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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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How the IPCC is more likely to underestimate the climate response

What the science says...

Select a level... Basic Intermediate

Numerous papers have documented how IPCC predictions are more likely to underestimate the climate response.

Climate Myth...

IPCC is alarmist

"Unquestionably, the U.N. Intergovernmental Panel on Climate Change (IPCC) was formed to build the scientific case for humanity being the primary cause of global warming. Such a goal is fundamentally unscientific, as it is hostile to alternative hypotheses for the causes of climate change." (Roy Spencer)

"Unquestionably, the U.N. Intergovernmental Panel on Climate Change (IPCC) was formed to build the scientific case for humanity being the primary cause of global warming. Such a goal is fundamentally unscientific, as it is hostile to alternative hypotheses for the causes of climate change."

Climate scientist Roy Spencer made this statement. He starts by suggesting something highly questionable isn’t open to being questioned. What he seeks to do is suggest, by inference, that the IPCC has an agenda, and this distorts the reports they produce. In other words, Spencer (and others) suggest that the IPCC exaggerates what the science says in favour of anthropogenic global warming. It is perfectly legitimate to question this assertion, since Spencer and others offer no evidence to support it.

Some critics go further, suggesting that the IPCC actively suppresses science that doesn’t support the theory that climate change is being caused by human activities. It is notable this ‘other science’ is rarely produced to support the accusation.

Does the IPCC accurately report the findings of science?

The IPCC was formed to report on a broad range of scientific enquiries into the climate, and our effects on it, and to summarise the science for laypeople. The science they summarise is published so it is simple to compare the primary science with the IPCC reports, and compare both to what actually took place.

There are numerous instances where the IPCC reports, which are summaries of published climate change science, have understated the case - hardly suggesting exaggeration in pursuit of an agenda. Here are some examples:

  • CO2 output from fossil fuels: observed emissions are close to the worst-case projections made by the IPCC, despite them offering a range of potential emission scenarios. (In fact, atmospheric CO2 is increasing ten times faster than any rate detected in ice core data over the last 22,000 years).
  • Sea-level rise is accelerating faster than the IPCC predicted. Actual sea-level rise is 80% higher than the median IPCC projection. By 2100 sea-level rise was predicted by the IPCC to be in the range of 18-59 cm. It is now believed that figure may be far too low, because estimates of contributions from Greenland and Antarctic ice-caps were excluded from AR4 because the data was not considered reliable. (This omission hardly supports the notion that the IPCC seeks to exaggerate global warming trends).
  • Each Arctic summer, sea-ice is melting faster than average predictions in the last IPCC report. The Arctic is experiencing a long-term loss of multi-year ice which is also accelerating.
  • The body of scientific literature has consistently shown that human greenhouse gas emissions are responsible for more global surface warming than has been observed over the past half century, whereas the IPCC only says that greenhouse gases are responsible for "most" observed warming over this timeframe.

In many similar cases, the evidence suggests that changes in climate are occurring faster, and with more intensity, than the IPCC have predicted. It is not credible to suggest the reports were biased in favour of the theory of anthropogenic global warming when the evidence demonstrates the IPCC were, in fact, so cautious.

In fact, there is evidence however to suggest that the exact opposite is actually the case, both in terms of the scientific evidence itself (see below) and the way the work of the IPCC is reported. A recent study (Freudenburg 2010) investigated what it calls 'the Asymmetry of Scientific Challenge', the phenomenon in which reports on science fail to evaluate all outcomes, favoring certain probabilities while ignoring others. They found that " scientific findings were more than twenty times as likely to support the ASC perspective [that disruption through AGW may be far worse than the IPCC has suggested] than the usual framing of the issue in the U.S. mass media".

Claims that the IPCC is alarmist are not supported by evidence, and there are clear indications that the opposite may be the case.

Basic rebuttal written by GPWayne

Update July 2015:

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 5 July 2015 by skeptickev. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

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Comments 51 to 75 out of 138:

  1. 'Don't expect SkS readers to fossick around in that mess. Cite one portion from WG1 that is based on 'grey literature.' ' I already cited on Rob

    [DB] Do you understand the distinctions between WG1, WG2 and WG3? Your link (essentially a newspaper article/blog post) deals with WG2, not WG1.

