Climate crises: half a millennium ago

by Judith Curry

[A] key message within Gore’s Climate Reality Project was that our recent strange weather and accompanying social problems are inextricably linked to the climate crisis. And say what you will about Gore, that part seems increasingly true. What’s more, there’s nothing new about such cause-and-effect. According to a new study, climate change has played a significant role in several of the  crises of pre-industrial Europe and the rest of the Northern Hemisphere over the course of the 300 years.

Time article

Ecocentric blogs at Time has an article entitled”Climate Change Caused Crises Half a Millennium Ago, Too.”  Some excerpts:

A team led by David Zhang of the University of Hong Kong collected as much data as they could find about climate, demography, agro-ecology, and the economy from the years 1500 to 1800 in Europe and found that these variables yo-yoed up and down along with the weather.

While  numerous civilizations did experience the same ups and downs as  global temperature over the centuries, the immediacy of the cause and effect varied. Sometimes the response to temperature change was almost instantaneous, while others time it took five to 30 years before the impact was fully felt. And as is the case with everything in the environment, a change in one area often triggered  a cascade of changes in others. Take for example the cooling that occurred from 1560 to 1660—a century within the 300-year era known as the Little Ice Age: plants couldn’t grow as much or for as long, so grain prices soared, famine broke out, and nutrition sank. Poor diet means poor growth even for survivors, and the late 16th century  saw a decline in average human body height by 0.8 inches. As temperatures rose again after 1650, human height crawled back up too. Before it did, however, sky-high grain prices and  accompanying real wage declines brought social problems more pressing than height.

“Peaks of social disturbance such as rebellions, revolutions, and political reforms followed every decline of temperature, with a one- to 15-year time lag,” the scientists wrote, adding that many such disturbances escalated into armed conflicts. “The number of wars increased by 41% in the Cold Phase.”

There were more peaceable responses too. Poorly fed or otherwise deprived people tend to decamp from where they’re living and move somewhere else, and migration rates increased in this era along with social disturbance. The problem was, in these cases the relocation wasn’t the hearty westward-ho kind of 19th century America, when well-fed settlers could live off the land (and the buffalo) while they sought new homesteads on the frontiers. Rather, migration among the hungry or unwell often leads to epidemics. It may be too much to lay the great European plagues of 1550 to 1670 entirely at the door of global cooling, but  dramatic climate shift and resultant poor health surely played a role. It was around 1650 as well that European population  collapsed, bottoming out at just 105 million people across the entire continent. Wetter countries with more fertile land or those with stable trading economies tended to do better in this eras of hardship, but no one was spared.

Discovery News

Discovery News has a related article with the creative title  “Climate change caused angry runts.”  Some excerpts:

“Our findings indicate that climate change was the ultimate cause, and climate-driven economic downturn was the direct cause, of large-scale human crises in preindustrial Europe and the Northern Hemisphere,” wrote the researchers, led by David Zhang of the University of Hong Kong, in the Proceedings of the National Academy of Sciences.

Between 1500 and 1800, every change in average temperatures correlated to a change in agricultural output and food supply. The climate changes did not result in immediate changes in population growth, so even in a cold year with poor harvests, the population kept going up. More mouths to feed with less grain meant a rise in food prices and starvation.

“Peaks of social disturbance such as rebellions, revolutions, and political reforms followed every decline of temperature, with a 1- to 15-year time lag,” reported the researchers.

As the civilizations of Europe developed new technologies and began conquering and colonizing the Western Hemisphere, the health effects of climate changes became less pronounced.

According to Zhang and his colleagues, “The mild cooling in Europe in the late 18th and 19th centuries brought about an upsurge in prices, social disturbance, war, and migration but not demographic crisis, because of social buffers such as cross-continental migration, trade, and industrialization.”

The researchers concluded that the economic downturns caused by climate change were the direct causes of the human crises. When a country’s economy and agricultural output didn’t suffer, their populations didn’t either.

“This result explains why some countries did not undergo serious human crisis in the Little Ice Age: Wet tropical countries with high land-carrying capacity or countries with trading economies did not suffer a considerable shrinkage in food supply, nor did some countries, such as New World countries with vast arable land and sparse populations, experience substantial supply shortage,” the researchers reported.

Wired Science article

I just spotted aother orticle that is worth reading on this, at Wired Science, entitled “Climate Shifts Sparked 17th Century Conflicts.”  Some critiques of the work:

Halvard Buhaug, a political scientist at Peace Research Institute Oslo, calls the research “good work with a lot of good data.” But he adds that it was “really surprising” and “unfortunate” that the authors didn’t discuss whether the findings continued to apply in the industrial period, when trade, technological development, and other processes have made societies less sensitive to the climate. It remains unclear, he says, whether this research is relevant for the present day, when humans are facing a period of rapid temperature changes.

The claim that this kind of analysis can pin down climate as the root of human history, particularly when the researchers examine long periods at a time, is “pretty hard to swallow for a historian,” says William Atwell, a historian at Hobart and William Smith Colleges in Geneva, New York. The authors, he says, ignore the effects of religion, trade, and other factors. For instance, during the “Little Ice Age” of 1500 to 1559, North American natives were dying en masse from diseases imported from the Old World, leading partly to the start of the African slave trade which, he argues, affected human history in a major way unrelated to climate shifts. “Not that [the researchers] don’t have interesting things to say,” he says, “but they’re attempting to be too precise” by putting dates and numbers on conflicts.

Paleoclimatologist Sebastian Wagner of Helmholtz Zentrum Geesthacht in Germany agrees that the time frames are too broad but for a different reason. The researchers prepared the data for analysis by “smoothing” it into 40-year chunks that, he says, could alter the significance level of the statistics. Additionally, he says, the paper looked only at temperature, not at other factors, such as changes in rainfall, that can drastically influence human society.

Zhang’s papers

Here are several of David Zhang‘s papers, the first one is the trigger for the news item:

The causality analysis of climate change and large-scale human crisis

David D. Zhang, Harry F. Lee, Cong Wang, Baosheng Li, Qing Pei, Jane Zhang, Yulun An

Abstract. Recent studies have shown strong temporal correlations between past climate changes and societal crises. However, the specific causal mechanisms underlying this relation have not been addressed. We explored quantitative responses of 14 fine-grained agro-ecological, socioeconomic, and demographic variables to climate fluctuations from A.D. 1500–1800 in Europe. Results show that cooling from A.D. 1560–1660 caused successive agro-ecological, socioeconomic, and demographic catastrophes, leading to the General Crisis of the Seventeenth Century. We identified a set of causal linkages between climate change and human crisis. Using temperature data and climate-driven economic variables, we simulated the alternation of defined “golden” and “dark” ages in Europe and the Northern Hemisphere during the past millennium. Our findings indicate that climate change was the ultimate cause, and climate-driven economic downturn was the direct cause, of large-scale human crises in preindustrial Europe and the Northern Hemisphere.

Published online before printOctober 3, 2011, doi:10.1073/pnas.1104268108.  Link to full paper [here}.

Global climate change, war, and population decline in recent human history

David D. Zhang, Peter Brecke, Harry F. Lee, Yuan-Qing He, Jane Zhang

Abstract. Although scientists have warned of possible social perils resulting from climate change, the impacts of long-term climate change on social unrest and population collapse have not been quantitatively investigated. In this study, high-resolution paleo-climatic data have been used to explore at a macroscale the effects of climate change on the outbreak of war and population decline in the preindustrial era. We show that long-term fluctuations of war frequency and population changes followed the cycles of temperature change. Further analyses show that cooling impeded agricultural production, which brought about a series of serious social problems, including price inflation, then successively war outbreak, famine, and population decline successively. The findings suggest that worldwide and synchronistic war–peace, population, and price cycles in recent centuries have been driven mainly by long-term climate change. The findings also imply that social mechanisms that might mitigate the impact of climate change were not significantly effective during the study period. Climate change may thus have played a more important role and imposed a wider ranging effect on human civilization than has so far been suggested. Findings of this research may lend an additional dimension to the classic concepts of Malthusianism and Darwinism.

PNAS December 4, 2007 vol. 104 no. 49 19214-19219, link to full paper [here].

Climate change and large scale human population collapses in the pre-industrial era.

Zhang, D.D., Lee, H.F., Wang, C., Li, B., Zhang, J., and Chen, J. (2010)

ABSTRACT

Aim  It has long been assumed that deteriorating climate (cooling and warming above the norm) could shrink the carrying capacity of agrarian lands, depriving the human population of sufficient food. Population collapses (i.e. negative population growth) follow. However, this human–ecological relationship has rarely been verified scientifically, and evidence of warming-caused disaster has never been found. This research sought to explore quantitatively the temporal pattern, spatial pattern and triggers of population collapses in relation to climate change at the global scale over 1100 years.

Location  Various countries/regions in the Northern Hemisphere (NH) during the pre-industrial era.

Methods  We performed time-series analysis to examine the association between temperature change and country-wide/region-wide population collapses in different climatic zones. All of the known population collapse incidents in the NH in the period ce 800–1900 were included in our data analysis.

Results  Nearly 90% of population collapses in various NH countries/regions occurred during periods of climate deterioration characterized by shrinking carrying capacity of the land. In addition, we found that cooling dampened the human ecosystem and brought about 80% of the collapses in warmer humid, cooler humid and dry zones, while warming adversely affected the ecosystems in dry and tropical humid zones. All of the population collapses and growth declines in periods of warm climate occurred in dry and tropical humid zones. Malthusian checks (famines, wars and epidemics) were the dominant triggers of population collapses, which peaked dramatically when climate deteriorated.

Main conclusions  Global demographic catastrophes and most population collapse incidents occurred in periods with great climate change, owing to overpopulation caused by diminished carrying capacity of the land and the resultant outbreak of Malthusian checks. Impacts of cooling or warming on land carrying capacity varied geographically, as a result of the diversified ecosystems in different parts of the Earth. The observed climate–population synchrony challenges Malthusian theory and demonstrates that it is not population growth alone but climate-induced subsistence shortage and population growth working synergistically, that cause large-scale human population collapses on the long-term scale.

Global Ecology and Biogeography. Oxford: Blackwell Science. DOI:10.1111/j.1466-8238.2010.00625x. [Link] to abstract.

JC comments:  this is the first time I have come across David Zhang’s research, which addresses some very interesting links between climate, weather and society.  I was particularly interested in the assessment of the role that vulnerability played in the climate-society: “When a country’s economy and agricultural output didn’t suffer, their populations didn’t either.”


299 responses to “Climate crises: half a millennium ago

  1. I think the cause and effect are getting mixed up here.

    The world is in an uncertain and fearful state right now, devoid of old certainties, which is driving both climate alarmism and social problems.

    The strange weather is, well, just strange weather.

    • I agree, Rick.

      The public lost confidence in world leaders and scientists because of “double talk” and manipulation of data and observations, but that continued in today’s news stories* on the Nobel Prize in Physics.

      The observations for which the Nobel Prize was given show that neutron repulsion is probably the source of energy that powers the cosmos and causes the universe to expand, but

      The stories (below*) imply that the observations confirm the “Big Bang” and “Dark Energy” stories.

      In fact, neutron repulsion negates the need for either:
      a.) A “Big Bang” origin of the universe, or
      b.) “Dark Energy” to keep it expanding.

      We live in a strange, strange world – too much like that described in the George Orwell’s book, “1984.”

      *Today’s news stories: http://www.telegraaf.nl/buitenland/10666472/__Nobelprijs_Natuurkunde_voor_supernova-onderzoek__.html?sn=binnenland,buitenland

      http://www.physorg.com/news/2011-10-perlmutter-schmidt-riess-nobel-physics.html

    • BlueIce2HotSea

      Can’t resist biting on your OT Nobel Prize bait. My apologies to our good host and all who may resent the diversion. (But I did wait 3 days.)

      Since our universe has apparently acquired both sentience and introspection, it would seem that planning for the future would not be out of the question. Does your neutron propulsion suggest a way to avoid the (cold) heat death implied by a Dark Energy fueled expansion?

  2. Judy, was just about to send that Time link to you…..

    It’s a logical connection, especially considering the limited ability to store food for long periods that existed back then. Any backyard gardener also knows the connection between warmth and growth. Water you can almost always get, warmth, not so easy…

  3. In short, climate alarmism and the socialist inclination and results are what kill people;

    http://motls.blogspot.com/2011/10/eu-carbon-trading-scheme-pays-for.html

    • In short, climate alarmism and the socialist inclination and results are what kill people;

      Ah… that would be “not really.” Maybe this time, but the cooling events of the medieval period and post-Renaissance didn’t have any “climate alarmists” and if they did, they would have singled out the cold as the climate issue rather than warming. The climate – cooling – events and consequences are well documented. A book was published discussing the topic in 1975 in fact. It wasn’t medieval “climate alarmism” that killed people. It was starvation and outright violence as populations tried to relocate to regions where there was food. The immigrations of the Pechnegs, Huns and various varieties of Goths are correlated to climate shifts. The leaders of the times weren’t socialists either. They disguised themselves beneath other handy rubrics.

      Socialism just might be seen as an effect of the Little Ice Age, but I think that would be stretching coincidence. There were too many real social problems to be angry about to blame socialism on an ice age, even a little one.

  4. Do you consider this publication to be a product of the “climate science community?”

    If not, could you explain why you consider it not to be?

    Sorry had to beat Joshua to his pet theory

  5. It’s not hard to anticipate how this information will be interpreted through the filter of two different ideologies:

    a) Cooling is bad, warming is good.
    b) Civilizations are adapted to existing climates and suffer from any pronounced deviation.

    I see both of the above as overgeneralizations. The more realistic message, as I interpret the study, is that the welfare of societies is strongly linked to agricultural sufficiency. In this regard, there have been recent data correlating climate change in past decades with changes in agricultural productivity, as well as projections for future correlations. The results seem to be mixed – some areas and some crops have done well or at least not suffered much, whereas others have been harmed in terms of total growth or protein content. The harm may have involved heat stress in some cases, but in others cases has involved drought and insect damage. I realize these statements deserve to be documented. There appears to be a large literature on the subject, and I will see if I can cite some informative references tomorrow.

    • randomengineer

      I see both of the above as overgeneralizations. The more realistic message, as I interpret the study, is that the welfare of societies is strongly linked to agricultural sufficiency.

      Man is only as resilient as his technology allows for. In a cooling world with shorter growing seasons modern man could create faster maturing crops. Modern man can create GMO’s.

      Medieval man poked at the ground with sticks and could grow relatively small amounts per are and had limited understanding; he was a slave to the weather, pestilence, etc.

      The paper shows that man is limited to what his technology allows. You don’t need a professor to grasp the obvious. At least you didn’t when I went to school.

    • Fred,

      You left off one response

      a) Cooling is bad, warming is good.
      b) Civilizations are adapted to existing climates and suffer from any pronounced deviation.
      c) nom, nom, nom (http://tinyurl.com/43e56jk)

    • Stirling English

      Jeez – you are feeling threatened today.

      Mosh stole your Candy this time (nice one Steven) and now your head is full of slavering beasts….

      A couple of valium and a nice lie down should cure it.

    • Shorter Stirling = nom nom nom

    • Stirling English

      Name name name?

    • You make the usual amount of sense, but mercifully you are brief this time.

    • The disingenuous “fudging” of cooling with “climate change” seems intended to give plausibility to the alarmism about CO2 impact, still. Yet there is nowhere in the data indications that warming “climate change” has ever caused a crisis, collapse, or even measurable hardship.

      So (a) is correct. All the misleading vocabulary games played by Warmists are without foundation.

  6. …evidence of warming-caused disaster has never been found.

    Most of these problems seem to be about cooling, not warming. The climate has steadily warmed since the Little Ice Age while the world population and standard of living soared in spite of horrific wars.

    The whole approach seems to be a variation of the old adage about the man with a hammer seeing nails everywhere: “To a man with climate science everything looks like the result of climate change.”

    • At one point, in the 1400-1600 era, i believe, Timbuktu in Africa was a thriving metropolis with a large population and thriving trade. With the spread of the Sahara the area in now barely habitable. The causes of the changes in the Sahara region aren’t linked to AGW and are poorly understood, but certainly are climate change.

    • Phil, you may be right about the timing for Timbuktu still being an important trading post.

      But livability in the Sahara was much further in the past. There are pictographs on stone in the middle of the Sahara, showing hippos and various ungulates, from when the Sahara was a savannah, about 6,000 years ago. There were large lakes in the Sahara at that time. As I understand it, the way the earth was oriented to the sun caused the monsoon to go much further northward; perhaps there were also stronger monsoons, since the earth was 1 to 2 degrees warmer during the “Holocene Optimum” which was from about 8.000 to 6,000 years ago.

      My fascination at how much the earth has changed in just 6,000 years was sparked by reading about a 4,000 year old tree in an area of the Sahara that used to be wet — the tree still survives, a taproot reaching water tens of meters below, and still flowers every year, in vain hope of propagation.

  7. warmer climate brings good times and colder climate brings hard times.

  8. To reword that a little.
    warm climate and high CO2 makes life good.
    cold climate and low CO2 makes life suck.
    green things grow better when it is warm and CO2 is high.
    we like green things.

    • There is more to it than just temperature or climate change. NatGeo recently had a good presentation on the little ice age, largely with no political bias. One of the key items I took away was that culture had a large effect on the outcomes in different countries. Notably, the peasants in France refused to change agricultural practices and switch from fragile grain crops to a more robust multi-crop diversified farm. It went so far that in the 1700′s a large part of the reason for the French Revolution was that there was a big shortage of bread in the cities. Meanwhile, farmers in England, Germany, Italy, etc. were successfully producing adequate amounts of food, just not so much wheat for bread.

      The idea that climate variability causes social upheaval didn’t even start to make it into the history books until 15-20 years or so ago. One of the critical points brought out in Jared Diamond’s book Guns, Germs, and Steel was that until only about 40 hears ago most of the world was just one, or at most two, bad harvests away from starvation. That has changed with the Industrial and Green revolutions so that now the primary cause of famine is politics and wars. For the most part local food shortages otherwise can be dealt with through trade and charity. Part of the reason for high grain prices now is biofuels such as ethanol. The subsidies for them have changed the market allocation and driven up prices of basic foods nearly world wide.

  9. [ "The claim that this kind of analysis can pin down climate as the root of human history, particularly when the researchers examine long periods at a time, is “pretty hard to swallow for a historian,” says William Atwell, a historian at Hobart and William Smith Colleges in Geneva, New York. The authors, he says, ignore the effects of religion, trade, and other factors. For instance, during the “Little Ice Age” of 1500 to 1559, North American natives were dying en masse from diseases imported from the Old World, leading partly to the start of the African slave trade which, he argues, affected human history in a major way unrelated to climate shifts. “Not that [the researchers] don’t have interesting things to say,” he says, “but they’re attempting to be too precise” by putting dates and numbers on conflicts.” ]

    AGREED!!!
    ” Everyone needs a scapegoat” even to the elimination of other contributions. The do is wet – therefore it must be raining outside.

