Nature Unbound VI – Centennial to millennial solar cycles

by Javier

Summary: Holocene climate has been affected in different periods by several centennial to millennial solar cycles. The ~ 1000-year Eddy solar cycle seems to have dominated Holocene climate variability between 11,500-4,000 years BP, and in the last two millennia, where it defines the Roman, Medieval, and Modern warm periods. The ~ 208-year de Vries solar cycle displays strong modulation by the ~ 2400-year Bray solar cycle, both in its cosmogenic isotope signature and in its climatic effects. The Centennial, and Pentadecadal solar cycles are observable in the last 400-year sunspot record, and they are responsible for the present extended solar minimum that started in 2008.

Introduction

In a recent review of Holocene climate variability (Part A, and Part B) it was shown that Milankovitch forcing was likely the primary driving force behind the general climate evolution from the Holocene Climatic Optimum to the Neoglacial period, for the past 12,000 years. Additionally, the ~ 2400-year Bray climate cycle (Part A), of solar origin (Part B and Part C), appears responsible for the main climatic subdivisions of the Holocene, and the climatic pessima that separate them, such as the Little Ice Age. Additional periodic climate variability in the centennial to millennial range is produced by the 1500-year oceanic cycle, and by several solar activity periodicities that, according to numerous authors, correlate well with climate variability.

The study of solar cycles and their climatic effect is hampered by a very short observational record (~ 400 years), an inadequate understanding of the physical causes that might produce centennial to millennial changes in solar activity, and an inadequate knowledge of how such changes produce their climatic effect. Despite this lack of a solid theoretical framework, paleoclimatologists keep publishing article after article where they report correations between solar proxy periodicities and climate proxy periodicities, and the observational evidence is now so abundant as to obviate the lack of a theory or well defined mechanism.

The millennial Eddy solar cycle

Every frequency analysis of Holocene solar activity reconstructions shows a strong peak at ~ 1000 year (figure 62 A & C, Darby et al., 2012; Kern et al., 2012). Wavelet analysis shows the ~ 1000-year periodicity having a strong signal between 11,500 and 4,000 yr BP, and between 2,000 and 0 yr BP, but a very low signal between 4,000 and 2,000 yr BP (figure 79; Ma 2007; Kern et al., 2012). The average duration of the ~ 1000-year cycle can be calculated from the grand solar minimum at 11,115 yr BP to the one at 1,265 yr BP (dates from Usoskin et al., 2016) for ten periods at 985 years, a span in very good agreement with the calculated 970 years from frequency analysis (Kern et al., 2012) and the calculated 983.4 years from astronomical cycles (Scafetta, 2012).

Figure 79. The 980-year Eddy cycle in solar activity reconstructions. a) Solar sunspot number reconstruction from cosmogenic 10Be and 14C isotopes. A regularly spaced 980-year periodicity is shown as arches above. The Eddy lows that correspond to this periodicity (orange bars) are numbered from most recent. Grand solar minima that correspond to these lows are indicated with boxes with their names. W/S/M correspond to the Wolff, Spörer, and Maunder minima. Source: A.K. Kern et al., 2012. Palaeo. 329–330, 124–136. b) Wavelet analysis of the sunspot number reconstruction, with the Eddy periodicity indicated by a continuous line, and the Bray periodicity by a dashed line. c) Scale-averaged wavelet power for the 800-1200 years band (Eddy periodicity, continuous line, left scale), and the 1700-2800 years band (Bray periodicity, dashed line, right scale). Notice that the Bray periodicity is continuous over the entire Holocene, while the Eddy periodicity is very strong in the early Holocene and very weak in the mid-to-late Holocene. Source: L.H. Ma. 2007. Solar Phys. 245, 411-414.

The 980-year solar cycle, despite its shorter period and variable amplitude compared to the Bray solar cycle, seems to have dominated Holocene climate variability between 11,500 yr BP and 4,000 yr BP. Several authors have noticed this solar forcing dominance during the early Holocene (figure 41; Debret et al., 2007; Simonneau et al., 2014). The Bond series of North Atlantic drift-ice record reflects a clear ~ 1000-year periodicity during the first 6,500 years of the Holocene that correlates with the 980-year Eddy solar cycle (figures 48 & 80; Debret et al., 2007).

Figure 80. The 980-year Eddy cycle correspondence to Bond events. a) Solar sunspot number reconstruction from cosmogenic 10Be and 14C isotopes. A regularly spaced 980-year periodicity is shown as arches above. The Eddy lows that correspond to this periodicity (orange bars) are numbered from most recent. Source: A.K. Kern et al., 2012. Palaeo. 329–330, 124–136. b) Holocene record of North Atlantic iceberg activity determined by the presence of drift-ice petrological tracers. Source: G. Bond et al., 2001. Science 294, 2130-2136. The correspondence is very clear for the periods when the Eddy cycle has high power.

The 1000-year periodicity displays very low power in solar activity wavelet analysis during several millennia (figures 79 & 81; Ma 2007; Kern et al., 2012; Steinhilber et al., 2013). When the amplitude of the 1000-year solar signal is adjusted by its wavelet power (figure 81), a high correlation between North Atlantic iceberg activity and the 980-year Eddy solar cycle corresponds to the periods when the 1000-year solar signal is high, while the correlation is low at periods of weak 1000-year solar signal, strengthening the relationship between climatic Bond events and solar activity, that has been acknowledged by multiple authors, starting with Gerald Bond himself (Bond et al., 2001). The unusually long Roman Warm Period (2500-1600 BP; Wang et al., 2012) coincided with the final part of this interval of low Eddy solar cycle activity, while known warm and cold periods have faithfully followed the since strengthened 980-year Eddy solar cycle (figure 81).

Figure 81. North Atlantic iceberg activity and the Eddy solar cycle. Blue curve, inferred iceberg activity in the North Atlantic (inverted) from petrological tracers. Source: G. Bond et al., 2001. Science 294, 2130-2136. Black curve, a 1000-year frequency cycle representing solar activity for that periodicity, whose amplitude reflects the relative power (colored bar) of that frequency in a solar activity reconstruction wavelet analysis. Source of wavelet analysis: F. Steinhilber & J. Beer. 2013. J. Geophys. Res. 118, 1861-1867. Periods of higher correlation between both curves correspond to periods of high signal amplitude, and a period of lower correlation corresponds to a period of lower signal amplitude. The last three warm periods (orange bars) and 2 cold periods (blue bars) are indicated. RWP, Roman Warm Period. DACD, Dark Ages Cold Period. MWP, Medieval Warm Period. LIA, Little Ice Age. MGW, Modern Global Warming.

The 980-year solar cycle was named the Eddy cycle by Abreu et al. (2010), and its lows have been numbered here, from more recent, as E1, E2, … (figure 79). The climatic effect of the Eddy cycle should manifest in the two periods when solar activity was most affected by this millennial periodicity. In the most recent period, we observe a millennial separation between warm periods: Modern Global Warming (present), Medieval Warm Period (~ 1100 AD), Roman Warm Period (~ 100 AD); and between cold periods: Little Ice Age (~ 1650 AD; E1), and Dark Ages Cold Period (~ 650 AD; E2). During the early Holocene, the lows of the Eddy cycle coincide with prominent climate change episodes defining a clear millennial periodicity (figure 82; Marchitto et al., 2010). E12 (11,250 BP) coincides with a particularly humid phase in northwestern and central Europe towards the end of the Preboreal oscillation (van der Plicht et al., 2004; Magny et al., 2007). E11 (10,300 BP) coincided with the first cold, humid event, of the Boreal phase (Björck et al., 2001; Magny et al., 2004b), while E9 (9,300 BP) matches the second Boreal event (Rasmussen et al., 2007; Magny et al., 2004b). E8 (8,300 BP) coincided with the outbreak of Lake Agassiz, and researchers are trying to differentiate the relative climatic contribution to the 8.2 kyr event from the solar minimum and the proglacial lake outbreak (Rohling & Pälike, 2005). E7 (7,300 BP) coincides with the last cold, humid phase of the sixth millennium BC (Berger et al., 2016). E6 (6,300 BP) is less well established in the literature, although clearly identified as a dry event in Oman caves speleothems (Fleitmann et al., 2007). E5 (5,200 BP) has been well described worldwide as an abrupt cold event (figure 44; Thompson et al., 2006).

Figure 82. Millennial climate change periodicity. Climatic and solar proxy records, spanning the early Holocene, 250-year smoothed and 1800-year high-pass filtered. Records are Soledad Basin G. bulloides Mg/Ca (SST temperature proxy, blue), tree-ring–derived 14C production rate (solar activity proxy, gold), ice core 10Be flux (solar activity proxy, gray), Dongge Cave (southern China) stalagmite δ18O (Asian monsoon proxy, light blue), Hoti Cave (Oman) stalagmite δ18O (Indian monsoon proxy, green), and North Atlantic stack of IRD petrologic tracers (North Atlantic iceberg activity proxy, red). Source: T.M. Marchitto et al. 2010. Science, 330, 1378-1381.

The identification of the Eddy cycle lows, as well as the Bray cycle lows (figure 64), allows an examination of grand solar minima (GSM) distribution according to the two main solar cycles of the Holocene. Usoskin (2017) gives a conservative list of 25 GSM that were identified in previous studies by different researchers for the past 11,500 years. There is a notable coincidence. Since the Eddy cycle is so close to one thousand years, all the lows of the cycle take place at ~ X,300 yr BP, with X being every millennia of the Holocene. We can observe in the list of GSM that 15 of them take place at ~ X,300 ± 80 yr BP (figure 83 a; Usoskin, 2017). Those GSM are assigned to the Eddy cycle given the good temporal coincidence (figure 83 b). Next, we have 9 GSM that coincide with the lows of the 2,475-year Bray cycle, and in fact define it (figure 83 b). Two of these GSM, at 10,165 and 5,275 years BP, also coincide with the Eddy cycle, as both cycles tend to coincide in phase when two Bray cycles (4,950 years), and five Eddy cycles (4,900 years) have passed.

Figure 83. Grand solar minima of the Holocene. a) Conservative list with approximate dates (in -BC/AD and BP) of grand minima in reconstructed solar activity. The name refers in some cases to a GSM cluster (cl.). The cycle states if the GSM shows a temporal coincidence with a low from the Bray (B), or Eddy (E) cycle. References: 1-listed in Usoskin et al. (2007); 2-listed in Inceoglu et al. (2015); 3-listed in Usoskin et al. (2016). Source: I.G. Usoskin, 2017. Living Rev. Sol. Phys. 14, 3. b) Sunspot based solar activity reconstruction from the radiocarbon record showing the disposition of the GSM associated with the Bray (blue) and Eddy (orange) cycle lows. Source of solar reconstruction: A.K. Kern et al. 2012. Palaeo. 329-330, 124-136.

Of the 25 GSM identified by Usoskin (2017) during the Holocene, only three are not located close to the lows of the Eddy or Bray cycles. The Oort (920 BP), Noach (4805 BP), and an unnamed GSM at 8995 BP, that could be considered part of the Boreal 2 cluster. Since 88% GSM occur during an Eddy or Bray low, it is unlikely that the next GSM will take place before ~ 2600 AD, when the next Eddy cycle low is expected.

The 208-year de Vries solar cycle

As previously described (see The 2400-year Bray Cycle), the de Vries solar cycle is strongly modulated by the Bray solar cycle. For about a millennium centered in each Bray cycle low, the de Vries cycle reduces solar activity every ~ 208 years, and when a cluster of GSM takes place, it establishes the average spacing between them (figure 61). Outside these windows centered in the Bray cycle lows, the de Vries periodicity has very low power in wavelet analysis indicating it has little effect on solar activity (figure 58). The climatic effect of the de Vries cycle matches its solar (cosmogenic isotope) signature.

In 1984, Charles Sonett and Hans Suess proposed that the 208-year cycle seen in solar activity proxies could be related to ~ 200-year periodicity changes in tree-rings width. This finding has been confirmed for tree-rings, which reflect changes in temperature or precipitation, in several regions of the planet. Anchukaitis et al. (2017) have constructed a tree-ring multi-proxy (54 series), extra-tropical Northern Hemisphere, warm season (MJJA), temperature record spanning 1,200 years (750-1988 AD). The record shows high and stable coherence and consistent phasing with solar irradiance estimates at bi-centennial time scales (194-222-year periods), the ~ 208-year de Vries solar cycle frequency (figure 84; Anchukaitis et al., 2017).