    Again, you asserted that the whole IPCC report, which includes WG1, was based on grey literature.

    Try again.

  2. As an FYI, you are not complying with this site's Comments Policy; specifically, this section:
    "No link or picture only. Any link or picture should be accompanied by text summarizing both the content of the link or picture, and showing how it is relevant to the topic of discussion. Failure to do both of these things will result in the comment being considered off topic."
    Which has resulted in your two three most several recent comments being deleted. You have elected to assign yourself the task of showing which section of WG1 is based on grey literature. Please proceed to do so.
  3. a reference from WG1 that is from a grey source; Vérant, S., 2004: Etude des Dépressions sur l’Europe de l’Ouest : Climat Actuel et Changement Climatique. PhD thesis, Université Paris VI, Paris, France, 204 pp.
    Response: [DB] Which portion of WG1 specifically? And why do you think this is a "grey" source (your comments still do not specifically comply, but this becomes tedious)? More is required than merely furnishing a source lacking a link.
  4. a reference from WG1 that is from a grey source; Jiang, Y.D., 2005: The Northward Shift of Climatic Belts in China during the Last 50 Years, and the Possible Future Changes. PhD Thesis, Institute of Atmospheric Physics, China Academy of Science, Beijing, 137 pp.
    Response: [DB] Um, no. This citation is covered by this SkS post here.
  5. the above are referred to as grey literature because they are; '"information produced on all levels of government, academics, business and industry in electronic and print formats not controlled by commercial publishing" ie. where publishing is not the primary activity of the producing body." (ICGL Luxembourg definition, 1997 - Expanded in New York, 2004)'
  6. krisbaum, you assign blanket mistrust to the category "grey literature." I guess you assume that because the PhD thesis was not published, it must not be trustworthy. Something must be "wrong" with it. You should let the thesis committees for these individuals know that you've caught on to their fraud. What is your assessment of these pieces of "grey" literature? Are they good science? PhD theses/dissertations are not published for a variety of reasons.
  7. DSL- my original point was that the IPCC does not produce a report solely on peer reviewed literature. It advertises the fact that it does - agreed? Its not whether the science is good or bad in the grey literature, you cannot tell the world your report is only based on peer reviewed literature - when in fact it isnt.

    [DB] Your citations are insufficient because you fail to demonstrate for each which specific portions of WG1 they are based on and why the reference you cite fully fulfills the role of citation for that section.

    Simply copy-pasting from fake-skeptic sources is insufficient. It is incumbent upon you to demonstrate the relevance of each source you cite to support your extraordinary claim.