  10. Sorry…The Dog is wet – therefore it must be raining outside.

  11. The ‘mantra’ of rising temps is still being preserved critique of the ‘Wired’ article, from the statement: ” . . . it remains unclear, he says, whether this research is relevant for the present day, when humans are facing a period of rapid temperature changes . . ”

    Sorry, the present day is not seeing a period of rapid temperature changes. Temperatures have been flat (or even a bit down) for a decade, and the ‘quiet sun’ may results in further reductions. And the rise of temps over the past 150 years overall surely is not ‘rapid’.

    As far as agriculture being able to feed the people, one easy approach is to GET RID OF THE CORN FOR BIOFUEL, and use it to raise livestock for protein consumption, especially here in the US.

    Technology and advancements today make people in general more able to adapt to changing weather conditions, so I would not expect the same type of ‘social upheavals’ as compared to 300 – 500 years ago from colder spells ( . .that is, without the political interventions that could drive the upheavals . . . ).

  12. “It has long been assumed that deteriorating climate (cooling and warming above the norm)….”

    Aren’t periods of warming and cooling the norm?

  13. Our findings indicate that climate change was the ultimate cause, and climate-driven economic downturn was the direct cause, of large-scale human crises in preindustrial Europe and the Northern Hemisphere.

    TRANSLATION:

    Our findings indicate that climate change [cooling] was the ultimate cause, and climate [cooling] -driven economic downturn was the direct cause, of large-scale human crises in preindustrial Europe and the Northern Hemisphere.

  14. For us Portuguese, with 900 years of History, these correlations are very clear! Cold was bad and warm was good!!! As simple as that…

    BTW, countries with a small history, like the USA, tend to disregard ancient Historical facts. So, it’s never been hotter for them. True, but not true for us Portuguese!

    Ecotretas


  15. Around 1250, the balmy days of the Little Climatic Optimum began slowly but surely to wane. England once again become inhospitable to wine grapes, and the Continent, vineyards that had flourished on hilltops had to be moved to lower, more protected sites.

    The cold that turned Greenland into frigid wasteland afflicted parts of Europe in the 15th Century. Temperatures began a decline that was not dramatic–they were, on the average, only 1 deg to 2 deg F below those of 1200–but winters became longer and more severe, and summers were cooler and shorter. This climatic phase would last more than 300 years and would come to be known as the Little Ice Age.

    As late as the 18th century, the Little Ice Age was still in full cry.

    Atmosphere
    Oliver E. Allen
    Page 157, 1983 Time-Life Books

    Global cooling between the Little Climatic Optimum and the Little Ice Age was about 2 deg F (1.1 deg C).

    Global warming between 1900 and 2000 was about 0.75 deg C
    http://bit.ly/qGcD9M

    Is it not possible that the current global warming is the climate recovering from the Little Ice Age back to the climate similar to the Little Climatic Optimum of the 1200s?

  16. Remember children there was a time where everything got linked to volcanoes, or to asteroids, or to whatever else was the scientific theory “du jour”. The only rational choice is to try to identify the serious results from the fashionable ones…

  17. Temperature will go up and down (AWG is passing fad), just make the best out of it.
    http://www.vukcevic.talktalk.net/LL.htm

  18. … evidence of warming-caused disaster has never been found

    That is why all the warming periods are identified with the “optimum” label. It is only in the current revision of history that they are trying to swap dark (cold) and golden (warm) ages.

  19. I read somewhere and sorry I forget where, that Atlanta was a very minor city until it burgeoned into the modern giant we see nowadays as a consequence of the invention of air conditioning. Sounds plausible.

    • Washington DC – Congress, bureaucracies, and embassies – used to basically shut down for the summer months pre-air conditioning. I recall reading that the Brit and Russian embassies used to provide tropical duty pay for work in DC.

    • There were two important events of decadal length that have allowed the Southern US to thrive as never before. The second was widespread air conditioning. The first was ridding the South of two widespread diseases. Malaria was finally extirpated in Tennessee in the earily 1950s. Earlier, hookworm was reduced from a widespread parasitical malady to a rare one. Before these diseases were eliminated or severely marginalized, no industry requiring workers to report regularly would move to the South.

  20. Stirling English

    But, but, but..this all based on a false premsie. Dr Mann conclusively showed us that there was no warming or cooling in the days prior to industrialisation. I understand that it’s often called the Hockey Stick

    Anyways it’s in the Third Assessment Report from the IPCC, so it must be true, and these people writing silly articles are probably deniers, contrarians and creationists. When not eating babies.

    • Hush. Dr. Mann is one of the world’s greatest scientists as can be seen from the huge amounts of grant money he brings in. All the money proves he was not wrong about the hockey stick.

      If Dr. Zhang’s work contradicts Dr. Mann’s, we will resolve any discrepancy in accordance with normal scientific mechanisms — we will compare the amounts each raises in grant funding, calculate which study increases our own chance of receiving more grant funding, and vote accordingly. This is what is meant by the expression ‘science is self-correcting’. One corrects the science in order to take care of one’s self.

    • Stirling English

      @stan

      Thank you for guiding me back to The Path of True Righteousness once more. I had obviously fallen by the wayside and was in danger of becoming corrupted by those peddlers of Reactionary Myth they call ‘Proper Science’.

      Now I see through ther lies and fables. Now the scales have dropped from my eyes. Now I understand that a climatologist’s world and worth is not measured by abstract flimflam ideas like Truth and Replication but by concrete achievements…measured in dollar bills, Awards and Noble Prizes and Doctorates.

      How foolish was I to be seduced by those siren songs casting doubt on One of The Greatest Scientists of All Time and A Magnificent Benefactor of Humanity. But even these pale beside the amount of lovely spondulix he has brought to Penn State.

      I promise to keep a Hockey Stick in my bedroom forever to remind me of my near slip into backsliding. I abase myself before you!.

  21. This all sounds suspiciously close to the “its not bas argument”.

    “”Two thousand years of published human histories say that warm periods were good for people. It was the harsh, unstable Dark Ages and Little Ice Age that brought bigger storms, untimely frost, widespread famine and plagues of disease.”

    http://www.skepticalscience.com/global-warming-positives-negatives.htm

    • Latimer Alder

      A while back you were stronlgy asserting that climatology was not/could not be an experiemental science. But we have some primitvive lab records (writings/artefacts/history) from times when the climate was warming and from when the climate was cooling. Pretty much they tell us that the warmer times were better to live in than the colder ones…..

      SS is great on doom-laden predictions of catastrophe, but being a chemist (part experimentalist, part theoretician) once upon a time, I much prefer to beleive what DID occur, not what some folk think MIGHT occur.

      This all assumes, of course that sceptics haven’t invented a Time Machine and gone back into history to suborn our ancestors into writing falsehoods in their journals and all the other stuff they would have to have done to invent what history and archaeology and all the other pieces of theh jigsaw tell us. It also assumes that Mann’s Hokey Stick is noyt a true representation of the temperatures over the previous millenium….which any fule kno.

    • simon abingdon

      “its not bas argument” means?

    • Typo. “bas” was meant to be “bad”.
      As in “global warming is not bad”.

  22. More garbage from SS.

  23. 911 Truthers could learn a lot from these guys.

    These papers are nothing but myopic conspiracy theory squared. Choose a conclusion and then search for any correlations no matter how weak that reinforce this conclusion and avoid considering any factors not related to the this conclusion and voila, you end up with a paper that confirms your original conclusion!

    We’ve had the data mining field of paleoclimatology.

    Now we have the fantasy world of anthropoclimatology.

    What’s next, epistoclimatolgoy? Does climate exist? Soon we will have:

    I think therefore it rains, (with a 30 year normal).

  24. Harold H Doiron

    So why do AGW believers want to limit CO2 emissions? To save us from what? Couldn’t our resources be better spent adapting to whatever changes are coming? We just don’t seem to have the capability to accurately predict temperature trends yet, much less pin down true root cause of temperature trends. I predict we are getting ready to cool some more, so what does this newly found research tell us we should do now?……limit or increase CO2 emissions?….I’m confused…not.

    • Yep, all the speculation and data lead to one best option: maximize CO2 production! “2,100 ppm by 2100!” should be our rallying cry.

      It will drive all the right people into a lovely apoplectic rage.

  25. Stirling English

    ‘To save us from what?’

    My personal view is that the answer is:

    ‘The Bad Things. You wouldn’t want The Bad Things to come and get you would you? The Bad Things would hurt and not be nice.

    Now, do what we tell you and we’ll keep The Bad Things away.

    But Mencken said it better:

    ‘The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by an endless series of hobgoblins, most of them imaginary’

    I invite nominations for who should play the role of Chief Hobgoblin at the Christmas Pantomime.

    • Sterling,

      Keeping a population alarmed allows the government of the day to impose new policies and generate more flowing capital to projects that usually confines the populace even more.
      If my country has put more restrictions on goods and services and your has not, who’s products will be cheaper and what country will attract “investors”?
      In this day and age, new research and technology are discouraged as you have to waste time away from your research to find investors at an approved government company or institution to get the government grants.
      You have to follow rules to keep science confined into the areas that “peer-reviewers” can comprehend as their knowledge is limited as well and lord help in the research is beyond the approved confined quarters.
      So areas such as mechanics and motion of this planet are out. Size measurements of this planet are out as it is mathematics. Distance measurements are out as this is mathematics. Speeds and variations are out as this hits mechanics.

      Just leaves protected theories left.

    • Mencken also observed:
      “For every complex problem there is a solution which is simple, neat and wrong”. — H. L. Mencken

    • In politics, it also applies to things that are not a problem, merely an opportunity.

    • Hey hey I saved the world today
      Everybody’s happy now
      The bad thing’s gone away
      And everybody’s happy now
      The good thing’s here to stay
      Please let it stay

      Doo doo doo doo doo the good thing

      Hey hey I saved the world today
      Everybody’s happy now
      The bad thing’s gone away
      And everybody’s happy now
      The good thing’s here to stay
      Please let it stay

      Everybody’s happy now

      – Eurythmics

  26. Throwing out the red meat so the “denizens” can have their food frenzy, eh Judith?

    So, this researcher says that despite facile claims being made about links between climate and large-scale social problems, the causal relationship hasn’t previously been scientifically verified.

    So, he gathers data to see if they support correlation, and perhaps causation. He finds that they do support a link, among other links, between climate change, notably cooling and social problems – and that this happened in societies that lacked the technical resources to prevent those problems.

    No wonder there’s a food frenzy: A scientists looked to see if data support an assumption of causation, and qualified the implications of his findings.

    Can’t have that whole scientificy-thing of looking to see if data support causation going on in there here parts.

    • Joshua,

      Why is the data so important?
      It only covers.00001% of the planets overall existence and has to do with the evolving climate that is slowing down.
      This fails in project how much faster the planet was in the past and how the parameters such as pressure, centrifugal force, density, etc was different than today.

    • Joe -

      It’s data about one causal factor for social problems in some societies in the past.

      The author qualifies the findings in ways that suggest that the impact of climate change is mitigated by a society’s technologies.

      As far as I’ve seen, he doesn’t speculate about how current climate change will impact society. From what I’ve seen, he doesn’t assert, as some would claim that he asserts, that his findings prove that current rates of climate change will cause problems in all of today’s societies, let alone any of them.

      He collected data to try to scientifically verify a casual relationship that has been asserted without verification.

      It’s data.

      People can make of it what they will. If people want to turn his findings into a socialist conspiracy to destroy capitalism, they’re entitled.

    • Joshua,
      Don’t take Steven’s teasing so seriously, dude.
      It reduces something you run out of frequently.

    • Joshua: I’d say that the food frenzy is on the climate orthodox side, and quite a lot of us are tired of this never-ending quest on the part of climate scientists, scientists, the media, academics, and other climate orthodox to link everything to climate change.

      You practically can’t read an article or listen to a program that doesn’t tack on a climate change moral at the end. Giant squids — climate change. Acne — climate change. Depression — climate change. Go ahead google them. It’s hard not to understand this as anything other than a full-court propaganda campaign on climate change.

      To a man with climate science everything looks like the result of climate change.

    • @huxley…

      I tend to agree with you, although when it comes to science remember that anything that can improve the chance of getting research funding is likely to be included.

    • AK: Oh yes, funding! That’s crucial, of course.

      However, keep in mind that I focus my comments to fit into a screenful or less, so I don’t cover all the angles or qualifications that I would in a full treatment.

  27. Dr. Curry,

    Extremely off topic.

    I was stupid enough to look into the Monckton-Lucia fracas and the use of the linear relationship of dF/dT=4F/T. Bad move on my part, because it has opened a can of worms.

    http://ourhydrogeneconomy.blogspot.com/2011/10/back-to-baking-bacon-bread.html

    To me, the equation is perfectly valid if the correct relationship between T and F is considered. Unfortunately, the correct relationship is not apparent in the K&T analysis.

    If you or anyone else would like to rip my logic to shreds, feel free to visit the link and provide an explanation.

    • No takers? Well, the correct form of the equation appears to be dF/dT=4eF/T, where e=0.825 for Earth’s effective emissivity. Pretty elegant little relationship verified by cartoon. LOL

    • Dallas – I agree, except for the purposes of relating change in surface temperature to changes in OLR at the top of the atmosphere, I would put the effective emissivity closer to 0.5 or 0.6 than 0.8. That is because the surface (at 288 K) radiates about 390 W/m^2 (along with smaller quantities of latent and conductive heat loss) while the OLR is about 239 W/m^2, but with some of the latter not involving the surface at all but emission by the atmosphere of absorbed solar SW radiation.

      It’s interesting to consider the origin of the standard equation, dF/dt = 4F/T in order to see where an emissivity value ε should be inserted. The SB equation shows the radiative flux F from the surface of a black body as F = σT^4. Therefore, for a flux change as a function of temperature change, dF/dT = 4 σT^3. This can now be multiplied by F in both the numerator and denominator. In the numerator, it is written as simply F, whereas in the denominator, it is written out as σT^4. This trick allows σT^3 to be canceled out between numerator and denominator, yielding 4F/T.

      Ordinarily, there would be no need to insert an emissivity value, which would also cancel out for objects that are not black bodies. However, the error made by Monckton was to use dF to refer to a different F from the F in the equation. The dF refers to changes in OLR, whereas he used F to refer to fluxes at the surface, which radiates in the IR like a black body. When two different “F’s” are involved, the equation no longer holds, unless emissivity is inserted to correct the flux involved in dF (the OLR) for the reduction relative to the flux at the surface due to the greenhouse effect, including back radiation. If we want to be consistent in our use of F and dF, we need to use the OLR flux of 239 and a radiating temperature of 255 K rather than a surface flux applied to OLR changes.

      None of this has much to do with the KT energy budget diagram, which makes no claims about the equation.

    • I agree that emissivity has to be included at the surface for the d(Fc+Fl+Fr)/dT relationship to be valid. So d(cFc+lFl+eFr)/dT , c=heat transfer coefficient, l=latent heat transfer coefficient and e=effective emissivity, is the proper long form of the equation at the surface. The interesting part is the radiation through the atmospheric window which has a lower value of e, or path of of resistance, compared to cFc and lFl. Also c for air to water is 100Wm-2/K versus 10,000 for water to air.

      As far as what OLR to use, 155Wm-2 as compared to 33C is the most reasonable value. With the correct emissivity, the ratios of temperature and flux are consistent. Both are the result of atmospheric effects and both are based on 239 and 255, so my approach agrees.

      What all this does imply, is that the K&T DWR is some what high, which is not unbelievable since it is not the easiest thing in the world to determine.

    • That should be higher value of e, of course.

    • Know the price of e,
      Sensitivity value.
      Ideally cynic.
      ========

    • I double checked Fred, 0.825 is the effective emissivity for radiant heat flow at the surface, Fc=24, Fl=78, so 392-24-78=290 290*.825=239 = TOA flux. 239-155=84 which is the 51 absorbed by the troposphere plus 33 through the atmospheric window. K&T seems to be off a touch. DWR would be 155+51=206 to 239, depending on the emissivity of the window to the 33Wm^2 flux.

    • I’m not sure what the 0.825 refers to, Dallas. The “effective emissivity” relevant to the equations of interest is an artificial figure with no physical meaning and will be less than that. It is the correction needed to make the Planck parameter for surface flux and temperature equal the parameter as ordinarily defined, which is the flux change in the OLR per degree change in radiating temperature. The latter is (4 x 239)/255 = 3.74 W/m^2/K. If you compute this for surface values, using surface radiative flux alone (390 W/m^2), you get 5.42. If you add latent heat and conductive flux to the 390, you get 6.83. Dividing either of these into 3.74 gives you 0.69 or 0.55 respectively as “effective emissivity” values you would need for the correction.

    • Dallas – I’ve reread your comment above, and looked at the link you cited, but I still don’t know what you’re talking about. However, I see no problem with the K&T budget.

    • Another way to get to approximately the same thing independent of the 4F/T equation correction is simply to say that if the Earth were a black body (emissivity of one) at 288 K, it would radiate 390 W/m^2 to space. It only radiates 239 W/m^2. This yields an “emissivity” of 239/390 = 0.61. I gather a figure of about this magnitude has been cited by some previous authors.

    • I doubled checked at science of doom on his most recent post and he comes up with the same number. For a 1 degree increase in surface temperature, flux increases by 3.3 Wm-2 or 3.3/4=0.825

      For dF/dT=4eF/T, that is the value of e.

      The 0.85 is the effective emissivity or the benchmark value of climate sensitivity, as he calls it, at the surface which I calculated using the simplified equation. I doubled checked at science of doom on his most recent post and he comes up with the same number. For a 1 degree increase in surface temperature, flux increases by 3.3 Wm-2 or 3.3/4=0.825, which gives the classic add 3.7W worth of CO2 and you get 1/0.825 equals 1.2 degrees of warming.

      http://scienceofdoom.com/2011/09/22/measuring-climate-sensitivity-part-one/

      It is difficult to explain, especially if you assume the K&T is right or think that climate sensitivity is a done deal, not a problem for me by the way. I was hoping someone with better math communication skills could help. The equations are there,

    • Dallas – You misunderstood the Science of Doom article. A 1 degree temperature rise at the surface (or anywhere in the troposphere given that a lapse rate equalizes temperature changes at all levels) is associated with a flux change of about 3.4 W/m^2 at the tropopause, not the surface. This is one of the well established figures in climate science, and is simply a “no-feedback” (i.e., Planck only) relationship, but it has nothing to do with effective emissiviity of the Earth/atmosphere system. I can’t find evidence of anyone using a figure of 0.825, but in any case, it doesn’t apply to the equations we’ve been discussing.

    • No force has been applied to the TOA, there is no sun at the third moment.

