Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


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.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

New? Register here
Forgot your password?

Latest Posts


The 97% consensus on global warming

What the science says...

Select a level... Basic Intermediate Advanced

97% of climate experts agree humans are causing global warming.

Climate Myth...

There is no consensus

"[...] And I'll mention that the stat on the 97% of - of scientists is based on one discredited study." (Ted Cruz)

At a glance

What is consensus? In science, it's when the vast majority of specialists agree about a basic principle. Thus, astronomers agree that the Earth orbits around the Sun. Biologists accept that tadpoles hatch out from frog-spawn and grow into adult frogs. Almost all geologists agree that plate tectonics is real and you'd be hard-placed to find a doctor who thinks smoking is harmless.

In each above case, something has been so thoroughly looked into that those who specialise in its study have stopped arguing about its basic explanation. Nevertheless, the above examples were all once argued about, often passionately. That's how progress works.

The reaching of scientific consensus is the product of an often lengthy time-line. It starts with something being observed and ends with it being fully explained. Let's look at a classic and highly relevant example.

In the late 1700s, the Earth-Sun distance was calculated. The value obtained was 149 million kilometres. That's incredibly close to modern measurements. It got French physicist Joseph Fourier thinking. He innocently asked, in the 1820s, something along these lines:

"Why is Planet Earth such a warm place? It should be an ice-ball at this distance from the Sun."

Such fundamental questions about our home planet are as attractive to inquisitive scientists as ripened fruit is to wasps. Fourier's initial query set in motion a process of research. Within a few decades, that research had experimentally shown that carbon dioxide has heat-trapping properties.

Through the twentieth century the effort intensified, particularly during the Cold War. At that time there was great interest in the behaviour of infra-red (IR) radiation in the atmosphere. Why? Because heat-seeking missiles home in on jet exhausts which are IR hotspots. Their invention involved understanding what makes IR tick.

That research led to the publication of a landmark 1956 paper by Gilbert Plass. The paper's title was, “The Carbon Dioxide Theory of Climatic Change”. It explained in detail how CO2 traps heat in our atmosphere. Note in passing that Plass used the term "Climatic Change" all the way back then. That's contrary to the deniers' frequent claim that it is used nowadays because of a recent and motivated change in terminology.

From observation to explanation, this is a classic illustration of the scientific method at work. Fourier gets people thinking, experiments are designed and performed. In time, a hypothesis emerges. That is a proposed explanation. It is made on the basis of limited evidence as a starting point for further investigation.

Once a hypothesis is proposed, it becomes subject to rigorous testing within the relevant specialist science groups. Testing ensures that incorrect hypotheses fall by the wayside, because they don't stand up to scrutiny. But some survive such interrogation. As their supporting evidence mounts up over time, they eventually graduate to become theories.

Theories are valid explanations for things that are supported by an expert consensus of specialists. Gravity, jet aviation, electronics, you name it, all are based on solid theories. They are known to work because they have stood the test of time and prolonged scientific inquiry.

In climate science today, there is overwhelming (greater than 97%) expert consensus that CO2 traps heat and adding it to the atmosphere warms the planet. Whatever claims are made to the contrary, that principle has been established for almost seventy years, since the publication of that 1956 landmark paper.

Expert consensus is a powerful thing. None of us have the time or ability to learn about everything/ That's why we frequently defer to experts, such as consulting doctors when we’re ill.

The public often underestimate the degree of expert consensus that our vast greenhouse gas emissions trap heat and warm the planet. That is because alongside information, we have misinformation. Certain sections of the mass-media are as happy to trot out the latter as the former. We saw a very similar problem during the COVID-19 pandemic and it cost many lives.

For those who want to learn more, a much longer detailed account of the history of climate science is available on this website.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

We know full well that we don’t have the time or capacity to learn about everything, so we frequently defer to the conclusions of experts. Without experienced people using their expertise to perform many vital tasks – and without new people constantly entering such occupations – society would quickly disintegrate.

The same is true of climate change: we defer to the expert consensus of climate scientists. Indeed, public perception of the scientific consensus with regard to global warming has been found to be an important gateway into other enlightened climate-related attitudes - including policy support. 

