is not MIS 11, 407 kyr BP, but MIS 19, 777 kyr BP, when obliquity, precession, and eccentricity all align for both interglacials (Pol et al., 2010; figure 17). In about 1000 years from the current analogue position MIS19 likely started its glacial inception as indicated by an accelerated cooling (figure 17 blue arrow). Afterwards during the next 15,000 years of low obliquity it experienced three Antarctic Isotope Maxima (AIM) that probably represent global warming events (figure 17 orange arrows). Two warming events have also been described for MIS 5e/d interglacial at the Eemian to Early Weichselian glacial transition (Boettger et al., 2009) indicating that strong warming events at the end of an interglacial could be a general feature of glacial inception, something that should be taken into account before claiming that the next glaciation has been delayed or abolished by the Current Warming Period.

figure-17

Figure 17. Alignment of the Holocene (red) and MIS 19 (black). From top to bottom: a) δDeuterium (‰, temperature proxy) of Holocene (red) and the 650 years averaged signal (dark red); b) MIS 19 δDeuterium (‰) data. In panels a) and b) the thin dashed horizontal lines correspond to the present-day (last millennium average) δD levels; e) eccentricity (dashed, right axis) and North Hemispheric June 21st insolation (solid, left axis); f) precession parameter (dashed, right axis), reported on inversed axis to evolve in phase with the NH insolation, and finally obliquity (°, solid, left axis). Source: Pol et al., 2010. Blue arrow proposed time for MIS 19 glacial inception, orange arrows Antarctic Isotope Maxima that probably represent warming events within the cooling trend.

After about 350 years from the low of the 0.4 kyr event, the post-LIA atmospheric and warming recovery could be close to end. Once it is finished there should be a natural pressure to return to a climatic state more adequate to current orbital conditions that should oppose anthropogenic warming. Whether this will result in a reduced rate of warming or even some cooling it is not possible to know. However barring some unforeseeable strong volcanic eruption the climate conditions from the solar variability point of view appear as favorable as during the long Roman Warm Period. The next low in the ~ 1000-yr Eddy cycle is not due until around 2700 AD (figure 18), followed by a low in the ~ 1500-yr oceanic cycle around 3000 AD. GSM outside the lows of the Eddy and Bray cycles have a much lower probability, since most GSM during the Holocene have taken place close to the lows of these two solar cycles (figure 18d).

It is very likely that anthropogenic warming has been overestimated, since solar variability warming is not properly accounted for, according to paleoclimatic data presented here, due to a poor understanding of its mechanisms. An unfavorable orbital configuration and the end of the post-LIA recovery should help determine the true extent of the anthropogenic warming over the next hundred years.

Assuming that half of the warming since 1950 is due to natural causes, that post-LIA recovery is due to end within the 21st century, that human CO2 emissions will stall and start declining within the next decades, and that the post-LIA natural warming is analogous to the global warming event reflected by a peak in Deuterium (AIM C) that took place 772 kyr BP during MIS 19 interglacial under similar orbital conditions (figures 17 & 18e), a temperature projection can be traced (figure 18f) that shows stable or slightly declining temperatures for the next centuries until the lows in the Eddy and ~ 1500-yr oceanic cycles bring them to negative anomaly (below 1960-1991 average) around 3000 AD, with the low in the Bray cycle around 4000 AD pushing temperatures well below LIA levels.

The period between the last Bray low 400 years ago, and the next in 2000 years that has been proposed to be named Anthropocene should be characterized by Pre-Glacial conditions, with declining temperatures, increased precipitations and flooding events in mid and high latitudes, increased El Niño conditions, increased snow, glacier advances and sea ice expansion. While the northern treeline is likely to retreat, forests should advance in mid and high latitudes, while diminishing in the tropics due to weakened monsoons. An increase in the latitudinal thermal gradient is likely to produce increased storminess and extreme weather events, just the opposite of what global warming has produced. But as planetary cooling is slower than warming, humanity will have ample time to adapt and develop successful strategies for the next global cooling.

figure-18

Figure 18. Solar cycles and temperatures during the Holocene. Major palinological subdivisions of the Holocene (names on top) match a 2500-yr regular spacing (light blue arches on top). (a) The global temperature reconstruction (black curve; Marcott et al., 2013 by the differencing method with proxy published dates) has been rescaled in temperature anomaly to match biological, glaciological, and marine sedimentary evidence, resulting in the Holocene Climate Optimum being about 1.2°K warmer than LIA (see Appendix). (b) The general temperature trend of the Holocene follows the Earth’s axis obliquity (purple), and significant downside deviations generally match the lows of the ~ 2400-year Bray cycle of solar activity (light blue bands labeled B-1 to B-4 that correspond to similar bands in previous figures). (c) Significant negative climate deviations manifest also in strong increases in iceberg detrital discharges (red curve, inverted; Bond et al., 2001) that generally agree well with the lows in the ~ 2400-year Bray cycle and ~ 1000-year Eddy cycle (orange bands) of solar activity. (d) Solar activity reconstruction (Steinhilber et al., 2012) shows that the majority of grand solar minima correspond very well with Bond events and tend to occur at the lows of the Bray (light blue bars) and Eddy (orange bars) cycles. Significant Holocene climate changes tend to occur when Bray and Eddy cycle lows coincide, like at the Mid-Holocene Transition that ended the Holocene Climatic Optimum and started the Neoglacial period, and the LIA that started the Current Warm Period, now proposed to be named Anthropocene. The regular spacing of the ~ 1000-yr Eddy cycle is shown by orange arches at bottom. Solar cycles can be projected into the future, when the situation could be analogous to interglacial MIS 19 (Marine Isotope Stage) AIM C (Antarctic Isotope Maximum) that is likely to represent a natural global warming event at 771 kyr BP (e). Considering all these factors, temperatures can be projected into the future (f) defining a Pre-Glacial period that could end around 4000 AD in the next glacial inception.

Given that the lows in the Bray cycle usually produce long term changes in climatic conditions after a significant period of climate deterioration that can last several centuries, and given the analogy to MIS 19, the next low in the Bray cycle, at around 4000 AD in two thousand years appears to be the first good candidate for the next glacial inception (figure 18f).

Conclusions

  1. According to cosmogenic isotopes, there is a near 2450 year solar variability cycle, named here the Bray cycle for its discoverer.
  2. At every low of this cycle for the past 10,300 years there have been significantly long grand solar minima or clusters of grand solar minima, as determined by cosmogenic isotopes.
  3. At every low of this cycle for the past 12,800 years there has been a significant period of climate deterioration, generally characterized by global cooling in land and sea, increased iceberg activity, glacier advances, atmospheric changes consistent with equatorward expansion of polar circulation, Hadley cells contraction, and changes in wind and precipitation patterns usually increasing at mid and high latitudes and decreasing at low latitudes with a weakening of the equatorial monsoons.
  4. After every low of this cycle for the past 12,800 years there has been a long lasting change in climatic conditions manifested mainly in high latitude changes in vegetation, and reflected in the palynological subdivisions of the Holocene.
  5. The lows in this cycle coincide with periods of crisis for human societies while providing also opportunities for adaptation an advancement, and often coincide with important cultural transitions lending support to the hypothesis that climate change acts as an engine for societal progress.
  6. Despite a clear and intense paleoclimatic effect, changes in solar activity are not properly accounted for in our current understanding of climate forcings due to our ignorance of the underlying physical mechanisms. This underestimation of solar forcing has the inevitable consequence of an overestimation of anthropogenic forcing.
  7. The paleoclimatic effects of very low solar activity lend support to Haigh’s hypothesis of solar induced atmospheric changes due to changes in irradiation and stratospheric ozone.
  8. No support for an approaching grand solar minimum comes from the analysis of the ~ 1000-yr Eddy and ~ 2400-yr Bray cycles. Analysis of these two long solar cycles indicates that we are probably in a prolonged warm period likely to last for several more centuries.
  9. Analogue analysis suggests an increased probability that the next low in the Bray cycle around 4000 AD could mark the start of the next glacial period.

References: bibliography

Appendix: global-holocene-climatic-optimum-temperatures

Moderation note:  As with all guest posts, please keep your comments civil and relevant.

490 responses to “Impact of the ~ 2400 yr solar cycle on climate and human societies

  1. Pingback: Impact of the ~ 2400 yr solar cycle on climate and human societies – Enjeux énergies et environnement

  2. Figures can be made bigger by opening them in a new tab and magnifying them to actual size.

  3. What an amazingly thorough study. I will print this out and read it.

    I looked at a brief record of sunspot counts and what impressed me most was the degree of chaotic randomness in the data.
    Not Gaussian.
    Here is the link:
    http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2767274

  4. …which all goes to say that The Old Farmer’s Almanac has more credibility than Western academia; and, that global cooling — not warming — may be on the way.

  5. The volanic hypothesis for the Little Ice Age isn’t that there were 600 or so years of volcanoes. It’s that there were several very large volcanoes in a 50-yr period in the 1200s, which caused sustained cooling with sea ice growth, and the increase in albedo and possibly a weaker sun led to centuries long cooling.

    https://www.sciencedaily.com/releases/2012/01/120130131509.htm

    • “The volanic hypothesis for the Little Ice Age”

      The volcanic hypothesis for the Little Ice Age gets in serious troubles to explain this figure:

      So a slight increase in vulcanism produced the coldest period of the Holocene, yet a large increase produced the Holocene Climatic Optimum? No way.

      • > No way.

        Here’s the abstract;

        Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century-scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required.

        http://onlinelibrary.wiley.com/doi/10.1029/2011GL050168

        People and evidence.

      • Javier wrote:
        “So a slight increase in vulcanism produced the coldest period of the Holocene”

        No, it was four very large eruptions in about a 50-yr span.

        Read the paper! Or least the press release I linked to above.

      • “People and evidence.”

        A coincidence of two periods (n=2) and a model. That’s not what I call convincing.

      • “No, it was four very large eruptions in about a 50-yr span.”

        In a 600 year long LIA.
        Figure 14 shows that the evidence is very clear that temperatures are only affected for a very limited time by volcanic eruptions. And that afterwards there is always a rebound in temperatures (orange bars).

      • Javier wrote:
        “In a 600 year long LIA.”

        NO, in a 50 year period.

        “Figure 14 shows that the evidence is very clear that temperatures are only affected for a very limited time by volcanic eruptions. And that afterwards there is always a rebound in temperatures (orange bars).”

        You still haven’t read the paper, I see, or even the press release. Look for the words “sea ice” and “albedo.”

      • > A coincidence of two periods (n=2) and a model. That’s not what I call convincing.

        In return, switching the pea over the SHOW ALL THE KYR BPS thimble is not what I find convincing either.

        People and evidence.

        ***

        The correct link to M12 is:

        http://dx.doi.org/10.1029/2011GL050168

    • Javier wrote:
      “Figure 14 shows that the evidence is very clear that temperatures are only affected for a very limited time by volcanic eruptions.”

      Your figure 14 shows it — 4 volcanoes in the 1200s, one with the largest emissions in the 2000 year period. Add an ice-albedo factor. Centuries of cooling afterward.

    • David

      The actual extensive UK observational evidence from farmers, sailors, clergy, land owners and the crop records that exist (some of which we translated from Latin) is that there had been numerous cold periods during the 13th century (glaciers advanced in the Alps) but by the last few decades of the century summers were warming up again

      This is not to say at all that the climate regained the stability it had enjoyed for several hundred years until around 1190 but sustained cooling had already passed. Lamb, Grove amongst others wrote extensively of this period using real records. A contemporary of Phil Jones, John Kington,, recently retired from CRU, references some notably warm summers in the 1280’s. 1288 was probably one of the hottest summers on record.

      In 1290 the entire year was warm with strawberries being eaten at Christmas. 1291, 1293,1296,1297,1298 and 1299 were all known to include very warm summers.

      The volcanic influence is very difficult to discern. A large eruption in a particular time and place might affect the local climate for a season or two and exceptionally a year or so, but observational evidence does not show the dire effects often attributed to volcanoes.

      tonyb

      • climatereason wrote:
        “A large eruption in a particular time and place might affect the local climate for a season or two and exceptionally a year or so, but observational evidence does not show the dire effects often attributed to volcanoes.”

        See the graphs on Arctic sea ice extent in the Miller et al paper I referenced, or Figure 4 in Masse et al 2008:

        http://shadow.eas.gatech.edu/~kcobb/abrupt/masse08.pdf

      • David

        I have cited you real observations by real people who were there at the time and told us of he weather hey exerienced and it’s effect on their crops.

        These observations have been complied by numerous people from groves to Lamb and those I cited were gleaned from the libraries and archives of the met office. I also cited you material from Kington a contemporary of Phil jones at CRU who himself was the protégée of Hubert lamb.

        Are you saying these events did not happen or are you saying you prefer novel proxies such as moss, algae and tree rings?

        I have had this discussion before with giss miller when his article about mosses and the little ice age first came out.

        As regards Greenland and Iceland, it may well be they were periodically cold but they are no proxy for Europe, the northern hemisphere or the globe. The cold conditions you describe are common in setting up blocking highs which, in summer, often results in very hot summers outside of the arctic and near arctic regions.

        The volcanic eruptions you cite, were accompanied, in Europe at least, and probably over a much wider area, by the conditions I have described.

        Tonyb

      • tonyb,

        Since the plots I’ve been promising you, and procrastinating doing, are topical to the subject of the OP, I’m feeling all the more obliged to stop being lazy and do them. Stay tuned.

      • Brandon

        Nature magazine is ready to rush the findings into print.
        Unfortunately Gates comes behind Brown so I will be cited as lead author…

        Tonyb

      • climatereason wrote:
        “In 1290 the entire year was warm with strawberries being eaten at Christmas. 1291, 1293,1296,1297,1298 and 1299 were all known to include very warm summers”

        And?

        There’s nothing that says some years can’t have warm seasons someplace. We’re talking about climate, not weather.

      • David

        For an lia from 1275 supposed to have caused cold summers the next twenty years seems to have brought a lot of warm ones.

        Perhaps the algae and moss aren’t as accurate as real life observations?

        Tonyb

      • climatereason wrote:
        “For an lia from 1275 supposed to have caused cold summers the next twenty years seems to have brought a lot of warm ones.”

        How many? Compared to how many “cold” ones?

      • David

        Seven warm summers in the 1290’s and 5 in the 1280’s with one of epic heat with two or three neutral and a couple of cold ones. The really colld weather in the 1200’s mostly occurred prior to the last few decades of that century. The observational material does not match that of the novel proxies. Perhaps the novel proxies are wrong, or perhaps they are merely relevant to Greenland and Iceland?

        I am writing an article on the 13th century climate so you will just have to contain your excitement…

      • climatereason wrote:
        “Seven warm summers in the 1290’s and 5 in the 1280’s with one of epic heat with two or three neutral and a couple of cold ones.”

        Where?

        Have we not learned that a season or a year doesn’t represent climate or climate change?

      • David

        What are you basing your notion of a change to he LIA on? Moss and algae. Perhaps those materials don’t give a reliable insight into climate change and perhaps, as observations demonstrate, volcanoes don’t have the impact being claimed for them?

        Tonyb

      • climatereason wrote:
        “What are you basing your notion of a change to he LIA on? Moss and algae.”

        Again, you’re citing warm summers. Where?

      • Somebody wrote that it was warm

        it was warm.2
        or was it
        warm.4?

        No wait, it was warm.33

        And they were well calibrated.

        UNless you have a METHOD of translating words (it was warm)
        into NUMBERS…

        you have NOTHING.

        and that method MUST BE REPEATABLE

        tony reads 10 documents. they all say warm, well one says kinda warm

        There fore 19.87

        I read those same documents…

        Therefore 19.23

      • Mosh

        Take up your argument with John Kington of CRU who came up with that data.but what does he know?

        Tonyb

      • climatereason wrote:
        “Take up your argument with John Kington of CRU who came up with that data.but what does he know?”

        You realize, right, that without specifics there can’t be a scientific discussion?

        I got the impression you were a scientist? Yes? No?

      • If there is no ice on fresh water, it is safe to assume the water temperature is above 0 C. If ice exists there, one may safely assume the temperature there is less or equal to 0 C. Historical accounts can’t be dismissed just because they might go against your narrative.

      • Tonyb,

        Nature magazine is ready to rush the findings into print.

        I wish.

        Unfortunately Gates comes behind Brown so I will be cited as lead author…

        You wish.

        After having built them up and hyped them beyond any reasonble semblance of utility or import …

        … I give you some plots. A short writeup on how they were constructed may be found on my blog.

      • Take up your argument with John Kington of CRU who came up with that data.but what does he know?

        Tonyb
        ###############################

        So you cant explain what he did?
        I thought not.
        So you are basically trusting someone else.
        here is the clue
        You have to convince me to trust him

        IF all you can do if Point to a person
        YOU
        HAVE
        NOTHING

        Science is NOT what one guy says.

        Science is the data and the method.

        When I tell you gravity is real, I dont demonstrate that FOR YOU
        i dont tell you to talk to newton.

        I tell You…

        DO X, and you will observe Y.

        That makes your understanding INDEPENDENT of me, independent
        of a book, independent of newton.

        So, the bottom line is YOU have NOTHING.

        there maybe be something… but YOU… got Zip

      • Mosh

        I would imagine hat John kingtons ,ethos is ,like mine, reading tens of thousands of references and sorting out those that have credibility and that are unproven.

        John Kington has been doing it paid for decades and working with phil jones , no novice when it comes to the subject, has produced numerous papers and written numerous books.

        https://crudata.uea.ac.uk/cru/pubs/byauthor/kington_ja.htm

        He is also involved in studying circulation patterns. So as far as credibility goes I would say he is pretty good.

        How are you doing with your project to check on the veracity of the thousands of readings you use, compiled by thousands of observers working with all types of instruments at varying times of day, taken at different heights?

        Tonyb

      • Mosh

        Hmm, my iPad likes to change words. Ethos should be method. Also ‘sorting out hose references that have credibility from those that are unproven.’

        Tonyb

      • Tony

        “I would imagine hat John kingtons ,ethos is ,like mine, reading tens of thousands of references and sorting out those that have credibility and that are unproven.”

        1. You actually have to DOCUMENT your METHOD
        for SORTING,, so that others can VERIFY that you
        didnt make mistakes.
        2. Im a skeptic I dont take things on trust. you are a believer
        IN YOUR OWN ABILITY to see the truth. science doesnt
        work that way.

        “John Kington has been doing it paid for decades and working with phil jones , no novice when it comes to the subject, has produced numerous papers and written numerous books.”

        1. I read two of his papers. NOT IMPRESSED, rather laughable
        in fact.
        2. Cite counts and page counts MEAN NOTHING. The bible has
        a lot of pages and cites

        https://crudata.uea.ac.uk/cru/pubs/byauthor/kington_ja.htm

        1. I saw that. and read some. A joke too funny

        How are you doing with your project to check on the veracity of the thousands of readings you use, compiled by thousands of observers working with all types of instruments at varying times of day, taken at different heights?

        1. It works great and verifies!!!
        2. But YOU MISS THE POINT OF SCIENCE. The Key is for
        YOU to check. Let me explain how this works

        Step A: we collect all the data we can. ( say like you collecting books)
        Step B. We SET ASIDE some portion of the data ( This would
        be like you not reading certain texts)
        Step C; We build our estimate which is a PREDICTION of what we
        did not observe
        Step D: Taking the data we set ASIDE we then compare our prediction
        with The set aside data
        This would be like you making a prediction of what you would
        find in the books you set aside.

        Step E: we publish our results. This includes

        1. The data we used. THE ACTUAL DATA. Not foornotes
        to the data, but THE ACTUAL DATA.
        2. We publish the method, in code. This allows you or anyone
        to rerun the analysis. with no work. your job? FIND THE ERROR
        3. Your next job is to consdier the things we did not
        A) data you have that we dont, for example

        So, We have already published what you ask for. You can check.
        you can test. you can IMPROVE, you can build on it, or REVERIFY
        or verify more extensively..
        You ( and the guy you cite ) have done ZERO of this. ZERO!
        Not science. Not reproducable. Not checkable. Not replicatable.
        ZERO

      • Mosh

        Good to see you back on form. Hope your health problems are now behind you.

        Tonyb

      • Brandon

        I posted a reply over at your blog but the comment has disappeared. It is very difficult to insert a message in the dialog box.

        If the reply has disappeared its a shame as it was totally brilliant…..

        tonyb

      • tonyb,

        Bummer. I show no record of a comment being posted. Try posting a short test message without any HTML, perhaps?

    • ulric wrote:
      “A strong Arctic Ocean cooling trend from Dec 1978 to Mar 1995 cherrypicking?”

      That’s precisely what cherrypicking is — arbitrarily choosing your starting and end points to give the result you want, regardless of whether they are statistically significant.

      • That is not arbitrary in the slightest, I determined when the cooling trend continued to. What you are suggesting in ignoring this cooling period is the same as ignoring the post 1945 cooling in the global mean.

      • ulric wrote:
        “That is not arbitrary in the slightest, I determined when the cooling trend continued to.”

        Really? What’s the cooling trend from 1978-1995, and what’s is its statistical significance?

        BTW, by 1995 Arctic sea ice volume had already lost 1.9 Mkm3 compared to 1978. Cool phase of the AMO?

      • This paper finds up to 1/3rd (at most) of Arctic Sept SIE 1979-2010 is attributable to the AMO:

        “Sources of multi-decadal variability in Arctic sea ice extent,”
        J J Day1, J C Hargreaves2, J D Annan2 and A Abe-Ouchi3
        Published 26 July 2012 • 2012 IOP Publishing Ltd
        Environmental Research Letters, Volume 7, Number 3
        http://iopscience.iop.org/article/10.1088/1748-9326/7/3/034011/meta

      • “BTW, by 1995 Arctic sea ice volume had already lost 1.9 Mkm3 compared to 1978”

        Cherry picking, and what exactly are you comparing there, maximum in ’78 and minimum in ’95? Very funny.

      • “This paper finds up to 1/3rd (at most) of Arctic Sept SIE 1979-2010 is attributable to the AMO”

        That’s a very poor analysis, and suggesting that the effect of the AO on SIE has reversed since the 1970’s is ridiculous. I suppose it never occurred for them to look at Summer NAO.

    • stevenreincarnated

      That argument (volcanoes causing the LIA) leads to the conclusion it would have warmed to where it was before the LIA considering only solar forcing. It also argues for large and persistent positive feedbacks. It would seem following the argument to its logical conclusion that almost all if not all of the modern warming can be explained by the lack of several large volcanoes in a space of 50 years combined with a small contribution from an increase in solar output.

  6. The 2100-2500 year cycle is clearly evident when looking at the solar proxy record. And we now know (at least within planetary theory) what causes this cycle.

    The outer 4 planets come into grand alignment every 4627 years (at least over the Holocene) and never repeat any patterns within that time frame. During the 4627 year cycle there are two LIA type events or deep clusters of grand minima. The two LIA events fall roughly at 2100 and 2500 years.

    The repeating 4627 patterns can be seen on my graph:

    I believe there is a 340 year anomaly in the Dendrochronology record that once removed shows a rather precise 4627 cycle across the Holocene.

    Scafetta is also seeing this in his latest paper :
    http://www.sciencedirect.com/science/article/pii/S0012825216301453

    It can also be seen in my plot of the solar path overlaid every 4627 years that shows the almost exact same path:
    http://www.landscheidt.info/?q=node/323

    Its all about knowing what causes grand minima inside Charvatova’s Disordered Phase. She was not aware, but my 2010/13 paper uncovered the secret.

    http://www.scirp.org/journal/PaperInformation.aspx?paperID=36513&#reference

    • I find the planetary hypothesis fascinating, but lack the capacity to judge if it is capable of producing the necessary effect on the Sun’s activity, which is a road block to its acceptance, as I understand.

      One of the problems I see is that solar cycles lack astronomical predictability. The Schwabe cycle is 11.4 yr but can come at any time between 8 and 15 years and nobody understands why. The same happens with the ~ 1000 and 2400-yr cycles. There is considerable deviation from the average that enormously complicates mathematical analysis. If someone could come up with a hypothesis that would explain not only the average period, but also the deviations that would be a huge advance.

      • “One of the problems I see is that solar cycles lack astronomical predictability. The Schwabe cycle is 11.4 yr but can come at any time between 8 and 15 years and nobody understands why.”

        My empirical model satisfies that, most sunspot cycle maxima to within a year, and exactly which cycles are weaker in each solar minimum.

      • Javier,
        I think solar cycle length is a different animal and does not look to be linked with the outer 4 planets. But Solar Grand Minima are predictable using astronomical records, just look for the alignment as shown (Saturn + 30deg) and you will see the it corresponds with the 2100-2500 Hallstatt periods.

        You wont find this exact alignment outside of the Hallstatt periods…check it for yourself?
        When you have this alignment (1472) there is a series of strong alignments either side that cause LIA type conditions. Its is a repeating pattern across the Holocene. The Saturn angle and corresponding tweaked solar inner loop orbit are the key.

      • Geoff,

        I trust you have done your homework. However with four planets to play you are bound to find a configuration with an angle that fits a period close enough to 2450 years. It probably doesn’t fit the exact dates that I have showed above, as they are slightly irregular: 10.3, 7.7, 5.5, 2.8, and 0.4. But for the shake of the argument let’s assume that it does fit. So now what? The evidence hasn’t showed you anything. You set on a quest and you completed it, but you have no idea if that particular configuration with specific angles is doing anything. Even if you predict the next one and you nail it, you still don’t know if that is a cosmic coincidence, because it was selected precisely for that.

      • wow…I am surprised by your response.

        Be sure I have done my homework over the past 8 years, the data is rock solid.
        As stated the 4 outer planets never repeat their patterns within 4627 years, so it is hardly likely to produce an outcome that suits me.

        I offer you a challenge…I say all grand minima happen when Jupiter, Uranus and Neptune are together with Saturn opposite.