      I have to get past this before I can get to the good stuff.

    • You are missing the sequence of moments. dF/dT=1 is before and atmosphere, before a sun, just a perfect BB in space. The first impulse is to add an atmosphere. If you are worried about the value of 0.825, I can derive it, but it is commonly known.

      First moment no atmosphere, second moment add atmosphere with 0.825 effective emissivity, third moment regained equilibrium in three layers. That is a little tricky to visualize. :)

    • If you ignore the change in albedo, then without an atmosphere, dF/dT would be 3.7 W/m^2/K. Do the calculations if you don’t understand that, using a solar input of 239, a surface temperature of 255, and the SB law for a black body.

      Dallas – please stop arguing, and instead try to learn some of these principles. You can’t do that here – you need to consult source materials.

    • If you leave out the sun as well and assume a “temperature of space”, dF/dT would be extremely small – much less than 1, which is to say that a very small flux change would mediate a very large percent change in temperature.

    • Fred I am not try to argue in a bad way, you are being very helpful.

      First, the albedo was already assumed to get the 255, Without clouds, the albedo would have been closer to 20%, I will save that for another day.
      “Another way to get to approximately the same thing independent of the 4F/T equation correction is simply to say that if the Earth were a black body (emissivity of one) at 288 K, it would radiate 390 W/m^2 to space. It only radiates 239 W/m^2. This yields an “emissivity” of 239/390 = 0.61. ”

      That is true. That would entail much more math to follow all the changes, by assuming what are the commonly accepted values, 0.825, 239TOA and 390@288 for the surface, it simplifies the problem. Using 0.61 I would have to estimate values for the coefficients for conductive an latent. By assuming their response is slow versus radiative, it simplifies things immensely, I could use d(cFr)/dT as first order, d(bFl)/dT as second order and d(aFc)/T as third order and have a pretty trick looking differential equation, but this method does work.

    • This really should be easier, though I know I am kicking butt on the crackpot index :)

      For a temperature radiative flux relationship, dF/dT=4F/T If you don’t understand that go away.

      dF/dT= 4*(aFc + bFl +cFr)/T, a=conductive heat flow coefficient, b=latent heat flow coefficient and c=radiative heat flow coefficient aka emissivity. Following me?

      If dF/dt=1, then

      T=4*(aFc+bFl+0.825Fr), Still with me?

      Equilibrium can be assumed for a steady state, equilibrium may never truly exist, it is a numerical concept. Agree?

      The Earth’s surface can be assumed to be in thermal equilibrium. Okay?

      If the Earth was floating in space all by itself at a temperature of 288K and with no atmosphere, T=390W.m-2, aFc=0, dFl=0 and C=1 Fr=390 Do I have to explain how I got that?

      Now you need a little imagination,

      If we suddenly add an atmosphere and following happens, aFc=24, bFl=76 and cFr=290 as it leaves the surface of the Earth.

      Okay, a little more imagination, once the surface and the atmosphere reach a steady state, equilibrium, For the briefest moment in time, we get aFc=24, bFl=76 and becomes 0.825 which changes cFr to 0.825*290=239.5, so for that moment all hell breaks loose, Then,

      T=4(aFc+bFc+cFc)+4GHe, That should be fairly simple to follow, do I need to expand that?

      4GHe=T-4(aFc+bFc+cFc)

      GHe=(T-4(aFc+bFc+cFc))/4

      So the initial Greenhouse effect(GHe) is,

      GHe=(288-4*(24+76+239.5)/4 = (288-4*339.5)/4 = -267.5

      GHe=-267.5 which has to be matched by Outgoing Longwave Radiation (OLR) in the second moment in time for the surface to regain equilibrium.

      390-267=122.5, the initial surface response to the GHe.

      As the surface of the Earth obtains equilibrium with the atmosphere,

      Surface (24+76+239.5+122.5)=462 is the initial peak radiation which will decay as equilibrium is approached. -267.5 is the initial value of the greenhouse effect which will decay as equilibrium is approached.

      The surface will reduce its emitted radiation by 462-390=72Wm-2 The radiation at the top of the atmosphere will decay to 239.5Wm-2

      At the surface, 122.5 decays to 72 yielding 50.5, the amount of radiation absorbed by the atmosphere. the GHe -267.5 decays to -267.5 + 50.5 = -217

      There is still no sun in the sky, this is the third moment in the existence of the atmosphere. Trenberth added the 72 to 267.5 to get 339 and then decayed that to 321, 339-321=18, the amount he mistakenly has for atmospheric absorption.

      Still with me?

    • “If dF/dt=1, then…” ??

      Dallas – I don’t want to be mean-spirited, but your calculations make no sense and have nothing to do with emissivity by any ordinary understanding of the word. You also have quite a few facts wrong about how the greenhouse effect operates initially and over time. I’m not sure why you’re confused, but there is no meaningful emissivity of 0.825 for anything resembling the Earth’s surface.

      To illustrate, let me try one more time to deconstruct this, using your value for ε of 0.825, a surface temperature of 288 K, and the SB law. We get Flux = 0.825 σ 288^4. This becomes 0.825 x 5.67 x 10^-8 x 688 x 10^7 = 322 W/m^2. Where do you find a radiated flux upward of 322 W/m^2? For a black body at 288 K, which is an accurate representation of the Earth’s surface in the infrared (well measured and not in doubt), the flux is 390 – there is no possibility for it to be significantly lower. At the TOA, it’s 239. I don’t see that 0.825 describes a flux that is informative about the surface, the TOA, or any other location that is particularly meaningful. It doesn’t relate to any definition of emissivity or flux that is used in climate calculations I’m aware of.

    • To illustrate my point that you’re confused about the GHE, when a forcing is applied to the TOA, the response of the surface flux is to increase gradually toward equilibrium. There is no mechanism by which it would jump upward and then decline toward equilibrium. I think it would be a good idea for you to consult a fairly rigorous description of the GHE because I’m sure you would like to understand it and are capable, but you don’t understand it at present.

    • dF/dT=1 is steady state, equilibrium.

      I didn’t get 322 as an upward flux that is the DWR on K&T. By assuming radiative response is much faster than conductive and latent to a radiative impulse, Fc and Fl can be assumed constant.

      0.825 suddenly added is an impulse forcing, pretty wicked on a planetary scale. That means that -217 is also a wicked impulse response which drops TOA radiation to near zero, It is a three layer equilibrium problem. Both impulse have to decay to steady state, the GHE impulse starts at -217 and has to decay if TOA is to regain equilibrium.

    • dF/dT=1 is steady state, equilibrium

      Dallas – Why don’t you step back and think about the problem rather than responding immediately. Obviously, dF/dT is not 1. At the TOA it’s 3.4W/m^2/K (you said it yourself earlier, using 3.3 instead of 3.4) and at the surface it’s even greater. Your analysis simply doesn’t make any sense and is factually wrong as well. You’re imaginative, but in the absence of a guiding theoretical framework, that has led you hopelessly astray.

  28. Dr. Curry,
    The assumptions of the first quote,
    “[A] key message within Gore’s Climate Reality Project was that our recent strange weather and accompanying social problems are inextricably linked to the climate crisis”
    is lacking in evidence.
    - what recent strange weather?
    There is no evidence that recent weather has been any stranger than any other period.
    - what climate crisis?
    There is no evidence we are facing a climate crisis.
    Perhaps establishing those two points beyond that of groundless assertion would make the rest of the long post more meaningful.
    If they cannot be, then much of the first section is moot.

    • Latimer Alder

      In the UK the weather is always a bit strange. We have evolved a technical term to describe it,

      We call it ‘typical British weather’.

      Because of our location it is entirely possible to experience weather from all four seasons within a 24 hour period. This is normal.

      So what is all the fuss about?

  29. For David Zhang’s work, the question that comes to mind is this:
    When did it become established that climate has ever not changed?
    Climate always changes and his study simply underscores this.
    We adapt to the changes.
    By redefining ‘change’ into ‘deterioration, either warming or cooling’ is this not making the terms less meaningful?
    One observation that comes to mind is that one reason everything seems to be climate driven is because workers are looking for evidence of climate influence.
    A similar phenomenon happens when someone who is shopping for a car, say a Ford Taurus, suddenly notices every Ford Taurus on the road.
    That does not mean Ford Taurus’s are taking over the road.
    Linking everything to climate- kidney stones to to the size of copepods- is a great way to get a lot of publications these days.
    But if something explains everything, does it actually explain anything?

    • For David Zhang’s work, the question that comes to mind is this:
      When did it become established that climate has ever not changed?

      Never. No-one has ever claimed that.

    • Every “Climate Change” believer is claiming that, more or less. When you use the Orwellian words Climate Change, you claim that climate started changing with human CO2.

    • No, when we use the term “climate change” we’re specifically referring to what is happening at the moment, which is largely due to human activity. It doesn’t imply anything about what happened in the past. And there’s nothing Orwellian about it, you’re reading far too much into it.

    • Why do you use that term like that? It makes no sense. Climate change is happening all the time. Climate will never stop changing. Do you want it to stop changing? When you use the term like that, you deny climate changes. That makes you a climate change denier.

    • Once again, you read far too much into it. Of course we can’t stop climate changing completely, but there are changes occurring which are largely due to human activity and which many people consider a) will be harmful to human civilisation if such activities continue and b) are likely to outweigh any climate changes due to “natural” influences, at least in the short term (ie the next few hundred years). Therefore it is perfectly rational for people to believe that it is both desirable and possible to prevent such changes occuring to an extent, even if we can’t do so completely.
      The only reason people might be confused by the use of the term “climate change” in this context is if they are wilfully trying to misunderstand.

    • Show me.
      ====

    • Show you what?

    • The CO2 effect. And not the Trenbert Effect, please.
      ==========

    • You’re still being a bit vague. If you want to understand how CO2 has an effect on climate you could start here

      http://scienceofdoom.com/2009/11/28/co2-an-insignificant-trace-gas-part-one/

      But the point here is what the AGW movement is actually arguing, not whether the arguments are correct.

    • “what the AGW movement is actually arguing”

      The people in the AGW movement don’t even know.

      Andrew

    • Sure there’s a radiative effect. Show it to me in the record if it’s big enough to worry about. And show me if it’s a bad thing, since we’re cooling.
      =============

    • But the point here is what the AGW movement is actually arguing, not whether the arguments are correct.

      That’s a revealing statement. In several ways.

    • hastur,

      “there are changes occurring which are largely due to human activity and which many people consider a) will be harmful to human civilisation if such activities continue and b) are likely to outweigh any climate changes due to “natural” influences, at least in the short term (ie the next few hundred years).”

      All speculations. You mean largely due to human CO2? Where is the warming? In this decade we have the highest atmospheric CO2 since 100,000s years, according to “many people” (I am not convinced). Do you also believe that human aerosol emissions “paused” the warming? And when the cooling really starts, what will it be then?

    • That’s a revealing statement. In several ways.

      Why? A claim was made that the “AGW movement” was making a particular argument. I pointed out that this was incorrect. We are never going to get anywhere if one side doesn’t even understand the argument the other is making.

    • Edim,

      I’m not sure to what extent aerosols have affected warming over the last decade. Certainly we have seen a pronounced solar minimum in recent years. But last year was still one of the warmest 2 or 3 on record, OHC continues to rise, glaciers and ice sheets continue to melt, arctic ice extent reached the secend lowest recorded level this year. And what makes you think that cooling is going to start any time soon.
      But this is really besides the point, which was your objection to the use of the term “climate change”.

    • Kim,

      We are not cooling. Regarding your question, are you asking for information about climate sensitivity? This is one of the best summaries.

      http://www.iac.ethz.ch/people/knuttir/papers/knutti08natgeo.pdf

      But this isn’t really the subject of this discussion.

    • hastur,
      The idea of climate not changing is one of the underlying fallacies of the AGW movement.

    • hunter,

      No, it really isn’t. Please give me an example where anyone in the “AGW movement” has said this.

    • What about the Hockey Stick?

    • In their fervor to remove natural variability, they actually came to believe it doesn’t exist. The answer to your question, hastur, is in the models.
      ===============

    • Latimer Alder

      Then why the headless chicken act and near panic if somebody suggests that climates might change in the future?

      Climate changes, human adapt. End of story

    • AK –

      People in the “AGW movement” have argued that the hockey stick proves “the idea of climate not changing”?

      Can you provide a quote? A link?

    • Would you please take a look at the Crook’t Hockey Stick? Put on your Jesus glasses first.
      ===========

    • @Joshua…

      They have massively argued that it proves the change in the 20th century, putatively caused by anthropogenic CO2, is “unprecedented”. If the change during the Medieval Optimum or Little Ice Age was of equal magnitude, then the 20th century isn’t “unprecedented”, and therefore can’t easily be attributed to anthropogenic CO2.

    • kim –

      That post was so lame, I assumed it was the product of the fake kim.

      Unfortunately for you, it wasn’t.

      A quote kim? A link, perhaps?

      You know, where someone in the “AGW movement” has argued that the hockey stick proves “the idea of climate not changing”?

    • AK -

      They have massively argued that it proves the change in the 20th century, putatively caused by anthropogenic CO2, is “unprecedented”.

      Whether one agrees with that argument or not, it is “massively” different than arguing that people in the “AGW movement” have argued that the hockey stick proves “the idea of climate not changing.”

      I’m skeptical about the argument that you presented, that they actually have made, but when I read distortions of that argument such as the one that hunter has presented, and that you have signed on for, along with kim, I can’t help but be skeptical of “skeptics.”

      At least the “AGW movement” arguments that have been made are arguable. hunter’s statement is, beyond any shadow of a doubt, completely false.

    • OK, now take them off and look all around. You can blink a bit, if you like. Stifle the tears, unless of awe.
      ========

    • AK,

      The HS only covers at most the last couple of thousand years, that’s a vanishingly small length of time in the context of the earth’s history, and we have a pretty good idea that over the last 10k years or so temperatures have been relatively stable. Even so, more recent hockey sticks (including Mann’s) have more variation in the “handle” than MBH98/99. So even if one accepts that the hockey sticks are likely to be a fair understanding of NH temperatures over the last 2K years that’s not the same as arguing that climate never changes.

    • kim,

      The models do allow for natural variability.

    • Heh, that’s why their projections are smack on the money.
      =============

    • @Joshua

      I’m skeptical about the argument that you presented, that they actually have made, but when I read distortions of that argument such as the one that hunter has presented, and that you have signed on for, along with kim, I can’t help but be skeptical of “skeptics.”

      So everybody’s exaggerating a little, and nit-picking one anothers’ arguments. The fact is that many AGW alarmists have argued that the 20th century warming was “unprecedented” and pointed to the original hockey stick as “evidence”. Whether they were actually claiming no change prior to the 20th century, or exaggerating for conversational (debational) effect is a semantic quibble. They may have softened their tune a little since then, but you said “anyone” and implied “ever”.

    • Latimer,

      Humans have adapted to changes which have occurred in the past, although human civilisation is very different to how it was during the MWP or LIA or in Roman times – in some ways we are better positioned to adapt, in some ways worse. But we have never experienced conditions in which global temperatures are 2-3C warmer than now (although such conditions existed in the more distant past), so ISTM to be a rather optimistic assumtion that it is not something we should be concerned about.

    • Left it in the wrong nest. Also, please not the paragraph that I forgot to tag to make it clear it was from your earlier comment.

      http://judithcurry.com/2011/10/04/climate-crises-half-a-millennium-ago/#comment-118918

    • @hastur…

      But we have never experienced conditions in which global temperatures are 2-3C warmer than now (although such conditions existed in the more distant past), so ISTM to be a rather optimistic assumtion that it is not something we should be concerned about.

      Concern certainly seems valid to me. OTOH I’m personally more concerned about frantic efforts to reduce CO2 emissions at the price of collapsing the economy. IMO people need to back off and separate their estimates of the science from their proposals to deal with whatever “problem” the science defines.

      Does the current science predict, with certainty or even high reliability, any sort of disaster in the next 20-30 years? If yes (in your opinion), please provide peer-reviewed references. If no, then discussions of “what to do about the problem” need to factor in the risk to the world economy of any proposed alternative.

      What is totally unjustified, IMO, is distorting the science for the sake of political or economic ideology or other agendas. The science, AFAIK, says pretty much that there’s a high probability of serious problems 50-100 years down the road if we continue BAU, with a probably lower but unquantifiable chance of major disasters real soon now and also a probably lower but unquantifiable chance of nothing in particular, or perhaps improvements.

      The gradual situations generally predicted by the models (and general is all they’re capable of right now, in ensemble, because individual models, and often even runs, are all over the board about everything but some level of global warming) won’t be any trouble to adapt to.

      More disturbing is the fact that the models almost all (AFAIK) tend to be bland and without major disturbances, which is probably an artifact of the simulation methods rather than being a feature of the real world being modeled. This is why the major disasters in the near future can’t be ruled out.

      Between that risk, and ocean acidification, about which I personally know enough of the science to be very, very concerned, I would strongly favor a solution that involves stopping the increase in atmospheric CO2 as quickly as is consistent with not crashing the world economy. IMO solutions to this problem are abundant, based on proper use of free-market capitalism with appropriate “level playing field” subsidies. The major problems here, as in dealing with famines, are political and ideological, not scientific, technological, or even economic (sensu strictu).

    • Latimer Alder

      @joshua

      You say

      ‘in some ways we are better positioned to adapt, in some ways worse’.

      In what ways are we less able to adapt nowadays than we were in the past?

      To gain a gold star you will actually have to focus your discussion on the ability to adapt, not witter on about the size of inconvenience in making the adaptations.

      I also observe that – according to all the theories, we are now approaching 1C above the temperature 100 years ago. Adaptation to +1 C hasn’t been an especially arduous – or even noticeable – process. Apart from yourself falling over in a dead faint at the notion of an average temperature of 290.0K rather than 288.8K. please explain why you think that adaptation to these slightly changed circumstances would be any different.

    • hastur,
      You are welcome to your opinions, but you are not welcome to your own facts.
      The very basis of this thread is a peer reviewed paper claiming that any change (deterioration, now) in climate is bad.
      To deny the HS is used to make this claim, and the memory hole treatment of past cliamte that was inconvenient to the team is an excursion by you into frankly lying.

    • Latimer -

      @joshua

      You say

      ‘in some ways we are better positioned to adapt, in some ways worse’.

      Was that comment directed at some other joshua posting here or at me? If it was directed at me, I suggest that you re-read my comments.

    • Latimer Alder

      @joshua

      You ask if my comment was directed at you?

      Yes it was.

      You suggest that I reread your comments

      I did and saw nothing different this time around. To recap.

      You stated:

      ‘‘in some ways we are better positioned to adapt, in some ways worse’.

      and I asked you

      ‘In what ways are we less able to adapt nowadays than we were in the past?’