  8. [DB] Um, no. - please be a bit more specific? Um no to what exactly?
    Response: [DB] Read the linked post, which documents that in detail.
  9. Right, krisbaum, and I am asking you if you think the PhD theses lack quality because they haven't been peer-review by journal reviewers for a journal. Have they been reviewed by experts? If you've been through a PhD defense, then you know the answer. It's entirely possible that the review was performed by scientists who do review work for journals. And I am quite certain that the IPCC reviewers didn't simply accept the theses as the equal of peer-reviewed, published work. The IPCC has used grey literature. They point this out themselves. What is your point? Do you have a hypothesis to share with the group?
  10. Leave it, DB! No statement could better cap off the pointless exercise that krisbaum has just performed. I think krisbaum thinks s/he is special for having had posts deleted. If so, we're all special.
  11. As someone who has been yelled at several times (and gotten over it) for doing the same thing you've just done, I must point out that it is possible to write better, more to-the-point posts. Give your thesis and supply the evidence. Don't dance around with insinuations and "look there! uh-huh . . . wink wink."
  12. Interesting. I wasn't aware of those ten grey literature citations in WG1. However I've tallied up the citations in the first 3 chapters of WG1 and there's 1745 citations in those chapters alone. So the grey literature citations make up less than 1% of the first 3 chapters of WG 1. This shows that krisbaum's claim is total bunk, but I may as well tally up the rest of the citations and show the relative percentage.
  13. Krisbaum, the with regard to the IPCC AR4 Working Group 2 report, the IPCC states:
    "The Working Group II Fourth Assessment, in common with all IPCC reports, has been produced through an open and peer-reviewed process. It builds upon past assessments and IPCC Special Reports, and incorporates the results of the past 5 years of climate change impacts, adaptation and vulnerability research. Each chapter presents a balanced assessment of the literature which has appeared since the Third Assessment Report[1] (TAR), including non-English language and, where appropriate, ‘grey’ literature."
    (My emphasis) Your thesis that the IPCC claims to not use grey literature is, therefore, clearly false. The IPCC has clearly delineated procedures for the use of grey literature. Clearly you are arguing a straw man. If you would actually like to address the issue of the quality of references used by showing scientific flaws in the references that have made it into the reports, you might have something interesting to discuss. As it stands your are simply trying to denigrate the reports by innuendo.
  14. To add to Tom's comment, the following passages are from the June AR5 WG1 Progress Report: "The IPCC provides governments with a clear scientific view of the current state of knowledge about climate change, its potential impacts, and options for adaptation and mitigation, through regular assessments of the most recent scientific, technical and socio-economic information published worldwide. These assessments are policy-relevant, but not policy-prescriptive." (emphasis mine) and "Working Group I, which covers the physical science of climate change, received 21,400 comments from 659 experts worldwide in the expert review of its first order draft, which ran from 16 December 2011 to 10 February 2012. Working Group I authors are now considering these comments, as they work on the second order draft, which will be available for expert and government review from 5 October to 30 November 2012."
  15. Tom; thats news to me! I havent seen that section before. Thanks! Here's what Pachauri has been saying--> “People can have confidence in the IPCC’s conclusions…Given that it is all on the basis of peer-reviewed literature.” – Rajendra Pachauri, IPCC chairman, June 2008 “The IPCC doesn’t do any research itself. We only develop our assessments on the basis of peer-reviewed literature.” – Rajendra Pachauri, IPCC chairman, June 2007 “This is based on peer-reviewed literature. That’s the manner in which the IPCC functions. We don’t pick up a newspaper article and, based on that, come up with our findings.” – Rajendra Pachauri, IPCC chairman, June 2008 i dont think i will write anything more to respond, all the links/evidence I give just gets deleted. Good luck with your climate studies.
  16. 'Interesting. I wasn't aware of those ten grey literature citations in WG1. However I've tallied up the citations in the first 3 chapters of WG1 and there's 1745 citations in those chapters alone. So the grey literature citations make up less than 1% of the first 3 chapters of WG 1. This shows that krisbaum's claim is total bunk, but I may as well tally up the rest of the citations and show the relative percentage. ' wher are you getting your numbers from? My posts got deleted because I didnt provide relevant evidence.
  17. Source for grey literature claim here.
  18. Krisbaum. You appear to have a very serious problem with 'grey literature'. Given (conservatively) that more than 99.9% of the denialist literature is at best 'grey', what from that body of commentary do you accept, and why? On the matter of the IPCC's use of grey literature, with which of their references do you have particular issue? The most obvious one that I can think of is the 2035 Himalayan glacier melt gaff, which appears to have originated with a tyographic error in reproducing the date 2350. Tellingly, the offending paragraph did not alter conclusions elsewhere in AR4, and if this is as serious as errors go in a document of many hundreds of pages, then even the most stringent scientific publisher would be proud.