Nine consensus studies

Let's take a look at summaries of the key studies, featured in the graphic above, into the degree of consensus. These have been based on analyses of large samples of peer-reviewed climate science literature or surveys of climate and Earth scientists. These studies are available online through e.g. Google Scholar. That slightly different methodologies reached very similar conclusions is a strong indicator that those conclusions are robust.

Oreskes 2004

In this pioneering paper, a survey was conducted into all peer-reviewed abstracts on the subject 'global climate change', published between 1993 and 2003. The work showed that not a single paper, out of the 928 examined, rejected the consensus position that global warming is man-made. 75% of the papers agreed with the consensus position while 25% made no comment either way.

Doran & Zimmerman 2009

A survey of 3,146 Earth scientists asked the question, "Do you think human activity is a significant contributing factor in changing mean global temperatures?" Overall, 82% of the scientists answered yes. However, what was most interesting was the type of response compared to the level of expertise in climate science. Of scientists who were non-climatologists and didn't publish research, 77% answered yes. In contrast, 97.5% of actively-publishing climatologists responded yes. As the level of active research and specialization in climate science increases, so does agreement that humans are significantly changing global temperatures. The paper concludes:

"It seems that the debate on the authenticity of global warming and the role played by human activity is largely non-existent among those who understand the nuances and scientific basis of long-term climate processes. The challenge, rather, appears to be how to effectively communicate this fact to policy makers and to a public that continues to mistakenly perceive debate among scientists."

Anderegg et al. 2010

This study of 1,372 climate science researchers found that (i) 97–98% of the researchers most actively publishing in the field support the tenets of anthropogenic climate change (ACC) as outlined by the IPCC and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers. 

Cook et al. 2013

A Skeptical Science-based analysis of over 12,000 peer-reviewed abstracts on the subject 'global climate change' and 'global warming', published between 1991 and 2011, found that over 97% of the papers taking a position on the subject agreed with the consensus position that humans are causing global warming. In a second phase of the project, the scientist authors were emailed and rated over 2,000 of their own papers. Once again, over 97% of the papers taking a position on the cause of global warming agreed that humans are causing it.

Verheggen et al. 2014

Results were presented from a survey held among 1868 scientists studying various aspects of climate change, including physical climate, climate impacts, and mitigation. The survey was at the time unique in its size, broadness and level of detail. Consistent with other research, it was found that as the level of expertise in climate science grew, so too did the level of agreement on anthropogenic causation. 90% of respondents with more than 10 climate-related peer-reviewed publications (about half of all respondents), explicitly agreed with anthropogenic greenhouse gases (GHGs) being the dominant driver of recent global warming. The respondents’ quantitative estimate of the GHG contribution appeared to strongly depend on their judgement or knowledge of the cooling effect of aerosols.

Stenhouse et al. 2014

In a survey of all 1,854 American Meteorological Society members with known e-mail addresses, achieving a 26.3% response rate, perceived scientific consensus was the strongest predictor of views on global warming, followed by political ideology, climate science expertise, and perceived organisational conflict.

Carlton et al 2015

Commenting that the extent to which non-climate scientists are skeptical of climate science had not so far been studied via direct survey, the authors did just that. They undertook a survey of biophysical scientists across disciplines at universities in the Big 10 Conference. Most respondents (93.6%) stated that mean temperatures have risen. Of the subset that agreed temperatures had risen, the following question was then asked of them: "do you think human activity is a significant contributing factor in changing mean global temperatures?" The affirmative response to that query was 96.66%.

Cook et al. 2016

In 2015, authors of the above studies joined forces to co-author a paper, “Consensus on consensus: a synthesis of consensus estimates on human-caused global warming”. Two key conclusions from the paper are as follows:

(i) Depending on exactly how you measure the expert consensus, somewhere between 90% and 100% of climate scientists agree humans are responsible for climate change, with most of our studies finding 97% consensus among publishing climate scientists. (ii) The greater the climate expertise among those surveyed, the higher the consensus on human-caused global warming.

Lynas et al. 2021

In this paper, from a dataset of 88,125 climate-related peer-reviewed papers published since 2012, these authors examined a randomly-selected subset of 3000 such publications. They also used a second sample-weighted approach that was specifically biased with keywords to help identify any sceptical papers in the whole dataset. Twenty-eight sceptical papers were identified within the original dataset using that approach, as evidenced by abstracts that were rated as implicitly or explicitly sceptical of human-caused global warming. It was concluded that the scientific consensus on human-caused climate change, expressed as a proportion of the total publications, exceeds 99% in the peer reviewed scientific literature.