      Since you assert that such ways exist I am sure that you will easily be able to list a few.

      I also observed

      ‘To gain a gold star you will actually have to focus your discussion on the ability to adapt, not witter on about the size of inconvenience in making the adaptations’

      to remind you to keep to the point of ‘ability to adapt’.

      The floor is yours.

      PS – you are of course free to withdraw your remark without penalty if you are unable to provide any convincing evidence of it.

    • Latimer,

      Actually it was me who said ‘in some ways we are better positioned to adapt, in some ways worse’.

      Firstly there are a lot more of us so we are more vulnerable to stresses on agricultural production and availability of water. Secondly, again partly due to the density of populations but also because of the nature of modern civilisation if certain places become unsuitable for human habitation it is rater difficult for us to move en mass to other more suitable areas.

    • hunter,

      Let me refresh your memory about the point I was making. You claimed that the “AGW movement” assumes climate never changed in he past. I asked for evidence of this which you have been unable to provide – instead you fall back on the same tired old arguments about the HS. The HS tells us that current temperatures are as far as we can tell unprecedented in the last 1,000 years or so – that doesn’t imply that climate has never changed before, not even that it hasn’t changes in the last 1,000 years.
      So once again let’s have some examples of anyone on the AGW side claiming that climate never changed in the past.

    • AK,

      I don’t have any mandate to speak for everyone who thinks it’s necessary to reduce CO2 emissions, but I’m pretty sure that most of us are keen to do it without collapsing the economy and are not motivated by any particular political or economic agenda (although our approaches to specific solutions may be influenced by such considerations). Personally I would put myself on the left politically, but I think free market solutions will have to play a part, and the costs of any proposed policies should obviously be taken into account. I’d also acually rather like to maintain my present lifestyle as far as possible.
      Other than there is much in your comment which I find reasonable. It’s certainly my understanding that the worst consequences will be further down the line, although I think there are particular which are already stressed and could be more vulnerable in the shorter term (I don’t have the time to dig out references right now). We have certainly seen some weird weather in the last couple of years, we will have to see how it pans out in the next few years to judge whether it is just a blip or the start of something more severe. However, even if changes will be largely gradual and the worst effects long term I don’t think that necessarily means it will always be easy to adapt, I think there be big challenges in some areas.

    • AK -

      The fact is that many AGW alarmists have argued that the 20th century warming was “unprecedented” and pointed to the original hockey stick as “evidence”.

      Again, that is accurate. As someone not well-versed in the technical science, I’m inclined to be “skeptical” of that claim, although I haven’t seen persuasive arguments that the “AGW alarmists” are wrong.

      Whether they were actually claiming no change prior to the 20th century, or exaggerating for conversational (debational) effect is a semantic quibble. Whether they were actually claiming no change prior to the 20th century, or exaggerating for conversational (debational) effect is a semantic quibble. They may have softened their tune a little since then, but you said “anyone” and implied “ever”.

      Please provide a quote, or a link, of where “anyone,” “ever” said what hunter claimed was an “underlying fallacy” of the “AGW movement.”

      So everybody’s exaggerating a little, and nit-picking one anothers’ arguments.

      I’m not inclined to so easily dismiss “exaggerating,” especially when those exaggerations are repeated ad nauseum for rhetorical purposes. In fact, I find it ironic that your basic point centers on “exaggeration” on the part of the “AGW movement” yet you seem inclined to dismiss overt, obvious, and unarguable (unless you can provide a quote or a link) exaggeration on the part of a skeptic.

    • The “unprecedented” claim applies to the period covered by the hockey stick.

      The HS can hardly be claimed to prove anything about temperatures say 100k years ago when it only covers 2k years.

    • @Joshua…

      I’m not going to dig up links to one of the more widely repeated mantras of AGW alarmists. The “Hockey Stick” in its original incarnation was repeatedly used (since 1988 IIRC) in support of the argument that the 20th century warming was anthropogenic. If you choose not to believe that, it’s no skin off my nose. Maybe somebody with more time to spend on it will provide such links.

      As for my attitude towards denialists who repeat talking points they don’t understand, see here. Granted, it’s about ocean acidification where I’m better informed than about the details of how GCM’s and such work.

    • Once again with the false balance. The “exaggerations” of the certainty of the Hockey stick have been amply documented in the scientific literature ( most recently in a Moberg paper ). These exaggerations where complained about privately in the mails. Briffa and osborne complained about Mann’s exaggerations. Overpeck asked Briffa to create something more compelling than the HS for Ar4. ( more compelling is a quote). Rind advised Briffa not to sweep the uncertainties under the rug. Overpeck told briffa to ignore Rind. Briffa complained that overpeck should not cave to pressure from Mann and Solomon and that the results of Ar4 were no more certain than Ar3. no progress on reducing the uncertainty had been made. In the end, Briffa hide the decline and broke the Rules for LA by passing a draft to Wahl for comments.

      As time has gone on the science has corrected itself and we are beginning to see the error bars WIDEN on the MWP. That means we are less certain that 20th century warming is unprecedented.

      So thats the exageration on the warmist side on this issue.

      Do skeptics engage in the same behavior. Yes. They claim that the MWP was definitely warmer. Their science is shoddy, cherry picked, you name it.
      Mann is over confident that thw MWP was cooler. Skeptics are overconfident that it was warmer.

      In the middle stands mcintyre. His argument is
      1. the data in cases is suspect
      2. the data in cases needs to be updated
      3. the data needs to be RELEASED and PUBLISHED.
      4. Standard methods, proven methods, should be tried first.
      5. If you have a new method ( Mann) that should be tested and evaluated
      by experts in stats and not used before it is tested.
      6. Its unclear whether it was warmer or not.

      Following the science since 2007 its my impression that the publications are moving toward McIntyre’s position on #1, # 3 (slowly), #4, #6

      Here is what you miss Joshua. The false balance is Policy makers read the IPCC. They dont read the garbage the skeptics put out. They dont read McIntyre. The science they read was exagerated, movement in the field since Ar4 suggests a movement toward the material excluded and the positions esposed by critics

      The asymetry is Not in the behavior of either side. Its in who has power

    • Latimer -

      I don’t recall making that remark. If you could post a link to a post where I said that, I would appreciate it.

      PS – you are of course free to withdraw your remark without penalty if you are unable to provide any convincing evidence of it.

      I’m not sure how to withdraw a remark, if I never made it. Suggestions for how to do so would be appreciated.

    • Latimer Alder

      @joshua

      On further study of the indentations within the blog, I see that I was mistaken and it as another correspondent who made the remark discussed

      Please feel free, on this occasion, not to reply.

    • Latimer –

      No probs. But I suggest that the next time someone indicates that you’re mistaken, it might be better to check rather than double-down by repeating your mistake.

  30. “Our findings indicate that climate change was the ultimate cause”

    Of course.

    “…David Zhang’s research, which addresses some very interesting links between climate, weather and society.”

    Of course.

    Dr. Curry, there is nothing here that is new
    From Zhang, Big Al, Joshua or you.

    Beat that, Kim. :P
    Andrew

  31. A topic that’s been covered here before, including the concept of climate as a stressor rather than a singular “cause” of a particular crisis.

  32. Zhang attributes 80% of disasters specifically to ‘cooling’ not some blanket terminology like ‘climate change,’

  33. The alarmists claim that the end of the 20 Th century warming is somehow more than normal so it must be caused by CO2, which is a giant leap in logic in itself.

    There are two possible meanings for the claim.

    The 1978 to 1998 warming which has ceased for many years now or the long slow 1/2 ° C per century warming which has continued since records began. Neither are outside of the bounds of natural variability.

    1) The 1978 to 1998 warming was not abnormal in fact it has happened 3 times since records began in the little ice age so it is hardly unnatural.

    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1860/to:2012/plot/hadcrut3vgl/from:1910/to:1940/trend/plot/hadcrut3vgl/from:1860/to:1880/trend/plot/hadcrut3vgl/from:1978/to:1998/trend

    1860 to 1880 = Least squares trend line; slope = 0.0104956 per year
    [total = .208]

    1910 to 1940 = Least squares trend line; slope = 0.0152788 per year
    [total = .456]

    1978 to 1998 = #Least squares trend line; slope = 0.0122255 per year
    [Total = .244]

    People who think it is somehow unusual are misinformed.

    2) If you are talking about the long slow 1/2 ° C warming of the last century that is quite normal too.

    According to peer reviewed ice cores studies.

    “It appears the warming of the 20th Century has been done before. It’s just business as usual for the planet.”

    http://joannenova.com.au/2010/12/where-is-the-positive-feedback-not-in-the-icecores/

    How they convinced so many people of an untruth is a mystery to me.

    • NetDr, It has come to my attention over the past couple of years, that most people seem to have never read their Bible. The Bible, is very clear about the very nature of mankind and his constant weaknesses in dealings with kings and princes. It even gives anyone who cares, a vivid description of people & times just like we all find ourselves in today. Just like learning how to fly by using a flight simulator where you begin by reading some book; apply what you’ve read to the control and there you are…

    • Latimer Alder

      The book ‘Zen and The Art of Motorcycle Maintenance’ has some interesting reflections on life as well. As do the works of W Shakespeare, Emily Dickinson, Groucho Marx, Pink Floyd, Bob Dylan and Jim Steinman.

      I commend them all – along with many more – to your attention as well as the bible, the koran, the talmud and numerous other ‘religious’ books.

    • “The alarmists claim that the end of the 20 Th century warming is somehow more than normal so it must be caused by CO2, which is a giant leap in logic in itself.”

      No they don’t. That’s a fine strawman you have erected.

    • Trenberth would disagree, wince he asserts that all modern weather extremes are proof of CO2 influence.

  34. Very interesting! And, of course, I immediatly correlated it with the history of my own country: the Netherlands.

    The dutch struggle for independence (end of 16th century) and its following “Golden Age” (17th century) coincidence with what Zhang describes as “Results show that cooling from A.D. 1560–1660 caused successive agro-ecological, socioeconomic, and demographic catastrophes, leading to the General Crisis of the Seventeenth Century. ”

    As everyone knows, the dutch are adept traders, and the grain trade with the baltic was an important one at that time (as was the trade with the far east). The earned wealth was used to reclaim land, increasing the land available to agriculture in the Netherlands itself.

    So the dutch empire might be a good case study for JC’s statement: “When a country’s economy and agricultural output didn’t suffer, their populations didn’t either.”

    • I just noticed that what I decribed as “JC’s statement” is in fact a quote from one of the articles. Sorry for the misattribution.

  35. They could have watched a documentary on the History channel about the Little ice Age to find out all this. Maybe they did.

  36. “A key message within Gore’s Climate Reality Project was that our recent strange weather and accompanying social problems are inextricably linked to the climate crisis. And say what you will about Gore, that part seems increasingly true. ”

    There are so many things wrong with this I don’t know where to start. Climate crisis? Strange weather? Social problems? What is he talking about?

    The so-called strange weather is no different than any other weather we’ve had in the past when similar natural drivers prevailed. I’ve watched Bastardi and D’Aleo accurately predict our so-called strange weather….hurricanes, tornadoes, droughts, flooding rains, season after season for years now without once having to bring increasing Co2 levels into the discussion. How have the climate modelers done in that regard? Embarrassingly poorly, that’s how.

    There’s a social problem all right, and it’s caused by politics, not climate.

    • pokerguy,
      Exactly.
      Every claim made at the beginning of the article is lacking support in reality. It is a faith based article, making assertions whose credibility are derived from faith, not evidence.

  37. Dr Curry,

    “[According to a new study, climate change has played a significant role in several of the crises of pre-industrial Europe and the rest of the Northern Hemisphere over the course of the 300 years."]

    I’m sure I’m not the only one to notice that this post revolves around the definition of ‘climate change’. The climate changes of 500 years ago would now be called ‘climate variability’. The glossary of the IPCC, references the current usage of the term ‘climate change’ as per the UNFCCC:

    Note that the Framework Convention on Climate Change (UNFCCC), in its Article 1, defines �climate change� as: �a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods�. The UNFCCC thus makes a distinction between �climate change� attributable to human activities altering the atmospheric composition, and �climate variability� attributable to natural causes.

    http://www.ipcc.ch/ipccreports/tar/wg1/518.htm

    The fact that the term ‘global warming’ has been changed to ‘climate change’ by those that believe in cAGW need not confuse any reader from identifying a very distinct difference between the sort of natural climate changes that may have happened 500 years ago with the sort of ‘climate change’ that serves Al Gore’s purpose. Unless, of course, one contends that the climate change of 500 years ago was also caused by anthropogenic CO2 emissions, in which case that opens a huge new debate!

    In addition, as hunter and others have pointed out… what crisis?

    • The UNFCCC defines climate change: “The UNFCCC thus makes a distinction between ‘climate change’ attributable to human activities altering the atmospheric composition, and ‘climate variability’ attributable to natural causes.”

      The UNFCCC thus enables widespread use of the Fallacy of Ambiguity outside its narrow domain. There was an alternative not chosen:
      - Anthropogenic climate change, versus
      - Natural climate variability

      But, I do not believe that would serve its political objective.

  38. Proof reading results… there should be no comma after IPCC and the second line of the paragraph after the link should read: “… by those who believe in cAGW…”
    :)

  39. A bit of research will show that during the global warming period that occurred roughly between 900AD and 1200 AD various cultures reacted differently and some thrived while others perished.

    Angkor, the capitol of the Khmer Empire in Cambodia, did not fare well at all and the multi year droughts contributed to its demise. The Incas of Peru however used the warming to their advantage. The warmer climate allowed the Incas to colonize higher and higher territories for maize cultivation while using the glacial melt as irrigation.

    On whether warming is better than cooling question, one only has to look at where the majority of the worlds population is located. It is certainly not in the arctic regions. I challenge anyone to point out anytime in history that a civilization has gained population during a ice age.When warming trends occur civilizations need to adapt however it is much easier to cope with adjusting your growing seasons to warmer weather than it is to have then shortened by cooling.

  40. Climate change is expected to affect food production significantly in the coming decades, but the consequences will vary by region as well as by timeframe. Much attention has been devoted to projected effects on agriculture – see the wikipedia overview for some references to recent articles. If ocean acidification is included in the analysis, adverse effects on the marine food chain should also be considered, but do not appear imminent. The reasons for the heterogeneity of response include the complex results of positive influences (warming in cold regions, CO2 fertilization effects, improvements in technology), combined with negative effects that include heat stress in hotter regions, droughts, floods, insect infestation, and reduced protein content of crops due in part to limited soil nitrogen availability. Evidence for recent adverse effects on global crop production shows that some of the anticipated effects may already be occurring, but the magnitude of the changes to date appears to be small.

    Rather than focus on the global picture and the extensive literature related to it, I thought it would be interesting to look at a few articles dealing with agriculture in China, for two reasons. First, China is a major and growing economic power and contributor to global greenhouse gas emissions. Second, any international effort to involve China in GHG mitigation efforts will be thwarted if it conflicts seriously with what China perceives to be its self interest. Part of that self interest involves current industrialization efforts that are likely to increase energy demands and thus fossil fuel consumption (although China is also actively constructing nuclear power facilities). A second part involves a longer term interest in China’s ability to feed its growing population, both nationally and regionally.

    Two informative articles on Chinese agriculture are by Wang et al and Piao et al. Both report a mixed picture. Overall, projected effects are likely to vary from a net benefit to a net reduction in crop yields, with the uncertainty related to the magnitude of CO2 fertilization effects – weak or absent CO2 fertilization portends a reduction, while a strong effect portends an increase in yields. In general, the effect of increases in insects and other pests, as well as reduced glacial runoff, has not been incorporated into the projections. The article by Piao et al reports some reductions in recent years relative to anticipated yields in the absence of climate change (probably mainly a drought effect), but overall yields have increased due to technological improvements in agriculture.

    A paper by Erda et al deals in greater detail with the offsetting effects of increased temperature and CO2 fertilization on Chinese crop yields, as well as the potentially deleterious effect of these climate changes on protein content.

    • Fred

      When you write-

      “Climate change is expected to affect food production significantly in the coming decades, but the consequences will vary by region as well as by timeframe.”

      The only reasonable response is duh. Of course the climate will change over time and that will impact different parts of the globe differently. If we could somehow maintain a stable climate….now that would be news worth writing about.

      Then you get into writing about what you KNOW to be completely unsupportable speculation based upon the current GCM’s.

      Fred-do you believe that the current GCMs can accurately predict the changes in temperature and rainfall in individual areas? I believe you know they can not and therefore you know the vast number of articles linked in “Wikipedia” are really little more than speculation. The other potential harms are also based on the same immature models are they not?

      IMO- this is an example of a “scientist” doing a disservice to society. You are intentionally spreading misinformation with the goal of implementing an agenda.

    • Rob – I’ll let anyone interested in reading the articles (mainly by Chinese scientists) form his or her own judgments as to what “agenda” they are trying to “implement” by spreading “misinformation”.

    • “I’ll let anyone interested in reading the articles… form his or her own judgments”

      Let freedom ring.

      Andrew

    • Fred

      The article(s) appear reasonable unless you realize that the models used to reach the conclusions in the articles are not of sufficient accuracy to allow a person to reach the stated conclusions.

      You have previous acknowledged that you relaize the the models are not yet sufficiently accurate to know what will happen in any specific region, yet you support the spread of misinformation.

    • Why don’t you write to the authors, Rob, and explain their mistakes to them, urging them to stop spreading misinformation?

    • You invite me to the Gingerbread Cottage of Wikipedia Climate? Rest assured, I’m leaving a trail of crumbs.
      =============

    • according to organizations such as The World Bank and the USA food production has increased significantly in the last 50 years. Exactly how much of that is due to improved farming and how much was due to the more favorable growing climate needs more research. However the fact remains that plants love Co2 and warm climates. Garbage in and garbage out on the models.

    • Jim – Farming has certainly improved. The effects of climate change appear to have been mixed, with evidence for a slight detriment (e.g., see the Science article I cited). CO2 fertilization loses its effectiveness at high concentrations, and warming well above levels to which current crop choices are adapted is also harmful on its own as well as associated with drought, pests, and diseases,. On the other hand, warming of regions that are currently on the cold side should be beneficial. I would invite readers to visit the links I cited (and links within those) for a useful perspective.

    • looking at overall crop production Fred we have had tremendous increases in production over the last 40 years. I am sure you can cherry pick a crop a region or a year where there was negative growth for a year but that is the nature of farming.

      Once again we can adapt to our changing climate or perish like the Cambodians I mentioned in an earlier post. It is much easier to adapt your growing season and crops to warmer temperatures than it is to a shorter colder growing season. An example would be Florida which is one of the top corn producing states in the USA. However the growing season for corn in Florida is from October through May or June, unlike Iowa corn which is produced int the summer months still.