Figure 84. Bi-centennial solar influence on Northern Hemisphere summer temperatures from tree-rings. a) Left scale: Reconstructed Northern Hemisphere mean MJJA temperature anomaly time series (black line), smoothed with a 30-year Gaussian filter. Right scale: Solar forcing relative to the period 1976-2006 CE, with the pink shaded region showing the range of the forcing reconstructions compiled by Schmidt et al. (2012), Geosci. Model Dev. 5, 185-191. b) Wavelet coherence between the Northern Hemisphere mean MJJA temperature anomaly time series and solar forcing variability from Vieira and Solanki (2010), Astron. Astrophy. 509, A100. Arrows indicate the phase of the relationship where coherence >0.65. In-phase signals point directly to the right of the plot. A continuous in phase coherence between tree-ring temperatures and solar activity is seen at the de Vries periodicity. Source: K.J. Anchukaitis et al., 2017. Quat. Sci. Rev. 163, 1-22.

The modulation of the de Vries cycle by the Bray cycle is also apparent in the climatic data. Breitenmoser et al. (2012) analyzed the ~ 200-year periodicity during the past two millennia using seventeen near worldwide distributed tree chronologies, and found significant periodicities in the 208-year frequency band, corresponding to the DeVries cycle of solar activity, indicating a solar contribution in the temperature and precipitation series. The result continued being significant after the removal of the volcanic signal, and was most prominent in records from Asia and Europe (figure 85; Breitenmoser et al., 2012). When the 180-230 years band-pass filtered variability was compared with that of solar variability, highlighting the de Vries cycle, it can be seen that as the de Vries signal increases after about 800 AD due to its modulation by the Bray cycle, the climatic signals start to synchronize with the solar signal and in some cases also increase their amplitude (figure 85). This synchronization means that after 800 AD the geographical region is responding to solar forcing, changing the climate according to the 208-year solar periodicity.

Figure 85. Climate response to the De Vries solar cycle in tree-ring chronologies over the past 2000 years. Band-pass filtered total solar irradiation (dotted red line) and tree-ring-derived climate data series in the range of periods 180–230 years for (a) Asia, and (b) Europe. The values in the brackets describe the variability in the band-pass filtered time series in relation to the corresponding unfiltered data series for the displayed time intervals. The synchronization, and in some cases amplitude, of the climatic signal correlates with the strength of the solar signal, indicating that the modulation of the de Vries cycle by the Bray cycle extends to its climatic effect. Source: P. Breitenmoser et al., 2012. Palaeo. 313-314, 127–139.

Phase relationships between hemispheric and global climate reconstructions from tree-rings and the solar irradiance time series indicate a lag of ~ 10 years (range, 5-20 years), with solar changes leading temperature anomalies, consistent with both climate modeling and other climate and solar variability studies (Eichler et al., 2009; Breitenmoser et al., 2012; Anchukaitis et al., 2017).

Other studies link the 208-year de Vries cycle to climate change, including Central Asian ice-cores (Eichler et al., 2009), Asian (Duan et al., 2014) and South American (Novello et al., 2016) monsoon-record speleothems, Mesoamerican lake-sediment cores as drought proxies (Hodell et al., 2001), and Alpine glaciers (Nussbaumer et al., 2011). The climatic effect of the de Vries solar cycle is thus well established.

The 88-year Gleissberg solar cycle

Despite the popularity of the Gleissberg solar cycle in the literature I have not been able to unambiguously identify this cycle as important for solar-climate effects. This is due to the Gleissberg cycle being different things for different researchers.

In 1944, Wolfgang Gleissberg, working at the University of Istanbul observatory, described a long solar cycle that could only be revealed by applying what he called a “secular smoothing” (a trapezoidal 1-2-2-2-1 filter) to a numerical sequence formed by the maximum sunspot values of the known 11-year solar cycles. According to him this numerical procedure revealed “a long cycle which produces systematic changes of the features of the 11-year cycle and which includes seven 11-year cycles, or 77.7 years.” The cycle thus described is not apparent in the sunspot record, and cannot be produced from it by frequency analysis.

As originally described, the Gleissberg cycle is unacceptable by modern scientific standards (and I would dare to say inexistent), and due to it the term Gleissberg cycle means different things to different authors. For some authors it is a frequency peak of ~ 88 years that appears in frequency analysis of the cosmogenic record (McCracken et al., 2013b; Knudsen et al., 2011; figure 86). Other researchers have found that applying the trapezoidal filter of Gleissberg separately to dates of solar cycle minima and maxima from sunspot records then merging them, one also obtains an ~ 80-year time domain periodicity (Peristykh & Damon, 2003). They interpret this result as confirmation of the cycle, that would simultaneously regulate the 11-year cycle amplitude and period. Yet the biggest group of researchers just call any periodicity between 50 and 150 years the Gleissberg cycle, often giving the name simultaneously to two different bands. Joan Feynman, sister of the famous physicist, has studied the centennial solar cycle under the Gleissberg flag of convenience (Feynman & Ruzmaikin, 2014).

Figure 86. The ~ 88-year Gleissberg cycle during the Holocene. a) Lomb-Scargle spectrogram on 14C solar activity reconstruction data grouped in 2000-yr windows, showing the distribution of spectral power for the 50-125 year range. b) The spectral power distribution calculated for a 2000-yr window centered at 2,225 BP. c) The spectral power distribution of a 2000-yr window centered at 4,525 BP, showing the Gleissberg cycle (~ 88 yr) as the most dominant feature in this frequency range for the 3,500-6,500 BP period. The result is reproduced using a 10Be solar activity reconstruction. Source: M.F. Knudsen et al. 2011. The Holocene 22, 5, 597-602. Supplementary material.

Of interest to us here is only the ~ 88-year periodicity present in cosmogenic records that we can also call the Gleissberg cycle, if only to avoid further confusion. The problem is that wavelet analysis shows that this periodicity was only apparent between 6,500 and 3,500 BP (figure 86). This explains why the cycle cannot be detected in the sunspot record. Whether it is a real cycle subject to a very long modulation, or a temporal pseudo-periodicity that emerged from the unknown interactions that generate long term solar variability, cannot be determined. It is also very unlikely that we will be able to determine if it played a significant role in the climate of the period. As the evidence indicates this periodicity is not currently relevant, we will not consider it further.

Other solar periodicities

By now it should be obvious that solar cycles are pseudocycles or periodicities that display a relatively high level of period and amplitude variability. Some of the cycles, like the ~ 2400-year Bray and the ~ 1000-year Eddy cycle, appear to be featured in records several million years old (Kern et al., 2012). The ~ 208-year de Vries cycle has been detected in ice-cores for at least the past 50,000 years (Raspopov et al., 2008b). Other periodicities however, like the 88-year Gleissberg cycle, have only been found for a few millennia.

Frequency analysis of 14C and 10Be display other clear peaks at 52, 104, 130, 150, 350, 515, and 705 years (McCracken et al., 2013b). Some of them could be harmonics of longer cycles. 6,000 and 9,500-year solar cycles have also been proposed (Xapsos & Burke, 2009; Sánchez-Sesma, 2015).

Is the Sun subject to over a dozen different cycles? Or are some of them simply artifacts and not solar variability cycles? Instead of assuming every peak in a frequency analysis constitutes sufficient evidence for the existence of a cycle, I only consider those where abundant evidence exists in the scientific literature that solar cycles match the climate evidence precisely. They are the Bray, Eddy, and de Vries cycles. Of interest are also the periodicities recognizable in the sunspot record, the Schwabe (11-year), Pentadecadal, and Centennial (Feynman) cycles. These last two might be simply harmonics of the de Vries cycle, but as they are currently observable, they may be useful to interpret the past, as well as project future solar activity.

It is worth noting, however, that multiple harmonic constituents in complex astronomical phenomena are a reality. Until the advent of computers, tides were predicted by complex “brass brain” machines. The first of these was built by Lord Kelvin in 1873. After identifying the spectral harmonic components from a long tidal data series at a specific port, machines that could handle up to 40 tidal constituents would produce a year of tidal predictions for that port in a few hours (Parker, 2011).

The Centennial (Feynman) and Pentadecadal solar cycles.

In 1862 Rudolf Wolf, after completing the first continuous record of sunspot numbers, “concluded from the sunspot observations available at that time that high and low maxima did not follow one another at random: a succession of two or three strong maxima seemed to alternate with a succession of two or three weak maxima”. That observation lead to the suggestion of the existence of a long cycle, or secular variation, the length of which was estimated at that time to be equal to 55 years (Peristykh & Damon, 2003). Thus, the Pentadecadal solar cycle is the oldest discovered secular variation of the sun.

Although the Pentadecadal solar cycle displays low power and is statistically non-significant in the sunspot record, it is very prominent in the 10Be record from the one year resolution Dye 3 ice core for the period 1420-1992 AD (McCracken et al., 2013a; figure 87).

Figure 87. Solar activity spectra during the last centuries. Fourier spectra of a) the 1610-2010 sunspot number and b) the annual 10Be data from Dye 3 ice core for the interval 1420-1992. Period in years. Main periodicities names have been added. Source: K.G. McCracken et al. 2013a. Solar Phys. 286, 609–627.

The Pentadecadal cycle should be responsible for the decrease in solar activity at Solar Cycle 20 (SC20) between 1965 and 1976 (figure 89, red arrows). This periodicity is interesting in that it could be related to the pentadecadal variability described in sea level pressure and temperatures in the North Pacific (Minobe 2000). Besides having the same length, the pentadecadal solar change that took place at SC20 was shortly followed by the well-known and studied Pacific climate shift that took place in 1976 (Miller et al., 1994). However, their relation at this time is speculative.

The Centennial solar cycle appears as a peak of ~ 104 years in cosmogenic isotopes frequency analysis, and as a decrease in maximum and minimum sunspot numbers at the beginning of each century since there have been telescopic sunspot observations. Despite this precedent, most solar physicists were expecting SC24 to have a slightly lower level of activity than SC23 and were surprised by the depth and duration of the 2008 minimum and the subsequent low activity of SC24. Of the 54 SC24 predictions published or submitted to the SC24 Prediction Panel in six general categories, spectral analysis predictions (figure 88 a, light blue; Pesnell, 2008) based on Fourier, wavelet, or autoregressive-based forecasts, outperformed all other categories, predicting below average SC24 activity (figure 88 b). In this real test, the use of long periodicities found in solar activity records, for which we have no explanation, fared better than methods based on our clearly inadequate understanding of solar physics. A subcategory based on polar fields produced a better prediction, but it can only predict the next cycle when it is close to the minimum, while spectral methods can predict multiple cycles in advance.

Figure 88. Solar Cycle 24 prediction. Solar Cycle 24 corresponds to a low in the Centennial solar cycle. a) 54 Cycle 24 predictions ordered by increasing predicted maximum, and color coded by categories as indicated in the key. The final maximum value is indicated by the red arrow. Source: W.D. Pesnell. 2008. Solar Phys. 252, 209-220. b) Solar Cycle 24 Panel consensus high (red curve) and low (orange curve) predictions, with the final sunspot number being lower than both. Source: NOAA. c) Average sunspot number prediction by a low-frequency modulation model (dotted curve) based on frequency analysis from sunspot and cosmogenic isotope records, compared to the average sunspot number since 1750 (continuous curve). Despite a low bias, the model predicted the current centennial minimum for cycles 24 and 25. Source: M.A. Clilverd et al. 2006. Space Weather 4, S09005.

Of the spectral predictions, the one published (Clilverd et al., 2006) used a low-frequency modulation model that has some clear inadequacies, like including the Gleissberg 88-year cycle that is no longer observable, assigning an extremely low amplitude to the 208-year de Vries cycle, and not including the modulation by the ~ 2400-year Bray cycle that we have discussed previously. However, since it included the 104-year Centennial periodicity, it predicted very low activity for SC24 (figure 88 c). Indeed, SC24 turned out to be the least active cycle in 100 years. With its faults corrected the model would have predicted accurately slightly more activity for SC24 than for SC14 (in 1904), instead of less. Importantly, the model also predicted in 2006 that SC25 will again be a below average cycle of similar amplitude to SC24. As we approach the 2019-2020 solar minimum the polar field method appears to confirm that SC25 will again be a below average solar cycle. A new prolonged solar minimum, like the Gleissberg minimum of 1879-1914, is being established by the Centennial cycle, and should last at least until around 2032. There is a petition to name this extended minimum as the Eddy solar minimum.

The Centennial cycle has been studied mainly by Joan Feynman. She started studying the Gleissberg cycle and realized the Centennial cycle was different, naming it Centennial Gleissberg Cycle, or CGC. To avoid confusion, the name Feynman cycle appears more appropriate. Feynman and Ruzmaikin (2014) have showed that this periodicity is observable on the Sun, in the solar wind, at the Earth, and throughout the Heliosphere. It is supported by the very weak solar wind at the SC23-24 transition, the weakest observed in the space age. Feynman cycle lows (extended minima) are characterized by very low annual sunspot numbers (less than 3, figure 89 a, black arrows and blue asterisks), and a slight increase in the duration of the 11-year cycle (figure 89 d).