        Prove me wrong?

      • Geoff,

        Sorry, probably a language misunderstanding since English is not my first language. What I wanted to say is that I believe you when you say that all grand minima happen when Jupiter, Uranus and Neptune are together with Saturn opposite. I am sure you have done your work well. I have already read you in the past when I looked into the planetary/baricenter hypothesis and I remember seeing those graphs with the A and B types.

        OK, but then what? What does it tell us that you have found a certain planetary configuration that coincides with all grand minima? After all you set out looking for it. Is it a coincidence or not, and if not how do you know? That is the problem of looking for something versus finding something. When you look for something you discard every other configuration for no good reason except that it doesn’t match the exact timing that you are looking for.

      • “You wont find this exact alignment outside of the Hallstatt periods…”

        The string at 76 BC, 104 AD and 286 AD seem to be right in the Roman Warm Period. Two at 2658 BC and 2479 BC are in one of the warmest periods of the Holocene. The one at 1830 doesn’t relate to a solar minimum either. The colder aspect of Ne+Ur is when they are in quadrature.

      • Thanks Javier, back in 2008 the data came to me from Carl Smith’s graph which showed perturbations in the solar angular momentum which coincided with solar slowdowns. I then found the perturbation (AMP event) happens at the same time as the planetary position described. Also at the same time I saw the solar inner loop orbit about the SSB was greatly changed as the inner loop tries to be an outer loop for the first half of its excursion.

        I then went back over the Holocene and saw the correlation continued, so I didn’t go looking for a match to my planetary position, the data just kept giving.

        What does this all mean? For me it is solid proof that Solar Grand Minima are connected somehow to the planet positions of the outer 4, and that the last 50 years of solar science are over turned. It will take time for the old crew to come on board, but it is happening slowly.

        Maybe one day Judith will do a piece on my paper…if so she will be the first to do so.

      • “During the 4627 year cycle there are two LIA type events or deep clusters of grand minima. The two LIA events fall roughly at 2100 and 2500 years.”

        In fact centered at the primary grand synod of the outer three Jovian bodies at 1542 years (+/-6yrs), one third of the 4627 year synod, the configurations repeat, and with the same phase relationship to Earth and Venus syzygies, unlike the ones halfway at 2224 and 2403 yrs. Thus the string at 76 BC, 104 AD and 286 AD repeats roughly 1542 years later at your 1472, 1651 and 1830 set.

    • I’ve seen excerpts in the northern Wei calander based on planetary movements and climate. I think they had a 391 year and 144 year cycle. I also saw the five pointed star that reflect the harmonic alignments, as well as another configuration that corresponds to the two backwards graphs you have on the both sides of your illustration. You are not alone in your thinking. There are mathematicians working on various aspects of this. Intriguing to say the least.
      For me it’s the first time I’ve seen the opposition of Saturn and J/U/N idea. I have seen other math that correlates well with the golden ratios. Maybe I just missed it or didn’t understand what was being said. That happens.
      If this is true then we can predict +/- when cooling will occur, how long it should last, and the length and duration when it will start to get warm again.
      One of the questions I have now is how this relates to a full blown ice age.
      Maybe you stated here somewhere, but where are we now in this cycle ? If I may ask.
      Thanks I saved your Web page.

      • I think we can now accurately predict future solar cycles out as far as we have data for the position of the planets (10000 plus years). But I bet I don’t get an invite for the SC25 prediction panel?

        Ice ages are a result of Milankovitch forces most likely and not linked to solar output. The Milankovitch forces seem to tell us the next ice age is thousands of years away.

      • As far as where we are now in the cycle is concerned we have had the weak event at SC20 and the medium event at SC24 should carry over to SC25. My theory is that if the AMP event is strong enough (they all vary over the 4627 year cycle) it can cause the solar poles to go out of sync (ie both poles the same polarity or one neutral) which then takes another cycle to repair. This should have ramifications on the solar Dynamo that suppresses SC25.

        After that we should see a recovery at SC26 and there looks to be no LIA events for around 2000 years …which agrees with Javiers data.

      • Thanks.. I will be watching with interest as to how this develops.
        No one would have watched the night sky, or developed math, without a definitive connection between where the stars are and climate. The world over among civilizations that had no knowledge of the others existence.

      • Geoff wrote:
        “I offer you a challenge…I say all grand minima happen when Jupiter, Uranus and Neptune are together with Saturn opposite.
        Prove me wrong?”

        I did that above,
        https://judithcurry.com/2016/09/20/impact-of-the-2400-yr-solar-cycle-on-climate-and-human-societies/#comment-813242

      • Geoff wrote:
        “I offer you a challenge…I say all grand minima happen when Jupiter, Uranus and Neptune are together with Saturn opposite.
        Prove me wrong?”

        Ulrich wrote:
        I did that above,
        https://judithcurry.com/2016/09/20/impact-of-the-2400-yr-solar-cycle-on-climate-and-human-societies/#comment-813242

        You better read the paper again, not all alignments are strong as seen at SC20, in fact most are weak, but the SC20 alignment was strong enough to dent one cycle but not strong enough to cause a full grand minimum. And periods like the MWP, Roman warming etc there are no strong alignments and no grand minima…that’s why they were warm.

        We have discussed this before and it is very clear in my paper that occasionally even a strong alignment can be “wasted”. The AMP event or disordered inner loop orbit is not tied to the solar cycle, so if cycle max has already past before the disruption has occurred then obviously it is too late. 1830 is an example in the modern record, and 573BC is another possible occurrence in the proxy records.

        All grand minima occur on the said alignment…show me one that doesn’t?

      • oops…stuffed up the tags.
        Geoff wrote:
        “I offer you a challenge…I say all grand minima happen when Jupiter, Uranus and Neptune are together with Saturn opposite.
        Prove me wrong?”
        —————–
        Ulrich wrote:
        I did that above,
        https://judithcurry.com/2016/09/20/impact-of-the-2400-yr-solar-cycle-on-climate-and-human-societies/#comment-813242
        ———————————————————————————
        You better read the paper again, not all alignments are strong as seen at SC20, in fact most are weak, but the SC20 alignment was strong enough to dent one cycle but not strong enough to cause a full grand minimum. And periods like the MWP, Roman warming etc there are no strong alignments and no grand minima…that’s why they were warm.

        We have discussed this before and it is very clear in my paper that occasionally even a strong alignment can be “wasted”. The AMP event or disordered inner loop orbit is not tied to the solar cycle, so if cycle max has already past before the disruption has occurred then obviously it is too late. 1830 is an example in the modern record, and 573BC is another possible occurrence in the proxy records.

        All grand minima occur on the said alignment…show me one that doesn’t?

      • “I think we can now accurately predict future solar cycles out as far as we have data for the position of the planets (10000 plus years). But I bet I don’t get an invite for the SC25 prediction panel?”

        Too funny.

        thinks he needs an invite to do science

      • Mosher says:

        Too funny.

        thinks he needs an invite to do science

        ————————
        I invite you to use science to prove me wrong.
        Study my paper closely and tell me where the data is incorrect?
        All the data is there…simple JPL.

        Bet you wont even look…..

        http://www.scirp.org/journal/PaperInformation.aspx?paperID=36513&#reference

    • Some big news today. In my previous post I highlighted what I think is a 340 year error in the INTCAL98 Holocene solar proxy record. Scafetta’s new paper and Javier have alerted me to an upgrade to the Holocene 14C record performed by Reimer et al (INTCAL04 and beyond).

      The Holocene record has been re written and the 340 year anomaly is REMOVED.
      The major LIA type events (red dots) now happen at 4627 year intervals along with the smaller events that occur in between at the green dots that form the Bray cycles. Remember the outer 4 planets only repeat their patterns every 4627 years.

      This has been mentioned in a post at WUWT by Andy May, but so far no comment. This is your chance Judith to be the first to investigate this correlation? Willis, Svalgaard and Anthony are quiet? (Watts has banned me, so I am unable to comment)

      • A very recent version of the solar proxy record by Adolphi & Muscheler (2016) which combines the C14 and 10Be records and perhaps gets the scaling of the solar events more correct. The base records are INTCAL13 & GRIP.

        The left to right direction is in reverse to the previous graph.

        The top graph with 0.7 scaling factor best shows the higher peaks and troughs that occur during the LIA and Hallstatt type events. The data shows us that the taller peaks occur when the outer four are experiencing grand conjunctions and the deeper troughs are when the J/U/N with S opposite position is strongest. Both these events cluster together, but not quite at the same time.

        The repeating 4627 year patterns across the Holocene are obvious.

  7. At the root of this neglect lie two fundamental problems. Solar variability is quite small (about 0.1% of total irradiation), and there is no generally accepted mechanism by which the solar variability signal could be amplified by the climate system.
    -0.1% of total irradiation is actually a very large amount of energy if you take into account the very small temperature range we transient effervescent beings live in.
    What degree of temperature range on the earth is involved?

    • “What degree of temperature range on the earth is involved?”

      Leif Svalgaard, a solar physicist, has manifested that a grand solar minimum could reduce average temperatures by about 0.1°K. Published literature on the subject indicates that a Maunder type minimum could reduce temperatures by about 0.25°K:
      Feulner, G., & Rahmstorf, S. (2010). On the effect of a new grand minimum of solar activity on the future climate on EarthGeophysical Research Letters, 37(5).
      Jones, G. S., Lockwood, M., & Stott, P. A. (2012). What influence will future solar activity changes over the 21st century have on projected global near‐surface temperature changes?. Journal of Geophysical Research: Atmospheres, 117(D5).

      Paleoclimatological evidence indicates a cooling of 0.3-0.5°K for a low in the Bray cycle (0.6-0.8°K for the LIA), although low resolution makes those changes not comparable to instrumental measurements as a similar sampling of the 20th century could give a very different result. Nevertheless the main problem is not the temperature change, but also the changes in precipitation patterns, and the long term effect. Jones et al., 2012, believe that the effects would disappear as soon as solar activity returns to normal and thus would be transitory, however available evidence indicates that the effects take centuries to pass, making the impact much higher and accumulative if there is a succession of grand minima.

      • And there are papers that have looked at possible solar changes in the future, and found that greenhouse gas warming easily swamps any cooling from a Maunder Minimum-like sun. Cooling by 2100 would only be, at most, 0.3 C below IPCC projections.

        “On the effect of a new grand minimum of solar activity on the future climate on Earth,” G. Fuelner and S. Rahmstorf, Geo Res Lett vol. 37, L05707 2010.
        http://www.pik-potsdam.de/~stefan/Publications/Journals/feulner_rahmstorf_2010.pdf

        “Increased greenhouse gases enhance regional climate response to a
        Maunder Minimum,” Song et al, Geo Res Lett vol. 37, L01703 (2010) http://www-cirrus.ucsd.edu/~zhang/PDFs/Song_et_al-2010.pdf

        “What influence will future solar activity changes over the 21st century have on projected global near-surface temperature changes?” Gareth S. Jones, et al, JGR v 117, D05103 (2012) doi:10.1029/2011JD017013, 2012.
        http://www.leif.org/EOS/2011JD017013.pdf

        See also:
        http://www.skepticalscience.com/what-would-happen-if-the-sun-fell-to-maunder-minimum-levels.html

      • “And there are papers that have looked at possible solar changes in the future, and found that greenhouse gas warming easily swamps any cooling from a Maunder Minimum-like sun.”

        Of course, if you believe in the mythical overbearing warming capabilities of CO2, then nothing can step in its way. No point in arguing that. One should not discuss with believers. Once scientists get a hold of true climate sensitivity we can have this conversation.

        I do not anticipate any grand solar minimum within the next 3-4 centuries so no relief should come from that. We are at the mercy of CO2.

      • Javier wrote:
        “Of course, if you believe in the mythical overbearing warming capabilities of CO2, then nothing can step in its way.”

        This anti-scientific comment alone invalidates everything you wrote in this post.

        You seem happy to cite papers and accept there comments when they say what you want. Then, when it comes to scientific results you don’t like, you brush them off with no problem at all.

        If you want to be taken seriously, don’t write absurd things like this.

      • Sometimes, different people see different things when they look at the evidence. Evidence always trump theory. In theory, at least.

        But if you believe in the overbearing capabilities of CO2, it’s a myth and nothing can step in its way.

        Sometimes, a measured tone ain’t enough, Javier.

      • David Appell says ..
        “This anti-scientific comment alone invalidates everything you wrote in this post.”
        This statement alone is anti-scientific.
        However, it does not invalidate everything else you say.

      • angech,

        “Both these values seem wrong
        0.1% of 287 K is 0.287 K.
        0.2% is 0.57 K.”

        I didn’t say they were right. I was just quoting. But I really doubt you can make a linear extrapolation all the way from 0°K

        “I doubt if the If the 0.1K reduction quoted was truly Leif.”

        There is too much noise to get the quote from WUWT, but IIRC Leif defends that from top to bottom of the 11 year cycle TSI changes by 0.1-0.2% (which is correct) and produces a change of about 0.1°K, and that a grand solar minimum like Maunder has the same solar activity as a 11-year minimum. Hence his conclusion that it should produce the same temperature change. I obviously disagree with the conclusion.

      • Thanks, agree first point and hope Lief can comment on range. 0.1 C seems too small.

      • Just as referencing Skeptical Science invalidates everything you write Appell.

        Bet you were the class know it all.

      • ting56 wrote:
        “Just as referencing Skeptical Science invalidates everything you write Appell.”

        They usually get things right. But I understand how it’s convenient for you to dismiss them wholesale instead of confronting the scientific arguments.

      • Sure they do David.

        Probably because they are such accomplished, peer reviewed climate scientists.

        Oh, wait.

      • ting56 wrote:
        “Probably because they are such accomplished, peer reviewed climate scientists.”

        No, because they take care to *cite* the peer reviewed literature.

    • The 0.12% in solar variability is an assumption. You left off the 0.02, which is rounding in AGW favor. When something is as large as the output from a star declines that much it is significant. The problem with the assumption is that plus or minus another 0.10% and the equation changes from doesn’t change climate to changes climate significantly. Cooling will start to occur at 0.15 change in variability. It makes you wonder why 0.12% was chosen.

    • Javier: There are other papers that have at this question, too, and have found much smaller climate sensitivities to solar:

      I looked at five papers on how solar changes influence mean surface temperatures:

      0.18 K/W/m2
      Camp and Tung, GRL 2007 doi:10.1029/2007GL030207

      0.07 K/W/m2
      Meehl et al, GRL 2014
      doi:10.1002/grl.50361

      0.03 K/W/m2
      Feulner and Rahmstorf, GRL 2010, first example doi:10.1029/2010GL042710

      0.08 K/W/m2
      Feulner and Rahmstorf, GRL 2010, second example doi:10.1029/2010GL042710

      0.07 K/W/m2
      Song et al GRL 2010
      doi:10.1029/2009GL041290

      • There are certain people here at Climate Etc who think the page was established purely to provide an outlet for their own ideas. You will find them commenting twenty, thirty, fifty times in a thread. Perhaps their need for attention would better be served by submitting a guest post that would stand or fall on its own merits. When we see certain names in the thread, the wiser among us simply keep on scrolling.

      • Hi oldfossil. You made me laugh, that old tune ‘we just keep scrolling along’. Side by side, Brenda Lee. Just remember, some people aren’t happy unless they’re miserable.

      • Did I forget to mention; misery loves company. You keep on scrolling oldfossil and if I may I’ll follow your lead. We seem to be seeking the same goal.

      • +1 old fossil.
        I try to scroll forward as well but I cannot help the urge to check whether these people also answer some questions posed to them instead of only asking questions. But I keep being dissappointed. Some of these people even parry inconvenient questions with even more questions in return.

        And some guys try to sound sciency by insisting that historical accounts of warm periods can be ignored because no numbers are assigned to the “warm” definition. The fact that historical accounts mention strawberries growing in winter months (for example) can then be conevniently ignored all of a sudden. Nice try.

        Very weak show all in all.
        Back to scrolling them away.

      • Old Fossil, sometimes the goal of the troll is to just make the discussion too tedious for lurkers to endure.

      • Appell’s argument appears to be valid and should not be ignored! Even Lean’s study confirms his assertion! Lean is generally considered a skeptic so it is not just a case of preaching to the choir:

        http://onlinelibrary.wiley.com/doi/10.1029/2010GL045777/full

        The most probable value of total solar irradiance representative of solar minimum is 1360.8 ± 0.5 W m−2, lower than the canonical value of 1365.4 ± 1.3 W m−2 recommended a decade ago. This new value, measured by SORCE/TIM, is validated by irradiance comparisons to a NIST-calibrated cryogenic radiometer in the new TSI Radiometer Facility. Uncorrected scattering and diffraction are shown to cause erroneously high readings in non-TIM instruments.

      • > There are certain people here at Climate Etc who think the page was established purely to provide an outlet for their own ideas.

        More so when their “own ideas” consist in five papers directly relevant to the discussion.

        For once DavidA made a constructive contribution, Denizens spit on him,

        Go team!

      • Willard, follow the thread ‘the denizens’ don’t appear to be disputing Appell’s assertion but rather just ignoring him as a troll.

      • It’s hard to dispute that there are papers published on solar variability, ordvic, and one might suspect why Denizens don’t cite much of that lichurchur.

      • ordvic wrote:
        “Willard, follow the thread ‘the denizens’ don’t appear to be disputing Appell’s assertion but rather just ignoring him as a troll.”

        But then, there’s a lot you guys have to ignore to maintain your antiscientific positions.


      • Follow the yellow brick road. Aren’t you the guys that like cartoons or am I in the wrong place?

      • This one‘s better, John Maurice.

      • Point taken pal. I leave it in your capable hands.

      • Or Willard, it could just be that people don’t particularly like obnoxious arrogant know it all plicks like David, even when they have something useful to contribute.

    • The 0.1% is an assumption.. a 0.05% additional variation changes the equation significantly. And in calculations used officially it’s 0.12%. An additional 0.03% isn’t that hard to imagine in the output from the sun.

  8. A skeptic??
    By 1904, Arrhenius became concerned with rapid increases in anthropogenic carbon emissions and recognized that “the slight percentage of carbonic acid in the atmosphere may, by the advances of industry, be changed to a noticeable degree in the course of a few centuries.” He eventually made the suggestion that an increase in atmospheric carbon dioxide due to the burning of fossil fuels could be beneficial, making the Earth’s climates “more equable,” stimulating plant growth, and providing more food for a larger population.

  9. “Solar variability is quite small (about 0.1% of total irradiation), and there is no generally accepted mechanism by which the solar variability signal could be amplified by the climate system.”

    It’s not to do with irradiance changes or anything else that directly follows the sunspot cycles, as that cannot produce the observed phase change between sunspot cycles and the AMO. Only the solar variability wind fits the bill.

  10. Reblogged this on Tallbloke's Talkshop and commented:
    Plenty for Talkshoppers to get their teeth into here.

  11. “As the root of this neglect lie two fundamental problems. Solar variability is quite small (about 0.1% of total irradiation), and there is no generally accepted mechanism by which the solar variability signal could be amplified by the climate system”

    This deserves consideration:

    http://joannenova.com.au/2015/01/is-the-sun-driving-ozone-and-changing-the-climate/

    • Stephen, I am aware of your work and I also think that it deserves serious consideration by scientists doing research about possible causes of the solar effect. To me it looks more and more likely that ozone is a fundamental piece of the puzzle.

  12. It is very likely that anthropogenic warming has been overestimated, since solar variability warming is not properly accounted for

    For what period are you addressing this assertion? Is it the IPCC standard – since 1950?

    Would you agree that solar activity observations since 1950 all point to there having been little trend, negative if anything? If so, are you arguing that prior increases are still exerting a significant warming influence, implying a rather large “pipeline warming” effect?

    • Yes, since 1950 too. My argument is that paleoclimatic evidence suggests that the climatic effect of a cluster of GSM is slow to pass.

      The recovery appears to take place intermittently during periods of normal solar activity (orange boxes in figure below), while it is interrupted during periods of below normal solar activity (blue boxes). As periods of low solar activity become less common and intense, the recovery picks up speed.

      Under this interpretation temperatures do not follow solar activity. They would be pushed down only when solar activity becomes insufficient to sustain them over a period of several Schwabe cycles.

  13. “Temperatures on Earth appear to depend mainly on orbital changes, firstly obliquity, but also precession and eccentricity, and oceanic cycles, and volcanic activity also play an important role at times, and therefore solar variability alone does not explain climate changes.”

    See here:

    http://www.newclimatemodel.com/the-real-link-between-solar-energy-ocean-cycles-and-global-temperature/

  14. Javier

    Very nice article.

    I wrote a piece called ‘ the intermittent little ice ages’ a year or two ago, which covers the period of my reconstruction of CET to 1539.

    I am currently working on the 13 th century part of this reconstruction. I am sceptical about the long term effects of volcanic activity. Looking at he annual records they have an impact for a couple of seasons or, exceptionally a year or so. I am ambivalent about the effects of sunspots. See Figures 6, 7, 8 and 9

    https://judithcurry.com/2015/02/19/the-intermittent-little-ice-age/

    There was certainly a down turn around 1190 or so. Generally the 13th century was cool. It warmed up considerably again at various times in successive centuries but there were certainly more cool periods than there had been prior to 1190 for several hundred years. Could the period from 1258 be called part of the little ice age? Probably not, which is why I inserted the word ‘intermittent’

    That climate changes should be a given. Unfortunately in recent decades it has been attributed to primarily the last century as man is said to have impacted considerably on a previously stable climate. Is there anything Unique currently gong on? I can’t see it at all, if you look through the sweep of the Holocene, as your article does.

    Our current period of notable warmth has, as yet, been relatively brief. Let’s enjoy it before the climate deteriorates again as history shows us is likely to happen although the depths of cold of an LiIA seem unlikely.

    Tonyb

    • Yes, I read the article when you posted it, and completely agree that the LIA was intermittent in nature. Several proxies support the idea that some of this intermittence is due to solar variability, as shown if figure 13.

      I also agree with the rest of your comment.

  15. Excellent paper, but I noticed this blooper:

    “In essence periods of low solar activity would coincide with planetary and solar configurations in an equilibrated figure known as the trefoil, while periods of high solar activity would be associated with disordered configurations (Charvátová & Hejda, 2014). ”

    This is back to front. The trefoil periods presage high solar activity and warmer periods according to Charvatova.

    • That is correct. I have misrepresented Charvátová’s argument. I wrote it backwards citing from memory and didn’t spot it later. Thank you.

    • Corrected, thanks.

    • Actually everyone is wrong on this front. Charvatova only looked at the solar proxy record when comparing her phases which does not have enough definition. When looking at the sunspot record it can be seen that her ordered phase (U/N together with trefoil pattern) has low solar activity but no solar grand minima and her disordered phase has BOTH grand minima and high solar activity.

      She does not understand what causes grand minima within her disordered phase, but it’s simple if you look at the individual inner loop orbits that go out of whack within her disordered phase.

  16. “During the 8.2 kyr event, the worse climate event of the Holocene produced by the coincidence of several solar and non-solar causes, farmers from the Levant and Southern Anatolia moved to the shores of the Aegean Sea and expanded into the Balkans.”

    Here’s the problem of referring to Greenland temperatures. That was a very warm event elsewhere, very warm on the Vostok ice core proxy, as were the other cold periods on GISP through the Holocene. Like between 2800-2400 BC when there was massive cultural development and city building worldwide, and the 8th Century AD which was the warmest part of the MWP for Europe, but the second coldest on GISP through the Holocene.
    http://qz.com/694925/the-indus-valley-civilisation-is-2500-years-older-than-previously-believed/
    http://digventures.com/2016/05/this-8000-year-old-underwater-village-was-discovered-by-a-lobster/#.V0PcijSk5fs.linkedin

    “The 3.2 kyr event with its two centuries long megadrought in the Eastern Mediterranean was not associated with a reduction in solar activity nor did it display the climate signature of a solar event.”

    According to my empirical solar cycle model, there was a solar minimum starting around 1360 BC lasting around 30 years, and the next minimum starting around 1250 BC and lasting around 60 years.
    That big warm spike in GISP then should tell you how much negative North Atlantic Oscillation conditions there must have been.

    • There is little doubt that the 8.2 kyr event was a huge global event. Methane concentrations took a severe beating of 100 ppb in short time and recovered afterwards (Kobashi et al., 2007), and CO2 changed course from decreasing to increasing at that time (Monnin et al., 2004). It is also well reflected in the Bond series.

      Kobashi, T. et al. 2007. Precise timing and characterization of abrupt climate change 8200 years ago from air trapped in polar ice. Quat. Sci. Rev. 26, 1212–1222.

      Monnin, E., et al. 2004. EPICA Dome C ice core high resolution Holocene and transition CO2 data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series 55.

      • Of course it was global, it was the warmest period in the Holocene for the Antarctic. Providing two links to Arctic studies says nothing about the rest of the planet.

      • “Of course it was global, it was the warmest period in the Holocene for the Antarctic.”

        I see you didn’t go to proxy school that day. First you should know that it is not unusual that Antarctica shows a movement opposite to the rest of the planet, like nowadays. And second, the proxy evidence is just overwhelming from lots of places.

        Stager, J. C., & Mayewski, P. A. (1997). Abrupt early to mid-Holocene climatic transition registered at the equator and the poles. Science, 276(5320), 1834-1836.

        Rohling, E. J., & Pälike, H. (2005). Centennial-scale climate cooling with a sudden cold event around 8,200 years ago. Nature, 434(7036), 975-979.

      • “I see you didn’t go to proxy school that day.”

        I’m giving you proxy schooling today.

        “First you should know that it is not unusual that Antarctica shows a movement opposite to the rest of the planet”

        Did you actually read and comprehend what I wrote above before making that comment? I don’t think so.

        “And second, the proxy evidence is just overwhelming from lots of places.”