      In regard to the Co2 levels, pick a study. For every one you cite that shows a negative effect from Co2 increases I wager I can counter with a study which shows a crop was positively affected by a increase. Some studies show that domestic crops respond more favorably than wild plants do, others studies show a decrease in nitrogen in the seeds. It’s probably a mixed blessing but quite frankly I don’t see anything anywhere worth a panic attack.

    • Jim – I believe you’re missing the point. Almost all field studies show some stimulation of plant growth (at least short term) with increasing CO2 up to a point where more CO2 fails to stimulate or even inhibits growth. These studies have generally been done at constant temperature. Temperature has effects that vary with region, but in the real world include increases in drought, insects, other pests, and limiting nitrogen availability. Overall, there is already a suggestion of net detriment on average (suggested by the study in Science), and evidence for a reduction in protein content.

      There’s no need to “wager” anything, but it would be useful not to decide in advance what you conclude based on generalizations about temperature and CO2.

      I agree with you that adaptation will be needed, not “panic”, but it’s also true that not all societies can adapt perfectly, and some are likely to suffer if the balance between harms and benefits of a changing climate shifts too far in the adverse direction. To date, the U.S. has fared better than some other parts of the world. As with other consequences of climate change, a combination of adaptation and mitigation will be more effective than either alone.

    • Fred,
      So we are at last in agreement that the AGW apocalypse is a significant over statement.
      As to CO2, it will take a LOT more CO2 than we are likely to see in the next century or two to worry about too much for plants.

    • Fred, the sorts of concentrations that CO2 loses it’s effectiveness in promoting plant growth is much, much higher than the doubling we generally talk about with regards to raised CO2 levels.

      Some time ago, some one whose ara of expertise posted here on climate etc regarding the topic of climate change and food production, and I followed up on his very interesting post. He basically explained that crop varieties of one form or another are a) much more resilient to weather changes than is generally assumed in discussions like this and that as climatic conditions change even over the short term, it is a trivial matter for farmers to select crops more appropriate to the changed conditions. He went on to describe crop types and the very wide range of conditions they can tolerate.

      He also mentioned that of course right at the margins, agriculture is vulnerable to climate change, so for example, a cooling climate can threaten the growing season in vulnerable areas in Canada. But generally, there are a huge variety of crop types that tolerate a wide range of conditions, and farmers will simply select the variety that suits the new climate – whether cooling or not.

      In fact, to underline that point, he appeared equally unfazed by a cooling climate as he was by a warming climate.

    • Agnostic – “resilient”, yes, but thriving, not necessarily. Regarding the declining effectiveness of CO2 at higher levels, I think you’re generally right, but that appears to depend on the individual plants, including differences between C3 and C4 crops – if you have a good data source, it would be worthwhile to link to it. The problem isn’t really the absence of some CO2 fertilization effect, but rather the damage from the effects of temperature, direct and indirect, with indirect effects such as insects, diseases, and drought probably more important. I don’t want to repeat earlier comments, but see above for evidence that recent climate change has already had an adverse impact, as well as a comment below for issues of land lost to seawater encroachment. In first world countries, crop substitution and relocation is much easier than elsewhere, so we should not dismiss quickly the possibility that a recent detriment will be magnified by future trends in vulnerable regions of the globe..

    • Fred, Haven’t we been told that the last century experienced unprecedented warming? And yet wasn’t there also a population explosion AND a food production explosion in the last century? What leads you to believe that the projected warming of the IPCC (assuming that it actually happens) will be catastrophic, when we have all observed exactly the opposite?

    • Jim – Currently, many parts of the world are undernourished, and a few are starving despite better food production overall. This suggests that any further impediment to feeding those people will cause harm. That includes many factors beyond climate change, but we should try to avoid any of the impediments. I haven’t used the word “catastrophic”, because that’s only one extreme along a spectrum of possibilities, many of which are undesirable even if not catastrophic. We actually don’t have a very good idea of how agriculture will respond to future warming, but the little evidence we have indicates some reason to expect adverse effects – probably more from drought, insects, and disease than from heat stress. Most agriculture has evolved to suit the climate where it takes place, and given that observation plus the existing evidence, I think we should prepare for the possibility of some harm until that is proven unnecessary.

    • “I think we should prepare for the possibility of some harm…”

      Fred, you ARE free to prepare for a warmer future — I would just ask that you don’t drag me into your preparations. The many “undernourished” in this world live in societies where individuals are not free to prepare for their future (North Korea for example). They live in centrally planned and controlled economies that are run by persons who know what’s best for everyone. Central planning once claimed a scientific basis as justification for it’s actions — just as climate “science” claims to be able to predict the future and how to engineer us into a better one.

    • Fred,
      That is a bit of wweasily answer from you.
      Ehrlich and gang predicted massive xenocidal scal starvation to start many years ago.
      The opposite happened.
      The rates of hunger worldwide are lower.
      The level of food security is up.
      you can’t really have it both ways: We are told, in great seriousness, that the past ~100 years are unprecedented warming, yet here we are making more food than ever.
      CO2 is up- dangerously, we are told- and here we are: more food, deserts greening, and according to NASA, more biomass than ever.

    • Fred, I have to say this is one area where your arguments are not at their strongest.

      “Agnostic – “resilient”, yes, but thriving, not necessarily.”

      All things being equal elevated temperatures and CO2 will improve plant growth for C4 plants more than for C3. In general CO2 is the limiting factor in plant development – increased amounts of it improve yield. A little googling revealed this gardners website giving tips on using CO2 fertilization:

      http://www.jasons-indoor-guide-to-organic-and-hydroponics-gardening.com/plant-growth-and-carbon-dioxide.html

      its backed up with results here:

      http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2486.2002.00553.x/full

      and a simple (maybe too simplistic for you) abbreviated version here:

      http://www.sjsu.edu/faculty/watkins/CO2plants.htm

      The post I referred to earlier is actually two posts here:

      http://judithcurry.com/2011/06/08/climate-change-and-food-insecurity/#comment-74400

      http://judithcurry.com/2011/06/08/climate-change-and-food-insecurity/#comment-74484

      by Hector Maletta

      The reasons that the Stanford University had for their results were unclear but may have been because of other factors that were limiting – it certainly wasn’t the excess CO2 (directly) nor was that implied in the article. Whatever those factors were they may will be controllable.

      What Hector makes clear in his excellent posts is that it is entirely possible to adapt to climate change with changing crop selections and opening and closing of areas for agriculture. Which is what would have to happen in any case, because Climate Change occurs whether it is man made or not. Adaption will be required for cooler/warmer drier/wetter climates because the climate is not static.

      I am quite skeptical of CAGW, and mildly skeptical that AGW is detectable, but pretty willing to entertain it because I do understand the science behind it. But I do think it is a major stretch to re-write centuries of biology on the basis of the need to find CO2 a pollutant. I know that is not your intention at all, but the Standford article is published in “Science”, known to have a warmist/alarmist bias. Your BS detectors should have been spinning as fiercely as mine, and while I appreciate that you accept the case for AGW or even CAGW, I do think it is sensible not allow advocacy of any position to affect the integrity of ones good judgement.

    • err..sorry…I said: “CO2 will improve plant growth for C4 plants more than for C3.”…it’s the other way around – my bad. (I knew one of them did better than the other…)

    • All things being equal elevated temperatures and CO2 will improve plant growth

      Agnostic – Both the empirical data from recent decades as well as an understanding of the basic phenomena indicate why this is incorrect, even though it would be true up to a point for CO2 alone. I’ve addressed this in several comments in this thread already, together with links to relevant literature, so it might save space for you or others to review those.

    • Yeah, Fred.

      But the really pertinent answer is whether or not the net overall effect .for humanity of a slightly warmer planet with higher atmospheric CO2 concentrations will be beneficial or negative on balance.

      Studies to date seem to show both conclusions (roughly equally, as far as I can determine).

      Since a) IPCC has installed a “consensus process”, which has introduced a bias for “bad news” and b) “bad news” is much more likely to get press coverage than “good news”, I would conclude that the net effect is very likely to be beneficial.

      Max

    • Here’s another way of looking at it. Imagine that you have a button on the wall. If you press the button, all the CO2 in excess of 280 ppm is ejected from the earth into the sun, never to be seen again. Do you push the button? The precautionary principle says no. The very real possibility exists that returning to 280 could seriously impact agricultural productivity in a negative way, causing famine.

      Like it or not, we’re only seen this level of productivity in a 350+ world, and going below 350 could very well be disastrous. That means we’re 40 ppm from famine.

      The PP says no fast moves, either way.

    • P.E. – The very daunting challenge is not to return CO2 to 280 ppm, but to prevent it from rising far beyond its current level. That requires a significant reduction in our rate of CO2 emissions.

    • Unless, of course, this is not your usual solar cycle minimum. See Leif Svalgaard’s Research Page:
      http://www.leif.org/research/Livingston%20and%20Penn.png

      Note in the link above that the trend line of “Umbral Magnetic Field” of sunspots (dots) has declined about 500 Gauss since the year 2000. There is a blue dashed line just below 1500. This represents the field value at which most sunspots become invisible.

      Visible sunspots were few during the Maunder and Dalton (sunspot) minima. These were natural climate cold periods (although Dalton was exacerbated by a volcano blowing its top). (There are still sunspots; they are just not visible using the techniques used during the minima.)

      For a more professional explanation, see:
      Livingston, William, and Matthew Penn. 2009. “Are Sunspots Different During This Solar Minimum?” American Geophysical Union 90 (30) (July 28): 257–258. http://www.leif.org/EOS/2009EO300001.pdf

      This phenomenon has been followed for some time now: Topic: Sunspot Magnetism—Livingston & Penn http://solarcycle24com.proboards.com/index.cgi?board=general&action=display&thread=855&page=1

      Perhaps, since the adverse effects of cold are more severe than that of the probable warming, we should prepare for cold.

  41. “Climate change is expected to affect food production significantly in the coming decades”

    Wag the dog.

    Andrew

  42. The claim that this kind of analysis can pin down climate as the root of human history, particularly when the researchers examine long periods at a time, is “pretty hard to swallow for a historian,” says William Atwell, a historian at Hobart and William Smith Colleges in Geneva, New York

    Indeed. Climate, while an extremely important one, is just one of many ingredients that shape human history. It’s the combination of those ingredients (such as the crop failure, oppression, and economic difficulty that combined to spark the French revolution) that determines whether a crisis occurs rather than any one aspect in isolation.

  43. Prof. Curry…

    You linked to a news story (Texas Sets Records During the Second Hottest Summer in U.S. History—and the Worst Is Still to Come) which in turn links to Anderson(2011), which says, among other things:

    … given a 2°C global mean temperature increase it is expected that for 70–80% of the land surface maximum seasonal-mean temperatures will exceed historical extremes (as determined from the 95th percentile threshold value over the second half of the 20th Century) in at least half of all years, i.e. the current historical extreme values will effectively become the norm.

    I’ve briefly scanned the article, but I can’t seem to see what they could mean other than that over at least 70% of the land surface the average temperature will be as high as what is the extreme temperature right now (averaged over 3 months). Have I interpreted this properly? They say they’re “avoiding biases introduced by the underestimation (or overestimation) of natural variability within numerical climate models” (supplementary material), and since they’re using a model (CMIP3) they’ve presumably avoided such errors as raising the temperatures without accounting for increased evaporation (and thus precipitation).

    Does this mean they’ve accounted for all the standard possible sources of error? I can’t tell from their language where this lies between a complete study and a back-of-the-envelope.

    Ref:

    Anderson, B.T. (2011) Near-term increase in frequency of seasonal temperature extremes prior to the 2°C global warming target Climatic Change Volume 108, Number 3, 581-589, DOI: 10.1007/s10584-011-0196-4

  44. ON MAN MADE GLOBAL WARMING

    IPCC’s prediction statement:
    For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected.
    http://bit.ly/caEC9b

    IPCC’s prediction graph:
    http://bit.ly/cIeBz0

    Girma’s prediction graph:
    http://bit.ly/cO94in

    Current observation graph:
    http://bit.ly/pMHO76

    You judge the data yourself.

    Don’t you think Hal Lewis was right?
    http://bit.ly/p0sO4l

  45. Here is another contribution to the link between climate and human experience, from the archaeological perspective. I haven’t even seen the book, let alone read it, but the following review may help others.

    A . Bruce Mainwaring, Robert Giegengack and Claudio Vita-Finzi, editors
    CLIMATE CRISES IN HUMAN HISTORY 216pp. American Philosophical Society.

    Paperback, $35. 978 1 60618 921 4

    Climate change has become a political battleground.
    Prophets of doom and global warming sceptics trumpet at one another like
    mammoths on a primordial steppe. We archaeologists are fortunately
    offstage, but the revolution in climatology, and our increasingly
    fine-grained data, raise an important question: What lessons about human
    responses to climate change can we learn from the past? This is why
    Climate Crises in Human History, the outcome of a University of
    Pennsylvania Museum conference in 2008, is important. Its fourteen
    authors bring the perspective of the past to bear on present and future
    climate change. Robert Giegengack and Claudio Vita-Finzi begin with a
    summary of what is, and what is not, known about climate change: do
    political leaders and scientists realize that the global climate has
    never been stable? Judging from current debates, many do not. As
    successive chapters show, the record of past climates is open to
    competing explanations.

    Sturt Manning argues that our knowledge of human interactions with
    climate over the past 50,000 years depends on radiocarbon chronologies.
    These are not neutral chroniclers of time, but an often imprecise record
    of cosmic ray interaction with the Earth’s atmosphere and short-term
    changes in solar magnetic activity. Fortunately the radiocarbon record -
    calibrated using tree ring chronologies – offers a framework for
    examining long-term relationships between the Sun, climate and human
    history. Archaeologists approach climate change from many perspectives:
    Stuart Fiedel offers a measured, but sceptical, review of a possible
    comet impact about 12,900 years ago, which might have triggered the
    1,000-year Younger Dryas cold period. Under this scenario, the comet
    also decimated the large mammals of North America and had disastrous
    effects on Clovis Palaeo-Indian populations.

    Richard Hodges discusses another climatic villain, the tropical volcanic
    eruption of ad 536, which has prompted apocalyptic accounts of
    widespread suffering, summer cold, and dust veils; but future research
    will have to shift the focus from documenting historical coincidences to
    establishing certainty. Paul Bahn cautions that with cultural evidence
    such as animal depictions in rock art, researchers wrestle with
    identification problems, environmental factors and accurate dating issues.

    From diverse approaches, we move to human responses. Were the reactions
    of our forebears to such phenomena as river silting and erosion cycles
    the result of climate change or the cause of them? Here again, a vast
    field of research is opening up. To pose just one question: are links
    between stream behaviour and solar minima reflected in the atmospheric
    radiocarbon records for the past 25,000 years? Jennifer Smith assesses
    responses using arid and semi-arid environments in North Africa, where
    Ice Age populations responded to desiccation events by moving within
    restricted areas or, during severe dry periods, by retreating to
    better-watered areas. In northern Mesopotamia, climatic shifts were
    always a challenge at the margins of settled lands, where pastoralism
    offset the risks of farming. New research summarized by Michael Danti
    shows that the climatic disruptions were not necessarily catastrophic,
    for there is strong evidence of cultural continuity during a period of
    marked aridity 4,200 years ago.

    Clearly human decision-making was a powerful catalyst. Vernon
    Scarborough and William Burnside argue that decision-making by any
    society is conditioned by the landscape in which it flourishes. They
    describe some of the complex variables embedded in the economic,
    political and ideological spheres of a culture confronted with climatic
    fluctuations. This is why the role of drought in the ancient Maya
    collapse is the subject of perennial debate, for the effects were often
    highly local. Nowhere did climatic oscillations at the end of the Ice
    Age have a greater effect than in southeast Asia, where sea levels rose
    dramatically. Cultural isolation could have resulted. However, Maru
    Mormina and Charles Higham show how the new conditions presented a
    unique window of opportunity for human expansion and cultural adaptation.

    We have here a tantalizing glimpse of the multidisciplinary research
    into ancient climate change that lies ahead. Future archaeologists and
    historians will be spending months in palaeoclimate laboratories working
    alongside climatologists: the data we need demand nothing less. This
    book reminds us that those who pontificate about climate change, present
    and future, would be well advised to look backwards. We have much to
    learn from our forebears.

    -

  46. Don A: Welcome back! Excuse my impertinence, but here’s an unwrapped version of the review you quote:
    ——————————————————
    Climate change has become a political battleground. Prophets of doom and global warming sceptics trumpet at one another like mammoths on a primordial steppe. We archaeologists are fortunately offstage, but the revolution in climatology, and our increasingly fine-grained data, raise an important question: What lessons about human responses to climate change can we learn from the past? This is why Climate Crises in Human History, the outcome of a University of Pennsylvania Museum conference in 2008, is important. Its fourteen authors bring the perspective of the past to bear on present and future climate change. Robert Giegengack and Claudio Vita-Finzi begin with a summary of what is, and what is not, known about climate change: do political leaders and scientists realize that the global climate has never been stable? Judging from current debates, many do not. As successive chapters show, the record of past climates is open to competing explanations.

    Sturt Manning argues that our knowledge of human interactions with climate over the past 50,000 years depends on radiocarbon chronologies. These are not neutral chroniclers of time, but an often imprecise record of cosmic ray interaction with the Earth’s atmosphere and short-term changes in solar magnetic activity. Fortunately the radiocarbon record – calibrated using tree ring chronologies — offers a framework for examining long-term relationships between the Sun, climate and human history. Archaeologists approach climate change from many perspectives: Stuart Fiedel offers a measured, but sceptical, review of a possible comet impact about 12,900 years ago, which might have triggered the 1,000-year Younger Dryas cold period. Under this scenario, the comet also decimated the large mammals of North America and had disastrous effects on Clovis Palaeo-Indian populations.

    Richard Hodges discusses another climatic villain, the tropical volcanic eruption of ad 536, which has prompted apocalyptic accounts of widespread suffering, summer cold, and dust veils; but future research will have to shift the focus from documenting historical coincidences to establishing certainty. Paul Bahn cautions that with cultural evidence such as animal depictions in rock art, researchers wrestle with identification problems, environmental factors and accurate dating issues.

    From diverse approaches, we move to human responses. Were the reactions of our forebears to such phenomena as river silting and erosion cycles the result of climate change or the cause of them? Here again, a vast field of research is opening up. To pose just one question: are links between stream behaviour and solar minima reflected in the atmospheric radiocarbon records for the past 25,000 years? Jennifer Smith assesses responses using arid and semi-arid environments in North Africa, where Ice Age populations responded to desiccation events by moving within restricted areas or, during severe dry periods, by retreating to better-watered areas. In northern Mesopotamia, climatic shifts were always a challenge at the margins of settled lands, where pastoralism offset the risks of farming. New research summarized by Michael Danti shows that the climatic disruptions were not necessarily catastrophic, for there is strong evidence of cultural continuity during a period of marked aridity 4,200 years ago.