Figure 89. The Feynman (Centennial) solar cycle. a) The annual sunspot number (SSN) record in 1700–2012 (grey curve, left scale). Black arrows and blue asterisks denote times when the annual sunspot number was less than 3, indicating the Feynman minima. Added to the original figure, the annual average aa index in 1868-2012 (dark green curve, right scale), and the position of the additional Pentadecadal cycle minima (red arrows). b) Wavelet spectrum of SSN. Solid lines mark the 11-year and 100-year periods. c) The integral spectrum obtained by averaging over the time axis. The dashed line shows the significance of this spectrum at the 1σ level. Red labeling added. d) The detailed wavelet spectrum in the 5.2-17.4-year period region. A slight increase in the duration of the Schwabe cycle is observed associated to the Feynman cycle lows, particularly ~ 1800 AD. e) The time series of the 80-110-year band. Source: J. Feynman & A. Ruzmaikin. 2014. J. Geophys. Res. Space Physics, 119, 6027–6041.

The Feynman cycle is the only long periodicity whose lows have been observed with modern instrumentation. The aa (antipodal amplitude) index that started in 1868 and measures the disturbance of the Earth’s magnetic field by solar wind, clearly displays the last full period of the Feynman cycle, with its lowest values in 1901 and 2009 (figure 89 a). In the Sun, surface differential rotation changes on a centennial time scale coincide with the observed phase change between the toroidal and poloidal magnetic field components and the time dependence of the dipole and quadrupole components of the poloidal magnetic field (Feynman & Ruzmaikin, 2014). Solar dynamo models still have to accommodate these centennial variations in the Sun.

Previous Feynman lows are associated with colder periods at the early decades of each of the past three centuries. The present extended minimum is associated with an unexpected hiatus in global warming that has yet to be adequately explained.

Conclusions

1) The ~ 1000-year Eddy solar cycle seems to have dominated Holocene climate variability between 11,500-4,000 years BP and in the last two millennia, where it defines the Roman, Medieval, and Modern warm periods.

2) The ~ 208-year de Vries solar cycle displays strong modulation by the ~ 2400-year Bray solar cycle, both in its cosmogenic isotope signature and in its climatic effects.

3) The ~ 88-year Gleissberg solar cycle is ill-defined in the literature and hasn’t manifested itself for the past 3,500 years.

4) Besides the ~ 11-year Schwabe solar cycle, the Centennial (Feynman), and Pentadecadal solar cycles are observable in the sunspot record. The ~ 100-year Feynman solar cycle is responsible for the present extended solar minimum.

5) In all cases a decadal or longer decrease in solar activity is associated with a decrease in temperatures and a change in precipitation patterns. A 10-year delay between solar changes and climatic changes is observed in some studies.

References [Bibliography]

Acknowledgements

I thank Andy May for reading the manuscript and improving its English.

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

115 responses to “Nature Unbound VI – Centennial to millennial solar cycles

  1. Pingback: Nature Unbound VI – Centennial to millennial solar cycles — Climate Etc. – NZ Conservative Coalition

  2. “Is the Sun subject to over a dozen different cycles? Or are some of them simply artifacts and not solar variability cycles?”

    Beyond sunspot cycles just one, simply solar minima of variable lengths and with variable intervals. That’s the true nature of the astronomical ordering of solar minima. Intervals between solar minima vary from seven to twelve solar cycles, and clusters of long minima between 400-1100 years apart. Expecting regular cyclicity is a mistake.

  3. I miss error bars on your graphs. How reliable are these reconstructions?

    • Most of my graphs are from publication figures that do not contain error bars. Sometimes the information is available in the original source. For example Bond et al., 2001 indicate that the standard error in the petrologic measurements is ±1%. As the Bond stacked series is the average of different petrological tracers that reflect the same parameter, i.e., change in drift ice, it is considered to be more reliable than the separate measurements. Sunspots records are almost never represented with their standard errors, but they are available when you download the data from Silso. In most cases I direct you to the original sources given. If the error is available, it is there.

  4. Javier

    Over on the other thread Robert Ellison has just linked me to an interesting paper regarding CET whereby The authors believe there is a clear link to an oscillating1000 year cycle

    https://www.nature.com/articles/srep46091

    Certainly something appears to happen at around the 1000 year mark and the evidence of the roman warm period and the mwp and the modern warm era all seem to point to this 1000 year period.

    What happened between 4000 years BP and the roman warm period? Does the bronze age warm period not fit into that date somewhere?

    Tonyb

    • Hi Tony,

      To tell you the truth, I don’t like that paper very much. I think they subject the data to a little bit of torturing. It is hard to see a ~ 1000 year periodicity in 350 years of data. And then they come up with a very strong Hale cycle, but the Hale cycle is hugely controversial, because it is only magnetic. And magnetic effects on climate have almost no support from evidence. How can it come so strong? Is it simply a harmonic of the 11-year cycle? But the 11 year cycle has a tiny influence on climate. It is all very weird.

      The 1000-year periodicity is however very strong in both long solar proxy records, and climate records, but has a gap between ~ 3000-5000 BP. The cycle was simply not prominent then.

      Medieval warm period was ~ 800 BP. Roman warm period ~ 1800 BP. 1000 years earlier, ~ 2800 BP there was no warm period, because a low of the Bray cycle took place, manifested in the Homer solar minimum about a century and a half after the Late Bronze Age collapse. The Minoan warm period took place earlier, before the Bray low, at ~ 3500-3200 BP and was allowed by the low power of the 1000-year cycle, that did not produce low solar activity at the time.

      This is a model of solar cyclicity for the past 3000 years that I made, with solar activity data and some climate information that will help you not to get lost.

      • Thanks Javier

        I said the paper was interesting , not that I necessarily thought it accurate. :)

        I think that climate data is routinely ‘tortured’ as it is frequently given much more weight and scientific credibility than it deserves. We are still in the neolithic age regarding our understanding of the climate, not helped by routinely accepting all sorts of proxies and dubious reconstructions based on data that routinely raises both eyebrows.

        Mind you, without this sort of stuff the climate industry would not function.

        As for the merits of this approximately 1000 year return minus a couple of examples, may be maybe not. I need lots of research funding to investigate that further….

        tonyb

      • Tony

        “…..Neolithic age regarding our understanding of the climate…”

        Exactly. The number of possible influences is mind numbing. This fine post and all other like material just keep adding to what might be at play. In spite of this, some have narrowed their focus with such a microscopic precision, they will never see the forest for the trees. I see an Emmy award winning situation comedy becoming very popular in 2100. It will depict all the scientists of today blathering on about their absolute certainty of what drives the climate. Guaranteed belly laughs. But the subtext will be how man’s lack of humility always gets in the way of clear thinking.

  5. Scientists > Journalists > Us

    Journalists are going off the rails because of the huge growth of the interwebs.

  6. Hopefully, a stronger more self-assured America can better withstand the next 30 years or more of global cooling.

  7. “The ~ 1000-year Eddy solar cycle seems to have dominated Holocene climate variability between 11,500-4,000 years BP and in the last two millennia, where it defines the Roman, Medieval, and Modern [Progressive Mannian] warm periods [modulated by Bush/Trumpian cycles].”

  8. Poincaré discovered chaos in his non-integrable Hamiltonians of the evolution of orbital systems.

    The working theory is that the solar magneto is modulated by the chaotic path of the barycenter of the solar system about the interior of the Sun. The mass of the Sun dominates orbital variability and creates an appearance of orbital stability – and presumably in solar magneto – and solar activity – variability. There is as well an ergodic chaotic fluid dynamic within the Sun.

    Either of these modulate solar activity in regimes and persistence. The search is for the origins of Hurst effects in climate – this is one source. The other source is the nonlinear planetary response to changing solar and orbital factors. There are no cycles as such – just patterns of chaotic change that repeat (ergodicity) over a long enough period. Fourier based spectral analysis will yield of sine waves of different frequencies – but it is an illusion. Useful as this is at the scale of the ~22 year Hale cycle of solar-magnetic reversal to a millennial scale climate variability. There are no independent processes operating at these different frequencies.

    Well there are broad processes which may for physical reasons exhibit a road. One possible explanation for the Younger Dryas is freshwater melt inflow – AMOC won’t stop entirely but the associated high northern cooling brings with it ice sheet growth and sea level falls.

    Are there other possibilities? In between wasting my time here – I have been reviewing the latest theories on the 100,000 year glacial problem.

    The 100,000 year problem is that the periodicity of glacials changes from ~41,000 years to ~100,000 years some 800,000 years ago. There are Milankovitch cycles of around 21,000, 40,000, 100,000, and 400,000 years – in the 100,000 year cycle involving orbital eccentricities the change in insolation is much smaller than with the 21,000 and 40,000 year cycles.

    One theory is that the 100,000 year regime is a synchronization of a resonant frequency of the Earth system with the 100,000 year eccentricity forcing. The mid-Pleistocene transition in this theory is the result of continental drift and sea floor spreading changing the resonant frequency.

    see – https://www.nature.com/articles/ngeo1756

    There are other theories.

    “Orbital inclination has a 100ka periodicity, while eccentricity’s 95 and 125ka periods could inter-react to give a 108ka effect. While it is possible that the less significant, and originally overlooked, inclination variability has a deep effect on climate,[11] the eccentricity only modifies insolation by a small amount: 1–2% of the shift caused by the 21,000-year precession and 41,000-year obliquity cycles. Such a big impact from inclination would therefore be disproportionate in comparison to other cycles.[8] One possible mechanism suggested to account for this was the passage of Earth through regions of cosmic dust. Our eccentric orbit would take us through dusty clouds in space, which would act to occlude some of the incoming radiation, shadowing the Earth.[11] In such a scenario, the abundance of the isotope 3He, produced by solar rays splitting gases in the upper atmosphere, would be expected to decrease—and initial investigations did indeed find such a drop in 3He abundance.[12][13] But the idea of an inclination effect has been deemed unnecessary (Rial 1999). However, there is still the possibility that the 100ka eccentricity cycle acts as a “pacemaker” to the system, amplifying the effect of precession and obliquity cycles at key moments, pushing the system out of a locally stable state and triggering a swift melting phase, by a small perturbation.[8][14]”
    https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/100%2C000-year_problem.html#cite_note-Ellis2016-20

    The link above is to a well written piece and there are a number of good references.

    I like the dust-ice albedo theory.

    “It is claimed that after an initial Milankovitch insolation cooling, the ice-sheet albedo contribution to cooling is so great, that subsequent insolation maxima cannot melt the growing ice sheets, nor raise temperatures. So the ice age deepens via increasing ice-albedo and cooling, and would continue to deepen almost indefinitely. However, after some 70 ky or so, CO2 concentrations lower to a value at which flora is decimated and new CO2 deserts are formed, especially in China and Mongolia. These large CO2 deserts cover the northern ice sheets with dust, as is recorded in the ice core data, and the ice sheet albedo is lowered sufficiently so that the next insolation maxima can melt the ice sheets.
    So in this proposal, the 85 ky or 115 ky ice age cycle is initiated by Milankovitch insolation, but modulated by the slow rate of cooling and CO2 reductions. An interglacial cannot occur, so it is claimed, until sea-level CO2 concentrations have reached 190 ppm, at which point CO2 deserts can form and dust storms can be initiated. And since the rate of ice sheet growth, and temperature and CO2 reduction have been fairly constant over the last 800 ky, the glacial-interglacial oscillation maintains a regular cycle.[20]”

    Was the Antarctic ice sheet responsible for the transition by modulating CO2 uptake and release?

    “The ~100 k.y. cyclicity of the late Pleistocene ice ages started during the mid-Pleistocene transition (MPT), as ice sheets became larger and persisted for longer. The climate system feedbacks responsible for introducing this nonlinear ice sheet response to orbital variations in insolation remain uncertain. Here we present benthic foraminiferal stable isotope (d18O, d13C) and trace metal records (Cd/Ca, B/Ca, U/Ca) from Deep Sea Drilling Project Site 607 in the North Atlantic. During the onset of the MPT, glacial-interglacial changes in d13C values are associated with changes in nutrient content and carbonate saturation state, consistent with a change in water mass at our site from a nutrient-poor northern source during interglacial intervals to a nutrient-rich, corrosive southern source during glacial intervals.” https://pubs.geoscienceworld.org/geology/article-lookup/44/12/1035

    What remains is a nonlinear response to insolation that involves CO2 and ice sheets. From the last glacial max – CO2 forcing had about a 2W/m2 increase and ice sheet albedo change amounted to some 25W/m2 less reflected SW.

    Fundamentally Javier’s entire series is a prolix and misguided attempt to distill an illusion of regularity in an irregular system. And that there are transitions – the 100ky problem and the mid-Holocene transition inter alia that are from robustly explicated – add to the problems.

    JC SNIP

    • … exhibit a road? Exhibit a broad appearance of regularity.