Myers et al. 2021

This study revisited the 2009 consensus among geoscientists, while exploring different ways to define expertise and the level of agreement among them. The authors sent 10,929 invitations to participate in the survey, receiving 2,780 responses. In addition, the number of scientific publications by these self-identified experts in the field of climate change research was quantified and compared to their survey response on questions about climate change. Perhaps not surprisingly, the study found that agreement on anthropogenic global warming was high at 91% to 100% and generally increases with expertise. Out of a group of 153 independently confirmed climate experts, 98.7% of those scientists agreed that the Earth is warming mostly because of human activities such as burning fossil fuels. Among the subset with the highest level of expertise, these being independently-confirmed climate experts who each published 20+ peer-reviewed papers on climate change between 2015 and 2019, there was 100% agreement.

Public Polls and Consensus

Opinion polls are not absolute in the same way as uncontestable scientific evidence but they nevertheless usefully indicate in which way public thinking is heading. So let's look at a couple taken 13 years apart. A 15-nation World Public Opinion Poll in 2009 PDF), with 13,518 respondents, asked, among other questions, “Is it your impression that among scientists, most think the problem is urgent and enough is known to take action?” Out of all responses, just 51% agreed with that. Worse, in six countries only a minority agreed: United States (38%), Russia (23%), Indonesia (33%), Japan (43%), India (48%), and Mexico (48%). Conversely, the two highest “agree” scores were among Vietnamese (69%) and Bangladeshis (70%) - perhaps unsurprisingly.

The two other options people had to choose from were that “views are pretty evenly divided” (24% of total respondents), or “most think the problem is not urgent, and not enough is known to take action“ (15%). American and Japanese respondents scored most highly on “views are pretty evenly divided” (43 and 44% respectively).

How such a pervasive misperception arose, regarding the expert consensus on climate change, is no accident. Regular readers of this website's resources will know that instead, it was another product of deliberate misinformation campaigning by individuals and organizations in the United States and other nations around the world. These are people who campaign against action to reduce carbon emissions because it suits their paymasters if we continue to burn as much as possible. 

Step forward to 2022 and the situation has perhaps improved, but there's still some way to go. A recent poll, Public Perceptions on Climate change (PDF), was conducted by the Policy Institute, based at King's College London, UK. It quizzed samples of just over 2,000 people from each of six countries (UK, Ireland, Norway, Poland, Italy and Germany). The survey asked the question: “To the best of your knowledge, what percentage of climate scientists have concluded that human-caused climate change is happening?” The following averages were returned: the UK sample thought 65%, the average of the whole survey was 68% and the highest was Ireland at 71%. Clearly, although public perception of expert consensus is growing, there's still plenty of room for strategies to communicate the reality and to shield people from the constant drip-feed of misinformation.

Expert and Public Consensus

Finally, let's consider the differences between expert and public consensus. Expert consensus is reached among those who have studied complex problems and know how to collect and work with data, to identify what constitutes evidence and evaluate it. This is demanding work requiring specific skill-sets and areas of expertise, preparation for which requires years of study and training. 

Public consensus, in contrast, tends to occur only when something is blindingly obvious. For example, a serial misinformer would struggle if they tried running a campaign denying the existence of owls. Everyone already knows that of course there are owls. There is public consensus because we see and hear owls, for real or on the TV or radio. But complex issues are more prone to the antics of misinformers. We saw examples of misinformation during the COVID pandemic, in some cases with lethal outcomes when misinformed people failed to take the risks seriously. There's a strong parallel with climate change: it is imperative we accept the expert consensus and not kick the can down the road until the realisation it is real becomes universal – but utterly inescapable.

Update May 1, 2024: Corrected a typo in the publication year for Plass (1956) in the at-a-glance section.

Last updated on 26 May 2023 by John Mason. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

Related Arguments

Further reading

Richard Black at the BBC investigates whether there is a bias against skepticism in the scientific community.