        Like the Aegean Sea warming at 8200 BP, and Lake Victoria drying up which is an increased La Nina signal and also completely the wrong sign for cooling but just what I would expect.

      • “Like the Aegean Sea warming at 8200 BP, and Lake Victoria drying up which is an increased La Nina signal and also completely the wrong sign for cooling but just what I would expect.”

        Funny that you should mention the Aegean Sea, because Marino et al., 2009 just show the coldest excursion in 5000 years in the Aegean Sea at 8.2 kyr according to S. elongatus in core SL21, as shown in figure 3f above.

        Marino, G., et al. “Early and middle Holocene in the Aegean Sea: interplay between high and low latitude climate variability.” Quaternary Science Reviews 28.27 (2009): 3246-3262.

        And Lake Victoria is at 1°S. Was its drying associated to a warm period or to the decrease in precipitations that takes place during grand solar minima at low latitudes?

      • “Funny that you should mention the Aegean Sea, because Marino et al., 2009 just show the coldest excursion in 5000 years in the Aegean Sea at 8.2 kyr”

        It says 8.8–7.8 ka BP cooling in the Aegean, that’s far too wide a window, there are huge warm peaks in GISP either side of the 8.2Kyr event within that period. Funny how you read what you wish to read in it.

      • “And Lake Victoria is at 1°S. Was its drying associated to a warm period or to the decrease in precipitations that takes place during grand solar minima at low latitudes.”

        So you claim, I would simply look at the regional ENSO response, as El Nino episodes and conditions increase through the weakest parts of solar minima, because of the increase in negative NAO/AO.

      • “It says 8.8–7.8 ka BP cooling in the Aegean, that’s far too wide a window, there are huge warm peaks in GISP either side of the 8.2Kyr event within that period. Funny how you read what you wish to read in it.”

        Hmm, I have showed you several articles listing about 20 proxies that the 8.2 kyr event was a global cold event. I have counteracted your Aegean Sea argument with data that shows a proxy indicating the biggest cold excursion, clearly visible to all in figure 3f, and yet you still defend your position based on… What data? What references? And now you accuse ME of reading what I want?

        I won’t spend any more time on this. You are welcome to believe whatever you want.

      • The issue is that right at 8.2Kyr where GISP is at its coldest, the Aegean spikes warmer again:

      • “And now you accuse ME of reading what I want?”

        Yes and quite correctly as you misquoted the paper, it says 8.8–7.8 ka BP cooling in the Aegean, rather than your “coldest excursion in 5000 years in the Aegean Sea at 8.2 kyr”. Scrutinise the graph better, there’s a warm spike in the middle of that cold period right at 8.2Kyr.

    • The 8.2 kyr cooling event was about -3 C in Greenland, too large to be caused by solar changes alone. The leading hypothesis is a meltwater pulse.

      https://en.wikipedia.org/wiki/8.2_kiloyear_event#Cooling_event

  17. The 2100-2500 year cycle is clearly evident when looking at the solar proxy record. And we now know (at least within planetary theory) what causes this cycle.

    The outer 4 planets come into grand alignment every 4627 years (at least over the Holocene) and never repeat any patterns within that time frame. During the 4627 year cycle there are two LIA type events or deep clusters of grand minima. The two LIA events fall roughly at 2100 and 2500 years.

    The repeating 4627 patterns can be seen on my graph:

    • That actually slips badly out of sync after just two steps. From 3322 BC to 5937 AD Jupiter moves ahead by around 90°.

      • More hand waving from you Urilc. If you plot the actual JPL data it can be seen clearly that the solar path is near identical each 4627 years. The only way this can happen is if the 4 outer planets are in the same position.

      • The 3322 BC Nep-Ura inferior conjunction:

        to the one just over 2*4627yrs later, in fact in 5936:

      • Actually some of that is because its the aphelion side of Neptune’s orbit, but from the synodic periods alone Jupiter would be roughly a year or 30° ahead.

      • I wouldn’t sniff at it, that slip may play a part in recent inter-glacial frequency.

      • Glad we agree on something…

    • According to the latest ephemeris JPL DE408 Jupiter moves away from the other 3 about 2 deg per 4627 years when looking at the grand conjunction. So not 90 deg, but the cycle will eventually breakdown. But it is certainly close enough to test solar events across the Holocene.

      • It certainly is a very useful analogue through the Holocene, and I find it intriguing that all four have aligned together best through the Holocene.

  18. I am having a couple of problems understanding several things in figure 2. I am taking all of your data at face value.

    Some observations which you can confirm.

    I see no glacial advance during B5 or 4 but glacial advance in the gap between B5 and B4.

    There are substantial temperature drops comparable or greater to the ones at the start of the Bray Cycle lows all through the record. In fact, the overall drop between B3 and B2 and B2 and B1 is far greater than the suggested solar cycle influences. I suppose you are suggesting orbital variation as the cause yet during the B2/B1 gap we had the MWP (I thought).

    Temperature rises during B5 and is flat during B4 and most of the other lows. Are you suggesting that the drop before the low is caused by solar variation because during the low I am seeing flat or rising temperatures?

    I guess I am having a hard time seeing a distinct solar influence in these Bray lows aside from anecdotal, historical evidence.

    • Different people see different things when they look at the evidence.

      I wouldn’t put too much trust on Marcott et al., 2013, temperature reconstruction. I use it because it is the only one available, but Steve McIntyre has already shown it has numerous defects, some of them corrected for this article. But there is plenty of evidence for each of the lows, as it is shown in subsequent figures.

      But one also has to take into account that there are a lot of things going on during the Holocene besides the Bray cycle. It has been sold as a stable period before anthropogenic forcing, while the evidence shows different.

    • “I am having a couple of problems understanding several things in figure 2. I am taking all of your data at face value.”

      he hasnt shown any data.
      ZERO data.
      Zero sources
      Zero Methods.

      This is a cartoon of what science is.
      There isnt a single chart in this thing which you could double check.
      Not a single one whichs says

      1. Use this data ( here it is)
      2. Use this method
      and
      3. You will find what I find

      • Then I must be hallucinating. I see several references to papers.

      • You’re not hallucinating, jim2. I see several references too.

        To see Moshpit’s point more clearly, take the first figure:

        Read the legend again, with my emphasis:

        Figure 1. Variation in 14C after removal of the long-term trend. An oscillation of the ~ 2400-year Bray cycle is superposed on the data to indicate times when periods of very low solar activity would be expected to occur (arrows). As with every solar cycle, there is some variability in the spacing that complicates mathematical analysis. Adapted to show correct cycle length from Clilverd et al., 2003.

        How is that figure adapted, you may ask?

        We just don’t know.

        This is Moshpit’s point.

        If you fear more hallucinations, go take a walk. Come back. We’ll talk about it.

      • “he hasnt shown any data.
        ZERO data.
        Zero sources
        Zero Methods.

        This is a cartoon of what science is.
        There isnt a single chart in this thing which you could double check.
        Not a single one whichs says

        1. Use this data ( here it is)
        2. Use this method
        and
        3. You will find what I find”

        For somebody used to read a lot of scientific articles, you seem to need a lot of assistance.
        All data is sourced in the bibliography. Go to the linked bibliography and check the sources.

        Regarding methods, as there is no original research in this article, there is no need for methods. I have never seen a methods section in a review article. I am just reviewing and comparing what researchers have published.

        1. Get the data at the sourced article
        2. Display it in parallel as I have done
        3. See what you can deduce

        Regarding scientific cartoons I am sure you have a lot of expertise.

      • “How is that figure adapted, you may ask?”

        Well, then ask. The sinusoidal curve has been adjusted to a period of 2450 years, which is the one that I found, for consistency with the article. The 14C data has not been changed in any way.

      • Javier said:

        Regarding scientific cartoons I am sure you have a lot of expertise.

        Yep. It looks like there’s trouble in CAGW apocalypse paradise.

      • > I am just reviewing and comparing what researchers have published.

        The whole Future Projections seems to go beyond what we usually call a review. Perhaps it’s just a vocabulary thing.

        Assuming it’s a review, then you should be able to find a quote and a citation for this claim:

        It is very likely that anthropogenic warming has been overestimated, since solar variability warming is not properly accounted for, according to paleoclimatic data presented here, due to a poor understanding of its mechanisms.

        If you can provide one, Javier, I’d gladly add it to my Contrarian Matrix. I’ll even include your pseudonym into my list of contributers.

  19. Figure 16. Global temperature reconstruction during major Holocene cooling events (blue curves; Marcott et al., 2013 by the differencing method with proxy published dates) has been rescaled in temperature anomaly to match biological, glaciological, and marine sedimentary evidence (see Appendix). Black curve instrumental temperature anomaly data from HadCRUT4.
    .
    This is Mannian style malpractice. Do NOT graft data of different sources and different time resolution onto each other.

    Reduce the time resolution of HadCruft4 to that of the proxy by low-pass filtering before comparison.

    Also Marcott et al was a crock anyway. Have you read and agreed with his processing before using his results?

    • “Do NOT graft data of different sources and different time resolution onto each other.”

      I agree. It is there for illustration purposes. As long as it is common practice people expect to see that as much as the coin or the pencil in a geological picture.

    • “Also Marcott et al was a crock anyway. Have you read and agreed with his processing before using his results?”

      As I said above, I use it because it is the only one available, but Steve McIntyre has already shown it has numerous defects, some of them corrected for this article. The processing is different. The choice of proxies is still debatable but I find it better to refer to published data where the original authors take responsibility that present an unpublished choice that can immediately be dismissed undermining the whole work.

  20. I understand the resultant climate on any planet as the interaction between elements in the macro and micro scale (planetary aspects, spacial alignments and configurations) as well as the interaction between external and internal forcing and their sources.
    It is my believe that through time, those change beyond cycles. Some cycles involved recover to any position in time and some others fail to recover to its original singularly identified configuration. Some events to repeat require to merge multiple variables in such a way that firstly; the number and type of variables have to be the same number and type in a specific moment in time, with the same magnitude and interact in the same sequence as to replicate a previous scenario in time named part of a cycle.
    With the question of time and cycles we are subjected to scales of time restricted by our data sets and capacity to identify sources of forcing and the effect derived from them.
    In the question of Solar’s effect over Earth climatic system I am able to identify the Sun as a source of a force interacting with it. And I reckon that its magnitude makes it the main source of energy fuelling the energy flows sustaining the dynamics involved.
    What I am concern is about the state of the dynamic systems which solar activity is fuelling.
    I have used the simile of cooking in my assessments and I believe that it serves to make a point. The variations in the energy being applied to cook are dominant over what happens in the pot to an extent defined entirely by what you have inside the pot. If you have oil you will fry your food. If you have water or any other GHG you will boil it. If you have dry food or if you have food containing water, …
    For the same amount of energy the output changes completely by the molecular composition of the matter transferring the energy being supplied as well as it also depends on the structure of the body absorbing the energy.
    From my point of view, Solar activity fails to explain one particularity relevant in the actual state of our climatic dynamics. Under solar minima we have an increase of temperature anomalies in different locations around the planet including the Arctic.
    The magnitude of the Solar influence is always explained having an impact within a Steffan-Boltzmann like stratification. Nowadays, the variations in temperature we see are subjected to zonifications which break the normalized concept of latitude vs Solar angle.
    The amount of energy required to bring this thermal energy through locations can only be explained by the composition of the mass of air carrying it and the alteration in the atmospheric dynamics holding a previously stable compartmentalization in latitude and altitude.
    In other words, I believe that we are facing an increase in the atmospheric mixing ratio due to a weakening in the stratification previously seen.
    This situation might not resemble any previous period since those previous periods had a zonification with the expansion/restriction of cold areas within latitudinal margins. This time, that is not happening.
    And I believe that it is related with the state of the “body” being “cooked”.
    Through paleo time scales, there has been a significant change in the properties of the body receiving the energy from he Sun, in Albedo, evapotranspiration rates and location, land cover… and configuration of energy flows absorbing, re-emitting, transferring or liberating energy.
    I think that the issue here is not the variations in the giving side but in the receiving one. The Earth is too small to suffer the effect of the Sun in some areas more than in others for the same latitude. That is what think.

    • “From my point of view, Solar activity fails to explain one particularity relevant in the actual state of our climatic dynamics. Under solar minima we have an increase of temperature anomalies in different locations around the planet including the Arctic.”

      Low solar increases negative NAO/AO, which drives the AMO and Arctic warming. It’s AGW that fails to explain AMO and Arctic warming.

      • ulric wrote:
        “Low solar increases negative NAO/AO….”

        How?

        “It’s AGW that fails to explain AMO and Arctic warming.”

        a) See “Arctic amplification,” which happens with any type of warming
        b) The AMO isn’t due to global warming — it predates it.

      • Appell, ““Low solar increases negative NAO/AO….”

        How?”

        It most likely has to do with the amount of energy absorbed in the stratosphere which most models don’t include. It is fairly recently that modelers started raising their ‘lids” to try can capture some of the things they initially missed. I believe that shift started in 2009 when scientists “discovered” the solar, stratosphere and oceans connection and people started getting more curious about the sudden stratospheric warming apparent cyclic nature. it is one of those subtle things doncha know.

        http://www2.ucar.edu/atmosnews/news/851/scientists-uncover-solar-cycle-stratosphere-and-ocean-connections

      • “See “Arctic amplification,” which happens with any type of warming”

        Not so, see the polar regions of Venus, they are hundreds of degrees colder than the rest of the planet. Rising GHG’s increase positive NAO/AO, that won’t warm the AMO and Arctic.

      • THanks for the ucar link. But it’s about changes in the Pacific.

      • Ulric: I meant the Earth, which has an ocean.

        Arctic amplification is very well known.

        http://earthobservatory.nasa.gov/IOTD/view.php?id=81214

      • “Arctic amplification” are just ‘magic words’ that no one bothers to think through. The only reason for the AMO and Arctic warming since 1995, is the decline in climate forcing that has caused the increase in negative NAO/AO since then, apart from the brief positive NAO/AO regimes around the last two sunspot maxima.

      • Here’s Arctic Amplification in action, it’s negative. UAH lt NoPol Ocean Dec 1978 to Mar 1995:

      • Appell, “THanks for the ucar link. But it’s about changes in the Pacific.”

        Right, but thanks to Brewer-Dobson circulation and the much long path length available at the poles and/or horizon there is a “global” impact that includes sudden stratospheric warming events which happen to be cyclic. The ucar link was just step one as far as I know.

        I haven’t kept current on the state of the polar stratosphere, but there seems to be plenty of job security in that area.

      • “The only reason for the AMO and Arctic warming since 1995, is the decline in climate forcing that has caused the increase in negative NAO/AO since then, apart from the brief positive NAO/AO regimes around the last two sunspot maxima.”

        What decline in climate forcing?

      • ulric wrote:
        “Here’s Arctic Amplification in action….”

        Again (as Steven wrote), no data, no sources, no way to check or understand this graph.

      • ulric: And why does your graph stop at 1995? (As if I have to ask….)

      • In fact, ulric, the NoPol ocean data from UAH LT shows +0.99 C of warming over the fulldata set 1978-present.

      • That’s what it says it is, UAH lt NoPol Ocean Dec 1978 to Mar 1995. It stops in 1995 because that’s when the cooling trend stops. The data is available on Roy Spencer’s site, whack it on excel and confirm.

        “What decline in climate forcing?”

        Solar wind pressure decline.

      • “In fact, ulric, the NoPol ocean data from UAH LT shows +0.99 C of warming over the fulldata set 1978-present.”

        Surprise surprise, cold AMO to warm AMO, who would have thought of that.

      • ulric wroet:
        “It stops in 1995 because that’s when the cooling trend stops.”

        That’s called cherrypicking. The full record shows NoPol Ocean warming by +0.99 C.

        (Sorry, I didn’t see the UAH on the line above NoPol.)

      • A strong Arctic Ocean cooling trend from Dec 1978 to Mar 1995 cherrypicking? You’re having a laugh.

  21. My claim is the 11 year sunspot so called normal cycle and the climate will not show a relationship because the noise in the climate system obscures the slight solar changes not to mention the variations within the 11 year sunspot cycle from maximum to minimum conditions cancel each other out.

    Only when the sun enters extreme prolonged periods of inactivity or activity for that matter are those two issues nullified and hence a solar /climate connection is able to be established. It is no longer obscured.

    I have come up with the minimum solar parameters needed in order to accomplish this by looking at the historical climatic record and how it has responded to solar activity. It shows each and every time the sun enters a protracted period of extreme inactivity the response in global temperatures has been down.

    That is fact and until data shows otherwise I think the case for a solar/climate relationship is strong.

    In addition the sun drives the climate therefore logic follows that any change in solar conditions has to have an effect on the climate to one degree or another. The point is how large is the effect and is it large enough to overcome the noise in the climate system which can obscure small minor solar changes.

    The other side is what are the extreme solar changes in regards to degree of magnitude and duration of time needed to change the climate through solar activity changes themselves and associates secondary solar effects?

    I am sure every one agrees that if solar changes are extreme enough there would be a point where a solar/climate relationship would be obvious. The question is what does the solar change have to be in order to be extreme enough to show an obvious solar/climate relationship?

    Again I have listed the solar parameters which I think satisfy this issue.

    • solar parameters needed for cooling

      solar flux sub 90

      solar wind sub 350 km/sec

      solar irradiance off .15

      cosmic ray counts 6500 units or more

      euv light 100 nits or less

      ap index 5 or lower

      imf 4.4nt or lower

      These were achieved from 2008-2010 and I think could come about again going forward.

    • ” The point is how large is the effect and is it large enough to overcome the noise in the climate system”

      It is the noise in the system.

  22. I have put forth those solar parameters /duration of time which I feel are needed to impact the climate and I think gong forward the solar parameters I have put forth will come to be which will then manifest itself in the climate system by causing it to cool. I dare say I think it has started already.

    How cool it is hard to say because there are climatic thresholds out there which if the terrestrial items driven by solar changes should reach could cause a much more dramatic climatic impact.

    Terrestrial Items

    atmospheric circulation patterns

    volcanic activity

    global cloud coverage

    global snow coverage

    global sea surface temperatures

    global sea ice coverage

    ENSO a factor within the overall global sea surface temperature changes.

    Solar Parameters Needed and Sustained.

    cosmic ray count 6500 or greater

    solar wind speed 350 km/sec or less

    euv light 100 units or less.

    solar irradiance off by .15% or more

    ap index 5 or lower

    Interplanetary Magnetic Field 4.5 nt or lower

    Solar Flux 90 or lower

    Duration of time over 1 year following at least 10 years of sub solar activity in general which we have had going back to year 2005.

  23. While volcanic activity during the past 2000 years does not correlate with solar activity.

    This is not true . Major volcanic activity has been shown to correlate with prolonged minimum solar conditions.

    Since 1600 ad 87% of all major volcanic eruptions have occurred during solar minimum periods.

    • That’s anecdotal data, Salvatore. You cannot make a point when half of the period considered fall into the definition of low solar activity. Any statistical test will fail on that data. You lack published sources.

      Holocene volcanic activity shows a very strong correlation with isostatic adjustments of the crust. The early Holocene was very active due to adjustments for the melting of the ice sheets. The late Holocene has been much quieter from a volcanic point of view. That is all that can be said about volcanic activity.

  24. 8.No support for an approaching grand solar minimum comes from the analysis of the ~ 1000-yr Eddy and ~ 2400-yr Bray cycles. Analysis of these two long solar cycles indicates that we are probably in a prolonged warm period likely to last for several more centuries.

    Another false assumption. Post 2005 the sun has been heading at least toward Dalton solar minimum conditions so the verdict here is out.

    In addition if solar variability is internal to the sun rather then due to planetary positions the reliance on a repeat of solar cycles based on the past would have to assume that no internal changes have taken place on the sun itself.

    A mighty assumption considering our limited knowledge about the sun.

    • “Another false assumption. Post 2005 the sun has been heading at least toward Dalton solar minimum conditions so the verdict here is out.”

      Look again to figure 18 in detail. Almost all GSM during the period represented belong either to the ~ 2400 or ~ 1000 year cycles, and the next low for those both can be easily calculated.

      If you believe in a SGM in the 21st century, from which solar cycle should it be coming? If it is not coming from a solar cycle, then how can you anticipate it?

      Leif Svalgaard has explained to you in detail with low avail that we are in a centurial minimum, and those happen every… well, century, and they have a reduced climatic effect. Nothing to do with a SGM which is a millennial type of event. And we already got a cluster of 3 GSM within the last 600 years. None is due.

      • I say since 2005 the sun has switched it’s mode from an active to inactive mode and what is telling is the extreme minimum in solar activity from 2008-2010 which no one including Leif saw coming.

        How does that fit into the picture Javier ? Do you have any thoughts on that?

        I think it shows that we just do not really know what to expect with solar activity going forward and good be an indication of more surprises as we go forward.

      • Our simple planetary model successfully replicates 4000 years of BE10 based solar reconstruction (Steinhilber et al)

        and predicts a solar grand minimum this century (nadir 2035)

      • tallbloke, you’re ‘Dark Ages’ period is placed on the warmest part of the MWP for Europe, in the 8th century, rather than where it was, from around 380 to 650 AD with a warm interval in the middle around 500 AD.

      • Tallbloke,

        “and predicts a solar grand minimum this century (nadir 2035)”

        What I like about your model is such a strong prediction over the next few years. Do you think your model could survive to a SC25 similar or more active than SC24? Leif Svalgaard is expecting SC25 > SC24 and he nailed SC24, and I am expecting SC25 = SC24 ± 10%. The answer in about 7 years. that’s nothing it is already 9 years since the demise of the Arctic was promised on short notice.

        Eddy cycle should be at a maximum around 2100, and Bray cycle is less than halfway up. They are not going to produce a SGM in the 21st century. Probably not even by 23rd century when Kirk will be around.

      • You are not seeing the big picture Salvatore..the current solar minimum is small and not like the LIA age events that occur every 2100-2500 years. We have just come out of a LIA event and the next one is 2000 years away. So we can expect overall warming like we saw 4627 years ago…check out the Holocene graph for 4627 years ago and that is our future.

      • “the LIA age events that occur every 2100-2500 years”

        GSM’s roughly every 820 years on average, varying between 400 and 1200 years. And there is a heliocentric progression that maps where each one occurs.

      • “We have just come out of a LIA event and the next one is 2000 years away.”

        Through the next 250 years according to the series that I found, and my discrete solar cycle model shows Maunder length solar minima from the late 2090’s and from 2200.

      • ulric wrote:
        “We have just come out of a LIA event and the next one is 2000 years away.”

        It won’t happen — warming from anthropogenic GHGs will easily swallow it, just as it will swamp the next ice age. Even if we cut back today, some portion of the warming, about 20%, lasts essentially forever. See David Archer’s academic papers, or his book

        “The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate,” David Archer (University of Chicago), 2008.
        http://press.princeton.edu/titles/10727.html

      • David Appell, I didn’t write that. The global mean surface warming of the last 100 years has made no discernible difference to the severity of regional cold events. Recent ones have been as severe as in previous solar minima, e.g. Dec 2010 and Mar 2013:
        http://climexp.knmi.nl/data/tcet.dat

      • Yeah, David Archer of 10 meter sea level rise fame.

        In other words another frustrated fantasy writer.

    • ulric wrote:
      “The global mean surface warming of the last 100 years has made no discernible difference to the severity of regional cold events. Recent ones have been as severe as in previous solar minima, e.g. Dec 2010 and Mar 2013”

      So it takes only two little months to disprove 50 years of HadCET warming (+0.21 C/decade) over that time period?

      • That doesn’t deserve an answer as it is patently not what I claimed.

      • ulric wrote:
        “That doesn’t deserve an answer as it is patently not what I claimed.”

        So what is the point? That Jupiter aligns with Mars, and peace will guide the planets?

      • I made a valid point about the recent regional cold events. Responding with petty facetious is most immature and troll like.

      • > That Jupiter aligns with Mars, and peace will guide the planets?

        It’s as if you know what you’re talking about, DavidA:

        This aspect brings great impulsiveness, insatiable desires, playfulness, and daring. You might be frequently trying to prove yourself, to others and/or yourself, and thus readily take on a challenge. You desire exciting experiences and may rarely be satisfied with your life as it is. You require much space and freedom, and you demand to be treated with fairness. You need to be careful that your behavior is deserving of these liberties, and that you treat others with the same respect. Many people with this position tend to flee when angry. This is not because they are afraid of confrontation, because they certainly are not, but when they are frustrated, a deep inner restlessness is stirred. Some people with this position can be quite self-serving, often without even realizing it, demanding freedom and space from others but not necessarily returning the favor.

        Another negative expression of Mars square Jupiter and Mars opposition Jupiter is a haughty or boastful attitude–some with this aspect in their birth charts feel they can get away with practically anything. Often they can, and even when they don’t, they are quick to recover from losses. However, this is generally due to a tendency to turn a blind eye to what has happened. Here again is the tendency to flee rather than reflect. They are quick to forget or ignore their mistakes, thus the chances of repeating them run high!

        https://cafeastrology.com/natal/marsjupiteraspects.html

      • ness

      • ulric wrote:
        “I made a valid point about the recent regional cold events.”

        One month on one single thermometer is now a “regional cold event?”

      • David Appell wrote: “One month on one single thermometer is now a “regional cold event?””

        Do you realise how widespread those two extreme cold events were? do you realise how many thermometers recorded them? or do you just loose touch with reality when you inappropriately attempt to dismiss something? I’m having trouble working out whether you are just being tricky, or really not with it.

    • timg56 wrote:
      “Yeah, David Archer of 10 meter sea level rise fame.
      In other words another frustrated fantasy writer.”

      Can you cite science, or provide an argument, the shows Archer is wrong?

  25. This shows the evidence of major geological events versus prolonged solar minimum periods of time.

  26. “Why would there have been dry conditions in West/Central Europe during the Spører minimum, when we have seen a general pattern of increased precipitations in this region during previous GSM?”