    • You have a tolerance for disrespect of distinguished scientists? Because they contradict pet ideas? This is the culture of anti-science.

    • “As with all guest posts, please keep your comments civil and relevant.”

      Comments about the glacial cycle are not relevant to this article.

      • None of these cycles are cycles – as I discuss.

        “Spectral analysis shows the below-average epochs are associated with enhanced ENSO-like variability around 2–5 yr, while the above-average epoch is associated more with variability around 6–7 yr. The LDSSS record is also significantly correlated with annual rainfall in eastern mainland Australia. While the correlation displays decadal-scale variability similar to changes in the interdecadal Pacific oscillation (IPO), the LDSSS record suggests rainfall in the modern instrumental era (1910–2009 ad) is below the long-term average. In addition, recent rainfall declines in some regions of eastern and southeastern Australia appear to be mirrored by a downward trend in the LDSSS record, suggesting current rainfall regimes are unusual though not unknown over the last millennium.” http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00003.1

        So 20 to 30 years regimes associated with the Hale cycle – or at least has a similar period give or take internal feedbacks. And a millennial variability that mirrors isotope variability. I have discussed the dynamical linkages a number of times. But there is also a much greater variability over the Holocene.

        Laguna Pallcacocha, ENSO proxy – greater red intensity shows El Niño conditions (Source: Tsonis, 2009)

        Moy et al (2002) present the record of sedimentation shown above which is strongly influenced by ENSO variability. It is based on the presence of greater and less red sediment in a lake core. More sedimentation is associated with El Niño. It has continuous high resolution coverage over 12,000 years. It shows periods of high and low ENSO activity alternating with a period of about 2,000 years. There was a shift from La Niña dominance to El Niño dominance some 5,000 years ago that was identified by Tsonis 2009 as a chaotic bifurcation – and is associated with the drying of the Sahel. There is a period around 3,500 years ago of high ENSO activity associated with the demise of the Minoan civilisation (Tsonis et al, 2010). It shows ENSO variability considerably in excess of that seen in the modern period. none of this is ‘cycles’.

        The glacial discussion was to show that Milankovitch “cycles’ – your first sentence – do barely anything in the scheme of things. Dynamic internal feedbacks do most of the heavy lifting in the spatio-temporal chaos of the Earth system.

        Irrelevant? You will have to do better than that.

      • associated with the Hale cycle

        Curious how you choose to believe in a cycle for which there is essentially no evidence of any effect.

      • To show the detailed characteristics of each spectral band based on the wavelet analysis of the driving force output, the time-averaged power spectrum of the driving forces is shown in Fig. 3. There are several spectral bands and the characteristic periods occur as spectrum peaks (red dots in Fig. 3) at 3.36, 7.5, 14.5, 22.6, 67.7, 90.4, 113.9 and 215 years, named L1 to L8, respectively. The blue dotted line in Fig. 3 is the 95% confidence level, and all scales pass the confidence test at the 95% level.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5384247/

        That’s the fun. We are looking for a stochastic trigger for 20 to 30 year regimes in the Pacific. The Pacific climate states are not independent – they are globally coupled quasi standing waves in Earth’s, turbulent, spatio-temporal glow field. It is not surprising to me that they found a 22.6 year spectral peak in CET.

        So what happens when things change in the system to cause a future climate shift? The system evolves as a result of a continuum of physical forces. Planetary orbits, fluid dynamics in the interior of the sun, energy flux and more than all – a complex and dynamic Earth response.

        Although Einstein said that past, present and future were a stubborn illusion – the Sun is 3 dimensional and evolves in the present governed by real but currently incomprehensible physics. We know bits of it. We know at core that things happen at the whim of the Dragon Kings.*

        So there is a solar cycle fitting the bill for the planetary response in decadal means and variance of quasi standing waves? What causes the Hale Cycle? What is the dynamic linkage to Earth systems? I’ll get back to you on that. It is suspected that solar UV/ozone chemistry modulate atmospheric paths and result in varying surface pressure at the poles. This is classic SAM and NAM.

        e.g. https://www.nature.com/articles/ncomms8535

        Multi-decadal variability in the Pacific is defined as the Interdecadal Pacific Oscillation (e.g. Folland et al,2002, Meinke et al, 2005, Parker et al, 2007, Power et al, 1999) – a proliferation of aperidic oscillations it seems. The latest Pacific Ocean climate shift in 1998/2001 is linked to increased flow in the north (Di Lorenzo et al, 2008) and the south (Roemmich et al, 2007, Qiu, Bo et al 2006)Pacific Ocean gyres. Roemmich et al (2007) suggest that mid-latitude gyres in all of the oceans are influenced by decadal variability in the Southern and Northern Annular Modes (SAM and NAM respectively) as wind driven currents in baroclinic oceans (Sverdrup, 1947).

        Collectively the processes produce 20 to 30 year warmer or cooler regimes of Pacific Ocean sea surface temperature – and abrupt shifts between that may be triggered by UV/ozone chemistry modulation of the polar annular modes. So in the hypothesis we are looking for changes in solar UV in the Hale Cycle. But the world moves on. The polar annular modes modulate welling up of the cold and nutrient rich abyss off the coasts of Peru and California.

        The influence of the polar annular modes on winds and oceanic gyres is shown schematically here.

        https://watertechbyrie.files.wordpress.com/2017/04/gyre-impact-e1492552484864.png – image sourced from – http://www.mdpi.com/2225-1154/3/4/833/htm

        * https://arxiv.org/abs/0907.4290

    • Robert I Ellison: Fundamentally Javier’s entire series is a prolix and misguided attempt to distill an illusion of regularity in an irregular system.

      I think that is incorrect. Javier has presented analyses of processes that are approximately periodic over identifiable subintervals of the recording epoch, and has demonstrated a lot of nonstationarity in the processes.

      Like this: Robert I Ellison: “Spectral analysis shows the below-average epochs are associated with enhanced ENSO-like variability around 2–5 yr, while the above-average epoch is associated more with variability around 6–7 yr. The LDSSS record is also significantly correlated with annual rainfall in eastern mainland Australia. While the correlation displays decadal-scale variability similar to changes in the interdecadal Pacific oscillation (IPO), the LDSSS record suggests rainfall in the modern instrumental era (1910–2009 ad) is below the long-term average. In addition, recent rainfall declines in some regions of eastern and southeastern Australia appear to be mirrored by a downward trend in the LDSSS record, suggesting current rainfall regimes are unusual though not unknown over the last millennium.” http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00003.1

      But a more ambitious attempt to analyse and relate a larger number of time series records.

      I dsiagree with your characterization of “prolix”; the quantity of evidence reviewed, and the depths of the discussions (e.g. his discussion of the “Gleissberg cycle”), require a lot of presentation words and graphs, and are well worth reading. It would be hard to present that much information more succinctly and still have it understandable at all.

      What remains is a nonlinear response to insolation that involves CO2 and ice sheets.

      and

      Poincaré discovered chaos in his non-integrable Hamiltonians of the evolution of orbital systems.

      I hope to live long enough to read presentations of systems of nonlinear dynamic systems that are complete enough, tested enough, and accurate enough to make reasonably dependable predictions at least decades ahead. I expect that the people capable of accomplishing that task will make use of the results of Javier and others like him: what dynamical system would be capable of generating the “oscillation” of the 1,000 year cycle presented here? Till then, Javier is a member of the large club of scientists who have not been able to do so yet.

      • Climate always changes. What causes approximately millennial and many other scales of variability?

        In the words of Michael Ghil (2013) the ‘global climate system is composed of a number of subsystems – atmosphere, biosphere, cryosphere, hydrosphere and lithosphere – each of which has distinct characteristic times, from days and weeks to centuries and millennia. Each subsystem, moreover, has its own internal variability, all other things being constant, over a fairly broad range of time scales. These ranges overlap between one subsystem and another. The interactions between the subsystems thus give rise to climate variability on all time scales.’

        What we are looking for – and have for decades – is a stochastic trigger. As well as dynamical linkages in the climate system. Small changes in orbits, solar UV and TSI or indeed greenhouse gases and land may cause a shift to an emergent state involving multiple changes in Michael Ghil’s sub-systems. It happens with a spectral peak frequency of 22.6 years – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5384247/ – and at the scale of glacials –
        https://www.nature.com/articles/ngeo1756

        Both papers that Javier summarily dismisses because there is this huge hole in his theories.

        Processes with consistently positive autocorrelation functions lead to large and long “excursions” from the mean as shown in Fig. 12 (lower panel), which often tends to be interpreted as nonstationarity. The latter, however, would require that the system’s dynamics changes in time in a deterministic manner, which does not happen here (and in most of the cases).” https://www.itia.ntua.gr/en/getfile/923/1/documents/hess-14-585-2010.pdf

        Although Demetris Koutsoyiannis is talking here about a toy model involving precipitation an groundwater – the principles remain. The essential is that despite the excursions – there are limits to variability of natural systems. It shows that the system is ergodic – it returns to all possible states over a long enough period. Which suggests that the data series would be stationary – if there were in fact records of such length.

        Using spectral analysis of data series will give you sine waves – but does mean that the Sun has a whole lot of processes going on to give independent cycles of various periodicity? Or that these sine waves reflect geophysical process at the scale that will repeat itself into the distant future? It is pure cyclomania that has no possible point, neglects fundamental physics and has no understanding of why climate data series behave as they do. Imagining that you can make ‘scientific predictions’ from this is a laughable conceit.

        “In a chaotic system, one wouldn’t expect cycles but rather oscillations. Even regular external forcing is likely to result in an irregular and possibly lagged response. While variations in the sun, planetary orbits and magnetic fields may appear cyclic on some timescales, they are not cyclic on much longer timescales.” Judith Curry

        One would expect quasi standing waves operating as chaotic oscillators in the globally coupled spatio-temporal chaotic flow field. Large excursions from means are triggered by small changes in control variables – like orbits or solar UV. Both of the latter evolve in a continuum of forces, have very little direct impact but trigger planetary responses that shift abruptly and produce large and persistent excursions from the mean.

        You are expecting a prediction? Climate will shift again – almost as certainly as day follows night – within a decade.

    • Robert
      I love your video of Poincare’s Hamiltonians.
      However a sufficiently robust and complete explanation does exist for the timing of interglacials over the whole Quaternary on both sides of the mid-Pleistocene revolution (MPR). It was given here by Javier recently.

      It is clear that nonlinear and chaotic dynamics play a role in the glacial cycle. The timing of interglacials indicates that the system is a periodically forced nonlinear oscillator, with the dominant forcing being obliquity.
      
There is a very compelling correlation between the the obliquity cycle and temperature lagged by 6,500 years, posted here recently by Javier.

      Prior to the MPR the glacial cycle followed obliquity (lagged by 6,500 years.)

      Due to a long term secular cooling trend, at the MPR obliquity alone was no longer able to provide a sufficient warming impulse to start and interglacial. It could only do so when precession modulation and eccentricity also provided a coincident warming impulse; this happens about every 2 or 3 obliquity cycles. This gave rise to the appearance that the 100,000 year eccentricity cycle was driving the cycle, while in reality it was – and is – still obliquity, modulated by the other two.

      Every 2 or 3 obliquity peaks – lagged by 6,500 years by the ocean’s thermal inertia, induces an interglacial.

      Which obliquity peaks induce interglacials and which do not is straightforwardly predictable from precession and eccentricity. Regarding precession, it is not precession per se but the modulation of precession that is the critical factor, that is, the oscillation in the amplitude of the precession peaks. This modulation follows eccentricity – the maximal peaks of precession modulation occur at the peaks of eccentricity.

      It is obvious from orbital considerations why precession modulation should follow eccentricity. In fact it simplifies analysis of Milankovich forcing to consider precession modulation and eccentricity as one and the same phenomenon. (This would also include insolation at 65N, which exactly follows eccentricity and precession modulation.)

      And that’s all it is. An obliquity peak – thermally lagged by 6,500 years, coinciding with a peak of precession modulation/eccentricity, causes an interglacial. Due to different timings, sometimes an eccentricity peaks will fall exactly half way between two lagged obliquity peaks. In this case you get a double-headed interglacial, as occured 200k and 600k years ago and will happen again 200k years in the future.

      • If you go past Poincare – you will find a number of theories for the 100,000 year problem.

      • Robert
        If you get past Poincare in my reply, you will see why obliquity with a 6500 year lag, is sufficient alone for glacial timing pre MPR and post-MPR with precession-eccentricity modulation:

      • You might find that the 6500 year lag covers a lot of planetary responses that cause all of the global temperature changes. There are unresolved problems – including the origin of the mid-Pleistocene transition. Orbital periodicities are the least interesting aspect.

        I discussed some of this – with reference to real science above. I don’t care what you think is obvious.

      • 6500 years is the time it takes a change in insolation to make a difference to ocean temperature and in turn climate.