    Clearly human decision-making was a powerful catalyst. Vernon Scarborough and William Burnside argue that decision-making by any society is conditioned by the landscape in which it flourishes. They describe some of the complex variables embedded in the economic, political and ideological spheres of a culture confronted with climatic fluctuations. This is why the role of drought in the ancient Maya collapse is the subject of perennial debate, for the effects were often highly local. Nowhere did climatic oscillations at the end of the Ice Age have a greater effect than in southeast Asia, where sea levels rose dramatically. Cultural isolation could have resulted. However, Maru Mormina and Charles Higham show how the new conditions presented a unique window of opportunity for human expansion and cultural adaptation.

    We have here a tantalizing glimpse of the multidisciplinary research into ancient climate change that lies ahead. Future archaeologists and historians will be spending months in palaeoclimate laboratories working alongside climatologists: the data we need demand nothing less. This book reminds us that those who pontificate about climate change, present and future, would be well advised to look backwards. We have much to learn from our forebears.

  47. Just finished reading a “Chronology of natural phenomenons in the Bohemian Kingdom from 663 to 1700″ by Strnadt, Anton; Prague, 1790 (in German).

    In my opinion the main reasons for death as described there were:
    1. Plague, 2. Plague, 3. Plague, 4. Other deseases, 5. Floodings, 6. Famine, 7. Cold, 8, Drought, 9. Heat, 10. Other.

    In every century there was plague, floodings, famine, bitter cold or droughts. There is nothing new, nothing unprecedented.

    • Joel, But today the AGW community has decided that every drought, famine, flood heat or cold is due to CO2.
      They are obsessed with CO2, and by golly, the see CO2 everywhere they look.

    • Wow.. 663 to 1700, and no one died of old age?

      Impressive Bohemian longevity. ;)

    • That depends on what you consider old age. I guess that back then old age was about 40-60. In a pre-industrial society, it would be hard to go 50 years without encountering a life threatening condition. Now, 90 is the new 50.

    • BlueIce2HotSea

      Now, 90 is the new 50.

      Not necessarily. Isaac Isimov’s biography of scientists dating back several thousand’s of year B.C implies something very different. Scientists as a group appear to always have had an astonishingly high life expectancy relative to general population.

      My guess as the reasons are:

      1) A famous scientist is one who has at least survived childhood, as most scientists usually establish their reputations in the 20′s and 30′s.

      2) A good scientist has historically been protected from serving as soldiers as their usefulness to the military as scientists normally far exceeds their usefulness in direct combat.

      Conclusion: childhood mortality skews the average life expectancy calculations for prior civilizations. The life expectancy for adult non-combatants has changed little.

    • Peter Davies

      hehe! I thought the same thing except that “natural causes” comes to mind instead of old age.

  48. “If you leave out the sun as well and assume a “temperature of space”, dF/dT would be extremely small – much less than 1, which is to say that a very small flux change would mediate a very large percent change in temperature.”

    Sorry, that is indeed a typo, dF/dT=0 in equilibrium, My bad.

    • Dallas – dF/dT is not zero in equilibrium, nor 1 for any temperatures of interest to us. If the climate is in equilibrium, and the temperature is changed, the flux will change. In the case of forcings, the flux change causes the temperature change. For feedbacks and some internal climate dynamics such as ENSO, a temperature change can precede and cause a flux change (followed by a further temperature change).

      For anyone who has followed the exchanges upthread and is wondering why dF/dT is cited as 3.4 W/m^2/K in some places and 3.7 in others, the latter figure is derived by differentiating the SB equation leading to the dF/dT = 4F/T formulation. The 3.4 or 3.3 figure is the modified result from GCM models accounting for regional and temporal heterogeneity. Neither involves emissivity for surface fluxes, however, because both apply to the TOA, not the surface.

    • “dF/dT is not zero in equilibrium, nor 1 for any temperatures of interest to us. If the climate is in equilibrium, and the temperature is changed, the flux will change.” Fred I agree completely, in the real world. However, in mathematics, one can establish conditions for momentary equilibrium.

      Actually, dF/dT is the rate of change of F with T so you are correct, d(dF/dT)/dt is the exact form I should have used when assuming equilibrium.

      The value dF/dT is interesting. At the top of the atmosphere the value approaches 1 at the surface the value approaches the emissivity of the material of the surface as emitted from a flat plane. Emissivity varies with the shape, composition and angle. For the surface, 0.825 is not unreasonable and is commonly used. The term Effective emissivity includes all the impacts, so the surface value would be the true effective emissivity, as best as I can tell.

      I am starting to get this debugged thanks to you Fred.

      http://ourhydrogeneconomy.blogspot.com/2011/10/call-for-mathematicians-greenhouse.html

    • Crap! I buggered that, e approached 1 at the TOA … not dF/dT, that approaches zero at the TOA.

    • http://www.electro-optical.com/eoi_page.asp?h=What%20Is%20Emissivity?

      Opacity may be the better term, but near the surface it is nearly the same both up and down. But for the problem, the emissivity of the surface changes from near BB to its average emission rate which would be 0.61 if not for the interaction of convective and latent fluxes. That is why the coefficients have to be added to the combined equation. Even for purely radiative transfer, dF/dT=4F/T assumes emissivity equals one. Which allows the simplification to drop the constant which includes e. For mixed flux applications it is not negligible. I discovered that the hard way but I am sure there is literature on the subject. If not I am got to have to write up how I determine the value, though it is implied in much of the literature.

    • There’s numbers in Paul K’s chalk scrawls.
      =============

    • Fred, the biggest issue still seems to be what the value e=0.825 actually is and whether the expand version of dF/dT=4F/T is valid with the use of e.

      I can’t prove it with mathematics, I can come close with logic.

      http://ourhydrogeneconomy.blogspot.com/2011/10/snake-oil-salesman-or-simple-logic.html

    • Fight that big fish. It’s hooked and struggling for your life.
      ==========

    • With e=0.825 at the surface and 0.61 TOA 390*(0.825-.61)=83.8 the surface radiant flux to the TOA, per NASA, 51 is absorbed by the atmosphere and the remainder would be 32 direct through the radiation window. Given the margin of error for satelite measurements, surface temperature measurements and e both at the surface and TOA, that is pretty damn close, K&T is wrong!

    • The line is thin. If you pass it to lucia she may not play it right.
      =========

    • I am number one on Lucia’s crackpot list, probably most blogs. You don’t say the grand poohbah of climate science screwed a sign and get heard.

    • The Trenberthogenic Effect has pervaded the whole intellectual climate. Even the Lord can’t be heard disputing Trenberth, but I think that entity has had a little talk with the sun.
      =================

    • The greenhouse effect let me count the ways.

      (390)*0.61 = 273.9 approximate GHE using TOA emissivity, correct for conductive 273.9-51=222 approximate greenhouse effect (Latent internal to lower atmosphere)

      (surface radiation-conductive )* 0.825 surface emissivity + conductive
      (390-24)*0.825+24=215.6 approximate GHE, (Latent is internal to lower atmosphere.)

      total flux absorbed by atmosphere from OLR and solar
      24+76+51+65=216 approximate Greenhouse effect. (surface calculations include latent)

      Pulse perturbation of dark earth
      http://ourhydrogeneconomy.blogspot.com/2011/10/call-for-mathematicians-greenhouse.html 216 Approximate greenhouse effect. (surface calculations include latent)

      Surface flux – TOA flux 155 Approximate green house effect less solar absorbed by atmosphere 51 yields 206 Approximate Greenhouse effect. (surface calculations include latent)

      The greenhouse effect is due to the resistance to flux through the atmosphere, it cannot feedback on itself.

      There are dozens of way to correctly estimate the Greenhouse Effect, Trenberth’s ain’t one of them.

    • Dallas,

      Playing with numbers and inventing requirements that they should obey does not prove anything. Your calculations fall in that class. They are just some numbers without any real relevance or real physical interpretation.

      You have asked somebody the add better mathematics to your calculations. Nobody has answered, because there’s no better mathematics, when the ideas are not valid.

    • Patience, Pilgrim.
      ===========

    • True Pekka,

      A perfectly lovely relationship, dF/dT=4F/T goes to waste because it requires a coefficient, since the Earth is not a true black body. Poor Poor equation. It keeps giving right answers, but the poor poor equation is destined to obscurity, because it was published in the lowly journal Energy and Environment, home of the crackpots of climate science.

      Then for the surface dF/dT=d(aFc+bFe+eFr)/dT=4(aFc+bFe+eFr)/T sits alone in the dusty corner. Even though aFe and bFe are known values for a limited range and coefficient e is approximately 0.825, a poor unitless value related to the effective emissivity of radiation from the Earth’s surface.

      If only, Dr. Kimoto had clearly stated the need for the coefficients of heat flux, a, c and e, in a mixed gas environment. Then, he and his equation coulda bean sombody :)

      Of course, since it is e that varies Fr, the utility of the equation is limited until e is verified. Even though, a hypothetical change in e is applied to the equation, from zero to the approximate value 0.825, which is a bit of trickery, no doubt. If one is silly enough to assume that the poor dusty equation is valid within very tight limits, it is insightful. Kinda like some old school modeling tricks used back in the day was computer time was expensive.

    • Pekka, by the way, the poor dusty equation in the hands of a crackpot discovered, the there is ~24 W/m-2 absorbed by the atmosphere in the K&T drawing that in the NASA drawing. If the authors happened to calculate an effective temperature of the Atmosphere using that ~24Wm-2, and then If, the authors happened to calculate a down welling radiation based on the effective temperature, then the error would be magnified 4 fold to ~100Wm-2. Of course, since the calculation for skin surface temperature warming based on 324 Wm-2 are coming along so well, I am sure that could not have happened :)

    • The point is that there is nothing special in the coefficient 0.825. The basic relationship with coefficient 1 is true for a black body, but not for a complex system like the Earth. It’s not accidental that the relationship is not badly off even for the Earth, but nothing in the playing with the numbers that you have done has clarified the issue much.

      You need first a good physical explanation on what you are doing. When you have that, you may start to estimate, what it leads to quantitatively. Unfortunately you start with something vague and stay vague. With that approach there is nothing to do or to expect.

    • True, I was very vague, because I don’t have access to the full text, I was flying blind. So I had to back calculate the value 0.825. Then I found that for a 3.3Wm-2 increase in DWR (which is still dislike, it is a restriction) there is a 1C change, on the science of doom, not less. 3.3/4 happens to be 0.825, without access to all the literature, it is a bit of a PITA.

      Remarkably, 0.825 appears to be a lovely value, And since no one asked why the DWR tends to be around 220 Wm-2 in all the silly approximations of the Greenhouse effect above, it happens to be because the emissivity looking down is smaller than 0.825, surprisingly, it is ~0.71, which is surprisingly in the mid-range of the surface emissivity and the TOA emissivity of 0.61. 220*0.71= 156 odd coincidence that?

      So if e has not been defined, name it the crackpot capt coefficient :) There I made into the Godwin thingy :)

    • Pekka,

      There are just too many things that jive for my calculation of ~220Wm-2 for DWR to be wrong. Using the Poission equation, the potential temperature of a parcel of air at 600mb and 250K, the temperature related to 220Wm-2, is 289K. The number even jives with the lapse rate.

    • Okay, Pekka,

      I know you probably think I fruit loops, but for equilibrium at T=288, e~0.825

      e is a function of the coefficients a and b with respect to T. As temperature increases, e approaches 1, it does not decrease with an increase in T. Which is a rather interesting result. There is a limit to the amount of warming. Not necessarily the limit that we may want or the one many might expect. Though in a system with an unstable region of operation, one I have been trying to point out. :)

    • I state in another way, what I have in mind.

      All the formulas used have been rough scaling laws or semiempirical parameterizations. They may agree with some data, but they lack full physical justification. Therefore it’s not possible to tell, whether they will be valid in a slightly different situation. Neither is it possible to derive any new results from them.

      Any interpretation of the formulas is only guesswork. The agreement with a specific interpretation may be purely accidental as long as the interpretation is not a full physical explanation, whose validity is verified in many different ways, or which is a direct and accurate result of a valid physical principle like the conservation of energy or Planck radiation law applied to materials, whose emissivities are known.

      We have all too many “theories”, which are not built in a proper way starting from a well defined situation and using well known physics as it should be. Rather these “theories” are random collections of bits and peaces that do not form a logical whole, but have been picked to provide the hoped for results like “disprovals” of valid physics. It’s pity that we have journals that accept willingly such articles. When a journal has done it prominently a few times, it’s not surprising that nothing published in such a journal is taken seriously any more.

    • Heh, must be on to something; Pekka distracts.
      =====================

    • That is very true, Pekka. This is an extremely complex problem, which I need to take to a more geeky forum on theoretical physics. So I am most likely chasing my own tail.

    • “(390)*0.61 = 273.9 approximate GHE using TOA emissivity, correct for conductive 273.9-51=222 approximate greenhouse effect…. There are just too many things that jive for my calculation of ~220Wm-2 for DWR to be wrong.”

      One thing that might be wrong is that your calculator needs new batteries.

    • Opps, dyslexia sets in. 237.29 not 273.9, double dyslexia actually. Can’t find my notes, but that should be 237.29-24=213.3 I will need to make a drawing but latent moves heat from the surface which is not effected by the radiation window until it condenses. Conductive is not subject to the window at all looking up but is looking down from TOA. The numbers are off because I am still working on averaged coefficients for aFc and bFl.

      I still do not have a solid proof for e=0.825 The way I determined it initial was if the wre not need for e, then 155/33 would equal 4, but it equals 4.7 that meant that 4/4.7= 0.85, which is close, but since the average emissivity of all of the Earth’s surface is 0.965 I used 0.82. The science of Doom site said 3.3 per degree was the “benchmark” value which 3.3/4=0.825. the results are close for either value.

  49. dF/dT=1 would still work, as long as it is in equilibrium, but =0 is much better.

    • To expand, any value for dF/dT will work in this stage, as long as it is not a changing value. I should reword that in the article.

  50. AD1300 event in the Pacific was pretty bad (end of the MWP)

    http://goliath.ecnext.com/coms2/gi_0199-7024384/The-A-D-1300-Event.html

  51. “JC comments: this is the first time I have come across David Zhang’s research, which addresses some very interesting links between climate, weather and society.”

    With three or more items, use ‘among’ rather than ‘between’.

  52. Let’s pause for a quick sanity check here.

    The Zhang study is pretty clear: periods of cold climate have been bad for humanity.

    To flip this around and extrapolate it into a warning of hard times resulting from postulated human-induced warmer climate is as nonsensical as blaming the past cold winters on AGW.

    It takes a fool or a charlatan to make such an extrapolation.

    It takes a sucker to accept it.

    Max

    • I’m not sure who made such an extrapolation – but there is another way to look at the data.

      Climate change has, in the past, as one of multiple factors, had an effect on the availability of food, and the availability of food, as one of multiple factors, can affect societies in negative ways (contingent on their technological ability to compensate).

      Do you disagree with that statement?

      If not – then it seems that maybe the major distinction between the extrapolation you criticize and the description I provided was the precise nature of the climate change. Would you contend that warming would, necessarily, not have any negative impact on food availability?

      It seems logical to me that cooling would have a more dramatic impact. I don’t know for sure, but I would assume that there are relatively more places on the planet where it is too cold to produce food than there are places where it is too hot to grow food. If that is true, then it seems that cooling would result in a relatively greater net decrease in areas where good can be grown.

      But does that necessarily prove that warming would result in a net increase in areas where food can be grown? Or further, even it it did, would that lead to an extrapolation that it would provide a net increase in food availability or affordability? For example, even if warming resulted in a net increase in arable land – would that increase be in areas where the logistical problems of cultivating that land wouldn’t cancel out the increase in the amount of land that could be cultivated?

    • The shadows jump around when you blow so hard.
      ==================

    • @Joshua…

      But does that necessarily prove that warming would result in a net increase in areas where food can be grown? Or further, even it it did, would that lead to an extrapolation that it would provide a net increase in food availability or affordability? For example, even if warming resulted in a net increase in arable land – would that increase be in areas where the logistical problems of cultivating that land wouldn’t cancel out the increase in the amount of land that could be cultivated?

      First off, the fact that regional cooling is usually associated with reduced agricultural output justifies a default assumption that it will be in the future. However, this by no means justifies any such assumption about a regional warming.

      Historical regional warming has often been associated with increased yield and/or value, e.g. the Medieval Optimum. Also, the global warming after 1970 was associated with northwards movement of the agriculture line in the Sahel (AFAIK), probably due to increased precipitation. Whether globally or regionally, it isn’t enough to look at temperature, you also have to look at precipitation. A default assumption that a warming change would be associated with reduced agricultural output is not justified. (Nor, IMO, an increased output. It would depend on the details and should be considered on a case-by-case basis.)

      One of the missing items in the Zhang et al. studies (AFAIK) involves the number of cultures not affected by such climate disturbances. My best understanding of current anthropological theory is that cultures evolve from robust with high productivity to higher density, more fragile, with lower net productivity (measured by labor, although higher by land area). They also tend to accumulate overhead in the form of parasitic religious or other bureaucratic hierarchies. The farther along they are in this process, the more vulnerable to any disturbance to agricultural productivity. This would include not only regional climate changes but major insect infestations (e.g. multiple years of locus infestation, etc.), river course changes, epidemics not related to poor nutrition, and the like.

      It’s worth considering that most of the major famines in the 20th century resulted from political and/or ideological situations that prevented food from getting to those who needed it, rather than such things as climate per se.

      I’m skeptical about any attempt to generalize from pre-industrial socio-economic situation to modern. Changes to climate may require new crops, many of them GM, may even change the relative productivity of various areas, but even Zhang et al. points out that when trade or other factors are available to make up for lost productivity, there is little correlation with social disturbances.

    • ‘parasitic religious or other bureaucratic hierarchies’. You said a mouthful there. So are the WWF and the IPCC religious or bureaucratic parasites?
      ======================

    • “You pays yer money and you takes yer choice.”

    • But if you want my general opinion, see this sub-thread, especially the link in the last comment.

    • AK -

      I found that post to raise some interesting points. If you’re interested in reading a response, check back later. No time to respond right now (I missed it earlier).

    • randomengineer

      Would you contend that warming would, necessarily, not have any negative impact on food availability?

      The answer is self evident if you give it 2 minutes of actual thought and look away from the chicken little chickenshit talking point sheet.

      Answer? Yes. At this stage in the societal and technological development S curves (funny how these always seem to appear correlated) of humanity, man currently has the ability to implement large scale green power generation e.g. spaceborne solar that could be in place within a single generation. What’s politically unacceptable in this era is easily changed by necessity. I’m talking about the ability and wherewithal.

      In the USA we already grow enough food to feed much of the world (although we’re choosing to foolishly burn too much of it via ethanol!) and a slow change in growing season etc would be simple adaptation of crop types and shift vis a vis latitude.