    There were two separate solar minima, one from around 1430, and another from around 1550. Take a look at England and Wales precipitation through the colder parts of the Dalton Minimum, annual totals as well as the cold dry Springs:
    http://www.metoffice.gov.uk/hadobs/hadukp/data/monthly/HadEWP_monthly_qc.txt

    “Whether it qualifies as a GSM or not is a matter of opinion as it was both brief and barely showed the required reduction in solar activity. Had the Dalton minimum taken place farther from us and isolated it would probably not have been considered a GSM. To make matters worse, most of the climatic effects during the Dalton minimum are of clear volcanic origin.”

    Barely showed the required reduction in solar activity? that makes no sense. Neither does the idea that most of the climatic effects were volcanic in origin, most of the cold through Dalton happened before Tambora.

    • Note the run of colder years 1807-1817 in the Dalton Minimum in CET, which is roughly SC5 maximum +1yr to SC6 maximum +1yr.
      http://climexp.knmi.nl/data/tcet.dat

      And note the lack of observed Aurora through that period, page 11:
      http://www.leif.org/EOS/92RG01571-Aurorae.pdf

      • 1785 was a decade before Dalton and as far as I know was not stratospheric, the VEI 5 in 1800 is too small, the mystery 1808/09 event is speculation, and Dalton had ended temperature wise by 1821. But typically the larger eruptions tend to follow the very coldest winters.

      • The most reliable evidence for the importance of volcanic eruptions in climate change is in my opinion the comparison of Greenland and Antarctic cores, as done by Sigl et al., 2015. They list four between 1785 and 1835 within the 40 most important eruptions of the past 2000 years in terms of aerosol forcing. I will go with that.

        A mystery eruption is not speculation. It is an eruption for which we have evidence in ice cores and other proxies but geologists have not been able to identify its origin yet.

        The 1808-09 eruption has been studied in detail:

        Cole‐Dai, J., et al. “Cold decade (AD 1810–1819) caused by Tambora (1815) and another (1809) stratospheric volcanic eruption.” Geophysical Research Letters 36.22 (2009).

      • It is speculation as to how large it was, and how great the effects would have been. I may have chilled the northern hemisphere summer of 1810 a tad before getting washed out. Hardly anything to do with decadal cooling.

    • “Neither does the idea that most of the climatic effects were volcanic in origin, most of the cold through Dalton happened before Tambora.”

      VEI 5 or higher eruptions in the 1785-1835 period:

      1785 (6) Grímsvötn (Iceland)
      1800 (5) Mount St. Helens (US)
      1808 (6-7) South Western Pacific region?
      1815 (7) Mount Tambora (Sumbawa, Indonesia)
      1822 (5) Galunggung (West Java, Indonesia)
      1835 (5) Cosigüina (Nicaragua)

      Six major eruptions, four of which within the biggest 40 of the last 2000 years according to Sigl et al., 2015, define one of the most active volcanic periods in two millennia in just 50 years. 10% of the major eruptions took place in just 2.5% of the period. That’s a four fold increase in the expected rate. It is certainly possible that most of the climatic effects seen during the Dalton minimum had a volcanic origin.

      • 1785 was a decade before Dalton and as far as I know was not stratospheric, the VEI 5 in 1800 is too small, the mystery 1808/09 event is speculation, and Dalton had ended temperature wise by 1821. But typically the larger eruptions tend to follow the very coldest winters.

  27. Grand solar minima occur when several solar cycles exhibit lesser than average activity for decades or centuries. Solar cycles still occur during these grand solar minimum periods but are at a lower intensity than usual. Grand solar minima have shown some correlation with global and regional climate changes.

    400 year history of sunspot numbers.
    Solar minimum events and approximate dates

    Event

    Start

    End

    Homeric minimum [9] 950BC 800BC
    Oort minimum (see Medieval Warm Period) 1040 1080
    Medieval maximum (see Medieval Warm Period) 1100 1250
    Wolf minimum 1280 1350
    Spörer Minimum 1450 1550
    Maunder Minimum 1645 1715
    Dalton Minimum 1790 1820
    Glassberg Minimum 1880 1914
    Modern Maximum 1914 2007

    A list of historical Grand minima of solar activity[10] includes also Grand minima ca. 690 AD, 360 BC, 770 BC, 1390 BC, 2860 BC, 3340 BC, 3500 BC, 3630 BC, 3940 BC, 4230 BC, 4330 BC, 5260 BC, 5460 BC, 5620 BC, 5710 BC, 5990 BC, 6220 BC, 6400 BC, 7040 BC, 7310 BC, 7520 BC, 8220 BC, 9170 BC.

  28. The data in the above shows solar minimums are random.

    • Incorrect…nothing is random. Grand solar minimum can only occur when Jupiter, Uranus and Neptune are together with Saturn opposite. This is a simple falsifiable statement. The key is to look at the single disordered inner loop orbit that occurs during this planetary position to quantify the downturn.

      We have just come out of this planetary position, and will need to wait for the next alignment in 170 odd years….but going forward for the next 2000 years we will not see the outer 4 planets produce LIA conditions. It’s a 4627 year clock that is very easy to read… if anyone bothered to look.

      • “Grand solar minimum can only occur when Jupiter, Uranus and Neptune are together with Saturn opposite.”

        What is the sum of gravitational forces on the Sun at that configuration, and how does it compare to other times?

      • David Appell,

        What is the sum of gravitational forces on the Sun at that configuration, and how does it compare to other times?

        Its not about the sum of the forces, what is happening is a reversal of velocity, solar angular momentum and torque. This changes the orbit shape of the Sun around the SSB for 10 years.

        Note the perturbation at the green arrows, this occurs at all grand minima or solar slowdowns like SC20. Also note the shaded area (Charvatova ordered phase) where grand minima do not occur (McCracken et al also found this)

        Svalgaard has no answer why grand minima do not occur when U/N are apart and only occur when U/N are together.

        The inner loop orbit highlighted in green is the result of the planetary position shown earlier. The shape is determined by the position of Saturn and can be used to quantify all solar downturns.

        Charvatova does not understand how this 10 year orbit (that can occur 3 times when N/U are together) is the key to grand minima occurring inside her very large window of disordered orbits (non trefoil)

      • When Jupiter, Uranus and Neptune are together with Saturn opposite, Europe gets hot Summers. This is a simple falsifiable statement. And I’m not kidding :) 1472-73, 1651-54, 1831-32, 2010.
        https://wattsupwiththat.files.wordpress.com/2011/09/weather1.pdf

    • ulric wrote:
      “When Jupiter, Uranus and Neptune are together with Saturn opposite, Europe gets hot Summers. This is a simple falsifiable statement.”

      Got anything that’s been peer reviewed and published in, you know, a real scientific journal?

  29. Judith, I like your blog and I trust your judgement. I made a comment which might not improve the discussion and I accept your criteria holding it back. It is a nice piece from Javier and I hope that the discussion brings some new insides unifying points of view. I am being sincere here, nor sarcasm or alike.
    I like to take care of those whom offer something valuable with independence of agreement or disagreement.
    Sincerely.
    Diego.

  30. I cant really see how that there can be a significant shift in the earths temp until there is a change in the earths tilt, of 23.44,as happened in the past

    • You can have significant shifts in climate without significant “global” changes in temperature. The LIA was likely a more NH event just like current warming is more of an NH event because of the differences in heat capacity of the land and ocean. It takes time for the SH oceans to transfer heat to the NH so you have a lag of 30 to 90 years while the ITCZ shifts to the cooler hemisphere, then another lag when the oceans try to return to a “normal” condition. So you don’t have a “global” temperature event unless the cause and feedback lasts long enough to be measured in both hemispheres at roughly the same time.

      Events related to precessional changes last more than long enough for 30 to 1000 year pseudo-oscillations to settle out so you have an easier to measure “global” impact considering many paleo methods only have roughly 200 year resolution. Then you would only notice the greater than 1000 years blips than can be “seen” in your paleo reconstructions.

      Since the NH has a larger change in “surface” temperature per unit “forcing” it tends to drive “global” temperature anomaly while global heat capacity could remain pretty stable, the hemispheric seesaw.

      “Global” temperature anomaly though doesn’t mean much to pre-industrial civilizations. They tend to have a more local focus.

      • “The LIA was likely a more NH event”

        The last glacial period was likely a more NH event. Over 90% of ice sheets formed over NH. We should correct textbooks because glaciations are likely a more NH event, not a global one.

        Reductio ad absurdum

      • The LIA as well as the MWP were world wide events. Confirmed by drilling samples world wide. As well as numerous other events.

      • Javier, “The last glacial period was likely a more NH event. Over 90% of ice sheets formed over NH. We should correct textbooks because glaciations are likely a more NH event, not a global one.

        Reductio ad absurdum”

        Not really, when you use “global” “surface” temperature as your metric. Heat capacity wise it was a global event and heat capacity is part of determining “sensitivity” which seems to be lost in the discussion. So if you actually consider the specific heat of land versus ocean, obviously cooling or warming is more easily measured in the predominately land regions. You need some indication of total energy to determine if there was a “global” impact.

        With the hemispheric seesaw, there is evidence that glaciation can start in either hemisphere, but of course there is more land mass in the NH that gets all the press. What is absurd is just using “global” temperature to estimate global climate impact when humans mainly populate the NH, then assuming the event was regional or global without considering more information.

      • rishrac wrote:
        “The LIA as well as the MWP were world wide events.”

        That’s not what this huge study found:

        “There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age…”

        “Continental-scale temperature variability during the past two millennia,” PAGES 2k Consortium, Nature Geosciences, April 21, 2013
        http://www.nature.com/ngeo/journal/v6/n5/abs/ngeo1797.html

      • Appell, good you are making my point for me. This study for there was a MWP and a LIA evident in the Pacific ocean intermediate water temperatures which would be a large portion of the heat content of the Earth. http://www.ldeo.columbia.edu/~blinsley/Dr._B._K_Linsley/Indonesia_&_Pacific_Intermediate_Water_files/Rosenthal.Linsley.Oppo%202013%20Pac.Ocean.Heat.pdf

        Sigl et al. 2014 is one of the newest updates to volcanic aerosols and indicates a volcanic lull that happened during the MWP and a couple of centuries of heavy volcanic activity followed leading into the LIA.

        There are tropical and sub tropical ocean paleo reconstructions that agree with the IWT reconstruction and the volcanic aerosols, but for some reason treemometer heavy reconstructions tend to disagree with other evidence. I would think that if more than 50% of the surface, oceans, the majority of the heat content, IWT and volcanic forcing reconstructions all indicate a global MWP and LIA, some should seriously question the methods used for treemometers.

        Wait, hasn’t there been some questions raised about “novel” methods used by some paleo climatologists?

      • PAGES 2k is about proxies on land. If there aren’t a global LIA and MWP on land, there can’t be one globally on land+ocean.

      • Appell, “PAGES 2k is about proxies on land. If there aren’t a global LIA and MWP on land, there can’t be one globally on land+ocean.”

        Really, Is this common core math?

      • Javier said “We should correct textbooks because glaciations are likely a more NH event, not a global one.”

        Can you correct the ice core proxies too?
        https://qph.ec.quoracdn.net/main-qimg-7a85660efcc5d30104f428a2024e1c23?convert_to_webp=true

      • ulric wrote:
        “Can you correct the ice core proxies too?
        https://qph.ec.quoracdn.net/main-qimg-7a85660efcc5d30104f428a2024e1c23?convert_to_webp=true

        What’s wrong with them?

        I thought that, here, evidence always trumps theory.

      • “What’s wrong with them?”

        Nothing at all, you just failed to notice my sarcasm.

      • PAGES 2k

        Isn’t that what the Gergis papers were based on?

        Peer reviewed I might add.

  31. As the root of this neglect lie two fundamental problems. Solar variability is quite small (about 0.1% of total irradiation), and there is no generally accepted mechanism by which the solar variability signal could be amplified by the climate system.

    Another wrong assumption ,that variability is over a very short time span.

  32. “GISP2 temperature proxy points to an important but not extraordinary cooling centered at around 5400 BP”

    A warm event for the mid latitudes, the 5.2Kyr cold-dry event happens 200 years later when Greenland is much warmer.

    • Yes, Greenland ice cores are not a very good proxy for Holocene temperatures, but we lack decent temperature reconstructions even on a regional basis for the first half of the Holocene. I’ve tried to explain that over WUWT, but GISP2 is their Holocene bible to a lot of them.

      Luckily we have many other proxies to give a better picture of the Mid-Holocene changes, and Lonnie Thompson made a fantastic job with the 5.2 kyr event.

      • And I have tried to explain there and here repeatedly for the last three years that GISP is largely an inverse proxy for the mid latitudes. Everyone just talks around it.

      • “GISP is largely an inverse proxy for the mid latitudes.”

        I wouldn’t go as far as saying that it is an inverse, but clearly the response is not linear and usually it responds in the opposite direction when the changes are not very strong.

        Kobashi in his reconstruction talks about these issues:

        “Greenland undergoes cooling when northern Europe experiences warming (positive NAO), and vice versa (Hurrell, 1995). Climate modelling and observations suggest that solar variability induces changes in atmospheric circulation similar to NAO/AO through ozone feedback in the stratosphere (Shindell et al., 2001; Kodera and Kuroda, 2002; Gray et al., 2010; Scaife et al., 2013). When solar activity is stronger (weaker), changes in the positive (negative) NAO/AO-like atmospheric circulation are induced (Shindell et al., 2001; Lean and Rind, 2008). Therefore, it can be expected that stronger (weaker) solar activity induces warming (cooling) in NH temperature, and relative cooling (warming) in Greenland through positive (negative) NAO. Consistent with this theory, Greenland temperatures have deviated negatively (positively) from the NH temperature trend when solar activity was stronger (weaker) over the past 800 yr (Kobashi et al., 2013).”

        Kobashi, T., et al. (2013) “Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes.” Climate of the Past 9, 5, 2299-2317.

        In my opinion this is related to polar vortex circulation, when the polar vortex expands it brings very cold temperatures over NH mid-latitudes, but at the same time it obviously warms to some extent very high latitudes as that cold air is substituted by warmer air at polar latitudes.

        However when the cooling is strong, Greenland also appears to show cooling. It is far from simple and one of the many reasons Greenland temperatures should not be used as a proxy for global changes. It also has all the cycles altered. There is a prominent 1250 yr cycle of which nobody appears to know much.

      • “However when the cooling is strong, Greenland also appears to show cooling.”

        Everything that I have pointed out at century scales through the Holocene fully contradicts that.

      • “Everything that I have pointed out at century scales through the Holocene fully contradicts that.”

        Well, I disagree. GISP2 and the Bond series show coincident cooling at 8.2, 7.5, 5.5, 1.4 and 0.4 kyr BP, but not at other times.

      • Yet you tried to dodge my 5.2kyr/5.4Kyr issue by claiming that “Yes, Greenland ice cores are not a very good proxy for Holocene temperatures”. OK lets work back through a string of them The very warm 8th century for Europe is the second coldest period on GISP in the Holocene. The Dark Ages cold period ~380-650 AD is decidedly warm on GISP, much warmer than the Roman Warm Period in the first few centuries AD. Around 1200 BC was one of the coldest dry periods of the Holocene for the mid latitudes. Another notable cold dry period that led to population displacement was around 2200 BC, warm again on GISP. The third coldest period on GISP ~2700-2450 was the greatest period of human culture development in ancient history, and is the best analogue for the last couple of hundred years of climate and weather patterns, ~4627 years back. No way was that cold in the mid latitudes. And that’s why I have no problem with challenging the popular ‘understanding’ of the 8.2Kyr event.

      • And what of the warm spike in GISP at around 1000 AD?
        Yes, strong mid latitude cooling in the late 10th and early 11th centuries. Yet most sceptics cling to it like a security blanket as supposed evidence of the MWP being warmer than now.

  33. A very well documented and informative piece. You touched on two elements that make a complete understanding difficult: Unknown mechanisms from solar changes with possible second and third degree derivatives and the possibility of cumulative effects. Given the relative tight range of
    temperatures over millions of years and the
    inherent homeostatic processes of earth this shouldn’t be a surprise. Great challenges for future generations of scientists.

  34. but on balance this is a great article.

  35. It is interesting to see how close a connection there may be between small climate changes and profound changes in the progress of civilisation.

    How fortunate we are that our present civilisation is so much more resilient in the face of a much faster and bigger alteration in climate. And how fortunate that the change in climate is in an exclusively beneficial direction! (sarc/off)

  36. Javier said:

    The explanation for this contradiction is that evidence always trumps theory….

    In a perfect world, maybe so, but I’m not nearly so sanguine. There are other theories of history out there that are not nearly so optimistic.

    For instance, according to Carrol Quigley’s theory of history, which is a cyclical theory based on materialism, our current dilemma is to be expected in societies or civilizations which have entered what he called the “Age of Conflict.” (Carroll Quigley, The Evolution of Civilizations)

    As Quigley explains, the Age of Conflict is “the most complex age” of all the stages that typify the rise and fall of civilizations. It is a period of declining rate of economic expansion in which there is “growing irrationality, pessimism, superstitions, and other-worldliness.”

    The declining rate of economic expansion is caused by the deadence of the ruling classes and the institutionalization of “the instrument of expansion.”

    The instrument of expansion — which formerly was engaged in “(a) increased produciton of goods, eventually reflected in rising standards of living; (b) increase in population in society, generally because of a declining death rate; (c) an increase in the geographic extent of the civilization, for this is a period of exploration and colonization; and (d) an increase in knowledge” — transmogrifies into an “instrument of irrationality.”

    The “vested interests” encourage the “growth of irrationality” because it serves “to divert the discontent of the masses away from their vested interests.”

    “[T]he institution of irrationality controls much of the intellectual life of the society,” Quigley concludes, and once this instrument of irrationality is created, the chances of it being reformed into an instrument of expansion once again “become almost nil.”

    Applying Quigley’s theory to CAGW, what we see is that CAGW is an instrument of irrationality, created by the governing classes, which serves to “to divert the discontent of the masses away from their vested interests.”

    • This would explain Trump.

      • It does explain Trump.

        Trump wants to restore the “instrument of expansion.” As Quigley explains:

        The declining rate of expansion is caused by the institutionalization of the instrument of expansion.

        The growing class conflicts arise from the increasing tension of evolution, from the obvious conflict of interests between a society adapted to expansion and the vested interests [who instead of investing the society’s surpluses into economic expansion, waste them on class oppression and failed imperialist wars].

        Usually there is a majority of the frustrated [represented by Donald Trump] struggling against the minority of vested interests [represented by the Republican-Democratic establishment], although usually neither side has any clear idea of the real issues at stake or what would give a workable solution to the crisis.

        All programs for sharing the surplus of the few among the discontented many [the Democratic Party “solution”] are worse than useless, since expansion can be resumed onlyif the three necessary elements of expansion* are provided, and the dissipation of surpluses among a large mass of consumers will not provide any one of these three necessary elements.

        On the contrary most revolutionary programs, aroused by the failure of the third element (productive investment), will merely make the crisis more acute by destroying the second element (accumulation of surplus).

        The only sensible or workable solution to the crisis of the civilization, Quigley continues, would be to reform or circumvent the old instrument of expansion, which by now has transmogrified into a dysfunctional “institutuion of expansion.” Such reform or circumention would establish “again the three basic elements of an instrument of expansion.”

        But Quigley was not very optimistic of this happening:

        Since the disgruntled masses know nothing about such things, and since the vested interests do not know much more and are usually concentrating their energies on an effort to defend their vested interests, a new instrument of expansion, if it appears, usually does so by accident and through the path of circumvention rather than by reform. If a new instrument of expansion does come into existence, the civilizaiton begins to expand again, the tension of evolution and the crisis subside, and the civilization is once again in the Expansion Stage.

        Without the advent of some revolutionary technolgical complex — like, for instance, that imagined by AK or the Mexican politilogue Jaime Jalife, which goes well beyond a revolution limited to only computing and information technology — I don’t see how Trump’s plan to restore the instrument of expansion has much chance of success.

      • ordvic,

        Well with that and a couple of bucks, you can go down to IHOP and buy a cup of coffee.

    • An interesting point of view Glenn, and I certainly agree with a lot of what you cite on Carrol Quigley.

      But science has been a hostage of powerful interests before, and in the end, for as long as scientific progress continues, sooner or later things get corrected, because false beliefs block progress and so they are removed. It is little consolation when the correction comes postmortem, as in the case of Weggener, but it has to suffice.

      • Javier,

        The part of your essay I enjoyed the most was the treatment of the interaction between the physical world and the human world (if one even believes the two worlds are separate.)

        Climate seems to impact the human world in important yet very complex and mysterious ways, as Michael Allen Gillespie explains:

        Nominalism sought to tear the rationalistic veil from the face of God in order to found a true Christianity, but in doing so it revealed a capricious God, fearsome in his power, unknowable, unpredictable, unconstrained by nature and reason, and indifferent to good and evil. This vision of God turned the order of nature into a chaos….

        While the influence of this new vision of God derived much of its force from the power of the idea itself and from its scriptural foundation, the concrete conditions of life in the second half of the fourteenth century and early fifteenth centuries played an essential role in its success. During this period, three momentous events, the Black Death, the Great Schism, and the Hundred Years War, shook the foundations of medieval civilization that had been weakened by the failure of the Crusades, the invention of gunpowder, and the severe blow that the LIttle Ice Age dealt to the agrarian economy that was the foundaiton of feudal life.

        While such a vision of God might have been regarded an absurdity in the twelfth and thirteenth centuries, the castrophes of the succeeding period helped make such a God believable.

        — MICHAEL ALLEN GILLESPIE, The Theological Origins of Modernity

      • Yes, Glen, I believe we have been shaped in many ways by climate, and with a different climatic history we would be very different.

        I like to think that the Biblical garden of Eden was placed in the Saharan savanna and its great lakes, and that the expulsion of paradise refers to the Saharan aridification that took place at the end of the African Humid Period between 6000 and 5000 years ago. The climate refugees that arrived to the Nile valley responded to the situation with knowledge, developing the Bronze civilization.

      • Javier:
        “Yes, Glen, I believe we have been shaped in many ways by climate, and with a different climatic history we would be very different.”

        And even weather events may have played major roles in history. Most of us speaking English now might be speaking Spanish if not for the intense storm that wrecked the Spanish Armada and most Japanese might be speaking Chinese if not for the typhoon that destroyed the huge Chinese invasion fleet.

        Undoubtedly, the next glacial period in our current ice age will be a major challenge for humanity. Hopefully the current interglacial warm period will be more like the fourth one back that lasted about 25,000 years (beginning about 418,000 years ago), in which case humanity might have as much as 12,000 years left to figure out how to avert it. Otherwise it will be a MUCH worse catastrophe than any of the worst alarmist global warming nightmares. People will look back and wish for global warming.

    • I was thinking of Trump more in the “irrational” context.

      But it looks like an interesting book, and I’ll get a copy.

  37. As it turns out, “the modern Grand maximum (which occurred during solar cycles 19–23, i.e., 1950-2009),” says Ilya Usoskin, “was a rare or even unique event, in both magnitude and duration, in the past three millennia.” ~Usoskin et al., Evidence for distinct modes of solar activity, A&A 562 (2014)

    • There is a lot of controversy over the existence of a Modern Grand Maximum. In any case I have not seen any clear evidence that solar grand maxima have a significant effect on climate during the Holocene. They still may have it, but I haven’t seen it, so I can´t comment on it.

      • Solar variations and volcanic eruptions are a wild card. Russian scientists argue that there was a Grand Solar Maximum that peaked in the late 20th century, and that we can expect a Grand Solar Minima (contributing to cooling) to peak around 2060… And finally, we can’t rule out unforeseen surprises. The hiatus in warming in the early 21st century was an unforeseen surprise. ~Judith Curry (House of Rep. Hearing, The President’s U.N. Climate Pledge, 15 Apr 2015)

      • Wagathon: If you’re referring to that crazy Abdussamatov paper

        http://icecap.us/images/uploads/abduss_APR.pdf

        it’s already apparent that his predictions, so far, are failing:

        http://davidappell.blogspot.com/2016/04/is-abdussamatovs-prediction-of-tsi.html

      • No one is expert in accurately forecasting which way the wind will blow. There is a possibility of a coming “Mini Ice Age” that Dr Habibullo Abdussamatov says may be headed our way based on a 200-year solar cycle. In the decades ahead we may fall prey to hucksters promising to bring back global warming — especially if temperatures drop to levels experienced during 1650 and 1850. “The last global decrease of temperature,” according to Abdussamatov, “was observed not only in Europe, North America and Greenland, but also in any other part of the world during the Maunder minimum of sunspot activity and of the total solar irradiance in 1645 to 1715.”

      • Wagathon wrote:
        “There is a possibility of a coming “Mini Ice Age” that Dr Habibullo Abdussamatov says may be headed our way based on a 200-year solar cycle.”

        It’s also possible Justin Bieber is the reincarnation of Jesus Christ.

        Until then, explain why Abdussamaatov’s prediction is already failing.

      • Wagathon,

        I see no signs of an upcoming grand solar minimum in the analysis of past solar variability. The chances of a Spører or Maunder-type of GSM are very small.

        Dr. Judith Curry is absolutely correct in that we can’t rule out unforeseen surprises. Given our orbital configuration, obliquity falling at its fastest pace and minimal precession factor, and given that our temperatures are significantly above the average of the past millennium, I would say that there are overwhelming odds that any surprise would be towards the cooling side.

      • Among others, the study by Japanese scientists Aono and Kazui, also discovered, “the existence of a widespread ‘Medieval Warm Period’ around the year 1000 [and Little Ice Age as well].”