        Curious how the AGW crowd expect a real time climate response from CO2 radiative balance change. They watch too much Harry Potter.

    • Interglacial timing and the MPR are a subject more than worth a post in their own right – maybe you could reformat your post as a new article and propose it to JC?

      I’m sure CO2 starvation-desertificaion and consequent dust are major features of the glacial maxima, but I doubt all atmosphere-based climate explanations (CO2, aerosols, acid, ozone, etc..) and this is no exception.

      There are recent papers that show that as ice sheets get bigger, they also get inherently unstable, and this term-limits the glacial maxima. Instability grows until some perturbation triggers a runaway reverse albedo feedback and the regular catastrophic interglacial inceptions.

      The system as a whole would seem to be a periodically forced nonlinear oscillator. Thus the periodic forcings don’t always need to be big.

      This recently posted figure from Javier seems to me to make it hard to avoid a central role for obliquity, with a 6500 year lag:

  9. Government scientists want to ignore decades-long unique and rare record-setting solar events, eschew counting sunspots and are more interested in parameterization-gazing than star-gazing, despite the fact that, “During solar maximum,” as anyone can read in wiki, “large numbers of sunspots appear and the sun’s irradiance output grows.”

  10. The study of solar cycles and their climatic effect is hampered by a very short observational record (~ 400 years), an inadequate understanding of the physical causes that might produce centennial to millennial changes in solar activity, and an inadequate knowledge of how such changes produce their climatic effect. Despite this lack of a solid theoretical framework, paleoclimatologists keep publishing article after article where they report correations between solar proxy periodicities and climate proxy periodicities, and the observational evidence is now so abundant as to obviate the lack of a theory or well defined mechanism.

    If you publish enough papers and repeat the same message enough times, you don’t really need to understand or prove anything. Anyone who disagrees will be blown away or covered by the papers.

    • You still need the underlying evidence. Evidence trumps theory anytime. A lot of things we don’t understand or can’t explain are real.

      • Javier: You still need the underlying evidence.

        I am glad you wrote that. I was going to post something similar, and was waiting to give you the chance to reply first. I have noticed that you often respond to comments on your postings, and I applaud that.

    • [P]aleoclimatologists keep publishing article after article where they report correations between solar proxy periodicities and climate proxy periodicities…

      What paleoclimatologists, who are usually academics in the soft sciences such as geography, very seldom manage to produce is compelling determinations of the physical relationship between their proxies and the climatic variables of interest. In no other science would their weak correlations and claims of existence of interdependent cycles based upon little more than raw periodograms be accepted as rigorous “evidence” for their conjectures. That’s why they tend to meet serious scientific challenges to their far-fetched theories not with increased scientific rigor, but with amplified polemical vigor.

  11. The “mystery” of the “anthropocene” clearly explained…

    Sent from my iPad

    >

  12. Thank you to Javier and Andy May for an interesting essay. I think that it is worth multiple readings.

    It is really hard to tell how much might stand up over time. As you note frequently, there is much selection: of data, of subsets of data, of smoothing techniques and smoothing parameters, with no hope of estimating how many tries of this and that were attempted and not reported. That said, this essay like the others has reviewed much published data.

  13. “5) In all cases a decadal or longer decrease in solar activity is associated with a decrease in temperatures…”

    Not if low solar drives a warm AMO.

  14. Whereas the basic ’11-year’ cycle persists over-twenty cycles without ever going chaotic, and whereas individual cycles are selfwise shape-consistent attack, rise, oft doubled at the peak, and longer slope down, sometimes with abrupt extensions, I’d thought the process of analysis should include phase and multiplication e.g. logarithmic “sceptrum” before any Fourier transform; and atop that, the tabulation of daily and monthly sunspots should be fitted to solar rotation or at worst Gaussian rather than its usual rectangular unit-weight filter like-Hadamard….

  15. I’ve long been aware of relationships between solar and climate variability. Hubert Lamb was working on it in the 1950s or 60s but his work was abandoned when the radiative theory of CO2 became attractive to political activists.

    Javier has done good work in summarising a lot of data.

    What we really want to know is the why and how so this may be an opportune moment to draw attention to a plausible hypothesis:

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

    • Stephen

      The work Lamb did on this is in his archives held at the University Of East Anglia.

      Phil Jones is now retired from there but is still very interested and very approachable. If there was anything you wanted to ask him about this aspect of the archives I suspect he would search it out or know something about it

      tonyb

    • “Stephen Wilde: For the moment I’m holding back to see how the real world behaves …”
      There seems to be a lot of science (much of which I don’t claim to understand) and little to no empirical data supporting anthropogenic carbon dioxide driving the climate. This post includes empirical data supporting natural variability. In addition to pro-AGW, anti-AGW, and luke-warm-AGW (with much respect to our hostess), science without empirical data puts me in the prove-it-AGW (PIAGW) category.

  16. “The average duration of the ~ 1000-year cycle can be calculated from the grand solar minimum at 11,115 yr BP to the one at 1,265 yr BP (dates from Usoskin et al., 2016) for ten periods at 985 years..”

    On GISP2 there are colder periods at 8160 BP and at 7175 BP, and warmer periods at 5205 BP, 4220 BP, and 3235 BP. How interesting.

    • Of the three coldest spikes in GISP, around 1200 BP was the warmest part of the MWP for Northern Europe (Esper). 4800-4500 BP saw a worldwide expansion of cultures and city building. Around 8200 BP saw expansion of village settlements in the Indus, Bulgaria, and England, and stronger trade winds as in the MWP. The pitch of those three cold spikes is a prime clue to what will be occurring through the next few hundred years, a repeat of the major solar minima of the 1350-1150 BC civilisation collapse period.

  17. I don’t think Ben Santer will be able to digest this very well. The WAR is being won with REAL SCIENCE like this, but hard-nosed “Santerists” will continue to turn their heads in favor of their Democratically controlled, highly populated, BIG CITY SCIENCE.

    Let’s hope our BIG GOVERNMENT education system will insert this into their environmental framework.

  18. Pingback: Bits and Pieces – 20171205, Monday | thePOOG

  19. Is the Sun subject to over a dozen different cycles? Or are some of them simply artifacts and not solar variability cycles?

    Either way, when it comes to climate change, the more the Sun matters the less humanity’s CO2 matters.

    • when it comes to climate change, the more the Sun matters the less humanity’s CO2 matters.

      I agree. The Sun appears to act through multiple pathways that are very poorly or not represented at all in the models. The models just include TSI variations in W/m², and some of then include solar induced ozone variability. None includes a realistic Quasi-Biennial Oscillation, and they are missing entirely some solar effects. As a result Sun’s effect on climate is underestimated, and this leads to an overestimation of the effect of CO₂.

      Modelers should be a little more humble and admit that what the models represent is what is inside their heads, and not the climate.

      • “Modelers should be a little more humble and admit that what the models represent is what is inside their heads, and not the climate.”

        Exactly what I say about the concept of ‘internal variability’. The AMO appears to be a powerful negative feedback to solar wind variability.
        https://www.linkedin.com/pulse/association-between-sunspot-cycles-amo-ulric-lyons

      • I will be dealing with some of the mechanisms for climate change, with special emphasis on what is known of solar-climate mechanisms in the continuation article that I am writing. A very complex issue that I am trying hard to make more accessible. The series hasn’t reached its end yet, but we are getting closer. I have to thank Judith for her patience and kindness.

      • Good. Here’s a couple of studies that I referenced in my article:
        Effects on winter circulation of short and long term solar wind changes
        http://www.sciencedirect.com/science/article/pii/S0273117713005802
        The interplanetary magnetic field influences mid-latitude surface atmospheric pressure
        http://iopscience.iop.org/article/10.1088/1748-9326/8/4/045001/meta

      • Thank you for the references Ulric. The Lam et al., 2013, paper I already had it, but the Zhou et al., 2014 is new to me. I will read it.

        The solar electric circuit effect is highly controversial because it appears to be small and localized. As you know, Leif Svalgaard is precisely an expert on that, and if I recall correctly he doesn’t think it plays much of a role. Nevertheless I have included it in one of my figures with a question mark, as it remains possible that it plays a significant role, after all.

        To me the hypothesis that solar variability plays a very important role in climate change is well supported in paleoclimatology, but more importantly the present extended solar minimum (Eddy minimum) offers us one in a hundred years opportunity to support or discard it. If the hypothesis is correct, we should not see any warming between 2003 and 2030. A strong warming ≥0.1-0.2°C/decade is incompatible with the hypothesis. Of course if we do see <0.1°C/decade it could be due to something else or a combination of factors, but at least t would be consistent with the solar hypothesis, and absolutely contrary to the CO₂ hypothesis.

      • The consensus of circulation models is inherently contrary to AMO warming anyway, with AMO warming being -NAO driven, but rising greenhouse gases expected to increase positive NAO.
        http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-5-6.html

  20. There’s a 1973 year period when various known lunar cycles – e.g. full moon, draconic year – line up exactly with the tropical year.
    https://tallbloke.wordpress.com/2015/01/06/two-long-term-models-of-lunar-cycles/

    As that’s 2*986.5 years maybe there’s a common (solar?) factor with the 980-986 year period referred to in this Climate etc. post.

    Wikipedia says ‘A tropical year (also known as a solar year)…’

  21. I am always amused by solar influences and climate debates as invertible link will be made between climate and sunspots. But I would protest there is so much more to the solar effect on our climate than just these eruptions.
    One instance is coronal holes, especially when they face Earth. These most certainly have an effect on our weather but remain largely a mystery.
    Last year this time (well around November to January) there was a persistent coronal hole that, every 28days or so, sprayed this planet with high energy particles. The upshot of which was that there was some stratospheric warming at the North pole, and the Northern Polar vortex moved south, a lot.

    Now if we had the records we could we see if such an event, or a more intense version, could have initiated the last LIA? And could not such an event at this solar minimum do such a thing now? This would mean that the polar ice would probably reduce, but the polar vortex would probably expand southwards ensuring more Northern land mass get buried in snow.

    If only we had records for Earth facing coronal hole events that were as extensive as sun-spot records.

    On the whole is it not true to say that during high sunspots episodes the equatorial areas are warmed, and during coronal hole events the polar regions are warmed?

    • tom0mason,

      The effect from the Sun on Earth is mediated by radiation, particles, and fields. Only the first one is usually considered for climate. Sun’s variability comes from long term changes and transient events. Solar particles and magnetic field arrive carried by the solar wind. Several pathways have been described for solar effects on climate. The most studied is an atmospheric top down mechanism that is quite complex and relies on the structure and ozone content of the stratosphere. It is mediated by solar UV activity, the Quasi-Biennial Oscillation, and ENSO. The energy and momentum provider for this pathway is not the Sun, but the gravity waves originated from the interaction between the tropospheric wind and pressure changes with northern hemisphere mid-latitude mountain ranges. Under certain conditions these waves more frequently get deflected by the stratosphere and impact the stratospheric polar vortex disorganizing it. When this happens the Arctic and North Atlantic Oscillations tend to become more negative and this pressure changes alter the average winter weather in the northern hemisphere. When the effect is prolonged the climate is altered. Volcanic eruptions interfere with this pathway big time, and their winter warming effect is due to it.

      Another pathway is also mediated by irradiation, but in this case by changes in the whole spectrum, that impact the ocean, and is described as a bottom up mechanism. The effect is most prominent in the Pacific, due to this ocean being the largest by far at tropical latitudes. This pathway is less studied, and appears to act through changes in SST and cloud cover, altering the humidity, the size of the Hadley cell, and troposphere to stratosphere circulation. It also has seasonal variability with its effect being higher during northern hemisphere winter.

      Another pathway even less studied is caused by the energetic particle rain at polar regions, where HOₓ and NOₓ chemical species are created in the polar regions of the thermosphere and mesosphere and transported down to the stratosphere where they destroy ozone. This pathway is particularly effective when the transport is done through a well formed polar vortex.

      And yet another pathway is the one Ulric Lyons was talking above. The changes in the solar magnetic field impacting the Earth at polar regions cause changes in surface pressure. This is known as the Svalgaard-Mansurov effect. Some scientists propose that the effect is mediated by changes in the Earth atmospheric electric circuit. This is a big unknown, and it is not known how much effect and at what latitudes might happen.

      Most of the research on this has taken place on the last 20 years and models are unable to reflect these pathways. Only the first two in a very rudimentary way by a few models. For all we know solar variability might have a very important impact on weather and climate, but due to the complexity of the pathways we are unable to say how much. Paleoclimatological evidence supports a big role. Climatic history for the past 400 years supports a big role. But all we hear from official sources is that Total Solar Irradiation changes are too small to have much of an effect and we are shown the models to prove it. And if the models can’t do it then it doesn’t exist. The most fraudulent argument is that solar activity has been declining for decades while temperatures have been increasing. It is fraudulent because it is based on the assumption that solar effect on climate is linear and proportional to solar activity. We do not know that. The evidence shows a disproportionate effect during prolonged periods of very low solar activity, like the one we have entered.