      Between the ability to quickly utilise “new” arable areas and use deslination tech and “portable” green power (spaceborne) even land that becomes too arid for what was originally grown can easily be repurposed. Cotton likes heat, for instance.

      Now, compare that to the notion that cooling might put MN (e.g.) under a quarter mile of ice. You can’t grow crops buried in ice. Cold is always equivalent to death. Warming is always equivalent to discomfort. Give me discomfort or give me death. We always choose discomfort. And that’s giving you a mile of leeway here and allowing for the notion that warming would have any discomfort at all. I say not.

    • steven mosher

      Can I suggest that the “benefits” of warming is under researched? One thing we know about the funding effect is that it drives the questions asked.. not the answers, but the questions asked. So that if youa re funded to look for the damage of climate change you will look for the damage. And you will find it. Your findings will not be wrong because you are funded. Thats not how the funding effect works. The effects works to limit investigation so you have an incomplete picture.

    • True. But politicians trying to act responsibly (or appear so) can reasonably ask for studies of “worst-case” scenarios, despite the fact that models currently can’t give any good estimate of their probability. Gather up all these “worst case” studies into one publication, get a little careless about communicating exactly what is known and what isn’t, and you get exactly what a politician looking for a way to frighten the population needs.

    • AK,
      You mentioned somewhere recently that you have some ideas about Ocean Acidification.
      If you have a moment, could you share your views on it?

    • @hunter…

      Below are two links to previous comments here.

      http://judithcurry.com/2011/09/20/4-degrees/#comment-113997

      http://judithcurry.com/2011/10/02/wedges-reaffirmed/#comment-117761

      A good starting point, not peer reviewed but pretty close to my understanding based on peer reviewed literature, is CO2, ocean acidification, and Calcium Carbonate formation and deposition by John Shepherd (NOC, Southampton).

      In general, my biggest concern regards ecological replacement. Many species in today’s oceans are adapted for the current pH, which is just a little higher than the point at which dissolved CaCO3 stops being supersaturated. That supersaturation appears to be necessary for aragonite deposition in many (probably most) of these species. A small lowering of pH may be enough to make the ocean surface involved unlivable for them.

      (Note that the critical pH will differ from one place to another depending on the concentration of other ions.)

      If many populous species in the sea can no longer survive, their ecological niches will be filled/replaced by other species’. The new niches will probably not be identical to the old, the new species will perform most of the functions the old did, but not all, not always in exactly the same way, and there will probably be new things they do.

      This will probably (IMO) lead to a massive reorganization of the ocean’s ecology. If it follows what (very little) we know of previous ecological replacements (e.g. the end-Permian extinction), there will be a reduction in biodiversity, and thus efficiency of function. This could very well lead to a major (order of magnitude) reduction in the ratio between atmospheric O2 and CO2 (due to a process called Photorespiration, which I’ve studied in the literature over the years, too extensively to provide simple links. More precisely, due to interactions between photorespiration and efficiency of photosynthesis.)

      I’m not completely convinced that this process isn’t already under weigh, responsible for the increasing CO2 in the atmosphere; I’m somewhat skeptical of the supposed link between burning fossil fuels and increased CO2 concentrations. But if tipping points are probably present in climate, they’re much more likely to be present in the marine ecology. It’s quite possible that the ocean will suddenly (over the space of a year or two) start pumping CO2 back into the atmosphere to the point it doubles or more.

      Note that this is all intuitive, based on my own understanding of (some of) the details of a (very) few of the life-forms that inhabit the ocean, mixed with some understanding of ecology, and more of generic complex non-linear systems. But I strongly suspect that most marine biologists have the same similar intuitions to mine, which is why you see them concentrating on measures that don’t seem that important to someone less familiar with marine and/or cellular biology and ecology.

    • Had biological niches never evolved we’d still be crawling out of the sea.
      =============

    • AK,
      Thanks for sharing your thoughts on OA / pH.
      I would ask how you reconcile that concern with the regular dynamic range of marine pH?
      Also, what about the apparently under considered role of bicarbonates?
      If we were dealing with a huge outgassing of CO2 as you are concerned with, would that not, by the way, have the effect of increasing marine pH?
      As a general rule, I find it a good policy to be deeply skeptical of any talk of sudden tipping points in any large complex and dynamic system.

    • @kim…

      I hope you’re being facetious. Most likely there was a specific niche (or collection of similar niches) occupied by the earliest amphibian tetrapods.

    • Evolving niches is an engine of evolution.
      ===========

    • @hunter

      I would ask how you reconcile that concern with the regular dynamic range of marine pH?

      pH is generally in equilibrium with atmospheric CO2 and other ion concentrations. Even assuming atmospheric CO2 to be well mixed, concentrations of other ions (e.g. calcium, magnesium, iron, etc.) vary from one part of the ocean to another.

      Also, what about the apparently under considered role of bicarbonates?

      If you’d read and understood the link I provided, you’d realize that bicarbonate does not vary independently. CO2, bicarbonate, and carbonate are locked into a fixed relationship that varies according to pH. See page 1 here.

      If we were dealing with a huge outgassing of CO2 as you are concerned with, would that not, by the way, have the effect of increasing marine pH?

      Not necessarily. There’s quite a bit of reduced (organic) carbon in the ocean. When an ecosystem changes to a much less diverse one (eco-catastrophe), it’s typical for the overall biomass to be reduced. All this extra carbon would be returned to the atmosphere/hydrosphere as inorganic (oxidized) carbon. CO2.

      As a general rule, I find it a good policy to be deeply skeptical of any talk of sudden tipping points in any large complex and dynamic system.

      That’s probably because you don’t understand them. AFAIK the better people understand systems that display Spatio-temporal chaos, the more likely they are to take the “tipping point” concept seriously. Of course, the term itself is just a metaphor, AFAIK the more temporal term is “bifurcation”. And even that’s just a metaphor when applied to spatio-temporal chaos.

      Anyway, I’m not going to try to convince anybody that ocean acidification is an issue. I’m convinced it is, most marine biologists seem to be convinced it is (for somewhat different reasons, AFAIK), and nobody can really come up with a good reason why it isn’t without demanding “proof” relative to an unjustified “default hypothesis” that I doubt many real scientists would agree with.

      Or repeating talking points of the sort provided by Glen Beck or Sean Hannity that they don’t understand well enough to know how invalid they are.

    • AK,
      Thanks for your response.
      For the record, I don’t listen to Glen Beck or Sean Hannity on climate at all, or much of anything else. I am trying to focus on some concerns I have from my own reading. The gratuitous swipes are not really constructive.
      The question I asked about reconcililng the dynamic nature of pH is a bit more than you answered.
      I have read from allegedly authoritative sources that the ocean pH range is dynamic seasonally and even more frequently,and over fairly large ranges.
      Certainly larger than the claimed observed change in the last ~150 years or so. Your answer did not seem to address that.
      Additionally, there seems to be a lack of data from actual experiments using increased CO2 concentrations that support the dire claims.
      The experiments I see seem to be based on projections.
      This is off topic, and I am hoping to avoid triggering some harsh response from you, but are you following limnology at all, and studies about the freeshwater role on the carbon cycle?

    • Not really. I looked into the whole ocean acidification thing fairly deeply a while back, and concluded that the issue falls into a fairly wide class for me: very concerning and very much worth doing something about, not worth the risk of crashing civilization by some of the more interventionist answers being offered. For me, the obvious presence of an ideological core bent on implementing a Marxist agenda is the most alarming aspect of the whole thing. Even that, IMO, is not worth distorting or perverting science over.

      There is an obvious need for far more research, and better science, in the carbon cycle. IMO much of that science will also support bio-technology that will make remediation/sequestration a fairly easy option. In a shorter time-frame than is being discussed for any but the most drastic mitigation schemes. Without any significant delay or slow-down to the highly desirable goal of improving the quality of life of everybody on the planet to match that of the middle-class in the US and better off parts of Europe.

      When people assert “there’s nothing to worry about” or “it’s an emergency” without proper scientific understanding or references, all it does is waste other people’s time. If they want to disagree with me on the urgency of agreed science, that’s their prerogative. If they want to disagree over scientific interpretations of reported observations, that’s their prerogative. But, even around here, I see a lot of assertion without understanding or backing.

    • On page 62 of this study is a map of the pH of the oceans.

      http://www.soest.hawaii.edu/oceanography/courses/OCN310/OCN310_Spring2011/doney_ocean_acidification.pdf

      Here is a map of the coral reefs and the level of endangerment they are believed to be in:

      ReefGIS – Reefs At Risk Revisited – Global 2011

      If you see a relationship between pH and reef endangerment you have a more vivid imagination than I do.

      There is also a question as to how much acidification is due to co2 and how much is due to other factors:

      News Release : Acid Rain Has a Disproportionate Impact on Coastal Waters : Woods Hole Oceanographic Institution

    • Joshua

      You ask

      Climate change has, in the past, as one of multiple factors, had an effect on the availability of food, and the availability of food, as one of multiple factors, can affect societies in negative ways (contingent on their technological ability to compensate).

      Do you disagree with that statement?

      No. But I believe the Zhang study shows the statement could be made even more precise by adjusting it slightly to:

      Extended periods of climate cooling have in the past, as one of multiple factors, had a limiting effect on the availability of food, and a limitation in the availability of food, as one of multiple factors, can affect societies in negative ways (contingent on their technological ability to compensate).

      Do you agree with this slightly modified statement?

      Max

  53. ‘even if warming resulted in a net increase in arable land – would that increase be in areas where the logistical problems of cultivating that land wouldn’t cancel out the increase in the amount of land that could be cultivated?’

    Having given your logic-chopping post the length of consideration it deserves, I am in a postion to answer your question.

    Yes. or maybe no. Possibly perhaps. We shall have to wait and see and react accordingly.

    Re forecasting the future..I am having difficulty with the 5:00 at Worcester. Torn between 6 and 3. What’s your advice, O Great Prognosticator? Need it in the next 30 mins please.

  54. The effects of climate change of food production involve several disparate elements. Most relate to agriculture, but effects on fisheries are also likely, ultimately including damage to the marine food chain from ocean acidification, although that prospect is not imminent.

    As mentioned in comments above, agricultural consequences of warming are likely to vary regionally. Some evidence on global crop production already suggests an overall net detriment from recent climate change, but how this will play out in the future is still vulnerable to model uncertainties. Unlike excessive cold, which tends to reduce crop yields directly, increased heat is likely to be damaging due to factors that extend beyond heat stress and include damage from insects, other pests, diseases, and most particularly drought. The issue is further complicated by the fact that warming will increase the fertility of some regions that are currently too cold for much agriculture, but are also not home to large populations. Matching populations to these new venues will be problematic. In theory, the inhabitants of Bangladesh could move to Alaska and grow pineapples, but a more realistic scenario involves a combination of uncoordinated population displacement and impaired welfare of populations who remain resident in affected areas.

    Although many studies have examined the impact of climate change on crops that continue to be grown on existing land, a separate issue involves land loss itself. This is mainly a consequence of sea level rise that inundates coastal land with salt water – even if the water recedes in some areas, impaired fertility is likely. The following two studies exemplify attempts to evaluate this. Both report on substantial land loss that varies greatly from one region to another. The first, a 2001 Study also addresses many other consequences of climate change (some discussed upthread based on later data), but is particularly interesting in its analysis of coastal land loss, in that the relationship between sea level rise and coastal flooding is fairly direct and not subject to enormous prediction errors for a given change in sea level. The analysis concludes that the potential for land loss might be abated in many regions by protective measures with a positive benefit/cost ratio. A different conclusion is reached in a 2004 Study that is more globally comprehensive in its analysis. It seems clear from both that protective measures must be a component of responses to sea level rise, but it appears unlikely that this will suffice or be affordable in the absence of efforts to limit the extent of the rise by curtailing future warming.

    Finally, although it might seem self-evident, arguments about how much sea level will actually rise over the remainder of this century can’t be resolved with a few comments in this thread, and are an invitation to cite cherry-picked data to support one’s conclusion of choice. Those arguments should probably be directed elsewhere – there are some previous threads in this blog that are appropriate.

    • Here is another attempt to get working links to the 2001 study and the 2004 study.

    • Increased CO2 is more likely to increase biodiversity than not. Energy from the sun not yet trapped by the biosphere could increase the sustainability of all living critters.
      =============

    • Fred

      The 2004 paper by Francesco Bosello, et all dealt with their assessment of sea level rise. You have cited that paper to support your contention that global warming will lead to harms for humanity.

      Ok here is my problem with what you have done. I believe that you know that sea level has NOT risen at the rate used in the subject paper. I believe you know that it has risen less than 25% of the rate used in the paper, so on that point alone the paper is without much merit. On an economic note, the authors fail to account for the positive economic impact that the infrastructure construction would have on the local economies.

      The 2004 paper you cited is at a pay site, but I was able to read an abstract and it is pretty clear that the paper was written to try to demonstrate that global warming is potentially harmful vs. being a realistic assessment. The authors of the paper “assumed” that sea level rise would significantly negatively impact southern Asian countries which drove the overall output assessment. Since sea level has not been rising at those projected rates that damage has not occurred.

      The paper also noted that adaptation steps could be taken to eliminate the potential harms, but that the authors were unsure if these steps would be taken. The paper seemed to “assume” that there could be harms to human health (that could possibly be mitigated with proper health care) if only governments would provide the health cafe to the poor.

      Pretty poor papers to cite to try to show that global warming will be harmful

    • I’m afraid it was predictable that someone would want to argue about the rate of sea level rise, although that is obviously not an issue to be resolved in a few comments here. Sea level rise is of course one of the major factors that will determine impacts on our civilization. It has been discussed extensively in this blog and elsewhere, and those discussions should be visited for a reasonable perspective. However, the papers I cited were worth reading, because coastal land lost to future flooding has properly become a cause for concern and estimation.

    • Fred

      You cited a paper that was based on incorrect assumptions and therefore forecasted incorrect results–that food production would be reduced.

      Why is a paper that was wrong really worth reading? How is it not similar to having an other fear that is not based on reality?

    • Rob – I will be content to let others read the paper(s) to make their own judgments.

    • Fred

      It is interesting that you can be made content by posting papers that you know make conclusions of negative consequences although the conditions that the paper was based on have not occurred. Seems deceptive, but if you are content I suppose that is a benefit.

    • Fred and Latimer

      Studies have been made on the effect of a slightly warmer temperature (and longer growing season) on crop yields in northern arable regions of North America, Europe and Asia.

      Other studies have shown that most crops would benefit from higher atmospheric CO2 levels, particularly those of the C3 variety (which comprise 90% of human crops).

      Studies purporting to show that AGW-caused climate changes in Africa will result in lower crop yields there have been shown to be unfounded.

      Recent observations show that the Sahel is beginning to green, as are portions of the Sahara. It is believed from historical records that some of these regions were greener than today in warmer times of the past.

      Studies on greenhouse warming generally agree that most of the expected GH warming will occur over the winter months and over higher latitudes, further supporting the notion of increased crop yield in northern arable regions.

      It is obvious from looking at a world map that any purported human-caused increases in sea level will not have a perceptible impact on the amount of arable land surface area of our planet. Nor will any suggested future lowering of the ocean alkalinity.

      So, without going into a detailed region-by-region analysis, it is reasonable to assume that a slightly warmer planet with higher atmospheric CO2 concentrations would lead to somewhat higher global crop yields, while a slightly lower global temperature with lower atmospheric CO2levels would lead to lower overall crop yields.

      If anyone has any credible information, which would suggest the opposite conclusion, I would be very interested in seeing it.

      Max

    • So, without going into a detailed region-by-region analysis, it is reasonable to assume that a slightly warmer planet with higher atmospheric CO2 concentrations would lead to somewhat higher global crop yields

      This is incorrect for global crop yields, Max, even though it is probably correct for some Northern regions. Please see several of my comments for both the reasons and the literature references.

    • Fred Moolten

      Your “several references” in no way invalidate my general conclusion that higher CO2 levels and slightly warmer temperatures will lead to increased crop yield overall, while slightly lower temperatures and lower CO2 levels will lead to decreased crop yield overall..

      In fact, the references cited below by Agnostic confirm it.

      Max

    • Striling English

      Fred’s speciality is to cite ‘several references’ but to be unable to give specifics when pressed. It gives some of the credulous the misleading impression that he is extremely erudite and even-handed. In reality, it often tries to mask a complete ignorance of the subject

    • When looking at a 600 million year timeline, atmospheric CO2 and temperatures have only been as low as present day levels during the late Carboniferous period and the early Permian I think there is little to worry about as far as a extinction of plant life as we know it. Seems to be those pesky ice ages that tend to kill off plant and animal life. We are CO2 impoverished and the Earth is quite cool when looking at the long term average.

      The last 200 years does not constitute a climate “normal”

    • Fred has histologically examined a neoplastic growth mislabeled as normal, and found it to be normal.
      =============

    • “Your “several references” in no way invalidate my general conclusion that higher CO2 levels and slightly warmer temperatures will lead to increased crop yield overall”

      Max – Readers are invited to visit the several references I linked to, including the one reporting reduced crop yields correlated with recent warming. I think they will reach a different conclusion.

    • Fred M: I did click on your links and hit bad links and paywalls. I did see one study that said current crop yields are down 3-5%, but I’ve lost track of which link that was. I appreciate your efforts to bring cites to the discussion, but I find that when I go to them I return with a different impression from what I find in your comments.

      You seem to spin a fair amount. I know we all do that, but this warming/cooling/agriculture has been one of your weaker expositions IMO.

  55. It certainly is no surprise to any student, even a casual student, of human history to discover that in pre-industrial times, poor crops = hard times, population deceases (delayed by a few years), and, if the crop deficit is extended, migrations. The Biblical stories of Joseph in Egypt and the stories of the Israelites in Egypt in the time of Moses are good examples.

    Extended droughts, repeated flooding, extended hard winters and non-existent summers have decimated civilizations throughout recorded history. It matters not to those civilizations whether the instant effect was caused during a colder period in their locality or a warmer spell. All that mattered was that the crops and herds they depended on for daily sustenance (and in colder regions, for winter stores and animal feed) declined or failed, once or serially.

    I suspect that measuring these ‘bad times’ by relating them solely to the ‘pales-climatic temperature reconstructions’ (and allowing whatever time slop-factor they need to get the desired result — ref, 40 year smoothing) is not entirely valid — crop failures are rather immediately devastating, though I suppose that successive years of poorer and poorer crops spreads the disaster over a short number of years, but nothing like 40.

    It doesn’t change history to call these events ‘Climate Change’ nor do these studies add much to our store of human knowledge.