More on what we're talking about when we say "scientific consensus,"  in an essay founded on Denial101x and scientific literature: Scientific Consensus isn’t a “Part” of the Scientific Method: it’s a Consequence of it. (or via

Further viewing

The "Climate Denial Crock of the Week" video series examines the list of "32,000 leading skeptical scientists."

Naomi Oreskes gives a thorough presentation of the development of our scientific understanding of anthropogenic global warming:

Lead author John Cook explains the 2016 "Consensus on consensus" paper.

Here is a video summary of the various studies quantifying the scientific consensus on human-caused global warming, as well as the misinformation campaigns casting doubt on the consensus.


Many thanks to Joe Crouch for his efforts in tracking down scientific organizations endorsing the consensus as well as links to their public statements.


On 21 Jan 2012, we revised 'the skeptic argument' with a minor quote formatting correction.


Prev  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  Next

Comments 726 to 750 out of 955:

  1. flavoid, sure I'll explain:

    We only look at papers stating a position on the topic (of which 97% state that humans are causing most global warming) because factoring in papers which DON'T address the topic would be ridiculous.

    Papers on needlepoint don't state that humans are responsible for global warming... ergo no consensus. See? Ridiculous.

    Happy to help.


    [PS] Perhaps flavoid could clarify their position about "self-selected dataset" by providing examples of papers that dont support the consensus that would be missed by the selection procedure.

  2. Flavoid, to put it another way: your statements have gone well wide of reality ~ you have missed the truth by a country mile !

    I don't know how you managed to get it so wrong. Very likely, you haven't actually read the paper Cook et al., 2013. Even just a read of the the paper's Abstract [see link at the head of this thread] will show you how wide of the mark you are. Read with a calm mind, and you will see how straightforward it all is.

    You will then also note the excellent quality-control of the Cook paper ~ and how the surveyed papers' authors themselves have expressed the same 97%  via their own assessment.

    So the matter of consensus is quite clear, too.

    Even mavericks like Dr R. Tol have admitted (in a slightly curmudgeonly way) that the "consensus" is 90+% .

    If there is to be a valid criticism of the "97%" as shown in the Cook paper, then the criticism [today] would be that the 97% is based on somewhat dated information [i.e. being on papers averaging about 10 years old by now].

    A present-day and deep-searching survey would now probably show a climate-scientist consensus closer to 99% .

  3. Has anyone looked at the rebuttal from José Duarte regarding Cook's 97% consensus paper? (

    He makes quite a good case about various biases being in the methodology along with pointing out how the claimed standards have not been met in various ways.

    From what I can tell he makes a pretty compelling case that the 97% consensus is way overstated as a result of those errors.


    [RH] Please inform us when Duarte gets his rebuttal through peer review and we can discuss it at that time.

  4. TheRobin @728, I have addressed Duarte's criticism elsewhere.  The upshot is that even if we allowed his criticisms as being entirely valid, and removed from the study all papers to which it applies, it would only reduce the consensus to 96.8%.  That reduction ignores that several of the papers on Duarte's list were classified as 4, and therefore did not contribute to the consensus value; and that no doubt there were opposite errors were papers supporting the consensus were excluded or classified as 4 (both of which are known to have been the case).  Ergo the 96.8% represents a generous overestimate of the impact of taking Duarte's criticism into account.

    It is astonishing how consistently critics of Cook et al (2013) fail to estimate the impacts of their criticism on the 97%; and how consistently the impacts are negligible at best.  There is a reasons why Duarte's criticism will not make it into peer review - but will be endlessly bandied around by those for whom rhetoric is more important than analysis.

  5. TheRobin @ 728, my viewpoint is much more the layman's , compared with Tom Curtis's more scientific assessment.

    I had a look through some of Duarte's blogging output, about a year ago.  That guy has a very weird way of viewing the world [to put it politely] . . . and my recommendation is that you will be wasting your time reading his ideas.   Life is too short, to make it worthwhile spending time sifting through such quasi-sapient ramblings.  Duarte is clearly intelligent, but his ratiocination is rather disconnected from reality.


    [PS] Eclectic - please refresh your memory of the Comments Policy. In particular, note the "no ad hom, no inflammatory tone, no accusations of fraud". Recent comments have pushed or been over the line.

  6. I just had a quick question. I know that all but two scientific bodies with national or international standing have endorsed anthropogenic climate change. The two that have not take no official position. I was just wondering exactly how many scientific organizations have national or international standing. Is it hundreds of organizations or scores of organizations?