      Coronal holes have the effect of increasing solar wind. In essence a similar but bigger effect during a short time takes place during coronal mass ejections. They don’t appear to have much of a climatic effect, so it seems that any effect of coronal holes is likely to take place over time. Low solar wind has been associated to the effects of the Maunder Minimum. It appears that all solar effects tend to work on the same direction, creating a synergistic effect. It is like a gentle push to the climate system to work in a different direction and requires quite a lot of time in that different direction to show an important effect.

    • “could have initiated the last LIA?”

      No the reverse, negative NAO/AO and cold Arctic incursions into the mid latitudes would be due to a lack of faster coronal hole streams. There are records of no aurora sightings for most of the colder years of the Dalton Minimum. You can check the coronal hole list for last winter here:
      http://www.solen.info/solar/coronal_holes.html
      The sudden stratospheric warming was February and March:

      • Ulric Lyons,
        Yes I agree with what you show however what I was wondering was the timing of such an event being immediately prior to the LIA coming into being. And not one big coronal hole but a protracted series of coronal hole events NOT necessarily huge ones but significant ones. Enough to cause the polar atmosphere to be in significant turmoil.
        Perhaps I see nature working in a different way from most of you. I understand that nature rarely give a big blinding flash of change, more often than not there are warning signals, and if we are adept enough we should recognize them. Sudden catastrophic change without warning is not nature’s usual method of change.
        ~~~~~~~~~~
        Funny that my notes (of from http://solarham.net/ reports) from last year show coronal hole appearing in November (weak), December, and January… for example …
        I noted

        December 5, 2016 @ 01:20 UTC
        Large Coronal Hole
        A recurrent coronal hole feature is moving across the Earth facing side of the sun and will become geoeffective beginning December 7th. Enhanced geomagnetic activity, including minor (G1) storm conditions will be possible after December 7th when a high speed solar wind stream is expected to arrive past Earth. Perhaps some good news ahead for aurora sky watchers. More updates to follow this week. Image below courtesy of SDO/AIA.

        December 7, 2016 @ 00:55 UTC
        Geomagnetic Storm Watch
        A minor (G1) geomagnetic storm watch is now in effect for the next three days. Coronal Hole #43 will become geoeffective and a high speed solar wind stream flowing from this zone is expected to reach Earth over the next day or so. Sky watchers at higher latitudes should be alert for visible aurora. Stay tuned to SolarHam.com for the most up to date information.

        and then

        December 28, 2016 @ 20:20 UTC
        Coronal Hole to Face Earth
        Middle latitude coronal hole #48 will become geoeffective by December 30th. A geomagnetic enhancement, possibly reaching storm levels will be possible once a high speed solar wind stream arrives past Earth. Perhaps some aurora to ring in the new year! More updates on SolarHam.com in the days ahead.

        And also later in January.

        And my notes, and a video made at the time by a amateur weather forecaster (JMA monitoring http://ds.data.jma.go.jp of the 10hPa over the Northern Hemisphere) was showing significant stratospheric warming (NOT a SSW) starting around 29th January 2016 — a shift of about 30°C over a few days. This warming was, of course, very unexpected at the time, and definitely later disrupted the weather pattern. It also lead to some bloggers being all fired up over the North Pole experiencing some sudden warming, and crying about ice melting when the temperatures there were still around -20°C.

        Oh-humm, as a mere weather amateur I think I’ll leave all you big brains to postulate further without my input…
        Thank-you for your very knowledgable replies, bye for now.
        Have fun.

      • CH777 returned as CH782, geoeffective 4-9th Jan, so you are not talking about the same coronal hole.
        http://www.solen.info/solar/coronal_holes.html

    • And more related to your question:

      “Solar wind drives the variability in the near Earth space. Coupling of solar wind and the magnetosphere feeds energetic particles into the inner magnetosphere through reconnection in the magnetotail. During the declining phase of the solar cycle long-lived high-speed solar wind streams are more commonly observed at Earth’s orbit. These accelerate particles to higher energies and in the process lead to enhanced particle precipitation into the atmosphere. Electrons from tens to hundreds of keV precipitate down to the mesosphere and upper stratosphere, where they can create nitrogen and hydrogen oxides. During winter, nitrogen oxides have enhanced lifetime in the polar night. They can descend down to the mid-stratosphere and destroy ozone, which leads to cooling of the high-latitude stratosphere. This enhances the meridional temperature gradient and westerly winds under the thermal-wind balance, thus accelerating the polar vortex. This mechanism is successfully modeled by chemistry-climate models. Dynamical changes in the stratosphere can descend down to the troposphere. During strong polar vortex, the northern annular mode (NAM) is anomalously positive. Positive NAM encloses the cold arctic air into the polar region and enhances the westerly winds at mid-latitudes. Enhancement of westerlies bring warm and moist air from Atlantic to the Northern Eurasia causing positive temperature anomalies. At the same time negative temperature anomalies are observed in the Northern Canada and Greenland. Our recent observations show that the positive relation between precipitating electron fluxes/geomagnetic activity and NAM exists during winter. Positive NAM pattern is observed during the declining phase of the solar cycle at least since the late 19th century. We also find that the quasi-biennial oscillation (QBO) of equatorial winds strongly modulate this relation at high latitudes. These results give additional evidence that not only solar electromagnetic radiation but also the solar wind can affect the climate.”
      Asikainen, T., Maliniemi, V., & Mursula, K. (2017, April). Winds of winter: How solar wind driven particle precipitation can affect northern winters. In EGU General Assembly Conference Abstracts (Vol. 19, p. 12916).

      NAM and NAO are the same. Coronal holes thus would create stronger solar wind, NAO positive, cooling in Greenland. Usually coronal holes happen more often during the declining phase of the sunspot cycle.

      • Thank-you Javier for such complete explanations.

        I was just musing on the effects of last year’s (to the start of this year) observation of the Northern hemisphere change in weather during the period that the coronal hole open for about 3 months (Nov to Jan). Effects that I noted at the time. There was some very effective stratospheric warming just after each time the coronal hole came around (the particles take longer to reach Earth than EM radiations, as they are travelling at less than the speed of light on a curved path), and subsequently the polar vortex shifted. I did also note that weatherwise we were moving into an Easterly QBO, and all the high pressure blocking this often helps set-up in the polar region.

  22. Javier,

    You have indentified some important cycles (along with spurious cycles) that exist in the solar proxy record, but you are missing some important details.

    1. The cycles you have listed are mostly pseudo cycles and do not repeat accurately.

    2. You do not understand the underlying cause of the pseudo cycles or why they are in fact pseudo.

    Saying that, I mostly agree with your outcomes, especially in regard to the next big LIA type event being thousands of years away.

    You have listed McCracken, Steinhilber and Beer many times throughout your presentation and I suspect you hold them in high regard. They understand completely what controls the solar proxy record and wrote a paper in 2014 stating solar barycentric anomalies are the cause. This paper was a mirror of my paper (2010 & 2013).

    Please take the time to investigate our papers which once understood bring all of your work together and supply the driver you need.

    It starts with the De Vries cycle (208 years) which is not a cycle but more a most common gap between grand minima. Every 172 years there is a cluster of solar barycentric anomalies (BA) that vary greatly in strength. On average there are 3 that cover an 80 year period. When we get 3 strong BA’s per 172 years we get sporer or maunder type conditions and usually at the same time we tend to get clusters of strong BA events that form LIA type epochs.

    The McCracken (2014) paper backs up mine and explains why the most common gap in grand minima is 208 years, it is simply because most 172 year groups do not contain 3 strong BA events.

    We all also agree that the BA events are different every 172 years but repeat every 4627 years almost exactly. I proved this with data that McCracken supplied to me from Steinhilber showing the solar path repeats almost exactly every 4627 years. It never repeats at any other interval.

    The Bray cycle is also pseudo as it is around 2500 years followed by 2100 years across the Holocene. This is because there is a weaker LIA type cluster offset centrally in the 4627 year cycle.

    Other points:

    SC20 was low because of a weak BA event at the time, SC24 has a medium strength BA at 2005 that will go on to most likely affect SC25.

    Most of the SC24 panel predicted SC24 to be Much higher than it was. Myself and McCracken et al predicted SC24 to be close to SC5 (based on the old method of counting) well before the event using our outlined method.

    The Gleissberg cycle is real but only seen across the sunspot record and is disturbed if there is moderate levels of grand minima (as seen across the LIA). The 208 year cycle also breaks down fundamentally over the LIA. The simple rule is that the greater the angular momentum of the suns arc the larger the cycle (not withstanding grand minima). The largest arc’s occur every 172 years, hence the 88 year Gleissberg cycle.

    • Geoff,

      1. The cycles you have listed are mostly pseudo cycles and do not repeat accurately.

      Please read in the article above:
      “By now it should be obvious that solar cycles are pseudocycles or periodicities that display a relatively high level of period and amplitude variability.”

      2. You do not understand the underlying cause of the pseudo cycles or why they are in fact pseudo.

      I don’t and I have never claimed otherwise. Moreover, nobody does. Some people believe they do, but there is a high chance they are wrong. They don’t even agree between themselves.

      …McCracken, Steinhilber and Beer … understand completely what controls the solar proxy record

      Perhaps or perhaps not. They have a hypothesis and some data. Most insufficient IMHO.

      Every 172 years there is a cluster of solar barycentric anomalies (BA) that vary greatly in strength.

      I have a problem with a 172 or 178 Jose cycle or Jovian planet alignment. It is not seen in the sunspot data or proxy data of the past centuries. We see the 52-104-208 harmonic series very clearly. There is no evidence for a 170-180 year cycle that affects solar activity.

      I do not doubt that there are astronomical cycles of such lengths, and that they repeat every 4627 years. What I doubt is that they affect solar activity. No evidence for that, and baricentrism is not much different from numerology. It will accommodate the evidence by changing the parameters, like different BA events and cluster offsets. Those that follow it start by deducing that the baricentric theory must be true, and then try to fit the evidence into the theory. I am from the inductive camp. I embrace the evidence and see where it takes me without rejecting any possibility. Perhaps some planetary hypothesis is correct, but it is clear that the evidence is lacking, so I won’t go there. So far baricentric hypotheses have been sterile. Different articles propose different things and none of them has lead to any advance in knowledge.

      The Gleissberg cycle is real but only seen across the sunspot record and is disturbed if there is moderate levels of grand minima (as seen across the LIA).

      Well, I can’t see it. Nor can most authors, as they are clearly talking about different things. That is never a good sign in science.

      The 208 year cycle also breaks down fundamentally over the LIA.

      No it doesn’t. It can be clearly seen in sunspots, auroral records, and cosmogenic isotope proxy records. It is labeled as orange dV (de Vries) in figure 61.

      • Solar minima cannot follow a 208 year de Vries pitch, it’s the wrong length, and solar minima occur on average nearly twice as frequently as that. From the sunspot cycle maximum of the first weak cycle, solar minima occurred from; 1018, 1117, 1217, 1320, 1428, 1550, 1672, 1805, 1884, 2014.

      • There are both a centennial and bicentennial periodicity. Solar grand minima are clearly spaced by the bicentennial periodicity.

      • Gleissberg is generally described as between 80 and 120 years, that is simply the variable length between solar minima.

      • If the Gleissberg cycle is the centennial cycle, then it is not the cycle Gleissberg described. And the Centennial cycle does not show 80-120 year variability. The sunspot record shows it at ~105 ± 5 years.

      • Javier,

        I have presented hard data along with McCracken, Steinhilber and Beer, if you choose to ignore this data then we can only presume you are cherry picking data to further your cause…..not good.

      • Yes, you have presented data. But what does that data exactly demonstrates? Nothing really. You set out to show that solar system barycenter angular momentum changes are responsible for solar variability, and of course you arrived to that conclusion, as you started from it. On the way you defined the rules and configurations that affect solar variability because… they coincide with times when solar variability was affected. All the time without being even aware of your circular reasoning. And of course you arrive to your destiny: a hypothesis that explains solar variability in terms of angular momentum changes. But having an explanation doesn’t mean it is the real one. Charvatova has a different one, and Scafetta another one. And the number of possible explanations is always much, much higher than the number of real explanations, that is why most hypotheses are wrong. But you work with something that nobody can explain in physical terms and that requires so much time that any meaningful prediction might take hundreds of years to happen. So anybody with a modicum of skepticism (and I’ve got a lot) will not buy the hypothesis. That it fits the data says nothing about whether it is right or not.

        And unlike you, I don’t have a cause to further because as I said (and you agreed), I don’t claim to know what causes the observed solar variability. At most you could say that I am furthering the cause of skepticism. And that is good, not bad.