        Moreover, researchers found that both the Roman Period (RWP) about 2,000 years ago, as well as the ‘Medieval Climate Anomaly’ (MCA), were warmer than today (Modern), based on current sea surface temperatures (see, Yan, et al., below)

        https://evilincandescentbulb.files.wordpress.com/2015/01/yan-et-al-2014-csb-graphsstgraph.jpg?

  38. Matt Lachniet has quite of bit of supporting work in this area of climate. I did not see him cited anywhere in this article.

    A 2400 yr Mesoamerican rainfall reconstruction links climate and cultural change http://geology.gsapubs.org/content/40/3/259.short

    A speleothem record of Holocene climate variability from southwestern Mexico http://www.sciencedirect.com/science/article/pii/S0033589410001122

    A 1500-year El Niño/Southern Oscillation and rainfall history for the Isthmus of Panama from speleothem calcite http://onlinelibrary.wiley.com/doi/10.1029/2004JD004694/full

    Orbital control of western North America atmospheric circulation and climate over two glacial cycles
    http://www.nature.com/ncomms/2014/140502/ncomms4805/full/ncomms4805.html?WT.ec_id=ZH-CN-NCOMMS-20140514

    • The amount of support is huge over the paleoclimatologists community. One wonders how there can be such a strong disconnect between scientists coming from a different background on the same topic.

      I have only cited about 1 in 20 articles since this is just a blog post, but I thank you for those references.

      • Javier

        As you say, there is a substantial disconnect between scientists coming from a climatological background and paleoclimatologists. It is a pity there were not some of them (and some historical climatologists) peer reviewing papers that were using novel proxies that emanated forth in the 1990’s.

        It is impossible to cite ALL the influential papers that support such studies as yours. I cited some 1000 references in one of my articles and readers complained it made it too long.

        tonyb

  39. Javier wrote:
    “The explanation for this contradiction is that evidence always trumps theory….”

    Yes. For example, we now know that neutrinos travel faster than the speed of light.

  40. This is a truly alarming manuscript, firmly putting the (C) into CAGW.

    The combination of both very high climate sensitivity *and* very high impacts it implies is truly terrifying.

    Modern forcings are changing much more rapidly and by much greater amounts than the changes causing these historic upheavals.

    So I suggest that we should from now on change the definition and refer to Cataclysmic Anthropogenic Global Warming.

  41. “The ~ 2400-yr cycle in solar activity could be a lower harmonic of the ~ 9600-yr cycle found by Sánchez-Sesma (2015) in 10Be records for the past 135 kyr. Alternatively the ~ 9600-yr cycle could be the result of a constructive interference between the ~ 1000-yr and ~ 2400-yr cycles.”

    Yet if they are actually quasi periodic events and not cycles as such, then no such interference can physically exist.

  42. Javier, Correct me if I’m wrong but you seem to have changed your tune?Here you are arguing that we will be going into a relatively stable climate period. You also seem to disavow my observation that we are at a 1000 year Eddy cycle:

    ordvic | June 27, 2016 at 6:43 pm |

    If we are on a true solar cycle the 1000 yr cycle (970) years:

    This will mean we are going into Oort Minimum after 2020.

    Javier | June 27, 2016 at 7:01 pm |

    Ordvic,

    This will mean we are going into Oort Minimum after 2020.

    Nope, the Oort minimum is part of the 208 year cycle, as the minimum that took place at the end of the 19th century (see filled red dots in figure above). The 208-years deVries cycle is only active during the lows in the 2500-years cycle. This is quite well known. You can look it up in the linked article.

    There is no upcoming Grand Solar Minimum, just the favorable configuration that corresponds to the highs in the 2500 and 1000-years cycles. We are facing a period of climate stability similar to the Roman Warm Period. Our solar configuration is similar to the year 80 BC, so we may be looking to three centuries of relative climate stability.

    curryja | June 27, 2016 at 9:52 pm |

    Javier, i still have your essay, will get to it soon. Thanks

    ordvic | June 28, 2016 at 12:44 am |

    Javier, Thanks for the link to your article. I liked figure six. But I don’t read it the same way you do. The period of 80 BC was a peak followed by a drop (in two stages) to a low around 80 AD. The stable periods were the two hundred years before Oort and 80AD?

    ordvic | June 28, 2016 at 12:55 am |

    BTW, Javier, I liked your article a lot and glad I ran into you (and it) today

    Peter Lang | June 27, 2016 at 7:14 pm |

    Thanks Ordvic,

    Where do the Bond Cycles fit into your picture? Are they the 970 year cycles?
    Bond Cycles and the Role of The Sun in Shaping Climate
    http://euanmearns.com/bond-cycles-and-the-role-of-the-sun-in-shaping-climate/

    ordvic | June 28, 2016 at 12:06 am |

    Peter, Thanks for the link. It looks like Bond cycles are very similar except they take into account oceans and he has them at about 1200 years long. He uses the same periods of reference however. Those look like this:

    I don’t understand Javier’s reasoning of it being about 86 Ad Roman Warming as that was also just before a minimum not a stable period.

    Peter Lang | June 28, 2016 at 3:55 am |

    Ordvic,

    Thank you for these two charts, Can you give links to where I can find them and where I can find an explanation of them.

    The first has lots of information. I hope it is from an authoritative site (I haven’t seen it before).

    Is the top section (Temperature anomaly, OC) consistent with the authoritative, broadly accepted charts of temperature over this period? If it is, then I wonder why more people are not concerned about the long term natural cooling trend and therefore, seeing human caused GHG emissions as being a blessing – i.e. and excellent risk mitigation strategy.

    It’s also interesting to see the increasing frequency of global glacier advances (central section).

    I don’t understand what is plotted in the bottom section (red, yellow, green, blue, indigo colours). It shows years in the vertical axis and years in the horizontal axis. But what does that mean? And what is the curved white line (it’s shaped like the hull of a Viking ship, with keel at about 5700 years BP :) ?

    The curved purple lie at the top shows obliquity has reduced from 24.2 to 23.6 and decreasing faster as time goes on. Where is the trough and when is it projected to occur. What is the effect on global average temperature of the continuing decrease in obliquity?

    Tell me a bit of a story about your interpretation of the significance of this chart.

    ordvic | June 28, 2016 at 8:00 am |

    The first chart Javier also uses in his article. The top part is a fairly well known anti-hockey stick from Marcott et al:
    http://content.csbs.utah.edu/~mli/Economics%207004/Marcott_Global%20Temperature%20Reconstructed.pdf

    The other part is from A.K. Kern:
    http://usp-br1.academia.edu/AndreaKKern

    The lower chart is from Robert Carter well known skeptic from England and Australia

    https://en.wikipedia.org/wiki/Robert_M._Carter

    The only significance here is I am pointing to the 1000 year cycle. Javier has more information of the cycle at his link.

    ordvic | June 28, 2016 at 8:29 am |

    One final comment. Before each warming peak, as seen on Carters chart, there is a 1000 year period where it bottoms out like a minimum. It then either rises in stages or very quickly like the last 200 year period since Dalton. Then it is usually followed by a fairly sharp decline. This is all related to well known solar cycles that are much different from Milankovich cycles involving orbits

    Peter Lang | June 28, 2016 at 9:03 am |

    ordvic,

    Thank you for the explanations and the links. The last link you gave is to a comment by Javier on WUWT. But again there is no reference to the authors and where it is published. I would like to be able to cite it, but if I am going to cite it I need to know where it is published, who are the authors, is it widely accepted, cited and what critiques have been published and responded to. In short, I don’t waht to refer to something that has been discredited or not published. I need to know if it is authoritative. At the moment I have no idea of that. I would expect the figure caption to fully explain the chart, like this IPCC chart from AR4 WG1 Chapter 6, Figure 6.1
    https://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-6-1.html

    ordvic | June 28, 2016 at 1:19 pm |

    Peter I couldn’t find who compiled the charts on photoshop. I’ll try again later. The top part of the Chart is from marcott probably figure 2:
    http://content.csbs.utah.edu/~mli/Economics%207004/Marcott_Global%20Temperature%20Reconstructed.pdf
    The bottom is from A K Kern et al, probably figure 8:

    http://www.sciencedirect.com/science/article/pii/S003101821200096X#bb0265

    Peter Lang | June 28, 2016 at 6:29 am |

    I found this link with lots of charts http://www.rankia.com/blog/game-over/3150008-ciclos-dansgaard-oeschger , but I have not found a link to your charts

    ordvic | June 28, 2016 at 8:14 am |

    Javier also used this chart here:

    https://wattsupwiththat.com/2016/02/11/solar-cycle-24-activity-continues-to-be-lowest-in-nearly-200-years/#comment-2142863

    Like I said I just showed them as reference to the 1000 year cycle and Javier has as good of an explanation as I’ve seen on his article linked

    Javier | June 27, 2016 at 7:28 pm |

    Peter,
    The Bond cycle does not exist. Bond events are a registry of every significant cold event during the Holocene. Some of the peaks correspond to solar minima of the 2500 and 1000 years cycles, while others come from the 1500 years oceanic cycle.

    Their spacing is a mixture of the dominant cycle of the period, during early Holocene the 1000 years solar cycle, and during the late Holocene the 1500 years oceanic cycle.

    Figure from:
    Debret M., et al., 2007. The origin of the 1500-year climate cycles in Holocene North-Atlantic records. Clim. Past Discuss., 3, 679–692.

    Peter Lang | June 27, 2016 at 7:53 pm |

    Javier,

    Could you please provide an explanation of the chart and a Legend. Perhaps copy the chart caption is it provides sufficient explanation. Also, it would be helpful if you include links to the sources when you post charts and explanations of other’s work.

    Javier | June 27, 2016 at 9:00 pm |

    Peter,

    A simple Google search on Google Scholar
    https://scholar.google.com/
    Will find for you almost any article referenced, and by clicking on its versions you will very often find a pdf copy hosted somewhere. In this case:
    https://hal-ephe.archives-ouvertes.fr/docs/00/33/07/31/PDF/cpd-3-679-2007.pdf

    Very few people are interested in going to the references, but for those that are interested, they have this easy way. As I have the articles on my hard disk (and head) I don’t need to run a search over the internet to find a pdf every time I write a comment.

    The figure is quite self explanatory. It is derived from figure 2 from that paper and shows the Bond series (the same as in the figure you posted) to which a Gaussian filter of 1000 years has been fitted to the early Holocene, and one of 1500 years to the late Holocene. The red numbers represent the original Bond event numbering by Gerard Bond in his 2001 article. He cheated a little, used the zero and didn’t count some peaks so the spacing would come as 1500 years when in reality is something like 1200-1300 years.

    This figure demonstrates that Bond events reflect an admixture of at least two different periodicities.

    ordvic | June 28, 2016 at 12:22 am |

    Correction 80 BC was what Javier said. That still places it just before the first dip of a minimum. If that is true then it would be just like Oort. And that would be the 1000 year cycle

    Javier | June 28, 2016 at 6:13 am |

    Ordvic,

    The stable periods were the two hundred years before Oort and 80AD?

    The Roman Warm period starts after the Greek Solar Grand Minimum (SGM) at about 300-200 BC and lasts until the start of the Migration Period around 350 AD when climate conditions start to deteriorate leading to very bad conditions around 550 AD. It is about 6 centuries of stable warm conditions centered on the millennial (Eddy) solar cycle with lows at ~ 300 BC (Greek SGM) and ~ 675 AD (Roman SGM).

    The Eddy solar cycle had it last low ~ 1675 during the Maunder SGM, and the 2500-years Bray solar cycle had it last low ~ 1450 during the Spører SGM. We have had over 3 centuries of climate improvement and we are close to the high in the Eddy cycle that will take place at the beginning of the 21st century.

    Provided there are no very big volcanic eruptions we are looking forward to about 3 centuries of climate stability with perhaps a slight cooling trend. Since almost all SGM coincide with the lows in the Bray or Eddy cycles we are probably safe from one for the next centuries. Our solar situation is similar to ~ 80 BC, with several centuries of warming behind and several centuries of stable climate ahead. We are very fortunate of the climate time we are living. The Greek Dark Ages, the Migration Period, and the Little Ice Age were very bad periods for humankind in general outside the tropics.

    cerescokid | June 28, 2016 at 6:56 am |

    Javier

    Thanks for the information. I had not seen any reference before regarding the Greek Solar Grand Minimum and found a couple of references indirectly on Google. Interesting.

    My intent is not to demean anyone’s work but the the entire solar debate at times seems populated by varying home brews with lots of amateur theories but few sources that give reasons to be confident in their scientific legitimacy. I will be spending more time in the future trying to make sense of it all. Thanks.

    Javier | June 28, 2016 at 10:14 am |

    cerescokid,

    The subfield of solar variability and climate change is a fringe subfield. Almost no astrophysicist believes in a sun variability-climate change connection because they mainly look at recent data and see no relation between the 11-years cycle and climate change and the solar irradiation variability appears too small to make significant changes in climate. Besides it has a bad reputation as a career destroyer subfield.

    On the other hand most paleo-climatologists accept a significant influence of solar variability on climate change because they take the long view and find a strong correspondence between climate records and solar activity records. There are hundreds of papers published every year where sun variability is used to explain past climate changes.

    What makes it a fringe subfield is that there is no known mechanism that can explain physically and with data how such small solar variability can exert such big climatic changes (as the Little Ice Age for example).

    I was myself very skeptical of a big solar role up to about a couple of years ago, when I started to check the data myself. The correspondence between past cold periods and low solar activity for the last 10,000 years is astounding. And it is not due to climate contamination of the solar record. The best corrected 14C records for carbon budget models show it very prominently. When confronted between evidence and theory I always go with the data. The theory will end up being incorrect or incomplete.

    Given the cyclical nature of solar activity we can start making better predictions of future solar activity and climate change. We are close to the peak of the 1000-years Eddy cycle. We might get a respite from warming during SC 24-25 (similar to SC 15-16 at the start of the 20th century) and perhaps a little cooling, but solar activity between 2050-2100 should be similar to the second half of the 20th century. Climate should be like a long pause with perhaps one or two decades of moderate warming.

    We can see very clearly how temperatures are following the 1000 years Eddy cycle following their own internal 60 years cycle that is probably an oceanic component set in lagged motion by solar variability.

    CO2 is probably enhancing natural warming, but the pause is showing that natural warming is likely to be the main cause for global warming for the past 350 years.

    cerescokid | June 28, 2016 at 10:42 am |

    Javier

    Thanks for the additional thoughts.

    “…there is no known mechanism that can explain physically…”

    This has been a pet peeve of mine that since scientists cannot identify a reason for some apparent correlations then it follows there is no causative relationship. Obviously correlations also don’t prove causations but at a minimum it should trigger more inquisitiveness and double down on further research rather than just blow it off as much of the establishment has.

    I keep wondering what will future generations know that this generation is clueless about.

    I hope you keep digging for more insights.

    edimbukvarevic | June 28, 2016 at 11:42 am |

    According to the establishment, no known mechanism implies no causation, which of course is another logical fallacy.

    ordvic | June 28, 2016 at 1:46 pm |

    A K Kern explains her chart in the text:

    http://www.sciencedirect.com/science/article/pii/S003101821200096X#bb0265

    Our analysis is in good agreement with the results of Yin et al. (2007). Both approaches indicate the de Vries cycle with periodicities of 225-years and an unnamed 352-yr-cycle (Fig. 7a and b). In addition to the peak at 225 years, our analysis shows an additional peak at 208 years suggesting slight shifts in the duration of the individual de Vries cycles (Fig. 7a). Peaks at 443 (441 in Yin et al., 2007), 522 and 561 years are also analogous to Yin et al. (2007). All these signals might represent a single quasi-periodic 500-year-cyclicity (Fig. 7a). Although this cycle is constantly expressed in the record (Fig. 8g), the splitting of its signal points to some variation of its frequency (Fig. 8g). The next significant peak occurs at 970 years, indicating the unnamed 1000-yr-cycle. Finally, the Lomb–Scargle periodogram shows a strong peak at 2210 to 2227 years, which represents the Hallstatt cycle (Fig. 7a). The Gleissberg cycle does not appear in the spectral analysis but is expressed by two very significant peaks above the 99% confidence interval at 88 and 151 years in the REDFIT analysis (Fig. 7b). This is explained by the presence of too much noise in the huge data set, which is removed using the REDFIT spectrum (Schulz and Mudelsee, 2002). This solar cycle displays a wide frequency band and temporal variation in power with a lower Gleissberg band of 50–80 years and an upper Gleissberg band of 90–140 years fitting excellently to the two-fold signal in the REDFIT spectrum (Ogurtsov et al., 2002 and Ma, 2009). The REDFIT analysis documents also the presence of a very prominent quasi-210-yr-periodicity of the de Vries cycle (Fig. 7b). Considering the wavelet spectrum, it is obvious, that the very high-frequency solar cycles (less than 60 years of duration) are poorly resolved (Fig. 8i), corresponding to the wavelet analysis of Yin et al. (2007). This may most likely be caused by the presence of noise due to the irregularities in theses solar cyclicities. The lower Gleissberg cycle, however, is still visible with its highest intensity from 5500 to 12,000 years (Fig. 8i). The upper Gleissberg cycle is also expressed with a prominent phase between 2500 and 8000 years.

    An important fact is the absence of any 1500-year-cycle (Fig. 7). This is a strong proof, that this periodicity is no solar cycle as suggested by Bond et al. (2001) but might result from other feed-back mechanisms (e.g. Braun et al., 2005, Versteegh, 2005, Bard and Frank, 2006 and Xapsos and Burke, 2009).

    The filtered data demonstrate a considerable modulation of the different solar cycles (Fig. 8c to h). The 1000-year-cycle shows a constant decrease in amplitude during the Holocene (Fig. 8h). The filtered quasi-500-yr-component has a comparable trend (Fig. 8g); its amplitude decreased strongly resulting in a moderate minimum around 5000–3500 B.C., then increased slightly again and becomes insignificant during the last 1000 years. In contrast, the expression of the 2210-yr Hallstatt cycle increases throughout the Holocene (Fig. 8f). The filtered 209-yr-component, representing the de Vries cycle, shows a much more complex pattern (Fig. 8e). It strongly alternates between high and low amplitude phases, but is overall steadily strengthening. Two major break-downs occurred around 5700–4500 B.C. and 2200–1500 B.C. The lower and upper Gleissberg cycles are also highly oscillating and display no phase-relation (Fig. 8c). The 151-yr-component develops a phase of extraordinary high amplitudes from about 4000–2500 B.C. and a second weaker phase from 700 B.C. to 200 A.D. (Fig. 8d), roughly coinciding with maxima in the de Vries cycle. The 88-yr-component, in contrast, tends to develop maxima in phases of low amplitude of the de Vries cyclicity.

    5.3. Solar cycles in Miocene and Holocene times – a comparison

    The close resemblance of the Lomb–Scargle periodograms of the Miocene records and the Holocene ones (Fig. 9) is strongly supporting our interpretation of the detected cycles as expression of variations in solar activity. The appearance of the 1500-yr-cycle as an “Earth-system-immanent cycle” is the major difference between both diagrams. This observation is of substantial importance as this cycle is also known from a Late Miocene lake in Greece (Weber et al., 2010) as well as it was indicated previously for Lake Pannon (Paulissen and Luthi, 2011).

    ordvic | June 29, 2016 at 4:56 pm |

    Peter, Javier compiled the graph.

    https://judithcurry.com/2016/06/27/are-we-headed-for-a-new-solar-minimum/#comment-792651

    • Ordvic,

      “you seem to have changed your tune? Here you are arguing that we will be going into a relatively stable climate period.”

      You could have condensed that entire thread into the part that interests you.

      It is the same I am saying here:

      “8. No support for an approaching grand solar minimum comes from the analysis of the ~ 1000-yr Eddy and ~ 2400-yr Bray cycles. Analysis of these two long solar cycles indicates that we are probably in a prolonged warm period likely to last for several more centuries.”

      I simply don’t see any factor in the near future (200-300 years) that could strongly change the temperatures in any direction. In figure 18 the scale is essential. I am proposing that it may take us several centuries to go back to early 20th century temperatures below the 1961-1990 average.

      • Yes I saw that in your conclusions but this is what I was talking about: Whatever its cause, the observed effect of the ~ 2400-yr Bray cycle is to result in long grand solar minima (GSM) or clusters of GSM at its lows. According to Usoskin et al., 2007:

        “the occurrence of grand minima depicts a weak (marginally significant) quasi-periodicity of 2000–2400 years, which is a well-known period in 14C data… no clear periodicities are observed in the occurrence of grand maxima.”

        This fits well with the observation that unlike the last glacial period, during the Holocene after it reaches its Hypsithermal or Climatic Optimum there are no warming events, just cooling events followed by recovery, and thus a warming period cannot be separated from the previous cold event without losing context. According to this view, a low in the Bray cycle would increase the probability of a long GSM or a cluster of GSM that would reduce temperatures and cause changes in precipitation patterns bringing about a general worsening of the climate for a few centuries. The end of the low would bring about a return to normal solar activity with a natural increase in temperatures that can also take a few centuries.

      • Sorry Ordvic,

        I might be a little thick today and I am not following your argument that includes such a long quotation. Could you make it simple for me?

      • Javier,
        I kind of thought we weren’t on the same page. My original argument was that we are at the start of the Eddy cycle that points to Oort as the model. In other words the first three or so solar cycles (The next 30 to 50 years)are at a minimum then the next three or so go back up. Oort is followed by wolf, sporer, maunder etc resulting in the bottom of a little ice age in 500 years.

        You seem to portray conflicting projections:
        You say:
        8. No support for an approaching grand solar minimum comes from the analysis of the ~ 1000-yr Eddy and ~ 2400-yr Bray cycles. Analysis of these two long solar cycles indicates that we are probably in a prolonged warm period likely to last for several more centuries

        Yet you also said:
        Whatever its cause, the observed effect of the ~ 2400-yr Bray cycle is to result in long grand solar minima (GSM) or clusters of GSM at its lows. According to Usoskin et al., 2007:

        “the occurrence of grand minima depicts a weak (marginally significant) quasi-periodicity of 2000–2400 years, which is a well-known period in 14C data… no clear periodicities are observed in the occurrence of grand maxima.”

        These are directly contradictory!

        The first says prolonged warm period
        The second says grand solar minima

      • Ok, Ordvic,

        I don’t see that as contradictory. The lows in the Eddy and Bray cycles appear to result in GSM that coincide with a reduction in temperatures and a worsening of the climate (change in wind and precipitation patterns). Between those lows, when no other factor (volcanic, oceanic) is cooling the climate, conditions are described as warm as the default situation in the interglacial.

        As we just passed the lows in the Eddy and Bray cycles 300-400 years ago, no other low is expected for about 500 years. The ~ 1500-yr oceanic cycle low is also just past. Therefore we should not expect GSM for the next 500 years at least. We are at a long interval that started 180 years ago and that is likely to last at least 300 more, and barring strong volcanic activity we should not expect strong deviations in the temperatures. If there is warming or cooling it should be modest in comparison with the changes that have taken place in the past 500 years.

        I think I have been defending this view for some time since I completed my analysis of past solar activity.

      • Javier.
        Well this seems to explain the differences I see in your analysis and also my own observations:

        “Between those lows, when no other factor (volcanic, oceanic) is cooling the climate, conditions are described as warm as the default situation in the interglacial”

        Thanks for responding with this explanation.

  43. Javier knows his material that no one can doubt.

    My only two disagreements with him are I think there is a major volcanic activity solar tie in and I think there is at least a 50% chance of a Dalton like minimum coming up which has started already.

    As far as predictions one would have to be correct time after time before I would take anything serious.

  44. “The 3.2 kyr event with its two centuries long megadrought in the Eastern Mediterranean was not associated with a reduction in solar activity nor did it display the climate signature of a solar event. Given the date it is probable that it coincided with a low in the ~1500 year oceanic cycle that also occurred around 1700 years ago at the end of the Roman Warm Period and during the LIA.”

    It is probable that ocean cycles are solar forced. But where is your evidence that “nor did it display the climate signature of a solar event”?

  45. I am very surprised that this graph isn’t posted here. I have posted it before.

    A 2500 year rainfall reconstruction correlated to cultural events.

    • Well, it is posted now. The problem of a proxy that only runs for 2500 years in an article on the 2400 year solar cycle is that it only includes one point. And that point is during the LIA, when we have lots of info from many places.

      Thank you for bringing it up. I have grabbed the graph into my precipitations folder and will look at it with detail.

  46. “The event started with a 50 year reduction in solar activity and temperatures around 2950 yr BP (figure 11a, b), that brought much needed precipitations to the Eastern Mediterranean”

    That region dries with weaker solar activity, like around 1200 BC. The nearest solar minimum started around 1040 BC and ended around 1015.* In fact in ~995 BC there is a cycle maximum very close to the 1727 type of configuration after Maunder. I’ll guarantee that there’s 50 years of stronger solar activity through that period.

    *I’ll gladly show anyone the solar cycle model who is interested. Judith has given up replying to me. Tallbloke is the only person that I have shared it with, but I haven’t been on speaking terms with him since he said I was dispensing with physics. I am trying to organise a video of it so that all can see it without having to obtain a suitable astronomy application.

  47. Javier says

    simply don’t see any factor in the near future (200-300 years) that could strongly change the temperatures in any direction. In figure 18 the scale is essential. I am proposing that it may take us several centuries to go back to early 20th century temperatures below the 1961-1990 average

    Javier it hinges on solar activity or lack of it . If my low solar average parameters are met I think you would agree global temperatures would be down.

    Will they be met is the question ? You think not but others disagree. Time will tell.

  48. You may also like this other review and comparison:

    Source: https://xkcd.com/1732/

  49. I do not know why, probably delibarately, people miss to refer to my findings on solar and climate variability. The cycles and driving mechanisms have long been solved. Moreover there is a whole science on that, not just some absurd “cycles”. The exact mechanism of solar wind even has been solved.
    This stance is out of me. Unbelievable shartfall in the communication of groundbraking ideas.