  7. Wikipedia has a pretty up to date listing of scientific organizations and their position on the climate here. They show four non-commital groups (all geologists, for some reason), with none expressing a group opinion contrary to the current consensus. 

  8. Thanks KR. I knew about the Wikipedia page, but I was hoping someone had already done the counting. Here is the simplified list from Wikipedia of scientific organizations that have endorsed anthropogenic climate change. I hope someone will let me know if I missed any or counted some twice.

    1. Inter Academy Council

    2. International Council of Academics of Engineering and Technological Sciences.

    3. National Science Academy of Australia

    4. National Science Academy of Belgium.

    5. National Science Academy of Brazil.

    6. National Science Academy of Canada

    7. National Science Academy of the Caribbean.

    8. National Science Academy of China.

    9. National Science Academy of France.

    10. National Science Academy of Germany.

    11. National Science Academy of India.

    12. National Science Academy of Indonesia.

    13. National Science Academy of Ireland.

    14. National Science Academy of Italy.

    15. National Science Academy of Malaysia.

    16. National Science Academy of New Zealand.

    17. National Science Academy of Sweden.

    18. National Science Academy of Turkey.

    19. National Science Academy of the United Kingdom.

    20. National Science Academy of Japan.

    21. National Science Academy of Russia.

    22. National Science Academy of the United States.

    23. National Science Academy of South Africa.

    24. National Science Academy of Cameroon.

    25. National Science Academy of Ghana.

    26. National Science Academy of Kenya.

    27. National Science Academy of Madagascar.

    28. National Science Academy of Nigeria.

    29. National Science Academy of Senegal.

    30. National Science Academy of Sudan.

    31. National Science Academy of Tanzania.

    32. National Science Academy of Uganda.

    33. National Science Academy of Zambia.

    34. National Science Academy of Zimbabwe.

    35. African Academy of Sciences.

    36. Polish Academy of Sciences.

    37. American Association for the Advancement of Science.

    38. Federation of Australian Scientific and Technological Societies.

    39. United States National Research Council.

    40. European Academy of Sciences and Arts.

    41. European Science Foundation.

    42. American Chemical Society.

    43. American Institute of Physics.

    44. American Physical Society.

    45. Australian Institute of Physics.

    46. European Physical Society.

    47. American Geophysical Union.

    48. American Society of Agronomy.

    49. Crop Science Society of America.

    50. Soil Science Society of America.

    51. European Federation of Geologists.

    52. European Geosciences Union.

    53. Geological Society of America

    54. Geological Society of London.

    55. International Union of Geodesy and Geophysics.

    56. National Association of Geoscience Teachers.

    57. American Meteorological Society.

    58. Australian Meteorological and Oceanographic Society.

    59. Canadian Meteorological Society.

    60. Royal Meteorological Society (UK).

    61. World Meteorological Organization.

    62. Amercian Quaternary Association.

    63. International Union for Quaternary Research.

    64. American Association of Wildlife Veterinarians.

    65. American Institute of Biological Sciences.

    66. American Society for Microbiology.

    67. Australian Coral Reef Society.

    68. Institute of Biology (UK)

    69. Society of American Foresters.

    70. The Wildlife Society.

    71. American Academy of Pediatrics.

    72. American College of Preventable Medicine.

    73. American Medical Association.

    74. American Public Health Association.

    75. Australian Medical Association.

    76. World Federation of Public Health Associations.

    77. World Health Organization.

    78. American Astronomical Society.

    79. American Statistical Association.

    80. Canadian Council of Professional Engineers.

    81. The Institution of Engineers Australia.

    82. International Association of Great Lakes Research.

    83. Institute of Professional Engineers New Zealand.

    84. The World Federation of Engineering Organizations.

    Scientific Bodies Rejecting Anthropogenic Global Warming:


    Scientific Bodies With No Official Position.

    1. American Association of Petroleum Geologists.

    2. American Institute of Professional Geologists.

    3. Candadian Federation of Earth Sciences.

    4. Geological Society of Australia.

    So, if your basketball team had a record of 84-0-4, that would be a pretty good year. If you tell me there is no consensus I would advise you to see a phychiatrist.