      • Javier:
        “Solar grand minima are clearly spaced by the bicentennial periodicity”

        Sometimes there are three in a row.

        “And the Centennial cycle does not show 80-120 year variability”

        It has done so in the last 400 years, with the length between solar minima varying between seven and twelve cycles. Which is why many papers quote similar figures.

        “The sunspot record shows it at ~105 ± 5 years”

        Dalton began in SC5, Gleissberg began in SC12, and the current minimum started in SC24. So we are actually looking at between 80 and 130 years, and with a long term astronomical mean of 108 years.

      • we are actually looking at between 80 and 130 years

        Hmm, no.

      • The Gleissberg Minimum is from SC12 to SC14, it did not start from SC14!
        Page 4:
        http://www.leif.org/research/On%20solar%20cycle%20predictions%20and%20reconstructions.pdf

      • Definitions are arbitrary. The centennial periodicity is from SC14. Look at figure 89 above in the article. Joan Feynman is the foremost expert on the centennial cycle having published several articles on it, and I agree with her.

      • “A new prolonged solar minimum, like the Gleissberg minimum of 1879-1914”
        https://judithcurry.com/2017/12/02/nature-unbound-vi-centennial-to-millennial-solar-cycles/

      • The Gleissberg minimum comprises the lows of the Centennial and de Vries cycles. The de Vries low affects SC12-13, and the centennial low SC14-15. That is my interpretation.

        Feynman sees the centennial low at the SC13-14 minimum and the SC14-15 minimum, as figure 89 shows. It depends on whether you consider the lows or the highs.

      • Your centennial definition is arbitrary, it even contradicts what you wrote in your post about Gleissberg being from 1879-1914.

        “The Gleissberg minimum comprises the lows of the Centennial and de Vries cycles. The de Vries low affects SC12-13, and the centennial low SC14-15. That is my interpretation.”

        There is no regular centennial cycle, de Vries cannot track solar minima, it’s the wrong length. There is only the variable, ~80-130 year Gleissberg cycle of solar magnetic minima.

      • Your centennial definition is arbitrary

        Joan Feynman’s definition is most definitely not. She defines the centennial lows very clearly as “when the annual sunspot number was very low (less than 3) indicating the CGC minima.”

        Feynman, J., and A. Ruzmaikin. “The Centennial Gleissberg Cycle and its association with extended minima.” Journal of Geophysical Research: Space Physics 119.8 (2014): 6027-6041.
        http://onlinelibrary.wiley.com/doi/10.1002/2013JA019478/full

        The problem appears to be yours.

      • Feynman:
        “The recent extended minimum of solar and geomagnetic variability (XSM) mirrors the XSMs in the nineteenth and twentieth centuries: 1810–1830 and 1900–1910.”

        Sloppy work. The bulk of negative NAO and cold years for Northern Europe in the Gleissberg Minimum was 1885-1895, i.e. between the sunspot maxima of SC12 and SC13 (+1yr). Dalton has the same pattern with 1807-1817 being the main cold period, between SC5 and SC6 maxima (+1yr), and a couple of cold years after that, 1820 and 1823. Which are the years that Silverman notes a lack of observed auroras for during the Dalton Minimum.

        “The dipole and quadrupole components of the solar magnetic field change in relative amplitude and phase.”

        Very interesting, the same phase change that I have noted here:
        https://www.linkedin.com/pulse/association-between-sunspot-cycles-amo-ulric-lyons

      • The bulk of negative NAO and cold years for Northern Europe in the Gleissberg Minimum was 1885-1895

        So what. There are more things going on in solar activity that the Centennial lows. If one looks carefully at a solar activity reconstruction, one can identify the lows quite clearly. The periods of highest activity usually fall between Centennial lows. 28 Centennial lows in 3000 years. The average is ~ 107 years. The same that comes from frequency analysis. The information is the same.

        Periods that have an active de Vries low (in dark orange with a filled red dot in the figure) have lower solar activity from earlier. That was the case at the Gleissberg minimum.

      • “So what.”

        So the Gleissberg Minimum effected the NAO most in solar cycles 12 and 13.

        “There are more things going on in solar activity that the Centennial lows.”

        Nothing more than the variable Gleissberg cycle as far as I can see. A mean of 10 cycles between solar minima +/- 2/3 cycles, and grand minima clusters every 400-1200 years.

        “28 Centennial lows in 3000 years. The average is ~ 107 years.”

        Which is 27 intervals in 3000 years, giving an average pitch of 111.11 years. Oh dear!

        “Periods that have an active de Vries low (in dark orange with a filled red dot in the figure) have lower solar activity from earlier. That was the case at the Gleissberg minimum.”

        The task here is to account for the variability of intervals between solar minima, that won’t be achieved by adding more fixed length cycles.
        And what’s the pitch of your orange de Vries lines on that chart? It looks more like 221 years overall and 214 years since 1200 AD. Oh dear!

      • The Centennial cycle is variable like all solar periodicities, but is a lot more regular that the 80-120 years you talk about. Your problem comes from where you place the cycle low within the Gleissberg minimum. You need longer data to do that correctly.

      • You are placing cycle lows, and with the wrong intervals, as I showed above. With 28 centennial lows over 3000 years one needs to divide by 27 and not by 28 to determine the pitch. I’m not placing anything, I’m purely observing where the weak cycles actually occur. According to Feynman, the centennial cycle is the Gleissberg cycle, and as we can see it is highly variable.

    • Geoff Sharp: 1. The cycles you have listed are mostly pseudo cycles and do not repeat accurately.

      Is that the definition of “pseudo cycle”, something not perfectly periodic?

      2. You do not understand the underlying cause of the pseudo cycles or why they are in fact pseudo.

      Are any of the cycles and pseudo cycles fully understood? The day/night cycle and annual cycle are not perfectly periodic; is “periodicity” something that you have have “amost”, or “within a margin of error”?

      An automobile engine running at varying speeds is also not perfectly periodic; is it a “pseudo cycle”? It is well understood, unlike natural oscillations that are only partially understood (I would say). Are there any natural oscillations that are as nearly cyclic as an automobile engine? I don’t think so, but there may be some. Even heart rate and neuronal action potential trains are not quite perfectly periodic.

      On the whole, you wrote a good post. Those are mostly definitional questions that I wrote. The “cycles” in Javier’s presentation are clearly non-stationary no matter what else you call them.

      Added in proof, so to speak: Also the word quasi should probably replace the word pseudo in my first post.

      Probably so.

  23. This article is an “elevator” or simplified version of AMP theory. (Barycentric Anomaly is the same as AMP event). Angular momentum perturbance.

    FORWARD: The Sun orbits the SSB (Solar System Barycentre) roughly every 10 years.

    There are 2 orbits consisting of an outer orbit that takes the Sun away from the SSB (outer loop) and a smaller orbit that returns the Sun to near the SSB (inner loop).

    The 2 orbits are controlled (99.96%) by the 4 outer planets.

    RULE 1:

    Outer loop orbits that reach the greatest distance from the SSB coincide with the largest solar cycles (sunspot count) along with inner loop orbits that come closest to the SSB.

    RULE 2:

    Occasionally (not randomly) the inner loop orbit can become distorted or disordered and attempt to be a quasi outer loop orbit. When the first half of this quasi orbit exceeds the distance of 1 solar radius from the SSB the associated solar cycle and the one following are highly reduced (Solar Grand Minimum).

    RULE 3:

    Rule 2 overrides Rule 1. (applies only to the second cycle in a Solar Grand Minimum)

    RULE 4:

    Solar cycle timing is NOT connected to outer or inner loops.

    DISCUSSION:

    Outer loop orbits that travel the greatest distance from the SSB and inner loop orbits that come closest to the SSB are 100% controlled by Uranus and Neptune. These events can only occur when U/N are together.

    Disordered inner loops orbits occur when J/U/N are together with S roughly opposing (U/N can be within approx 60 deg of their 360 deg conjunction).

    The 4 outer planets repeat their positions in relation to each other every 4627 years. A trace of the solar path of the Sun about the SSB is slightly different each orbit (outer and inner) over 4627 years. Disordered inner loop orbits vary in shape and those that have the first half of the orbit furthermost from the SSB coincide with the deepest solar downturns. The stronger disordered orbits can cluster together and these events occur twice in the 4627 year cycle. These clusters appear as Little Ice Age type events across the Holocene.

    The New Solar Physics 101 theory is completely falsifiable. There are rare occasions across the Holocene where a strongly disordered inner loop orbit does not coincide with a Solar Grand Minimum (2 solar cycles less than 50 SSN on the Wolf scale), but there are no deep Grand Minima that are not associated with strongly disordered inner loop orbits. It was seen in 1830 that the timing of a disordered inner loop orbit can occur near solar cycle max which negates a larger proportion of the reduction effect.

    I invite the scientific community to provide evidence to falsify the “The New Solar Physics 101” theory.

    Geoff Sharp 2017.

    REFERENCES:

    Solar path generation tool. http://www.arnholm.org/astro/index.htm

    JPL ephemeris DE430. https://ssd.jpl.nasa.gov/?planet_eph_export

    Are Uranus & Neptune Responsible for Solar Grand Minima and Solar Cycle Modulation?
    http://arxiv.org/ftp/arxiv/papers/1005/1005.5303.pdf and http://www.scirp.org/journal/PaperInformation.aspx?paperID=36513&#reference

    Powerpoint presentation (summary) http://www.landscheidt.info/images/AMP_Events.pptx

    Images:

    solar powerwave

    • Thank you for the information, Geoff. I’ll look it up.

      However I must say that it looks that you arrived to your rules and hypothesis by comparing your a priory deduction that solar barycenter oscillations are responsible for solar variability with solar variability data used to deduct them. You have arrived not through observation, but through deduction. As such supporting evidence is absolutely crucial, and that can only come from future observations. I see that you anticipate SC27 to be less active than SC26. That could be an initial test, as prolonging known periodicities indicates SC27≥26.

    • Sunspot cycles and solar minima are finely ordered by quadrupole phase relationships between Earth and Venus and the gas giants. They cannot be effectively correlated to the gas giants alone.

  24. I have posted a hopefully basic explanation of our theory that has many links and will come out of the spam bin eventually. Also the word quasi should probably replace the word pseudo in my first post.

  25. Pingback: Considering the sun in climate change

  26. Javier,

    You have mentioned a petition to name the possible forthcoming solar grand minimum after Jack Eddy. Anthony Watts and Dr. Svalgaard are behind this petition which robs the original predictor of the possible upcoming grand solar minimum.

    Landscheidt was the first to predict a period of solar grand minimum starting around now and should be recognised for this achievement just as you prescribe that Bray should be recognised above Hallstatt for the 2100/2500 year cycle in LIA cluster events across the Holocene solar proxy record.

    Landscheidt’s methods are now seen to be not quite correct, but he was very close and provided the platform for the enlightenment now achieved.

    • Geoff, I was merely reporting the petition, that is in Eddy’s Wikipedia page. If Landscheidt predicted a solar minimum for SC24-25 in a publication, of course scientific precedence should be an important factor to consider in support for his name for the minimum. However don’t keep your hopes high. Eddy is widely known and well considered, while Landscheidt is not, and many would think that his name in a current minimum would be akin to endorsing his theories.

  27. Thanks for sharing, Javier. These cycles and how they fit together are fascinating.

  28. Re ‘The 980-year Eddy cycle in solar activity reconstructions.’

    980 years is exactly 2/3rds of the claimed 1470 year cycle.
    http://core.ac.uk/display/23508542

    • Yes, but Stephen Obrochta has this to say about the 1470-year peak:

      “GICC05 and the North GRIP (NGRIP) ice core strongly suggest that the GISP2 chronology contains significant inaccuracies, and thus NGRIP superseded GISP2 as the key last-glacial reference series. GISP2 on it’s original chronology (Meese-Sowers) exhibited an inconsistent climate/annual layer thickness relationship; Svensson et al. (2006) note that: “the existence of the proposed 1,470yr cycle depends on the exact timing and phasing of the onset of D–O events, and … this is exactly where we believe that the GISP2 time scale is inaccurate.” Furthermore, the GISP2 age scale places the Toba Eruption about 4,000 years too early (e.g., Svensson et al., 2013).
      The GICC05 chronology has been transferred to GISP2 though high-precision volcanic synchronization with NGRIP (Seierstad et al., 2014). This largely corrects the inconsistent climate-layer thickness relationship of GISP2 (Obrochta et al., 2014a) and drastically changes the characteristics of the time series. The sharp 1,470-year peak that dominated the millennial band is removed, with power redistributed to a larger number of low-amplitude peaks (see figure on last page). While one of these is near 1,500…”

      https://www.clim-past-discuss.net/11/C2548/2015/cpd-11-C2548-2015.pdf

      My own calculations over published data indicate the oceanic cycle is actually ~1500 years and not ~1470.