    • > I do not know why, probably delibarately, people miss to refer to my findings on solar and climate variability.

      And now this list even includes you, Dimitris.

      Got any cites?

    • Are you serious? The Global Journal of Physics? A predatory/fake publisher of the pay to publish anything system. Well, that’s too bad. Nobody will ever cite that except by mistake.

      Perhaps Judith should run a post on predatory publishers, a parasitic internet breed that is another symptom of modern science losing its way under the “publish and perish” axiom. One would think that scientists ought not to be good candidates for being swindled but these people show otherwise.

      • First this is another publisher, don’t mess with the word global they share. Secondly your critique should be on the text, not the publisher. Thirdly the value of a scientific paper is decisive of it’s content.

      • I would like to add that apart from climate variability, the exsplanation of the solar wind phenomenon is probably the greatest breakthrough of my paper.

      • Dimitris,

        I don’t know if you have been deceived or you are trying to deceive us. The Global Publishing Corporation is in Beall’s list of Potential, possible, or probable predatory scholarly open-access publishers.
        https://is.muni.cz/do/econ/soubory/aktivity/vav/60942097/Supplement_2_Bealluv_seznam.txt

        “The first one is published by a firm called Global Publishing Corporation. I have added this publisher to my list. The second one is published by a firm called Council for Innovative Research. This publisher is already on my list, and I recommend that you not submit papers to any of the journals from these publishers. Thank you for alerting me to Global Publishing Corporation, which is a dangerous publisher.”

        Your paper is not published. It is posted in the web of a scammer in pdf format. That is worse than unpublished, because it becomes unpublishable. If you send your paper there they will publish it even if you don’t pay them, but then your effort is dead forever. This is like being a victim of a Nigerian prince. I just hope you didn’t pay them. The impact factor is usually fake, as these type of journals are not listed nor rated in the Journal citation report:
        http://about.jcr.incites.thomsonreuters.com/full-titles-2015.pdf

        I can judge on the merits of your work, being outside my area of expertise, but judging from where it has ended it is clear it hasn’t gone through any quality filter.

      • it is clear it hasn’t gone through any quality filter.

        Javier,

        please can you describe the “quality filter” used for your guest article here.

        Thank you.

      • verytallguy

        “please can you describe the “quality filter” used for your guest article here.”

        So you don’t see the difference between a blog post and a published article? Interesting.

        The only quality filter for my article is Dr. Judith Curry’s criterium to accept it or reject it, and I can tell you that it is a lot higher than for those fake journals. She made me completely rewrite the first article. That should give you an idea.

        Have you tried to submit a guest post to Climate Etc?

      • So you don’t see the difference between a blog post and a published article? Interesting.

        Your inference doesn’t follow from my question.

        The only quality filter for my article is Dr. Judith Curry’s criterium to accept it or reject it,

        So your quality filter is a single review by a person of your own choosing. That sounds not dissimilar to the standard your’re criticising.

        and I can tell you that it is a lot higher than for those fake journals.

        The evidence would suggest otherwise.

        https://judithcurry.com/2016/09/18/is-the-arctic-sea-ice-spiral-of-death-dead/

        Have you tried to submit a guest post to Climate Etc?

        No.

      • verytallguy,

        “The evidence would suggest otherwise.”

        You are not looking at the evidence in an unbiased way. The only requirement to get an article published in a predatory journal is to send it. They will request payment but will publish it anyway if you don’t pay.

        This is a real example of the papers that predatory journals will publish:

        From:
        https://scholarlyoa.com/2014/11/20/bogus-journal-accepts-profanity-laced-anti-spam-paper/

        Now you might be very tall but you stand very short when you compare Judith’s blog to a scam industry. If I were her, you would already be out of here.

      • This is a real example of the papers that predatory journals will publish

        Javier, nowhere have I supported predatory journals. To be clear, I do not.

        *you* have claimed a “quality filter”, and I have given you an example of low quality work that has recently passed that filter.

        Here is another example.

        https://judithcurry.com/2015/05/06/quantifying-the-anthropogenic-contribution-to-atmospheric-co2/

        So, forgive me, but your “quality filter” will impress no-one outside of the bubble of climate change “sceptics”.

        I have not, and have no intention of reading Dmitri’s “theory”, but for you to criticise him on the absence of a “quality filter” and mocking his ability to get cited as a result does seem a mite inconsistent: you’ve written a blog post that will never get cited with no more quality control than review by the blog owner.

      • I don’t know why you insist so much on the journal, it is just a new journal, about two years old and it regular comes out almost bimonthly with new articles.

      • By the way I am not deceiving anybody, my job has been first class science and major discoveries have arisen. What about quality control? The quality is within my work. We are talking about discoveries here, not reports. You have messed with the meanings. Isaac Newton hadn’t published his work in any journal bythe way.

      • > The only quality filter for my article is Dr. Judith Curry’s criterium to accept it or reject it, and I can tell you that it is a lot higher than for those fake journals.

        How can you tell, Javier?

      • I read the paper and blog of Dimitris Poulos. Totally delusional is my first reaction and secondly there is no peer review of any worth happening at the said Journal.

        Sadly there are so many loonies like Dimitris with so called “empirical models” that drag the planetary theory down.

    • Curiously, the ~250yr “synodic cycle” of Earth-Venus much touted by Dimitris Poulos as a climate factor corresponds to a spectral TROUGH in the estimated power density of del18O isotope series from GISP2. See: http://s1188.photobucket.com/user/skygram/media/graph1.jpg.html

      • The Greenland record refers to thousands, not hundreds of years. Moreover the Earth-Venus syzygy duration changes over time. It should be around 80 years, if memory serves, some ten thousand years ago. When the syzygy stops, ten thousand years ago, we fall in an ice age. read the paper thoroughly.

      • The Greenland record refers to thousands, not hundreds of years.

        The length of the GISP2 record is in many thousands of years. But the frequency scale of the GISP2 power density is denominated in cycles per 2000 years, which makes the central period of the 8-th spectral estimate 250 years. Clearly, it is in a deep spectral trough, contrary to the claim of an ostensibly important ~265-year climatic cycle. Learn to read power spectra.

      • over thousand of years the 250 year cycles change because of changes in planetary orbits, you can’t find them in any spectrum. they do not last 250 years anymore, they last 80 years for example.

      • now what’s that? I told you before that the frequencies change over thousand of years, becouse of changes in planetary orbits, you can’t find them in any spectra.

      • already told you, the frequency changes over thousands of years from 250 to say 80 years, due to changes in planetary orbits, so you can’t find it in any spectra. Spectral analysis is primitive.

      • Dimitris:

        Your rationale is wholly unpersuasive. Even if an oscillation gradually shifts its frequency, it will register as a wide peak in the power density spectrum, not as a trough. Since there’s no peak anywhere near the 80yr period in the shown GISP2 spectrum, I suspect that your claimed “cycle” exists only in your mind.

      • 1sky1 over a period of thousands of years shifting frequencies cancel themshelves. anyway there are two peaks at 180 and 400 years. but this is of minor importance.

      • The claim that “over a period of thousands of years shifting frequencies cancel themselves” in power spectrum analysis is sheer nonsense. Nor are there any spectral peaks at 180yrs and 400yrs. There’s a sharp one at 167yrs and a very broad peak centered at ~667yrs, encompassing periods from somewhat less than 500yrs to over 1000yrs.

      • It’s no nonsense. It’s like trying to find harmonics in a sine wave power spectrum. As for the exact periods in the power spectrum is of minor importanse. Anyway power spectrums are nonsense all the way. Even the consideration of O18 as a proxy other for some rugh culculations is nonsense. Finally I am not writing here to make fourrier analysis discussion. Just wanted to present some of my findings. And they are quite well documented. Even if you were correct on the frequencies you should try to find out what is going wrong with them.

      • Anyway power spectrums are nonsense all the way. Even the consideration of O18 as a proxy other for some rugh culculations is nonsense.

        In other words, any empirical evidence that contradicts your claim of a 265yr cycle is ipso facto “nonsense.” LOL!

      • contradicts? nope. a power spectrum can’t contradict anything. especially a δ18Ο one.I have explained that within my paper too.

      • the δ18Ο can’t prescribe the climatic varianility, only stucks to the highs of it. but this is another chapter. even if it did you would only see a 250 year frequency in say the last 2000 years about.

      • a final note is that anyway we can not quantify anything from the above spectrum because it lacks basic data to work on. how many years have been used to produce it for example. the whole 400000 years gisp2 record or just the last 10000 years? etc you can’t make science on a napkin.

      • see figure 6 in my paper to understand how absurd the δ18Ο proxy is.

  50. Why doesn’t this essay include a discussion of

    Zharkova, V. V. et al. Heartbeat of the Sun from Principal Component
    Analysis and prediction of solar activity on a millennium timescale. Sci. Rep. 5, 15689; doi: 10.1038/srep15689 (2015)?

    • In between other things as not being really relevant to the subject I consider Zharkova et al., 2015, to have been already shown incorrect. Leif Svalgaard has already been over that numerous times. Zharkova’s model does not correctly reproduce the past.

      • Thank you. This submitted manuscript by Usoskin and Kovaltsovwas interesting:

        A two-wave dynamo model by Zharkova et al. (2015) disagrees with data on long-term solar variability. http://arxiv.org/abs/1512.05516

        I look forward to its publication.

      • Yes, Usoskin is saying the same as Leif Svaalgard.

        But that is not a submitted manuscript, but an extended version of a comment sent to Sci. Rep. It probably means that it might not be published anywhere. It has been deposited in arXiv so interested parties can read it.

  51. “The Eddy cycle is modulated by a longer cycle resulting in very strong lows (both in solar activity and climate worsening) during the early Holocene at 11.2, 10.2, 9.2, 8.2, 7.2, 6.2 and 5.2 kyr BP, followed by subdued lows at 4.3..”

    OK on GISP, 8.2 and 7.2 are both cold, and 5.2 and 4.3 are both warm.

  52. Javier,

    Been waiting for a lucid overall description of global climate changes over long periods of time. This is it. While I don’t have enough learning to tell me if this is completely correct, it’s put together well enough to convince me this is the best there is for now (that I’ve seen, at least).

    I would like to see a more thorough analysis of the transition zones between glacial/interglacial/glacial, but I think you hinted at some possible reasons in your discussion (meaning, I need to go read it again and more thoroughly).

    Again, thank you for all your hard work and for making it “lucid” and “reasonable” to boot.

    Also a big thanks to Judith for allowing guest blogs such as this and all the others.

    GeoffW

    • Thank you for your kind words Geoff,

      I have some articles on the glacial-interglacial cycle, and in the abrupt climate changes of the glacial period (Dansgaard-Oeschger events) that are unpublished in English. I don’t know if Judith would be interested in those.

      If you read Spanish I can provide a link.

      • I have a resource (my daughter : ) who is bilingual in Spanish. If you could provide a link, she might provide me with a verbal reading (she is, except for short translations, too busy (grade school teacher) to translate it to English).
        Or, maybe Judith can provide you another guest blog? Maybe a shortened version of what is in Spanish?
        Anyway, thanks again.
        GeoffW

      • Also wanted to commend you on your patient (and many) replies to various comments, questions, and a correction or two that you graciously accepted. This is, without a doubt, a very tough crowd : )
        GeoffW

  53. Reblogged this on The Climate Realist's Resource and commented:
    Here’s an excellent essay posted at Climate Etc., an excellent, climate realist blog run by Dr. Judith Curry, a climate scientist, climate realist, and professor at Georgia Tech, by a guest author named Javier. The article has a great summary of the solar effect on climate, more particularly the effect of the ~2400-year Bray solar cycle on climate, and I thought it so good I should share it with you. (Javier and I share many similar views on the effects of solar activity variations on climate and their implications for current climate debates.)

    • I didn’t reblog this, and without comment, because the author thinks GHGs don’t matter, which is totally whacked. He bows down before every piece of paleoclimate data that he thinks supports his preferred ideas, while ignoring the voluminous data published about the warming influcences of anthropogenic GHGs.

      What can you do, except laugh? (No, I didn’t blog that last comment, either.)

      • > What can you do, except laugh?

        Chill, if only because (a) you’re not funny, and (b) audits never end, (c) spamming leads to moderation, (d) you have nothing to gain from food fights, (e) if you can’t keep your cool facing Goblins, what will it be when you’ll meet level bosses?

      • Willard wrote:
        “(b) audits never end”

        Please, by all means, honestly audit to your heart’s content. And beyond.

        That’s far more than Javier has done.

      • DavidA,

        Me and Javier already exchanged our secret handshake. My job is done for now. We’ll see when he’ll take PaulS’ question more seriously. This may take a while. It will be on another thread.

        Javier’s the most serious contrarian we’ve had since a long while, so we should welcome him.

        My comment wasn’t about Me or Javier anyway, but about your own performance. At this rhythm, you’ll burn yourself and you’ll antagonize everyone. You’ll become the souffre-douleur of Denizens, and you’ll soon have to cater to a gangbang of comments.

        I don’t think this is the ball you wish to play. Replace “ball” with “communication objective” if you don’t get what I’m saying. You have something better to contribute.

        In any case, please rest assured that if I had to choose a player on my team, I’d even pick Wagathon before you. This should give you a fair idea idea of how much stylelessness you’re sweating with your comments.

      • Willard wrote:
        “At this rhythm, you’ll burn yourself and you’ll antagonize everyone.”

        a) I rarely comment on this blog; I’m just in a mood lately.

        b) I honestly couldn’t care less what you or anyone else here thinks of me, Willard. Given the content in these comments, antagonizing everyone would be a honor — especially “no-GHGs” Javier.

        I realize you all want to stay in your comfy zone, finding support in your mutual denialism.

      • > I rarely comment on this blog […]

        Number of “David Appell |” on this page: 46.

        Number of comments to date: 241.

        From where I come from, what you do is called eating the puck. Nobody wants to play with somebody who eats the puck all the time. Including your team mates.

        Here’s a reminder of how this is supposed to go:

        The primary aim of conversationalists should be to keep the conversation going in a way that’s enjoyable to all. This requires some suppression of individuality: no long lectures on one’s own children or merchant ventures; no insistence on one’s own views of some novel. At the same time, everyone has to have a unique perspective to contribute to move the conversation forward. And Bizell & Herzberg (The Rhetorical Tradition, 2nd Ed.) provide a nice summary of where conversations are supposed to end up:

        Harmony among conflicting viewpoints, not the victory of one of them, should be the ultimate goal (and the topics discussed in Scudéry’s conversations are usually left unresolved for that reason).

        Note that “harmony,” unlike “consensus” requires diversity. We do in fact have to live with irresolution in the blogosphere. But can we come to like it?

        https://scientistscitizens.wordpress.com/2011/08/05/some-communication-principles-for-an-e-salon/

        You are not doing a simulatenous exhibition here, playing against everyone at the same time. There’s nothing to win, you know. It’s just a series of exchanges. Then comes another blog post.

        The tears of the world are a constant quantity.

      • David Appell,

        “the author thinks GHGs don’t matter, which is totally whacked. He bows down before every piece of paleoclimate data that he thinks supports his preferred ideas, while ignoring the voluminous data published about the warming influcences of anthropogenic GHGs.”

        You are making things up and building your own strawman probably because you didn’t read the article, where it clearly says:

        “To the natural warming caused by the post-LIA recovery we have added the anthropogenic warming. Nowhere is the anthropogenic effect more noticeable than in the status of the cryosphere. Globally glaciers have retreated to a point last seen around 5000 years ago, during the Mid-Holocene Transition at the start of the Neoglacial period. That is the reason why organic remains like Ötzi, the iceman from Tyrol, from 5200 BP are being uncovered. It is possible that the cryosphere is particularly sensitive to greenhouse gas warming, since water vapor content is very low when the air is very cold. Nevertheless we cannot rule out that global average temperatures are approaching values that took place during the 5.2 kyr event as figure 16 suggests.”

        The issue of how much GHGs are contributing to current warming has been beaten to death in this blog so I don’t think it would be constructive to repeat it here.

      • > The issue of how much GHGs are contributing to current warming has been beaten to death in this blog so I don’t think it would be constructive to repeat it here.

        Repeating the things that would substantiate your actually would be constructive, Javier, since you claimed that It is very likely that anthropogenic warming has been overestimated, without really arguing for it.

        All you did was a review, after all, notwithstanding a little data fiddling here and there.

      • “Repeating the things that would substantiate your actually would be constructive, Javier, since you claimed that It is very likely that anthropogenic warming has been overestimated, without really arguing for it.”

        It is simple arithmetic, Willard. If the effects of the solar variability of the Bray cycle take centuries to pass as evidence supports, and this solar effect warming has not been accounted for, then it is obvious that part of the warming assigned to GHGs does not belong there.

      • > It’s basic arithmetic.

        It’s actually accounting, Javier, as in solar variability warming is not properly accounted for.

        That accounting rests on a appeal to ignorance, i.e. according to paleoclimatic data presented here, due to a poor understanding of its mechanisms.

        That we don’t know how to “properly” account for solar variability neither imply we don’t (which would be false) or that it’s underestimated, which we don’t know yet.

        Pretty basic indeed.

      • > It’s basic arithmetic.

        Make that “It is simple arithmetic.”

      • Willard, thanks for the language tips. One never ends learning a language, not even the first.

        Simple accounting is my argument then, whether it convinces somebody or not. If we didn’t know that solar variability had such a large influence on climate change we cannot have properly accounted for it. There is at least a significant error in our attribution coming from this side.

      • > [T]hanks for the language tips.

        My point wasn’t semantical, Javier, unless we consider algebraic semantics. Even then, it’d be like using a bazooka to kill a mosquito. Were I using a semantical argument, what the hell you mean by “very likely” in It is very likely that anthropogenic warming has been overestimated.

        One does not simply show some graphs, tell the short history of human civilization in a few longuish paragraphs, and then state that something is very likely. Certainly not the way IPCC interprets “very likely.” You simply have no basis to issue such modality.

        From the fact that we don’t know everything we’d like to know about the Sun (some still suspect it’s made of iron), doesn’t follow that our estimate is very likely too low, whether this passes Judy’s “review” or not.

        That’s just crap.

      • I should revise before hitting send:

        (1) Were I using a semantical argument, I’d be asking what the hell

        (2) From the fact that we don’t know everything we’d like to know about the Sun (some still suspect it’s made of iron), doesn’t follow that our estimate of the impact of the Sun’s impact is very likely too low […]

      • Gosh.

        Sometimes, WP, you really suck.

      • Are you talking to me? Because those are certainly not my views.

      • > Are you talking to me?

        You must be new here, Another.

        I first responded to DavidA’s “What can you do, except laugh?” Followed an exchange with DavidA.

        Then I responded to Javier’s “I don’t think it would be constructive to repeat it here.” Followed an exchange with DavidA.

        The “>” is Markdown’s way to mark a quote. I use it instead of emphasis or blockquote because I use emphases and blockquotes for something else.

        Sometimes I don’t mention the name of the person because I don’t feel it matters. Responding to comments instead of addressing to persons helps defuse antagonism.

        Hope this helps.

      • Willard,

        Following your convention:

        > Sometimes, WP, you really suck.

        Sometimes, I really miss Usenet.

      • Damn Willard, you are beginning to grow on me.

        Kind of like Mosher did some time back.

    • Willard, again, I don’t care what you think.

      I’ve commented in the last 4-5 days. Hardly ever before that, just once in awhile.

      Scroll past me if you’d prefer.

    • Thanks JustAnotherPerson.

      I think more people should realize the huge amount of evidence supporting an important role for solar variability in climate change.

      • Absolutely correct. That’s why I have a list of papers on the solar influence on climate at my blog. Now, of course, man has certainly contributed significantly to the warming we’re seeing, but the current lack of focus on the natural influences on climate in my opinion hurts climate science as a whole and biases results towards those favoring human domination of climate.

      • JAP wrote:
        “…the current lack of focus on the natural influences on climate in my opinion hurts climate science as a whole and biases results towards those favoring human domination of climate.”

        I suspect you don’t try to keep up with the scientific literature. It’s a torrent, but here are some things I have noticed passing by:

        Papers that find a minimal impact from a future grand solar minimum:

        Feulner and Rahmstorf (2010)
        http://onlinelibrary.wiley.com/doi/10.1029/2010GL042710/abstract

        Meehl et al (2013)
        http://onlinelibrary.wiley.com/doi/10.1002/grl.50361/abstract

        Maycock et al (2015)
        http://centaur.reading.ac.uk/40588/

      • JAP: More, with their findings for climate sensitivity to solar:

        five papers on how solar changes influence mean surface temperatures:

        0.18 K/W/m2
        Camp and Tung, GRL 2007 doi:10.1029/2007GL030207

        0.07 K/W/m2
        Meehl et al, GRL 2014
        doi:10.1002/grl.50361

        0.03 K/W/m2
        Feulner and Rahmstorf, GRL 2010, first example doi:10.1029/2010GL042710

        0.08 K/W/m2
        Feulner and Rahmstorf, GRL 2010, second example doi:10.1029/2010GL042710

        0.07 K/W/m2
        Song et al GRL 2010
        doi:10.1029/2009GL041290

      • A Google Scholar search on “solar forcing” returns 13,600 results, 1,420 since 2015 (viz. in either 2015 or 2016).

      • Geoff Sherrington

        Javier,
        Thank you for shining a light on past natural, but unusual, events. I have not read about these events and their associations so thoroughly compiled before
        Underlying the bulk of the bloggers comments here is a harsh fact.
        Fact is, nobody has yet demonstrated an ability to attribute changes in climate to either man-made or natural.
        We know that natural continues, we suspect with patterns similar to the past.
        We have only guesses about man-made.
        I wish David Appell would pull his head in and not pollute your thought-provoking essay with assertions and papers based on guesses. Guesses like what the value of climate sensitivity is, however defined.
        You know, fundamental matters.
        Geoff.

      • Thank you Geoff,

        “Fact is, nobody has yet demonstrated an ability to attribute changes in climate to either man-made or natural.”

        I think that is the bottom line of Judith’s blog.

        “I wish David Appell would pull his head in and not pollute your thought-provoking essay”

        It doesn’t bother me the least. This is internet. There are polemicists, some coming from humanities specialized in rhetorics and argumentation with enough reading, thinking that science is like a TV debate. Best is not to engage them. The cold truth is that the amount of evidence supporting a very important role for solar variability in climate change is staggering. That cannot be changed. And it is not accounted for in current AGW hypothesis. Just one more piece of damning evidence. But it doesn’t matter either, because the climate is not going to do what they think is going to do, so theirs is a lost cause.

  54. Willard has style and while many may disagree with his POV on many things, I for one, often learn from and enjoy interacting with him. There are some commenters here, however, who tend to be abrasive when their POV or on-line behaviour is challenged and resort to belittling their opponents and/or posting ad hominens rather than addressing the arguments being put by their opponents.

    I also believe that Judith shouldn’t allow commenters to post more than (say) 10 comments on any thread, with the exception, of course, those who have contributed the head posting and need to reply to those who have commented. I post this not caring what anyone thinks of me or of what I say, only that I honestly care about CE being maintained as a good and informative read for people who are genuinely interested in the science and policy aspects of the climate debate.

    • Many patients worked to bring these flaws to light: They wrote blogs; they contacted the press; they successfully submitted carefully argued letters and commentaries to leading medical journals. They even published papers in peer-reviewed scientific journals.

      They also filed Freedom of Information Act requests to gain access to the trial data from Queen Mary University of London, the university where the lead researcher worked. The university denied most of these, some on the grounds that they were “vexatious.”

      Critics painted as unhinged

      The study’s defenders painted critics as unhinged crusaders who were impeding progress for the estimated 30 million ME/CFS patients around the world. For example, Richard Horton, the editor of the Lancet, described the trial’s critics as “a fairly small, but highly organised, very vocal and very damaging group of individuals who have, I would say, actually hijacked this agenda and distorted the debate so that it actually harms the overwhelming majority of patients.”

      Press reports also alleged that ME/CFS researchers had received death threats, and they lumped the PACE critics in with the purported crazies.

    • “In the meantime, a Freedom of Information Act request from Australian patient Alem Matthees was making its way through the legal system.

      Matthees had asked for the anonymized data necessary to analyze the study using its original standards for success, but Queen Mary University of London had refused the request, arguing that malicious patients would break the anonymization and publish the participants’ names to discredit the trial. It again cited the death threats.”

      sound familar guys?

  55. Javier “What degree of temperature range on the earth is involved?”
    ” a grand solar minimum could reduce average temperatures by about 0.1°K”
    a Maunder type minimum could reduce temperatures by about 0.25°K:

    Both these values seem wrong
    0.1% of 287 K is 0.287 K.
    0.2% is 0.57 K.
    Silly to restrict solar variability to just 0.1%
    Your reference
    Feulner, G., & Rahmstorf, S. (2010). in fact gives a range of values for 0.1 and 0.25% reduction backing up my assertion in that they range from 0.32 to 0.68 K.
    Furthermore the Maunder Minimum was colder than this so if one attributed it solely to the sun decrease you would have figures of 0.5% for the sun and 1.43K for the temperature decrease.
    I doubt if the If the 0.1K reduction quoted was truly Leif.
    That figure comes from the expected impact of a minimum in a model with rising CO2 till 2100.

    • angech,

      Silly to restrict solar variability to just 0.1%

      Read paragraph nine of Feulner & Rahmstorf (2010):

      [9] Climate forcings for these millennium simulations were taken from Crowley [2000] for the volcanic forcing, from the compilation by Jansen et al. [2007] for preindustrial greenhouse gas concentrations, and from Joos et al. [2001] for carbon dioxide and other anthropogenic constituents since the beginning of the industrialised era. Two different reconstructions for the total solar irradiance (TSI) were used. One is based on 10Be isotope measurements from an ice core [Bard et al., 2000] and is scaled to a 0.25% reduction of TSI during the MM relative to the TSI in the year 1950 of 1366 W/m2 [Jansen et al., 2007], while the other infers TSI from a model of the Sun’s magnetic flux [Wang et al., 2005] after 1713 and uses Bard et al.’s [2000] TSI scaled to a 0.08% reduction in MM TSI relative to 1950 for earlier epochs [Jansen et al., 2007]. This higher value of the TSI during the MM agrees well with recent TSI reconstructions [Steinhilber et al., 2009].