  9. A point about messaging to the public. In the "Consensus of Scientists" video, John Cook makes the well-reasoned point about relying on expertise. But I think the general public could reasonably still be confused by the fact that non-expert scientists aren't showing nearly as strong of a consensus based on the current surveys. Is this because the wrong question is being asked of them, at least in terms of the type of question that is relevant to the public? Should there be a different survey that asks whether they trust the findings of the climate scientists in regard to climate change? In other words, should the quesiton be posed so that non-experts are not being asked about their personal confidence based on their expertise but rather of their trust in the findings of climate scientists, who are the experts? If the question was posed in such a way, would it show a much broader support in the science community for the acceptance of climate change and the need to act? Would this clarify the messaging to the public by separating a scientist's personal expertise from their support for the relevant experts? I guess one could just point to all the scientific societies that give the same supporting message on climate change, but maybe that could still be miscontrued by the public as a "top-down" opinion being pushed by representatives rather than an accurate reflection of the opinions of individual scientists.

  10. If the body of evidence is so strong and the concensus so overwhelming, why is it that no organisation, including IPCC, will directly answer the question "what percentage of forecast global warming is due to greenhouse gas emissions". They seem happy to forecast temperature rises to a tenth of a degree over a decade, so presumably have data to segregate causes.


    Welcome to Skeptical Science. Please take the time to review the comments policy and ensure future comments are in full compliance with it.

    In particular, please note the ban on sloganeering which your comment runs dangerously close to. This means that you must back your assertions with references/data.

    Your comment seems strange because it appears that you have not in fact read what the IPCC says. It does not "forecast" as such, nor do models have any skill at decadal level prediction of surface temperature. The report most certainly does have an attribution statement on warming.

    "It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period."

    That statement is discussed in more detail here.

    You will find discussions here more productive if you do not raise strawmen arguments (ie make sure what you claim someone says is in fact true).

  11. dfern @735, here are the IPCC's AR5 attribution of recent warming (1951-2010) to various anthropogenic factors based on their figure 10.5:

    Note, OA stands for Other Anthropogenic factors, primarilly the aerosol direct and indirect effects and Land Use Change, all of which are negative forcings.  As indicated, the certainty of the total anthropogenic contribution is much greater than that for the decomposed elements.  The figure needs a slight qualification in that it does not include the uncertainty of the correctness of the models, so that the actual uncertainty is larger than that shown, but not quantifiably so.  To allow for this, the IPCC AR5 stated that at least 90% of the Probability Density Function of anthropogenic contribution (ie, the equivalent of the area under the orange line, once model uncertainty is accounted for) lies above 50%.  They used a technical short hand to say that, but that is the ghist.  Note that expanding the uncertainty will reduce the peak, and broaden the area under the curve, but ill not shift the position of the peak, so that the most probable anthropogenic contribution is 108% over that interval, and the most probable greenhouse gas contribution is 138%.

    In short, your supposition that the IPCC has not directly answered the question as to the percentage of warming contributed by anthropogenic factors, or even greenhouse gases is false.

  12. There definitely is a consensus that CO2 can increase temerature,

    BUT NOBODY KNOWS BY HOW MUCH, that part is NOT consensus. According to believers the icecaps would have been long gone by now and we would be in knee deep water in Florida.

    There is no consensus on CATASTROPHIC climate change.

    Over the past 11,000 years the Earth has had temperatures above today's average temperature about 9 times. We are now at average temp according to this data: GISP2 below


    During evolution, the CO2 was many thousands of ppm and man was definitely not around then and yet life was possible during this "catastrophic" CO2 level


    [RH] Shortened link. Please note that use of all caps is against our commenting policy.

    [TD] Your comments are most appropriate on several other threads. Please read the following, and if you want to comment further on those topics do so on those threads, not this one:

    "...the icecaps would have been long gone by now." You need to provide a reference for your claim. I'm unaware of anyone who has claimed that. For actual peer reviewed scientific projections of ice loss, type into the Search field at the top left of any page relevant terms such as ice, sea ice, land ice, and glacier, and choose from among the resulting hits. Here is one of those: Read the Intermediate tabbed pane of "How the IPCC is more likely to underestimate the climate response," scrolling down to the section on Arctic sea ice.