  56. I’ve just spotted a really good article from the New Security Beat
    http://www.newsecuritybeat.org/2011/10/el-nino-conflict-and-environmental.html

    on a related article in Nature entitled “Civil conflicts are associated with the global climate
    http://www.nature.com/nature/journal/v476/n7361/full/nature10311.html

    • Those two links are for the same article.

    • Dr. Curry,
      These articles are really no different from the eugenics age articles attributing all of humanities woes to bad breeding.
      If you go to millenialist fundamentalists, they see the world’s troubles as proof of their interpretation of prophecy.
      A few decades ago, when HIV was new, plagues were seen as the great shaper of history.
      The lens of faith can easily determine what is seen.

    • Well now, the study does show some rather startling correlation (if it is statistically valid). But, of course, this does not demonstrate “causation”.

      “Extended droughts -> crop failures -> food shortages -> famines -> civil unrest -> wars and/or revolutions” seems like a logical sequence

      Tying this all to ENSO might be a bit of a stretch, though, since our REAL knowledge of ENSO shifts over historical times is limited.

      Anther logical link could be:

      “Extended colder periods -> crop failures -> food shortages -> famines -> civil unrest -> wars and/or revolutions” (see Zhang study for first part of this sequence)

      Here the result is the same, but the root cause might even be an opposite one.

      But, hey, I can show you that global temperature has followed global consumption of McDonalds’ hamburgers with an R2 of well above 0.9

      Max

    • hunter, From what you have written above you should be ready to read about the end of the ‘church age’, covered in the little book of Jude. If you have time left why not read Revelation as well. It follows. We may be somewhere in chapter 10. We’ll see. Read just, one more book.

  57. “I’ve just spotted a really good article…”

    Dr. Curry,

    Do you mean you’ve *read* the article?

    Andrew

    • Pretty indeed. Change is ubiquitous.

    • Edim

      Excellent point! I had not thought of that heavy-handed moral to what really is a beautiful vintage work of craftsmanship.

      Change is both ubiquitous and well-bounded.

      Where the change truly unlimited, the maps would soon be a uniform brown with no distinguishing features at all, and utterly uninteresting.

      Which you could produce in the Mississippi if you increased its flow while curtailing its capacity, as is happening with the Carbon Cycle.

      But despair not — so intertwined the flow and capacity of the Mississippi with the climate and climate with Carbon Cycle — you may see your dull brown smudge come about.

  58. Fred Moolten at: http://judithcurry.com/2011/10/04/climate-crises-half-a-millennium-ago/#comment-119435

    Both the empirical data from recent decades as well as an understanding of the basic phenomena indicate why this is incorrect, even though it would be true up to a point for CO2 alone. I’ve addressed this in several comments in this thread already, together with links to relevant literature, so it might save space for you or others to review those.

    Fred, this statement is not correct. The empirical data from recent decades shows that my statement that “all things being equal, elevated temperatures and CO2 levels will improve plant growth” IS correct. There are numerous studies on this, it’s on the level of the Tyndal gas effect with regards to CO2 in that is long established in botany. I linked to a non-climate science website of gardener who makes use of this knowledge in order to improve plant growth – his ‘real world’ finding is that 1500 ppm is about ideal for optimum plant growth.

    Secondly, you have NOT addressed this with your ‘several’ comments, and the links you provide are NOT relevant. The reason I think you think you have covered this is because you are confusing two issues:
    1. the biological effect of CO2 on plant organisms
    2. climatic effects perhaps coupled with CO2 on crop yields.

    I will reiterate the points in my main response to you but before I do, I think it worth mentioning that there is no reason to confuse science in this way. As Hector pointed out, the main limiting factor for agriculture is water, which in turn is affected by climate. You could argue that CO2 affects the climate which then affects the main limiting factor, but NOT that CO2 will be a limiting factor in the sorts of concentrations being considered. Additionally, a warmer climate means longer growing seasons, so the extra seasonal warmth is generally beneficial.

    http://judithcurry.com/2011/06/08/climate-change-and-food-insecurity/#comment-74400

    http://judithcurry.com/2011/06/08/climate-change-and-food-insecurity/#comment-74484

    Here are again the comments by Hector, posted here for your convenience. The bottom line is that there are a range of crops that are optimal for different climate scenarios. The example Hector uses is this:

    Climate change modifies the boundaries of agro-ecological zones and (at each juncture) price and climate considerations make farmers prefer one or another form of farming (crop mix, technology, etc.) including changing land use (e.g. to livestock)…….IPCC climate change projections involve increases between 1.5 and 4.5 C (worldwide average), with maximum increase in the Arctic and much less in temperate and tropical latitudes. Take current temps in any corn growing area of the US, add 2-3°C, and you get the conditions now existing a few hundred miles South of that place. Seeds from Mexican or Brazilian corn are already available that are quite suitable for that situation. In the meantime, large swaths of land in the Northern US and Canada will have by then a longer no-frost period, enabling cultivation where none was possible, or longer-growing crops, and/or higher yields in the appropriate crops (say wheat, either spring or winter).

    It is probably worth knowing as far in advance as possible what sort of climatic changes we can anticipate. It is likely that there will be some winners and some losers. Overly rapid climate change would probably be difficult and possibly dangerous. This starts playing to Dr Curry’s general theme for preparing for multiple outcomes – which in my opinion the most sensible position. You may validly argue that if climate sensitivity is as high as you and the IPCC expect, then measures to slow down the rate of change by mitigating emissions is reasonable. What you CAN’T do is re-write the rule book on biology to support that position.

    • Agnostic – The evidence to date indicates that globally, the recent warming has been associated with a reduction in crop yield (see the Science article). This doesn’t mean that all regions suffer, but this is a global average, and can’t be derived from studies in a single region. The probability that this will project into the future is of course uncertain to some extent, but there is reason to believe that the fertilization effects of CO2 will be offset, and in some regions outweighed, by the detrimental effects of increased temperature – heat stress, but to a greater extent insects, other pests, and droughts. If one then adds in the loss of coastal land due to sea level rise, there appears to be a significant probability of a net detriment. Much discussion of the land loss effect (see the two articles I referenced) concerns the utility of adaptive measures to protect against land loss. Are they worth the cost of implementing them? There is no disagreement I’m aware of that without those measures, food production will suffer.

    • The evidence to date indicates that globally, the recent warming has been associated with a reduction in crop yield (see the Science article)

      Fred this is not what the evidence shows and I suggest you re-read the Science article because it does not provide evidence of this assertion. Nor does it imply altogether that higher CO2 levels reduce crop yields. You appear, on the face of it anyway, to be too influenced by what is clearly an article biased toward the “CO2 is bad” orthodoxy. If you read the article carefully they cannot fully explain the results and if you look at the construct of the experiment it does not appear to me to be a particularly good one with particularly convincing results.

      You are very poorly defining the framework of your assertions: You can validly propose that because CO2 affects the climate, and climate affects the hydrological cycle, certain regions have been affected by lack of water – by far the most important limiting factor for crop growth. I would disagree with it, and it may be wrong, but it would an entirely valid thing to propose.

      But it is frankly rubbish to point to CO2 as having a limiting affect on crop growth, which IS what you have said, and that “warming has been associated with reduction in crop yield” which is a direct quote. And you have NOT provided any evidence to substantiate these assertions, and if you did, it would fly in the face of centuries of botanical studies. It would therefore be subject to the deepest skepticism until those claims could be fully reasoned and substantiated.

      but there is reason to believe that the fertilization effects of CO2 will be offset, and in some regions outweighed, by the detrimental effects of increased temperature

      Actually there is NO reason to believe this. And you have not cited any evidence for this belief. On the contrary there is plenty of evidence that the opposite is true, which I have pointed you to only a tiny fraction. Again you are confusing ‘warming’ with climate change – and while warming constitutes climate change of a sort it ignores what is truly important with respect to agriculture which is water availability. Again I suggest you meditate on Hectors very interesting and well-informed informed thoughts on the subject.

      And those thoughts touch on the rest of your points pertaining to drought, insects and heat stress (which I think now we can pretty much dismiss as a serious issue). Certainly drought and insects are a danger to crop yields and may offset any gains from extra warmth and CO2, but insects can be managed with clever organic farming techniques, and drought offset with irrigation provided the water is sourced sustainably.

      If climate change – either warming OR cooling – occurs too rapidly, then there may not be an opportunity to adapt efficiently and really that has always been the main concern surrounding climate change. But this rapid change appears less and less likely to be occurring as time goes on, and suggests that adaptation will be no more than easy or difficult than if the climate changed entirely naturally – that is, it might always be something to which we have to adapt.

      Again, I suggest you make your case of mitigating emissions based on detrimental effects that you can properly measure and identify using good science, don’t re-write the rule book on botany because it happens to undermine your case. You are scathing toward the skydragon-slayers because you perceive them to be questioning well established science, you therefore have no business doing the same thing toward well established botany.

      I will make one more point on this by offering you an argument that you could make; Even though extra warmth and CO2 may be beneficial to plants, it may also be beneficial to their enemies (insects and disease etc). Could the beneficial effect of elevated temperatures and CO2 on crops enemies mean that crops are threatened beyond a net gain, or would we be able to ameliorate those effects as part of our adaption to new conditions?

    • I’ve looked at the links you provided, Agnostic, and while they provide useful information, I don’t think they don’t contradict the main points I’ve tried to make about recent and future consequences of global warming. The evidence to date indicates that globally, the recent warming has been associated with a reduction in crop yield (see the Science article). This doesn’t mean that all regions suffer, but this is a global average, and can’t be derived from studies in a single region. The probability that this will project into the future is of course uncertain to some extent, but there is reason to believe that the fertilization effects of CO2 will be offset, and in some regions outweighed, by the detrimental effects of increased temperature – heat stress, but to a greater extent insects, other pests, and droughts. If one then adds in the loss of coastal land due to sea level rise, there appears to be a significant probability of a net detriment. Much discussion of the land loss effect (see the two articles I referenced) concerns the utility of adaptive measures to protect against land loss. Are they worth the cost of implementing them? There is no disagreement I’m aware of that without those measures, food production will suffer.

    • sorry for the largely duplicate posts – the first one disappeared and then reappeared.

  59. There seems to be some confusion as to what the study citing reduced crop yields actually says. It does not state there has been a reduction in yields and a cursory examination of crop yields both in total and per acre show production going up. It is stating there is less production than there would have been if the climate hadn’t changed and increased co2 and improved farming methods had been able to influence production free of temperature/precipitation changes. Rather speculative estimations I can only guess, not having access to the full paper.

  60. Fred Moolten

    Citing a Science article, you wrote:

    The evidence to date indicates that globally, the recent warming has been associated with a reduction in crop yield

    The actual record shows that this is totally false.

    Global grain production trends are shown here:
    http://bigpictureagriculture.blogspot.com/2011/04/how-does-need-to-double-world-crop.html

    Before moving forward, let us look at what has happened to grain production over the last 40 years. In 1970, the production of corn, milled rice, and wheat was 788 million tonnes. By 2010, the production of those three grains was 1.912 billion tonnes, an increase of 142 percent.

    Looking at the grains individually, corn production increased from 268 million tonnes to 814 million tonnes, an increase of over 200 percent. The production of milled rice increased from 213 million tonnes in 1970 to 452 million tonnes in 2010—an increase of over 110 percent. Wheat production, the largest of the three grains in 1970, was 307 million tonnes. By 2010, wheat production had increased by over 110 percent to 648 million tonnes.

    For all three grains, the 40-year increase was over 140 percent.

    In addition, soybean production was 42 million tonnes in 1970. By 2010, world production of soybeans had increased to 258 million tonnes—that’s a whopping 513 percent increase.

    Citing data from the Food and Agriculture Organization of the United Nations (FAO), a separate report on global rice production tells us:
    http://irri.org/knowledge/publications/rice-today/rice-facts/seven-billion-and-counting-what-does-this-mean-for-global-rice-food-security?print=1&tmpl=component

    During this period, global paddy rice production more than doubled from 312 million tons in 1970-71 to 677 million tons in 2010-11.

    This is an increase of 117 percent, similar to that cited in the other report.

    Fred, you cited a model study in Science, which showed other figures, presumably the paper by Lobell et al.
    http://www.sciencemag.org/content/333/6042/616.abstract

    My advice to you: Do not blindly accept anything you read, just because it happens to suit you. Go back to the data source to find out what is really going on.

    Max

    • Max,
      The observed increases in production do not tell much, if anything at all about the influence of changes in climate, and by changes I mean all changes, not only AGW. The paper of Lobell et al is more relevant, because it tries to separate the climate based changes from the other trends.

      On the other hand the caveats stated by the authors are essential:

      Any model has its limitations, and we recognize a few caveats that are common to statistical models. Our approach may be overly pessimistic because it does not fully incorporate long-term adaptations that may occur once farmers adjust their expectations of future climate. Examples of this would include expansion of crop area into cooler regions, switches to new varieties (17), or shifts toward earlier planting dates, although there is little evidence that the latter is happening beyond what is expected from historical responses to warm years (18). Moreover, the incentives to innovate have been limited in most of our sample period because prices have been low. On the other hand, our estimates may be overly optimistic because data limitations prevent us from explicitly modeling effects of extreme temperature or precipitation events within the growing season, which can have disproportionately large impacts on final yields (19). For example, although we captured the decline in growing-season total precipitation for wheat in India, there has also been a trend toward heavy rain events as an increased fraction of total rainfall, which is likely harmful to wheat yields (20).

      In addition they note that the positive effect on growth of increased CO2 is of the order of 0.065% increase per extra ppm of CO2 in atmosphere for C3 crops wheat, rice and soybean, but very small for maize, which has C4 photosynthetic pathway.

      All in all the paper doesn’t paint an overly gloomy picture on the consequences of a modest increase in temperatures. Large changes would require extensive adaptation, which may be beyond reach, if the changes are fast.

    • Pekka

      The 2.5 times increase in key grain production (wheat, corn, rice) over the same period touted by IPCC (AR4 WG1 Ch. 3, p.240) as

      “a time when global mean temperatures began a discernable upward trend that has been at least partly attributed to increases in greenhouse gases in the atmosphere”

      tells me very clearly that Fred’s statement below has been directly refuted by the facts

      The evidence to date indicates that globally, the recent warming has been associated with a reduction in crop yield

      The model-derived conclusion by Lobell, which he and you both cite, tries to “sell a story”, which is not substantiated by the facts on the ground, i.e.:

      - Temperature rose by a few tenths of a degree from 1970 to today
      - Over the same period crop production more than doubled

      Don’t fall into Fred’s trap, Pekka. It will only make you look silly.

      Max

    • Pekka

      [Something went wrong with the formatting, so am reposting this]

      The 2.5 times increase in key grain production (wheat, corn, rice) over the same period touted by IPCC (AR4 WG1 Ch. 3, p.240) as

      “a time when global mean temperatures began a discernable upward trend that has been at least partly attributed to increases in greenhouse gases in the atmosphere”

      tells me very clearly that Fred’s statement below has been directly refuted by the facts

      The evidence to date indicates that globally, the recent warming has been associated with a reduction in crop yield

      The model-derived conclusion by Lobell, which he and you both cite, tries to “sell a story”, which is not substantiated by the facts on the ground, i.e.:

      - Temperature rose by a few tenths of a degree from 1970 to today
      - Over the same period crop production more than doubled

      Don’t fall into Fred’s trap, Pekka. It will only make you look silly.

      Max

    • Max,

      I’m trying to avoid all traps, both Fred’s and yours.

      Identifying weather related changes of a few percent, while other changes are very large is certainly difficult. I don’t think that you try to tell that the large increases in production are due to different weather conditions, as there is so much else in the overall figures. To gain some knowledge model-based research is the only real possibility. I haven’t made any attempt to study, how far one should trust their results. Therefore I only told, what they had written on the caveats.

      My last sentence, was not based on that paper, but I consider it self-evident. Major climatic changes would certainly require a lot of adaptation. By major climatic changes I mean such that affect significantly both the temperatures and the spatial and temporal distribution of rainfall.

    • Pekka

      You are waffling.

      Fred wrote that “the recent warming has been associated with a reduction in crop yield”

      The facts showed that they increased more than two-fold over this period.

      No matter how you try to rationalize it, Fred’s statement was WRONG.

      Max

  61. steven

    Thanks for link to study debunking Lobel et al.

    The main issue here, to me, was that this model study ignored the actual facts on global production of wheat, corn, rice over the recent period of warming.

    The data clearly show that production of these grains has increased more than two-fold over this period of slight global warming.

    Fred had claimed that just the opposite was true (citing Lobel).

    This just shows me how far from reality some of these model studies really are.

    Max

    • Max, I don’t think the Lobel study claimed a reduction in actual production. They were claiming a reduction in the potential production. From the abstract (which is all I have read recently anyway)

      “Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, carbon dioxide fertilization, and other factors. ”

      So it isn’t really fair to say they ignored the real world.

    • steven

      I appreciate your fine point of distinction, but the Lobel model study is of little interest to me.

      Fred claimed that “the recent warming has been associated with a reduction in crop yield”

      This is a very clear statement.

      I demonstrated to him, based on actual crop data over “the recent warm period” that this statement was false.

      There was NO “reduction in crop yield”.

      In fact, there was a 2.4-fold increase in overall global crop yield over the period 1970-2010

      Model studies that do not consider the actual facts are of little value or interest to me.

      Had the study stated (and documented) that “the 140% observed increase in global crop yields might have been even higher had there not been an average 0.5C increase in globally and annually averaged land and sea surface temperature over this period”, that would have been a tenable albeit debatable conclusion.

      But this is all beside the point.

      Fred made an incorrect statement and I corrected him by showing him the actual facts.

      Max

    • manacker

      Did you look into the figures for cost of production?

      The increased productivity happened arguably mostly due intensive application of ammonia-based fertilizers and use of heavy machinery and extensive irrigation, all reliant in one way or another on petrochemicals.

      With petrochemical costs expected to rise faster than rate of crop yields, the importance of the potential production figures becomes greater, and the steroid-like contribution of CO2 lesser.

      While I don’t pretend papers like http://www.fao.org/fileadmin/templates/wsfs/docs/expert_paper/How_to_Feed_the_World_in_2050.pdf are mostly right or mostly wrong, most of them overlook the problem that ammonia will be on the order of five times more costly in 40 years than it is today, based on current trends.

      That 2.5x productivity level cannot be maintained without incredible levels of subsidy, or substantial changes in process.

    • Bart R

      Regarding crop yield improvements 1970 to today, you ask

      Did you look into the figures for cost of production?

      No.

      This was not the topic of discussion.

      It was the erroneous claim by Fred Moolten that crop yields had declined 1970 to today because of global warming.

      I simply showed him that the data do not support his claim. In fact, crop yields of all major crops have increased by almost 2.5 times since 1970, so there has obviously been no observed negative impact from global warming, as Fred claimed.

      Everything has gotten more expensive since 1970 (just look at energy costs!), but that is totally beside the point.

      Max

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