      “The 1500-year cycle has undergone 8 oscillations in the past 11,700 years. If the cycle had a periodicity of 1470 years, instead of the observed ~ 1500 years, the accumulated drift would be of 240 years which is larger than what is observed in the proxy data presented. As the Holocene data is also in agreement with the new GICC05 age model, the DO cycle must actually be closer to 1500 than 1470 years.”

      https://judithcurry.com/2017/09/15/nature-unbound-v-the-elusive-1500-year-holocene-cycle/

      Obrochta thinks the 1500-year cycle is a solar artifact from 1000 and 2400-year solar periodicities. I don’t. I think it is a periodicity caused by a tidal cycle.

  29. There are different ideas in other papers e.g.:

    Rapid, millennial-scale climatic oscillations of 1470 ± 500 years are evident in numerous palaeoclimatic records in the North Atlantic and Pacific (Bond et al., 1997, 2013; Braun et al., 2005; Schulz, 2002; Turney et al., 2004)…
    This cycle’s periodicity of ∼ 1470±500 years is stable.

    http://www.clim-past-discuss.net/11/4895/2015/cpd-11-4895-2015.pdf

    The +/- 500 years puts us back to 980 years or forward to 2 * 980.

  30. Javier – I’m not trying to discuss any 1500 year cycle, that’s your theory.

    All I’m saying here is that the 980 year cycle is 2/3rds of the well-known (even if debated) Dansgaard-Oeschger cycle of 1470 years.
    http://en.wikipedia.org/wiki/Dansgaard%E2%80%93Oeschger_event

    Quoting from a paper that was accepted:
    ‘Many palaeoclimate records from the North Atlantic region show a pattern of rapid climate oscillations, the so-called Dansgaard–Oeschger events, with a quasi-periodicity of ∼1,470 years for the late glacial period’
    http://www.nature.com/articles/nature04121

    The maths says 980 * 3 = 1470 * 2. It could be argued that makes either the D-O or the ‘Eddy’ redundant in terms of separate naming, and the D-O was there first – but I digress.

    • The maths says 980 * 3 = 1470 * 2.

      Yes, but even assuming that both 980 and 1470 are the correct periodicities, as there are doubts about it, it could just be by chance.

      Some scientists believe the 1000, 1500 and 2500-year cycles are related, others don’t. When studied in detail, while the 1000 and 2500-year cycles have almost indistinguishable climatic effect, the 1500-year cycle is very different. But some people reduce climate change to temperature change, and then it all looks the same.

  31. Yes, you have presented data. But what does that data exactly demonstrates? Nothing really. You set out to show that solar system barycenter angular momentum changes are responsible for solar variability, and of course you arrived to that conclusion, as you started from it. On the way you defined the rules and configurations that affect solar variability because… they coincide with times when solar variability was affected. All the time without being even aware of your circular reasoning. And of course you arrive to your destiny: a hypothesis that explains solar variability in terms of angular momentum changes. But having an explanation doesn’t mean it is the real one. Charvatova has a different one, and Scafetta another one. And the number of possible explanations is always much, much higher than the number of real explanations, that is why most hypotheses are wrong. But you work with something that nobody can explain in physical terms and that requires so much time that any meaningful prediction might take hundreds of years to happen. So anybody with a modicum of skepticism (and I’ve got a lot) will not buy the hypothesis. That it fits the data says nothing about whether it is right or not.

    Javier, there is no circular reasoning going on, only data and observations that seem to align together over the Holocene. The disordered inner loop orbit along with the angular momentum perturbation (barycentric anomaly) is quantifiable using multiple methods, so we can differentiate between strong medium and weak disruptions to solar activity in respect to grand minima.

    Not only does the timing of grand minima in respect to the disordered inner loops but also the depth of the individual grand minimum coincides with the disruption strength of the associated orbit in nearly all cases. Yes the strength was determined from observations across the Holocene but they remain consistent across the Holocene, so some confidence is assured.

    Scafetta’s theory is different but our theory is compatible with Charvatova’s. We have identified the individual disordered inner loop orbits that create her disordered orbit phases that cover around 120 years that include ALL solar grand minima across the Holocene along with quantification enabling prediction and accurate hindcasting.

    McCrackens diagram backs up Charvatova’s theory showing that grand minima do not occur during the ordered phase (U/N opposed) across the Holocene, and they are the experts in this arena.

    • there is no circular reasoning going on

      Yes there is, even if you are not aware of it. You get the information to decide what parts of the astronomical cycles cause a decrease in solar activity from solar activity records, and then propose that those configurations cause a decrease in solar activity. The hypothesis is built from solar proxies and then explains solar proxies.

      So how does your hypothesis explain that from Jose cycle 31 to 42, a period of over 2000 years between 2800 BP and 5000 BP, essentially no grand solar minima took place, as the figure above from McCracken shows? What happened to the planets then? Did they change the way they moved?

      The good part is that there is no evidence to say that your model is wrong. The bad part is that there is no evidence to say that your model is right. What would be its prediction? That in the future grand solar minima will not take place during the disordered phase (40% of the time), but might or not take place during the ordered phase? That’s pretty vague.

      • You really need to understand the theory before criticising.

        The records of solar slow downs come from proxy records and Sunspot counts. The theory very accurately accounts for the much higher resolution sunspot records. Right down to the minor slow down at SC20 coming after one of the highest cycles recorded.

        The theory is totally falsifiable, if the maunder and dalton minima didn’t occur at their precise times along with SC20 and SC24 the theory is busted.

        Do the planets change the way they move across the Holocene? Of course they do and in fact the outer 4 never repeat their positions in relation to each other over a 4627 year cycle. This is a widely known fact. All the disordered inner loop orbits over this period vary and exhibit varying disruption strengths (as per rule 2). The major differentiator is the position of Saturn in relation of J/U/N opposite. The 2000 year period you refer to was a time of weak disordered orbits, we are now entering a similar period which agrees with your research…go figure.

        If you took the time to investigate the science properly you would find the data stacks up and that with some small changes to your Bray cycle timing the theory would back up your work.

        The future is easy to predict, no grand minima will occur during the ordered phase (as seen across the whole Holocene) and we will see weak grand minima separated by roughly 200 years for about 2000 years…I think we agree on this but my reasoning has a driver.

      • Geoff,

        The theory is totally falsifiable

        No it is not. It cannot be falsified using the same past data that was used to build the hypothesis. Even wrong hypotheses agree with the data used to build them. It could only be falsified by future data, or by past data not discovered yet.

        I’ll try to look at the hypothesis with more detail, although it requires quite a lot of time investment. My problem with it is not that I believe it to be wrong or right, It is that I believe there is no way to know, and therefore quite unproductive.

  32. I did an article on this post for CFACT. Got some negative comments. No surprise, debate is like that.
    http://www.cfact.org/2017/12/07/considering-the-sun-in-climate-change/

    • Thank you for your article David.

      Yes, that is the nature of the debate. Everybody has an opinion and most people get their opinion just on a few facts or even worse memes. I have argued the “solar activity-temperature moving in opposite directions” meme several times with Leif Svalgaard. It is a fallacy to assume that for the Sun to play an important role on climate change, TSI must be a primary driver of temperatures. It is clear that the answer is no. TSI is not the primary driver of surface temperatures. In fact temperatures are affected by many things so one should never expect a very good correlation with just one.

      The proxy record is clear that only long periods with well below average solar activity are associated with significant cooling, and the Sun just had a clear above average activity period that lasted most of the 20th century (from about 1930 to about 2005). One should expect warming through most of that period, and that is what we had. Since about 2005 we are having below average solar activity. So far we have not had much warming, if any, besides the now ended strong El Niño.

      So if going forward no warming takes place up to around 2030, then the solar-climate connection would have passed a very strong test, as the main alternative hypothesis (CO₂) did not predict the pause and has consistently predicted more warming.

  33. Javier – re. ‘Yes, but even assuming that both 980 and 1470 are the correct periodicities, as there are doubts about it, it could just be by chance.’

    I have a solution for this now. It may appear in a blog post soon.
    Thanks for the discussion.

  34. Geoff,

    As I understand it, your curve in this figure comes from your personal quantification method of angular momentum disturbances. According to your method, disturbances that occur with Saturn at one side of the Jupiter’s opposition to the Sun’s axis (type A) have a stronger effect on solar activity than those when Saturn is at the other side (type B). Obviously you have come to this conclusion by comparing angular momentum disturbances to solar activity, therefore you cannot say that this agreement supports your hypothesis. The agreement has been made by you.

    This doesn’t mean that you are wrong. Your curve clearly defines the 2500-year Bray cycle. Obviously because it is adjusted to the Homer to Maunder SGM. However it doesn’t pick the 1000-year Eddy cycle very well. And specially it does not predict the 2600 AD SGM that the Eddy cycle predicts.

    Although the Bray and Eddy cycles have nearly indistinguishable effect, they appear to be different. The 104-208 Centennial-de Vries cycles display modulation by the Bray cycle, not by the Eddy cycle. And the Eddy cycle is not modulated by the Bray cycle either. There is also a long period when the Eddy cycle had low power, but the Bray cycle was not affected. Due to all this, I believe they don’t have the exact same cause and more than one phenomena is involved.

    3000 years is not very much in terms of solar activity, since we have reconstructions for the past 11,700 years. I don’t know how difficult it would be to extend the angular momentum record for the entire Holocene. Solar cycles have irregularities, because they are pseudo-cycles. The Bray cycle is missing a low at 7,700 BP and has an additional one at 12,800 BP that shows in IntCal13 (see my figure 57). And the 1000 year cycle was very strong in terms of solar activity effect between 11,700 and 5,000 BP.

    If your curve can reproduce those features without further adjustment to quantification method it would inspire more confidence that it is not the product of an artificial match between angular momentum changes and solar activity. If it only reproduces the 2500-year Bray cycle, then we would have a hypothesis for this cycle, not for all solar activity. If it doesn’t reproduce either, then the hypothesis is probably wrong.

    • Hi Javier, great that you are understanding some of my theory, there are very few who have a handle on it.

      In the beginning I Just looked at the Holocene curve and observed the angular momentum perturbation, planet angles and orbit shape of the Sun at the major downturns etc. They are easily quantified so once observed I moved on to a similar period in the Holocene and found the patterns pretty much repeated across the whole Holocene. You might call that circular reasoning but the relationship stood up across the whole period. The chance of this happening by random chance is extreme, as McCracken et al pointed out.

      My graph from 2009 is very rudimentary but good enough to show the underlying trends coincide. My aim is to one day have someone with the programming skills to output a Holocene curve based on my theory’s rules only, my guess is it would match the solar proxy record very closely.

      I have looked back much further than 3000 years and the data holds true, a great example is the 2000 year period centered at -2000 which is made up totally of weak type A and B events.

      When looking at Bray type events I prefer to place the marker in the middle of the cluster. The Sporer at around 1470 and at -573 for the next marker. -573 does not show a strong grand minimum but is one of the few times across the Holocene where a strong type A doesn’t show a big fall, but I think I know why.

      I don’t think the Eddy cycle is real and is just perhaps an artefact of the DeVries cycle and doesn’t look strong when looking over the whole Holocene. I think a slightly amended Bray cycle that modulates the DeVries cycle (160-208 years) is all that is needed to hindcast and forecast the Holocene.

      I think our work is complimentary, and would just love someone to build that model to make it more compelling. The true cycle though is not fleshed out, most probably because the proxy record is not long enough. Pick any point on the Holocene proxy record and go back 4627 years, the solar output should be the same.

  35. Lower solar equates to lower overall sea surface temperatures and A slightly higher albedo. The result global cooling which is now happening.

    • No it is not happening right now. So far December has a higher anomaly than November had, and November is not going to be lowest anomaly of 2017. 2017 is highly likely to be the 2nd warmest year in the record. It will increase the 30-year trend. It is the warmest El Niño free year in the record. We are in a robust warming regime.

      • JCH,

        You are both talking different things. The 350-year long warming trend since the bottom of the LIA is undeniable, and unlikely to be undone in a very long time.

        Surface temperature measurements indicate a cooling trend for the past 22 months. This is to be expected after a strong El Niño.

        Due to low solar activity and eastward QBO a colder than average Northern Hemisphere Dec-Mar is anticipated. If equatorial Pacific La Niña conditions persist, it should lower global temperatures starting in Spring.

        Therefore there is a chance that SAT will be lower in 2018 than in 2017, as it is going to be lower in 2017 than in 2016.

        One thing you need to understand is that being able to extrapolate doesn’t mean that you know what the future holds. All I know is that we are not seeing as much warming as we were told to expect by the world leading experts.

  36. less uv light lower sea surface temp

    major volcanic activity increase and global cloud /snow coverage increase equates to a slightly higher albedo

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