  19. krisbaum - I counted 5284 citations of peer-reviewed scientific literature in Working Group 1 of the 2007 IPCC report (the physical science basis). The 10 citations of grey literature therefore equals 0.19 % of the citations in that report. This is in stark contrast to your claim @ 40: "Something like 1/3 of the references in the last report are grey literature - WWF reports, Greenpeace, news, un-peer reviewed.. etc.." Your claim is total bunk.
  20. Krisbaum, It is difficult to discuss the IPCC with you because you appear to have no understanding of how the IPCC works and what its intended goals are. The Intergovernmental PCC was formed to inform the world's governments about the possibility of climate change. As such governments choose the experts who write the reports. Who do you suggest would be better to choose the experts- you? Your suggestion that someone else should choose the experts is absurd, there is no-one else who could choose them. In any case, if you do not like the experts chosen you can complain. While I have not heard of anyone replaced because they were complained about I would be surprised if no-one has been removed from a position. The experts include scientists from the oil industry. I am astonished that you complain that an expert had only earned his PhD two years before he was made a lead author. It sounds to me like he was a rising scientist who was willing to take on a job. Experts agreed he was qualified, what data do you have to contradict their assessment? I note this person wrote the 1994 report. If you have to look that far into the past to find a complaint the reports since then must be perfect. Your suggestion that governments should not have any involvement in the SPM is also absurd. The whole purpose of the IPCC is to develop a consensus report for governments to use. The SPM is a political document based on the underlying scientific report. It is the responsibility of the governments of the world to ensure an accurate summary is made. As I recall, the US representative was booed because of some statements he made. The USA generally tried to make the SPM less sure than WG1 and other , more progressive countries, fought to keep the SPM more true to the scientific report. Complaining that a political document was compiled by governments is just arguing for arguments sake. The scientific report has been drafted and reviewed several times before the SPM is written. Final edits are small. Changes are agreed on by expert reviewers. You are arguing that if the report is not perfect, by your ever changing standards, it is not dependable. You will never be pleased since you can just change your standards again. In many countries reports are written and published in different ways than we do in the USA, Europe and Australia. In these areas the gray literature is where the data is. When the IPCC experts used these reports they review them before citing them. You are insisting that the IPCC produce a perfect report, 3000 pages long, in a world that is not perfect. Why do you accept denier garbage that has errors in every paragraph when the IPCC must be perfect?
  21. Micheal Sweet maybe explain how you come to the conclusions that you have written above??? it looks like a lot of opinion to me....
  22. Krisbaum's difficulty in obtaining reliable information is transparent in others of his unsupported statements: "it is fairly common knowledge that aerosols do not travel far from their source typically 10km or so. You need localised measurements to get any kind of global pattern." This assertion is not supported by any scientific reference in the post. Anyone looking at a satellite picture of China's dust traveling over the Pacific will come to the conclusion that saying "10km or so" is so removed from reality as to indicate deep ignorance of the subject. Earlier Krisbaum was mentioning the lack of a historical depth to the science of atmospheric aerosols. If one does explore the subject, however, one of the first things to be found is 19th century research centered on studying the reports of ships receiving dust from the Sahara while thousands of km away in the Atlantic. Not 10 km, thousands. This remains a common occurrence, that can easily be seen on satellite pictures. On this one from NASA, the dust crosses the entire Atlantic: Th entire Atlantic, not 10 km. It should be noted that this is dust picked up from the ground, not injected directly in the stratosphere by a volcano. How quickly that latter type travels around the world has already been studied extensively. I do not believe that it is even necessary to post any reference on that, as it takes only a few seconds on Google to find an entire list. The picture of Saharan dust above took me less than 10 seconds to find. In light of this, it is safe to say that this statement: "it is fairly common knowledge that aerosols do not travel far from their source typically 10km or so" is total nonsense that can not possibly form in the mind of anyone actually trying to get information on the subject. Now, let's examine this: "You need localised measurements to get any kind of global pattern." There is a contradiction of terms in the first place, but let's consider that what was meant was something like: you need many, gridded local measurements to get etc etc. It still makes no sense. Aerosols that do not reach the upper atmosphere have no global climate influence. The impossible-to-pronounce- Icelandic volcano that disrupted air travel not long ago did not create a real forcing because aerosols did not go high enough. Having a local record will tell only how some aerosols could have affected that local area. Records from Greenland, where there are no local sources, show the amount of well mixed aerosols, that are present in the atmosphere at large and can be a global forcing.