      F&R are being rigorous including the Bard et al. (2000) 0.25% reduction because using it gives a result that’s within two standard deviations of proxy temperature reconstructions of the LIA … i.e., they can’t rule it out. However, if you look at the results in Table 1, the 0.1% value gives modeled temperature values much closer to the proxy reconstructed temps. Here’s what F&R have to say about that:

      [12] To assess how the model used in this study responds to pronounced long‐lasting minima in solar forcing, we take the modelled values for the global mean temperature averaged over the time intervals of past grand minima of solar activity and compare them to a reconstruction of past global temperatures [Mann et al., 2008] (see Table 1 and Figure 1). For the Wolf, Spörer, Maunder, and Dalton minima, the model driven with weak variations of solar forcing (MM TSI 0.08% below 1950) shows excellent agreement with reconstructed temperature anomalies relative to 1961–1990, while for a stronger decrease of solar activity during grand minima (MM TSI 0.25% below 1950) modelled temperatures are about 0.15°C cooler. At first sight this appears to favor the low‐amplitude TSI history, but cannot exclude the high‐amplitude variations of solar irradiance due to uncertainties in the reconstructed forcings and temperatures as well as in climate sensitivity. Indeed, the high‐amplitude forcing is still within the 2 s uncertainty range of the global temperature reconstructions shown in Figure 1.

      So yes, it would be silly to *insist* on 0.1% TSI reduction from 1950 during the MM as the only plausible value. At the same time, implying that the higher 0.25% is equally plausible is fraught when multiple consilient lines of evidence point toward the lower value. You might check out Lean/Sheely (2000/2005) as further support for a 0.1% TSI change from the MM to present.

      • Thanks Brandon,
        You have the ability to read and put up the relevant bits of papers and argue from them.
        This paper shows a model compared with a model agreeing with that model.
        There are a lot of problems in that approach as you know.
        Worse on reading your post it is evident that the authors only used the period 1961-1990 for 0.1% where agreement was excellent ignoring the fact that the previous Minima did not agree.
        Did you miss that?
        Further they imply strongly that the 0.25 % is much more likely when they said for the same period earth was 0.15 C too warm in 1961-1990 using that figure, which means it was correct for all the previous Minima.
        Having to work out what people mean from what they do not say is a pain but rewarding.
        As anoilman said at another blog
        “Cherry picking and grasping at wrong conclusions is not a good stance to take on anything.”
        Not that you are cherry picking, the authors were, and you should be good enough to recognize and admit this.
        Unless you agree with Willard that anything goes.

      • angech,

        This paper shows a model compared with a model agreeing with that model.

        Technically, everything is a model, even “observations”. I’m afraid you’re going to have to disambiguate. Try quoting the paper directly to illustrate what you mean to say.

        Worse on reading your post it is evident that the authors only used the period 1961-1990 for 0.1% where agreement was excellent ignoring the fact that the previous Minima did not agree.

        Did you miss that?

        I guess so, because I don’t understand what you’re arguing. Even a cursory examination of TSI reconstructions demonstrates that they don’t agree with each other, and one of the main points of the paper was to check how sensitive their simulations were to that discrepancy.

        Which I think is *good* science — the *exact opposite* of cherry picking — fer cryin’ out loud! :-)

  56. 7. The paleoclimatic effects of very low solar activity lend support to Haigh’s hypothesis of solar induced atmospheric changes due to changes in irradiation and stratospheric ozone.

    This piqued my interest, let’s follow the trail.

    Javier’s Bibliography takes us here, a 1996 paper in science, no less, using a GCM (boo denizens) to investigate the 11 year solar cycle, and effects of UV vs total TSI therein.

    https://workspace.imperial.ac.uk/physics/Public/spat/jo/The%20impact%20of%20solar%20variability%20on%20climate.pdf

    It is “interesting” of course, that Javier chooses to rely on GCM results for this aspect of climate, but totally rejects them for others.

    Anyway, the obvious question is where does this fit into current scientific understanding. Helpfully, the UN set up the IPCC for that. Haigh’s work is referenced extensively in chapter 8 of AR5, including Haigh 1996.

    http://www.climatechange2013.org/images/report/WG1AR5_Chapter08_FINAL.pdf

    Here we discover:

    As UV heating of the stratosphere over a SC has the potential to influence the troposphere indirectly, through dynamic coupling, and therefore climate (Haigh, 1996; Gray et al., 2010), the UV may have a more significant impact on climate than changes in TSI alone would suggest. Although this indicates that metrics based only on TSI are not appropriate, UV measurements present several controversial issues and modelling is not yet robust

    That seems pretty equivocal, and there is no hint anywhere that these effects are well understood enough or of large enough magnitude to affect the overall conclusions of the chapter.

    Other aspects of Chapter 8 are rather less equivocal:

    It is unequivocal that anthropogenic increases in the well-mixed greenhouse gases (WMGHGs) have substantially enhanced the greenhouse effect, and the resulting forcing continues to increase

    What does Haigh think of this? Well, she did help to write it!

    Contributing Authors:
    … Joanna Haigh (UK)…

    From which it seems more than possible that the “Haigh hypothesis” does not, in fact, offer substantial support to Javier’s Conjecture. And Haigh’s signature on the document strongly mitigates against Javier’s

    6. Despite a clear and intense paleoclimatic effect, changes in solar activity are not properly accounted for in our current understanding of climate forcings due to our ignorance of the underlying physical mechanisms. This underestimation of solar forcing has the inevitable consequence of an overestimation of anthropogenic forcing

    or his later

    mythical overbearing warming capabilities of CO2

    One begins to wonder if proper application of a “quality filter” might be appropriate to Javier’s Conjecture.

    • Thanks, Very Tall.

      Not sure what you’re referring to as the Javier Conjecture, but let’s not forget Stephen Wilde’s hypothesis mentioned in that comment and summarized below:

      Summary of the Stephen Wilde Hypothesis

      In essence: The Sun affects the ozone layer through changes in UV or charged particles. When the Sun is more active there is more ozone above the equator and less over the poles, and vice versa. An increase in ozone warms the stratosphere or mesosphere, which pushes the tropopause lower. There is thus a solar induced see-saw effect on the height of the tropopause, which causes the climate zones to shift towards then away from the equator, moving the jet streams and changing them from “zonal” jet streams to “meridonal” ones. When meridonal, the jet streams wander in loops further north and south, resulting in longer lines of air mass mixing at climate zone boundaries, which creates more clouds. Clouds reflect sunlight back out to space, determining how much the climate system is heated by the near-constant incoming solar radiation. Thus the Sun’s UV and charged particles modulate the solar heating of the Earth.

      http://joannenova.com.au/2015/01/is-the-sun-driving-ozone-and-changing-the-climate/

      Do you prefer solar winds, UVs or good old cosmic rays?

      • Willard, 

        Conjecture:
        an opinion or conclusion formed on the basis of incomplete information.

        Hypothesis:
        a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.

        Our narrative is thus :

        Javier’s (for it is he) unfortunate misunderstanding (let’s be charitable here)  of Haigh’s position led him to think her hypothesis was that solar UV variation dominates climate change. 

        [aside: yes,  we know her hypothesis actually seems to be the IPCC consensus position, which she helped write,  but shhh,  don’t let on to Javier]

        Javier spent many years toiling to put together a chronology of climates past. Rivers ebbed and flowed, glaciers waxed and waned, whole civilizations rose and fell. 

        Alas,  befuddled by incomplete information,  Javier jumped to a conclusion,  and formed his considered opinion:

        Javier’s Conjecture:
        It was the Sun wot done it. By mysterious 2nd order effects.   AGW is bunk.
        (for long version see conclusions 1-9)

      • Willard,

        it is interesting that Javier feels Stephen Wilde’s work is worthy of “serious consideration”. (perish the thought that it be given frivolous consideration, that wouldn’t do at all).

        One wonders what quality filter Javier applied before reaching this conclusion.

        Incidentally, one also wonders what this effort of due diligence to Javier’s work might teach denizens or others as to the value of the quality filter applied before guest posts are accepted at Climate Etc.

        As to “solar winds, UVs or good old cosmic rays?”

        I’d like to weasel out of that and instead propose Force X from outer space. It all lines up perfectly with the Javier Conjecture

        http://scienceblogs.com/stoat/2014/06/18/force-x-from-outer-space/

      • Thank you for the clarifications, Very Tall.

        I’d be tempted to word Javier’s Conjecture thus: It is very likely that anthropogenic warming has been overestimated.

        The reason invoked is rather interesting:

        since solar variability warming is not properly accounted for, according to paleoclimatic data presented here, due to a poor understanding of its mechanisms

        I’m not sure how paleoclimatic data alone can lead us to conclude anything regarding the quality of our accounting for solar variability. An interpretation seems to be missing, or at least an interpretation of an interpretation.

        The “poor understanding” is also a bit unclear to me. Does it mean that he, Javier, has a better understanding than (say) the IPCC? This would mean that if (say) the IPCC would have the same understanding of the solar mechanisms as Javier’s, it’d correct its accounting. But then, how can (say) the IPCC could miss Javier’s Conjecture if it only rests on a review of the lichurchur?

        Something’s amiss.

  57. I find Javier’s: “Impact of the ~ 2400 yr solar cycle on climate and human societies” a mixture of anthropology with a history of climate changes. I found it interesting and informative.

    There is a reason why civilizations have been fascinated with the sun. The sun is important. The idea that civilizations have had episodes of feast and famine coincident with environmental changes is not earth shattering either. Vast and complicated religions existed to explain changes of people’s circumstances, the religions kept the focus upon the sun.

    The commingling of sun observations and more recently the noted changes in the sun’s type of energy output means another step forward in understanding our world and its place in the universe. Exciting stuff.

    As the science behind climate science is not settled, and has acquired a certain religious fervor to it, it is also not surprising that when the sun’s role in climate change is re-raised, there is push-back by some, scrutiny by others, and enthusiasm for further elucidation by still more.

    We know intuitively, just like those ancients so long ago, that it is the sun, just how much? how does it all work? Important questions to be pursued in earnest were it not for the mitigation religion that currently dominates research monies allocations.

    Yet, another look at the sun is an informative step forward.

  58. Did someone say fascinated by the sun? The Mayans were also.

  59. Denizens might also like:

    The efficacy (E) of a forcing is a measure of its capacity to generate a temperature response in the earth’s system. Most Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models assume that the efficacy of a solar forcing is close to the efficacy of a similar sized Green House Gas (GHG) forcing.

    This paper examines the possibility that a change in short wave solar forcing may more readily contribute to ocean heat content (OHC) than a similar change in long wave GHG forcing. If this hypothesis is shown to be correct, then it follows that equilibrium restoration times at the top of the atmosphere (TOA) are likely to be considerably faster, on average, for a change in GHG forcing than for a similar change in solar forcing.

    A crude forcings model has been developed that matches almost perfectly (R2=0.89) the National Oceanic and Atmospheric Administration (NOAA) temperature series from 1880 to 2010. This model is compared to and performs much better over this period than the United Kingdom Met Office’s (HadGEM2) contribution to the CMIP5 (R2=0.16).

    It is concluded, by implication that the efficacy of a GHG forcing is likely to be considerably lower than the efficacy of a similar sized solar forcing.

    http://www.witpress.com/elibrary/wit-transactions-on-engineering-sciences/83/27156

    Go team!

    • WIT Press is listed here as a predatory, or possibly predatory, journal:

      https://scholarlyoa.com/publishers/

    • Other suspicious aspects of that paper:

      1) The author isn’t a scientists, nor affiliated with an academic institution, but is apparently an engineer with “SRG Industries.”

      2) His first equation is wrong, since not all radiation initiates at the surface. The proper equations to use are the Schwarzschild equations, sometimes called the two-stream equations, which take into account the fact that the atmosphere itself radiates.

      3) His/Her abstract says “Most Coupled Model
      Intercomparison Project Phase 5 (CMIP5) climate models assume that the
      efficacy of a solar forcing is close to the efficacy of a similar sized Green House Gas (GHG) forcing.”

      I have never heard of “efficiency” regarding a climate forcing. Has anyone else here?

      4) He/She spells “greenhouse” as “green house.” Sign of an amateur.

      I’m afraid this has all the hallmarks of junky science. Has anyone else referred to this paper since publication, anywhere?

      • Appell, “I have never heard of “efficiency” regarding a climate forcing. Has anyone else here?”

        It has been a pretty common topic. https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-8-5.html

        The paper isn’t going to be, but the topic is.

      • Thanks for that link.

        Now, wanna address the paper’s other issues?

      • appell, “Now, wanna address the paper’s other issues?”

        Nope, I wasn’t impressed. Solar efficacy though is complicated by aerosols which should have “normal” value depending on your reference initial condition which means that “normal” stratospheric and tropical ozone would also need to be estimated. Best guess though, solar has a higher average efficacy than GHGs.

      • Explain why it’s justifiable to use the Beer-Lambert law instead of the Schwarzschild equations.

      • Appell, a “crude” model is just that, you don’t need to justify “crude.” And as I said, I see no reason to critique that paper because I wasn’t impressed.

        You can avoid both by just using the SW radiant energy available at the surface like you would estimating the energy for a solar pond and get a similar “crude” estimate. The biggest problem is without knowing “normal” aerosol optical depth and “normal” ozone you are still just making a SWAG anyway.

      • “Appell, a “crude” model is just that, you don’t need to justify “crude.””

        Even crude models don’t violate basic physics.

        This model does.

      • > I have never heard of “efficiency” regarding a climate forcing.

        Sign of an amateur.

      • Appell, “Even crude models don’t violate basic physics.

        This model does.”

        Then perhaps you should write a nice critique for the author. If you are curious about how the efficacy of solar forcing can vary though in sea water, a simple solar pond is a great example.

        Since about 30% of the incident solar energy reaches a depth of 2 meters in the liquid and CO2 induce back radiation only impacts the thin skin layer mainly by reducing heat loss, there appears to be a touch of difference in how the two forcing elements impact liquids, one being more efficiency at adding heat energy to the liquid than the other.

        https://is.muni.cz/www/384/30618518/Solarpond.pdf

        Of course that requires considering the incidence angle in one case and not the other, almost like you need different equations to determine the average power available for the liquid ocean and the gas “insulation”. I believe about 70% of the surface is liquid if that matters.

      • Javier knows his stuff you just do not agree with him, hence your commentary.

  60. Pingback: I numeri del Sole, roba da venerdì. | Climatemonitor

  61. John321 claims that the 250 year frequencies do not show in O18 spectra from Greenland. But the frequency changes over thousands of years from 250 to say 80 years, due to changes in planetary orbits, so you can’t find it in any spectra. Spectral analysis is a primitive method.

  62. Pingback: Solar Forcing in Our Climatic and Atmospheric Dynamics. Location, Location, Location (by Diego Fdez-Sevilla, Ph.D.) | diego fdez-sevilla, PhD.

  63. Cook and Lewandowsky have a new offering, The ‘Alice in Wonderland’ mechanics of the rejection of (climate) science: simulating coherence by c*ism

    “CO2CO2 keeps our planet warm ….”
    — Ian Plimer, Australian climate “skeptic”, Heaven & Earth, p. 411
    “Temperature and CO2CO2 are not connected.”
    — Ian Plimer, Australian climate “skeptic”, Heaven & Earth, p. 278
    “Why, sometimes I’ve believed as many as six impossible things before breakfast.”
    — The White Queen, in Through the Looking-Glass, and What Alice Found There

    http://link.springer.com/article/10.1007/s11229-016-1198-6

    We can note here that Javier is continuing the great tradition of Climate Etc in confirming the work of Lewandowsky:

    1) Javier relies for Haigh (1996) for his theory of solar UV mediated climate change, a result reliant on GCMs
    2) GCMs also predict warming due to CO2
    3) Javier nevertheless rejects warming due to CO2, but instead predicts cooling

    It’s a near – perfect example of mutually contradictory opinions from those rejecting climate science.

    • That’s the ticket. Refer to a cartoonist and a psychologist in a science discussion.

      What was that percentage of replication for psychology research? 40%?

      • You could try addressing the point of Javier’s simultaneous embracing and rejecting the results of GCMS of you were actually interested in the science.

      • Not my area of expertise. Unlike some, I’m not going to pretend I’m qualified to express an opinion on Javier ‘s post. On the other hand, I am capable of discerning crap work when I see it. And that is basically anything John Cook is associated with.

      • Though I will agree that his long, oh so very long post, does seem full of conjecture. And I did skip sections, stopping only to read the parts about climate impacts to civilizations.

        I’m personally of the opinion that much of what passes for science that supposedly tells us about the planet’s past contains a high degree of conjecture.

      • And that is basically anything John Cook is associated with.

        I’m led believe that’s what is termed an “ad hominem” remark, a Bad Thing.

  64. So if the Hallstatt cycle is a topic of study in astrophysics http://arxiv.org/abs/1602.02483 and climate has effected human history prior to 1830 and GHGs are real, I’m missing some dots. What part isn’t real? GHGs, history, the sun? You guys are hard to follow some times.

  65. A Speleothem Record of Great Basin Paleoclimate
    January 2016
    DOI: 10.1016/B978-0-444-63590-7.00020-2
    In book: Lake Bonneville – A Scientific Update, pp.551-569

    https://www.researchgate.net/publication/306525834_A_Speleothem_Record_of_Great_Basin_Paleoclimate

    “The lag behind NHSI of d18O variations suggests that the forcing is indirect. Several possible forcings are associated with the Great Basin d18O variations. First, it is clear that CO2 concentrations increase abruptly around the MIS 2/1 and MIS 6/5d transitions, which may explain some of the warming over Terminations I and II. However, Nevada d18O values drop steadily throughout the Holocene, whereas CO2 remains high and even increases slightly over the last 8000 years (Ruddiman, 2003). Similarly, the strongly low d18O values during MIS 5d and MIS 7 happen during intervals with intermediate to high CO2 values. Thus, the CO2 changes may amplify a warming already in progress around ice volume terminations but are unlikely to be the source of the climate change, because they are decoupled during prominent intervals such as MIS 1 and 5d. A related hypothesis suffers from similar problems: the extent of the Laurentide Ice Sheet (LIS). The LIS retreated over the MIS 2/1 and MIS 6/5 transitions when temperatures in the Great Basin warmed (as inferred by increasing d18O values). However, decreasing d18O values from 8 ka to modern happened in the absence of any ice-sheet regrowth, and the prominent MIS 5d and MIS 7 minima also happened when ice sheets were small. Thus ice-sheet extent cannot be the primary driver of Great Basin d18O variations. The clear conclusion is that neither CO2 nor ice-sheet extent were the sole or dominant controls on Great Basin paleoclimate over orbital timescales.”

    • “the CO2 changes may amplify a warming already in progress around ice volume terminations but are unlikely to be the source of the climate change, because they are decoupled during prominent intervals such as MIS 1 and 5d.”

      Yes, it is known as the Holocene temperature conundrum, very well explained by:
      Liu, Z. et al. 2014. The Holocene temperature conundrum. PNAS 111, E3501-E3505.

      In essence for 7500 years during the Holocene temperatures were decreasing while CO2 was increasing and the current favored hypothesis cannot explain it.

      Figure 53. Changes in greenhouse gases during the Holocene. Black curve, global temperature reconstruction by Marcott et al., 2013. Purple curve, Earth’s axis obliquity cycle. Red curve, CO2 levels as measured in Epica Dome C (Antarctica) ice core, reported in Monnin et al., 2004. Blue curve, methane levels as measured in GISP2 (Greenland) ice core from Kobashi et al., 2007. Notice the great effect of the 8.2 kyr event on methane concentrations. Green curve, Simulated global temperatures from an ensemble of three models (CCSM3, FAMOUS, and LOVECLIM) from Liu et al., 2014, shows the inability of general climate models to replicate Holocene general temperature downward trend. Grey bars, periods that correspond to lows in the 2450 years Bray cycle, labeled as H1 to H5. Orange bars, proposed lows in the 985 years solar cycle. Pink bar, 8.2 kyr BP climatic event. Major Holocene climatic periods are indicated.

      According to the green curve (models) temperatures should have been rising, not lowering during the Holocene. And yet another indication that our current understanding of natural forcings is incorrect.

      • “And yet another indication that our current understanding of natural forcings is incorrect.”

        Or, more likely, our current understanding of what happened due to mankinds rise during the early Holocene is incomplete….
        http://hol.sagepub.com/content/early/2011/02/07/0959683610387172.abstract

        Can natural or anthropogenic explanations of late-Holocene CO2 and CH4 increases be falsified?
        Abstract:

        “Concentrations of CO2 and CH4 in the atmosphere rose slowly during the millennia prior to the industrial era. Opposing explanations for these increases have invoked natural and anthropogenic sources. Here we revisit this argument using new evidence to see whether either explanation can be falsified (disproven, in the sense proposed by German philosopher Karl Popper). Two lines of evidence suggest that natural explanations for the CH4 increase are falsified: (1) the absence of any sustained methane increase early in seven interglaciations prior to the Holocene; and (2) weakening emissions during the last 5000 years from the two largest global sources of CH4– north tropical and boreal wetlands. Consistent with this interpretation, a new synthesis of archeological data from southern Asia reported in this issue indicates an exponential increase in CH4 emissions from expanding rice irrigation during the last 5000 years. Neither the anthropogenic nor the natural explanations for the CO2 increase can at this point be falsified. Previous studies that rejected the early anthropogenic hypothesis based on the small size of early farming populations ignored a rich array of archeological and historical evidence showing that early farmers used much more land per capita than those in the centuries just before the industrial era. Previous interpretations of very small terrestrial (anthropogenic and other) carbon emissions during the last 7000 years based on the δ13CO2 record failed to incorporate credible estimates of very large carbon burial in boreal peat lands during the late Holocene. Allowance for larger burial in peat deposits requires much greater emissions of anthropogenic carbon to balance the δ13CO2 budget. The prevalence of downward CO2 trends during equivalent intervals early in previous interglaciations poses a major problem for natural explanations of the late-Holocene CO2increase.”

      • Ruddiman, I think, argues that the decreasing temperature trend since the optimum was the result of orbital variation. However, it was counteracted by human farming and a land clearing, primarily that resulting in large CH4 rise over the period.

        http://www.humansandnature.org/william-ruddiman-and-the-ruddiman-hypothesis

        As I have said before I think there is a potential feedback cycle between large volcanic eruptions and human populations and agricultural activity.

        1- A large eruption results in one or more years of poor harvest.
        2- Population decreases and seed stores are depleted.
        3- This results in reduced agricultural activity and reforestation.

        Or,

        1- Years without large eruptions.
        2- Good harvests and population increases.
        3- More agricultural activity and land clearing.

        Add to this the effect of diseases – the plague(s) and the massive die off of native American populations after contact. New World farming also apparently required a lot of cleared land. The die off would have resulted in a reforestation and carbon sequestration during the time of the LIA. There is a brief downward dip in CO2, I think, at that time.

        Large increases in Asian populations from mid-1700’s to early 20th century produced increases in CH4 from rice farming and may have started the rebound from the LIA before modern CO2 from industrial activity became the dominant driver.

      • Tony Banton,

        “Or, more likely, our current understanding of what happened due to mankinds rise during the early Holocene is incomplete….”

        That is “in addition to”, not “instead of”.

        “Two lines of evidence suggest that natural explanations for the CH4 increase are falsified: (1) the absence of any sustained methane increase early in seven interglaciations prior to the Holocene”

        Ruddiman hypothesis is based mainly on assumptions and data selection. No wonder is being so heavily contested by the experts in carbon balance.

        In this particular case Ruddiman is even dishonest, because the data on MIS19 was published a year before and was available much earlier, and MIS19 is the closest astronomical analog to the Holocene. MIS19 completely destroys that argument as it shows not one but four methane increases, the first being very analogous in relative time and magnitude to ours. I think it is too much to ask us to believe that Ruddiman didn’t know that and just stopped short of checking MIS19.

        “early farmers used much more land per capita than those in the centuries just before the industrial era.”

        Give me a break. How much more land? 7000 years ago there were very few people in the planet and they were not very efficient at cultivating so supplemented with a lot of hunting, fishing and gathering. Now we have to believe that in the good old days everybody was a big landowner? Capable of turning over a huge surface without a decent plow? Laughable.

        Enough said. That hypothesis is not serious and is kept alive by going to the press and writing books every Tuesday and Thursday.

      • James Cross,

        You are focusing on trying to understand why GHGs changed the way they did during the Holocene, but that is not the issue. The experts believe they know how to explain those changes.

        What nobody can explain is that given those changes temperatures dropped instead of increasing. You see that is the matter of the problem because when you plug those gases into models (see figure in my post above) the models say temperatures have to increase not decrease. Trouble in paradise.

        Possibilities:

        – Models are fundamentally flawed
        – CO2 and methane sensitivity is way lower than assumed
        – Natural forcings are a lot stronger than assumed
        – Several of the above are correct
        – All of the above are correct

        Mark just one. Incorrect answers penalize.

      • That hypothesis is not serious

        Javier, is seriousness desirable? Were these words of yours meant to be a serious comment?

        mythical overbearing warming capabilities of CO2

        I’m not sure whether to take you seriously or not, Javier.

      • > Mark just one.

        You can mark zero too.

        Lots of theories.