  23. Krisbaum @29, I grew up (mostly) in Mount Isa, Queensland. The ore in Mount Isa has a high sulphur content, a fact made plain to us when the prevailing easterly wind failed, and the plume from the copper smelter stack (red and white hoops) settled over the town, resulting our filtering out the SO2 inefficiently with our lungs. Occasionally it would rain with a westerly wind, in which case the SO2 was filtered out efficiently by the rain water, killing every rose bush in Mount Isa with a dilute acid. The effect of rainfall with the prevailing easterlies can be seen in the barren western hills behind the mine, stripped even of the hardy spinifex seen in the foreground. The reduced vegetation was apparent up to 30 miles west of the mines: The relevance of this? When I was relatively young I read of a study in Mount Isa Mines internal magazine, Mimag, which traced the flue gas from Mount Isa by its isotopic composition as far as the coast of Africa. I believe it was the west coast of Africa, meaning the gas had crossed most of Australia, the Indian Ocean, and then Africa itself to come to the Atlantic. I'm not certain about the west coast, however, although I am certain about it reaching Africa. Now, given one certain instance of industrial SO2 emissions travelling a third of the way around the world, are you going to seriously argue that industrial SO2 emissions from Europe or North America can't reach Greenland? Yeah, I know. Mimag is grey literate so any information in it can be ignored by you whenever you don't like the consequences - never mind that we take mere blog posts as law when they criticize the IPCC. So, how about we take a different approach. When you identify the major source of SO2 within 10 km of the GRIP drill site, and how that source miraculously synchronized its emissions with European and North American industrial emissions, I'll believe the SO2 in the ice cores did not come from industrial emissions. If you cannot identify that source, however, I will treat your suggestion that the ice cores do not provide a record of European and North American industrial emissions of SO2 with the scorn it deserves.
  24. Michael Sweet @70, it is possible that Krisbaum's objection to a recent recipient of a doctorate becoming a Lead Author is an exagerated idea of what Lead Authors actually do. In the IPCC writing process, Lead Authors are one of a team of five more Lead Authors, each team lead be two or three Co-ordinating Lead Authors. Consequently, lead author does not get to write a chapter by themselves, and are not even the most senior people involved in writing a chapter. It is true that a Lead Author might be asked to write a particular section within a chapter based on particular expertise, but such a request would be decided upon by the Coordinating Lead Authors and other Lead Authors in a meeting, and the resulting section would be subject to review by the full authorship group prior to completion of the first order draft. The upshot is that a Lead Author, despite the exalted title is just a relatively minor member of a team. As such, objections to recent recipients of doctorates being Lead Authors just show a lack of understanding of the process involved.
  25. Allowing Krisbaum his best argument, he relies on the "research" summarized at the inaccurately named NoConsensus website. Their "citizen audit", ie, a review by a group of biased, unqualified people, has found that a total of 21 chapters of the IPCC AR4's 44 chapters receive a failing grade of F, based on percentage of grey literature used. Of course, it is very clear that that is not a troubling statistic. To start with, something, they take great lengths to downplay is that WG1, as a whole receives an A (93% peer reviewed) in their arbitrary marking system. Based on their methodology, therefore, they should have every confidence in the IPCC AR4 WG1 report. Second, they entirely fail to adress the quality of the grey literature used. Among items listed as "grey literature" are academic monographs, academic books, CSIRO and other scientific institution reports, major government reports, and of course, anything produced by the IPCC itself. In fact, I have so far not come across a single item of "grey literature" that would not be cited without qualm in any academic literature. The website does mention citation of press releases, which would clearly be inappropriate - but do not give any indication of the frequency of citation of such dubious literature. I have heard of, but not investigated just one example of such dubious reference in 18,500 references (ignoring duplicate citations). The failure of the site to list frequency of citation of news releases, or papers by "advocacy groups" like the World Wildlife Fund suggests to me that such a listing would severely damage their case. Nor is it obvious to me why the IPCC should reject out of hand any information from such groups. Finally, the group provides no measure of reliance on grey literature. The IPCC must consider all views on the subject, and therefore consult (and hence include as references) some truly atrocious works. Therefore, the mere citation of a reference in no way shows that the views in that reference, or facts adduced in it, have been accepted by the IPCC report. A serious attempt to audit the IPCC on this point would need to not only show that the IPCC cited grey literature of dubious quality, but that facts contributing to the conclusions of the IPCC where obtained solely from such unreliable grey literature. No attempt to show such a pattern of reliance on dubious sources has been undertaken. Again, I suspect strongly that is because deniers have tried unsuccessfully to impeach the IPCC reports as generally inaccurate, and know the futility of such an approach. Consequently they take an indirect approach in which they can obfusticate the difference press releases and Academic textbooks to create a false impression of unreliability.

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