      • “Give me a break. How much more land? 7000 years ago there were very few people in the planet and they were not very efficient at cultivating so supplemented with a lot of hunting, fishing and gathering. Now we have to believe that in the good old days everybody was a big landowner? Capable of turning over a huge surface without a decent plow? Laughable.”

        I think perhaps your understanding of pre-industrial agriculture is laughable. You are right early farmers were not very efficient but they had a lot of land and that is why they used slash and burn.

        From the Ruddiman link I provided earlier.

        “The question he asked me [was] is it possible that people in the past used more land per person than they used today?” says Ellis. “And from my point of view, from my experience—and really pretty mainstream experience—is that obviously they used a lot more land per person in the past. Land was basically free back in the origins of agriculture. There was no land shortage. People used the least labor methods which is burning out the landscape and throwing out a few seeds. . . . They used large amounts of lands per person to farm.”

        A typical pattern I observed in Costa Rica (typically in mountainous and marginal areas) in the 70’s was to chop down rain forest, set the brush afire, when it cooled, dig holes several feet apart, and drop in some corn into them. Too much work to plant them close together and anyway some of the corn varieties would grow ten feet tall. Beans would be planted in the corn field after the corn matured by throwing beans into the weeds that grown up around the corn then chopping down the weeds. Probably most agriculture was exactly like this in most of the world outside of Europe with the exception of the areas of Asia where rice cultivation was done.

        “You are focusing on trying to understand why GHGs changed the way they did during the Holocene, but that is not the issue. The experts believe they know how to explain those changes.”

        What experts and what is the explanation? I keep encountering the “natural variability” argument to explain the LIA and MWP on this blog.

        Let me guess. Your explanation is “the Sun”?

        According to Ruddiman we have been cooling since the Holocene maximum (with the exception of the recent hundred or years) so the cooling isn’t any mystery or conundrum.

        From the link:

        “Vavrus and Ruddiman both point out that the net temperature effect is still a slight cooling for the earlier period. They calculate the 1.2 K effect from models with and without human effects. They both point out that what the anthropogenic warming did was to significantly, but not totally, cancel the natural cooling dynamic caused by the precession cycle. “Were it not for that artificial warming, the climate system probably would have cooled significantly,” Vavrus says. “

      • James Cross,

        You keep going around the question in circles. The issue is not where the GHGs were coming from. The issue is that those GHGs were in the atmosphere and should have produce warming according to models, but they didn’t.

        Ruddiman does not present evidence for his hypothesis. He just gives explanations. That’s probably OK for people from Humanities but in Science you don’t go anywhere with just an explanation.

        I think perhaps your understanding of pre-industrial agriculture is laughable. You are right early farmers were not very efficient but they had a lot of land and that is why they used slash and burn.

        We know the agricultural practices of people from archaeology. Slash and burn is not common practice except in certain types of soil (tropical), and certain areas. So the argument requires even more land for person since most people in the antiquity did not practice slash and burn. Costa Rica is far from typical. Again we get into the issue of data selection.

        What does he mean that probably agriculture was done everywhere in the world like in Costa Rica in the 70s? What kind of an argument is that? In Brazil Terra preta do negro is an amazing system developed thousands of years ago that does not rely on slash and burn.

        I mean if you want to believe him, by all means do. But he is not presenting any evidence, just handwaving. And it is all pretty unbelievable from what we know from other fields.

        The experts that refute Ruddiman include the late Wally Broecker, Thomas Stocker, Atte Korhola, L. Menviel, Joy Singarayer and J. Chapellaz. That you are not aware of the scientific debate surrounding Ruddiman hypothesis between CO2 and methane experts means that you have accepted it uncritically. Perhaps you are doing the same with AGW.

        Now back to the fundamental question. How is it possible that the increase in those gases did not warm the Holocene?

      • Javier,

        The Ruddiman argument is the GHG DID warm the Holocene. They just didn’t warm it enough to counteract all of the cooling from orbital variation.

        The part about Costa Rica was my personal experience and the pattern is far from atypical. Small farmers throughout the world in rain forest areas do exactly the same thing.

        Let’s get some terminology straight.

        There is a subsistence pattern in rain forest areas that involves cutting forest, burning it, planting crops like cassava, farming it for a year or two then moving on to a new area as yield diminishes. This is done usually by small tribes and requires a fair amount of rain forest per person. So it cannot sustain large populations. This is probably what you are thinking of and it would not have significant impact in my view on GHG, especially since the rain forest grows back after they move on.

        Then in modern times you have the farming of small and sometimes large farmers who are moving into forested and sometimes marginal areas. These are not subsistence farmers. Their objective is to knock down as much forest as possible as quickly as possible, get a crop or two out of it, then typically plant grass and raise cattle when the yield drops.

        So the question is what was done in the New World in pre-Columbian times. It was probably more like the second pattern above, judging from the estimates of populations and the obvious fact that the farmers did not have access to plows or domesticated animals to pull them.

        Aside from that, we have rice cultivation in Asia which has different economics associated with it and produces methane. With rice cultivation, more manual labor and more intensive cultivation in the same area would increase yield and drive population growth which would lead to ability to input more labor in the rice paddies. So in Asia the pattern would be intensive cultivation.

        Regarding terra preta, it is basically the refuse heaps from around the villages as can be determined by the presence of pottery shards, charcoal, and bones as its key components. As a village moved from one location to another the soil around the old village could have been planted with fruit trees or tubers (or may have already had them growing for that matter). However, it is not clear that by itself would have been sufficient to sustain large population without other techniques such as the second slash and burn technique mentioned above.

      • The Ruddiman argument is the GHG DID warm the Holocene. They just didn’t warm it enough to counteract all of the cooling from orbital variation.

        Well that much is probably true, but in that point Ruddiman is clearly with me in thinking that at least two of those possibilities that I outlined are true:
        – Models are fundamentally flawed, as they don’t support what he says
        – Natural forcings are a lot stronger than currently assumed as the orbital variation had to cool a lot more than is thought

        So I guess that if you believe in Ruddiman hypothesis you are also with me in those two possibilities. You make a very good skeptic.

        On the other issue I also point that the Tropics have been sparsely populated in the past. Hard to make an argument that affects the entire planet if even the global population was very low to start. A small part of a small amount leads to an anecdote.

      • > Natural forcings are a lot stronger than currently assumed […]

        What do you think your conjecture would imply regarding climate sensitivity, Javier?

      • Javier,

        I am a little more of a skeptic than you might think.

        Regarding pre-industrial population.

        Asia more concentrated where labor/rice cultivation worked.well.

        In the New World, in the Midwest, Southeast, Mexico, and Central America large scale corn cultivation.Used a lot of land per person.

        The tropics without cutting down the rain forest can only support small populations.

        Regarding orbital forcing vs. climate models, I think you need to look at the possible impact of volcanic eruptions. We probably have not only gaps in that record but also in incomplete understanding of all of the effects. That was what I was suggesting in an earlier comment.

        So from the Holocene maximum until recent you might have:

        1- Some amount of warming from human activity and GHG
        2- Some cooling from orbital variation
        3- Some amount of cooling from volcanic activity and possible side-effects

      • “Regarding pre-industrial population.”

        We are talking way pre-industrial. 7,000 years ago it is estimated that there were 4 to 6 million people in the entire world. A few hundred of thousands living in the Tropics. That’s the size of the population that started the Ruddiman revolution. As the increase in CO2 and methane has a linear trend over the entire period, that population was as effective as the near 500 million of 1600.

        Now if you divide the entire land surface of the Earth between 5 million, there’s a lot more land for each, but that is not how it works.

        The Ruddiman hypothesis comes short on many issues.

        “I think you need to look at the possible impact of volcanic eruptions.”

        I have already done that. During the Holocene vulcanism has been on a declining trend from the early Holocene high levels.

        So we had more vulcanism when it was warmer and less vulcanism when it was cooling. Doesn’t look like a significant factor.

        “1- Some amount of warming from human activity and GHG”

        No evidence that human activity was non-negligible in terms of warming.
        Certainly Some amount of warming from increase in GHG

        “2- Some cooling from orbital variation”

        Clearly the most significant factor, as temperatures track orbital variations

        “3- Some amount of cooling from volcanic activity and possible side-effects”

        Yes but all evidence points that volcanic effects are short lived during the Holocene, so no trend can come from that.

        To me the only congruent explanation is that orbital variation is directing temperature changes during the Holocene and GHGs are a secondary factor, probably an order of magnitude less relevant. And until the industrial revolution changes in GHGs are coming mainly from natural sources, as most experts believe.

      • “What do you think your conjecture would imply regarding climate sensitivity, Javier?”

        As that depends on the interplay between several forcings and feedbacks that are so unknown that for some of them not even the sign is known, I would not dare advance a conjecture.

        However since IPCC already believes that more than 100% of the recent warming experienced since 1950 has been due to anthropogenic factors I seriously doubt that it can be increased even further. Probably there is no ceteris paribus there and several of the forcings and feedbacks are incorrect simultaneously. After all they are trying to play a zero sum game there without knowing all the parts, so if something is unknown or miscalculated its effect would be added to or subtracted from another component.

      • Regarding terra preta, it is basically the refuse heaps from around the villages as can be determined by the presence of pottery shards, charcoal, and bones as its key components. As a village moved from one location to another the soil around the old village could have been planted with fruit trees or tubers (or may have already had them growing for that matter). However, it is not clear that by itself would have been sufficient to sustain large population without other techniques such as the second slash and burn technique mentioned above.

        That’s one theory. Another, the other side of a dispute, “sometimes in bitingly personal terms,” is that these were raised farming terraces of a culture that supported a very high population density (thus providing the population necessary to create all that pottery).

        The dispute itself, “over whether the vast river basin could provide the resources for indigenous cultures to grow beyond small, autonomous villages”, has important political implications, so that like Biblical Archaeology and, of course, climate change, the science seems to have been badly perverted in pursuit of political/ideological agendas.

      • “What do you think your conjecture would imply regarding climate sensitivity, Javier?”

        As that depends on the interplay between several forcings and feedbacks that are so unknown that for some of them not even the sign is known, I would not dare advance a conjecture.

        Yet your conclusion #6 tells us of the inevitability of such implications:

        …This underestimation of solar forcing has the inevitable consequence of an overestimation of anthropogenic forcing.

        Something appears rotten in the state of Denmark.

      • > As that depends on the interplay between several forcings and feedbacks that are so unknown that for some of them not even the sign is known, I would not dare advance a conjecture.

        Thank you for your non-response to a simple algebraic question, Javier.

        That’s all I needed to know.

      • Given all the implied curve-fitting going on in the OP, I don’t feel terrible answering the Holocene conundrum with some linear regressions which can actually be justified on the basis of known physical mechanisms:

        65NJul is summertime insolation according to Berger 1991. I chose the 3800 year offset because that gives the ECS value of 3.00 C/2xCO2. The best fit in this model is obtained with an offset of 4600 years, ECS under that scenario is 2.6. Setting the offset to zero gives an ECS of 5.6.

        CO2EQ is calculated from the natural log of CO2 in ppmv, and the square roots of CH4 and N2O in ppbv, multiplied by the coefficients 5.3525, 0.0315 and 0.1131 respectively to get forcing in W/m^2. I summed those values and divided the whole mess by 5.3525 to get the equivalent of ln(CO2). Using CO2 by itself returns similar results; the only place where CH4 and N2O make much difference is over the Younger Dryas, which is why I bothered to include them.

        The 30 year offset to CO2EQ doesn’t do much to the regression results, I put it in to account for lag in the 20th Century warming response:

        The final year for temperature data in that plot is 2015, and I’ve set CO2EQ to stabilize at ~400 ppmv until 2100 (a guy can dream). The ~0.5 degree discrepancy between temperature and prediction can easily be accounted for by the current downward energy imbalance of ~0.5 W/m^2.

      • brandonrgates,

        “I don’t feel terrible answering the Holocene conundrum with some linear regressions which can actually be justified on the basis of known physical mechanisms”

        I don’t think you can outdo the calculations and known physical mechanisms of a model. After all that is the idea after making models, because computers are much better at making calculations. So if you arrive to a different conclusion than CCSM3, FAMOUS, and LOVECLIM, I would assume that you arrived to the wrong conclusion. That is unless you disagree with the models on some specifics that make you think that they are flawed and want to defend those disagreements.

      • Javier,

        I don’t think you can outdo the calculations and known physical mechanisms of a model.

        I know that I can’t reproduce the calculations of an EMIC like CLIMBER2, LOVECLIM or FAMOUS, or a full-blown AOGCM like CCSM3 — I don’t have the maths or physics to even remotely attempt it. However, my linear regression is also a model. The range for ECS I obtain of 2.6-5.6 K/2xCO2 on the basis of such simple curve-fitting being in accordance with far more complex physical models suggests the enhanced greenhouse effect is not so mythical as you have alleged.

        More to my point, I don’t have to invoke some as-yet unknown physical response to long-period solar variability to provide a plausible explanation for the past 22 ky, and I do it using only two free parameters.

        Contrast the model you imply here, but don’t make explicit as I have done:

        Frequency analysis of solar variability during the Holocene identifies several cycles (McCracken et al., 2013), with the most important being the 11.4-yr Schwabe cycle, the 87-yr Gleissberg cycle, the 208-yr de Vries cycle, the ~ 1000-yr Eddy cycle, and the ~ 2400-yr cycle. Even longer cycles can be identified from 10-Berilium (10Be) records in ice cores, like a 9600-yr cycle (Sánchez-Sesma, 2015). Comparison of climate and solar variability records leads to the important observation that the length of the cycle correlates with the amplitude of the climate effect observed and in general the longer the cycle the more profound effect it appears to have on climate.

        The 1000, 2400 and 9600 year cycles do a bang-up job explaining TSI reconstructions of Steinhilber, whom you’ve cited, but not such a good job of explaining the Shakun and Marcott composite temperature record I present above. In conjunction with orbital forcing, sine curves at those periods do a fair job of explaining the Alley 2000 Greenland temperature reconstruction — but here’s the catch: only with wildly different regression coefficients from those which explain TSI variability as reconstructed by Steinhilber.

        Your “model” only “works” when you piece things up into different time periods and show the correlations to the temperature record with arbitrary scalings.

        You don’t have a consistent, formal model at all, only appeals to some unknown physical effect(s) and visual correlations across a variety of selected time periods of interest.

        So if you arrive to a different conclusion than CCSM3, FAMOUS, and LOVECLIM, I would assume that you arrived to the wrong conclusion.

        Irony. Those models all “assume” that CO2 forcing isn’t “mythical” as you so charmingly put it.

        That is unless you disagree with the models on some specifics that make you think that they are flawed and want to defend those disagreements.

        Too many flaws to list, and redundant for me to attempt an enumeration as that has been done in gory detail by climate modelers themselves in refereed journals and IPCC assessment reports. Way I learned it, that’s called doing good science. Perhaps you’re familiar with the concept?

        Specific to this conversation, I thought your citation — which I thank you for providing as it was an interesting and informative read — Liu et al. (2014) The Holocene temperature conundrum, laid out the case rather well in the “Uncertainty in Climate Models” section, and the conclusion wrapped it up fairly neatly:

        The significant discrepancy between the Holocene global cooling inferred from proxy reconstructions and simulated warming in climate models reflects the Holocene temperature conundrum, which poses an important test for our understanding of climate changes and for the evaluation of climate models of their climate sensitivity to GHGs, ice sheets, orbital insolation, and volcanic forcings. Given the current uncertainties in both the reconstruction and model sensitivity, however, this model-data discrepancy could be attributed to either the seasonal bias in the SST reconstructions or the model bias in regional and seasonal climate sensitivity. If the M13 reconstruction is correct, it will imply major biases across the current generation of climate models. To provide a credible benchmark for future climate models, however, the proxy reconstructions will also need to be reexamined critically.

        As blunt as those final two sentences read, I think it is folly to jump to the conclusion you have that GHG forcing can be completely dismissed as imaginary. Nowhere do Liu et al. say such a thing, and nothing you’ve written here offers me any compelling reason to come to your conclusion.

      • Co2 follows temperature. Look at the yearly temps and co2 ppm anomolies for any of the last 55 years. The icing on that is that production of man made co2 continued to increase. Some variations I will be told. But when it is each and every year ? No way. I can agree there is some warming, I cannot agree that co2 is the cause. In fact the record refutes warming by co2. When the temperature dropped so did the ppm for that year. The only variable there was temperature. Don’t worry, NOAA is hard at work correcting that. They’ve changed the numbers in just the last year so the graphs are a shade different. I’m sure after about 10 or 15 years that they will correct this oversight to conform to AGW.
        You have a steady rise in co2 production and in atmospheric co2, but the yearly rises are determined by temperature.

    • Thank you both for trying to help me sort this out.

  66. Happy day, Willard. I’m your quote of the day on http://neverendingaudit.tumblr.com/. You gave me a nom de blog, you promised me internet fame, now if you’re doing tee-shirts, I should get one. You want my mailing address? Keep on pal you crack me up!

  67. “The role of solar variability on climate change, despite having a very long scientific tradition, is currently downplayed as a climatic factor within the most popular hypothesis for climate change.
    As the root of this neglect lie two fundamental problems. Solar variability is quite small (about 0.1% of total irradiation), and there is no generally accepted mechanism by which the solar variability signal could be amplified by the climate system.”

    The fundamental problem is in assuming that must be about changes in irradiance. When it cannot be anything that directly follows the sunspot cycles, as it has be the inverse of the sunspot cycles during a cold AMO, and following the sunspot cycles during a warm AMO. And overall weaker during a warm AMO.
    https://judithcurry.com/2016/09/20/impact-of-the-2400-yr-solar-cycle-on-climate-and-human-societies/#comment-812821

  68. I find this filling in the gaps of Bray ‘cycle’ events with Eddy ‘cycle’ events illegitimate, as if the Sun was schizophrenic. Apart from teasing periods out from proxy data, there is nothing orbital hinting at such a regular 2400 year cycle, or to keep it repeating regularly for >13Kyrs.
    The evidence that we have is that solar minima occur on average roughly every 10 solar cycles (+/- 3 cycles), and can brief and moderate like the Gleissberg Minimum in the late 1800’s, or severe and last for 5 solar cycles. The correct solution to mapping the clusters of protracted and severe solar minima (GSM’s) will render Bray and Eddy obsolete, and explain why and where they breakdown.
    On top of that, extreme temperature events occur consistently and regularly with a predictable logic, at syzygies and quadratures of the four giants, at scales of a year or two. Such as the two times the River Nile is known to have frozen in 829 and 1010, and a matching pair 953 years later at 1784 and 1963. The positions of Earth and Venus ultimately decide which seasons see the worst cold, and all these cases it included winter.

    • This is most of the Jovian syzygy and quadrature logic that I have ascertained, from correlations to regional temperatures and NAO/AO conditions etc. It speaks of magnetic connections from the Sun to each body, interacting with a solar equatorial quadrupole magnetic structure. I have no explanation for the apparent polarities.

      With weaker solar activity marked ‘cold’, and stronger activity as ‘hot’.
      Jupiter opposite Neptune = cold.
      Jupiter square Neptune = hot.
      Saturn opposite Neptune = hot.
      Saturn square Neptune = cold.
      Jupiter opposite Uranus = hot.
      Jupiter square Uranus = cold.
      Saturn opposite Uranus = cold.
      Saturn square Uranus = hot.
      Uranus opposite Neptune = hot.
      Uranus square Neptune = cold.
      Saturn opposite Jupiter = cold.
      Saturn square Jupiter = hot.
      Such that a configuration of say Jupiter opposite Uranus, both square to Saturn, has three hot aspects, and occurred in the warmer years 1975-76, 1948-49, 1934, 1906.

    • The Bray cycle and the Eddy cycle are grounded in evidence. Climatic evidence, as presented here, as these cycles come out repeatedly from frequency analysis of climatic proxies, and cosmogenic isotope evidence.

      Your planetary models are pure theory without a supporting physical mechanism and zero evidence. They involve a significant amount of circular reasoning, as they are selected on the basis of certain coincidences that are later used to try to demonstrate that they are significant. That you find some coincidence with some climatic events means nothing.

      I suppose you are aware of all this if you have studied some theory of science and you will not wonder why you find so hard to convince others. Between the main characteristics of a good scientist, a healthy dose of skepticism should be at the front. You won’t get passed that.

      • That is all based on observation. Nothing has been specially selected, all permutations have been explored and tested extensively. You are doing the pure circular reasoning, you began what you tried to end with. And it’s guaranteed to miss 2/3 of GSM’s as they occur on average every 820 years.

        “The Bray cycle and the Eddy cycle are grounded in evidence.”

        Come off it, you made false claims about Eddy, on GISP, 8.2 and 7.2 Kyr are both cold, and 5.2 and 4.3 Kyr are both warm. And you haven’t got definitive evidence that Bray is a regular cycle, as you haven’t got a clue as to what may cause it.

        “Between the main characteristics of a good scientist, a healthy dose of skepticism should be at the front.”

        Seeing you with full and firm belief in your own climate forecast based on Bray, and an Eddy cycle that comes and goes without explanation, I’m certain that you need to take your own medicine.

      • “The Bray cycle and the Eddy cycle are grounded in evidence.”

        The power spectrum studies arrive at an average figure of 2300 years for Hallstatt, and 2,241 years from Damon and Sonnett. Yet you try to kid yourself that it’s 2450 years with no other justification other than that you can join the dots on a small selection of climatic events +/- 100 years. That is conformation bias, and twisting the evidence.

    • Javier commented:
      “Your planetary models are pure theory without a supporting physical mechanism and zero evidence.”

      That’s hilarious, considering that you categorically reject all the huge amount of evidence for aCO2 warming.

      You can’t have it both ways. (Well, you can perhaps, if you’re willing to hide your true identity.)

    • thanks for the link Oliver, it seems that my 265 and 251 year model (refering to sun-spot cycles and solar wind variations) is a composite of total solar irradiance. Total solar irradiance has already started falling down and now that temperatures shall have a steep drop too it will be a relief and joy to see the calculations verified.

  69. “Figure 1. Variation in 14C after removal of the long-term trend. An oscillation of the ~ 2400-year Bray cycle is superposed on the data to indicate times when periods of very low solar activity would be expected to occur (arrows). As with every solar cycle, there is some variability in the spacing that complicates mathematical analysis. Adapted to show correct cycle length from Clilverd et al., 2003.”

    Clilverd et al give the ‘correct’ length at 2300 years.
    http://sci-hub.cc/10.1046/j.1468-4004.2003.44520.x

    • “Mark A Clilverd, Ellen Clarke, Henry Rishbeth, Toby D G Clark and Thomas Ulich look forward to a little less solar activity in 2100, using direct and proxy records of past solar and geomagnetic activity.”

  70. Javier

    My congratulations on this magisterial review of the case for solar influence on a century and millenial timescale. Plus the highly informative account of the decisive effect of climate excursions on human migrations and civilization developments and the concept of population overshoot. Highly informative, many thanks!

    While I remain skeptical of a strong forcing effect of solar on climate, in view of some of Willis Essenbach’s criticisms, nonetheless as I have said before the model of climate that I prefer is the weakly forced nonlinear oscillator, which is periodically forced from outside – such as by solar cycles. The weakness of the forcing means that the emergent climate will not rigidly follow the solar oscillations (that would be “strong” forcing”) but in an indirect and complex way. Thus evidence of the solar effect is hard to pin down at the level of the 11 year sunspot cycles, but comes into view at the century-millenial time scales.

    The weakly forced nonlinear oscillator paradigm can address criticisms that solar changes are not energetic enough to change climate and especially the oceans. With this nonlinear model, they dont need to be. The proximal forcing of climate in my view is nearly always the oceans and THC (except maybe a supervolcano like Mount Toba). But if the earth’s internal ocean current dissipative heat engine is (as it inevitably must be) chaotic-nonlinear, then fine forcings such as Milankovich orbital and solar, can push it between attractors and probabilistic valleys.

    • Sounds like a reasonable explanation Ptolemy2, but there is quite a lot of evidence that the main effect of solar variability is through the atmosphere rather than the oceans. I suppose a coupling could be defended easily.

      • “I suppose a coupling could be defended easily.”

        Easily, negative NAO/AO drives a warm AMO:

      • ulrich
        I guess causation is likely bidirectional in this case.

      • That’s the evidence of the strong solar forcing effect on the oceans at the level of the 11 year sunspot cycles, which was not so hard to pin down. Apparently not ‘chaotic-nonlinear’, either.

      • ulrich
        If the link is so clear then presumably you can cite several peer reviewed papers confirming this.
        Actually I dont see any relationship between your green and red lines

      • plotemy,
        There is an apparent phase reversal that you are not seeing. No one has written about this before.

  71. Looking at the three coldest episodes on GISP through the last 10Kyr, at around 6200 BC, 2730BC, and 740 AD, the pitch is 3470 years. Then taking any warm spike, and working forward or backwards on that pitch, typically coincides with more warm spikes in the series. That is typical of the behaviour of different types of cold event configuration clusters, all returning at the same pitch, and exactly what I would expect. I can’t yet see why it should be 0.75 of 4627 years though.

    • That suggests a repeat of a 3.2Kyr event through the next 250 years. Agreeing with my heliocentric solar cycle model which shows a pair of particularly long solar minima, from the late 2090’s, and from around 2200.

    • That graph is probably sourced from GISP2 delta18O, but the zero on abscissa is incorrect. That point is ~+1200. I have had problems with that.

  72. Pingback: Weekly Climate and Energy News Roundup #242 | Watts Up With That?

  73. Pingback: Solar variability and the Earth’s climate | Andy May Petrophysicist

  74. Pingback: Solar variability and the Earth’s climate | Watts Up With That?

  75. Pingback: Earth’s obliquity and temperature over the last 20,000 years | Watts Up With That?

  76. Pingback: The Cosmic Problem With Rays | Watts Up With That?

  77. Pingback: Nature Unbound I: The Glacial Cycle | Climate Etc.