    "...we would be in knee deep water in Florida." You need to provide a reference for your claim. I'm unaware of anyone who has claimed that. For actual peer reviewed scientific projections of sea level rise, type "sea level" into the Search field at the top left of any page, and choose from among the resulting hits. Here is one of those: "How much will sea levels rise in the 21st Century?" After you read the Basic tabbed pane there, read the Intermediate one.

    "There is no consensus on catastrophic global warming." "Catastrophic" is too ambiguous a term; scientists' projections are much more specific. Read "Positives and negatives of global warming." After you read the Basic tabbed pane, read the Intermediate and then the Advanced.

    "Over the past 11,000 years the Earth has had temperatures above today's average temperature about 9 times. We are now at average temp according to this data: GISP2 below." The GISP2 graph you linked has as its most recent data the year 1855. Not even 1955, but 1855. So it does not show anything like "today." Also, it reflects the temperature only from a single spot in Greenland, which is not at all representative of the entire Earth. Read "Most of the last 10,000 years were warmer." To learn about temperature indices that are representative of the entire Earth, and that go up to much closer to today, read "Real skepticism about the Marcott hockey stick." Then use the Search field to look for more posts  about Marcott, and posts about PAGES 2K.

  13. Why do we analyze only a few hundred years back.

    We need to look back 11,000 years and you will see that the temperature has been much higher in the past and increased at a much faster rate in many occasions in the past. We focus to much on the recent past and its wron to base conclusions on this tiime period alone.


    [TD] This comment is redundant with your previous one. Don't do that.

  14. Hathawad:

    If you want to learn about these things, go to the "View All Arguments" at the bottom of the thermometer image on the upper left of each page (below "Most Used Cliamte Myths"). You wll find nearly 200 links to various myths, of which your brief posts have covered a surprisingly large number for so few words.

    Your assertions are completely unsupported, and that counts for nothing at this site.

    ...and read the comments policy (link just above the box you type your comment in)

  15. Hathawad @737:

    1)      "There definitely is a consensus that CO2 can increase temperature, but nobody knows by how much"

    IPCC AR5:

    "The equilibrium climate sensitivity quantifies the response of the climate system to constant radiative forcing on multicentury time scales. It is defined as the change in global mean surface temperature at equilibrium that is caused by a doubling of the atmospheric CO2 concentration. Equilibrium climate sensitivity is likely [probability of 66% or more] in the range 1.5°C to 4.5°C [0.41- 1.22 C/(W/m^2))](high confidence), extremely unlikely [probability of 5% or less] less than 1°C [0.27 C/(W/m^2))] (high confidence), and very unlikely [probability of 10% or less] greater than 6°C [1.6 C/(W/m^2))] (medium confidence)."

    That is very simple to interpret.  If your assessment of the Probability Density Function (PDF) of the Equilibrium Climate Sensitivity (ECS) shows a probability that the ECS lies between 1.5 and 4.5 C less than 66%, you are in disagreement with the IPCC, and your assessment lies outside of the consensus.  If your assessment is that the probability that the ECS is less than 1 C is greater than 5%, you are in disagreement with the IPCC, and your assessment lies outside of the consensus.  If your assessment is that the probability that the ECS lies above 6 C is greater then you are in disagreement with the IPCC, and your assessment lies outside of the consensus.  As a result it is clear that Nick Stokes estimates of the ECS, though low, are clearly within the consensus while those of deniers claiming an ECS of 1 C or less are not.

    I included in the quote from the IPCC the values interpreted as a Climate Sensitivity Factor, which allows you to simply multiply out a forcing to see the temperature response to that forcing.  Thus, at doubled CO2 the forcing is 3.7 W/m^2 +/- 10%.  From the forcing and the Climate Sensitivity Factor, the temperature impact of CO2 at equilibrium is easilly calculated.  In short, the temperature impact of CO2 is known within a significantly constrained range that excludes most denier estimates of the impact.

    2)    "According to believers the icecaps would have been long gone by now..."

    No climate scientist of any repute has claimed that the ice caps (ie, kilometers deep layers of ice covering Antarctica and Greenland, and some thinner ones on islands in the Canadian Archipelago) would have melted by now, or even by the end of the century.    Wieslaw Maslowski and Peter Wadhams has predicted an early loss of Arctic sea ice (ie, the very thin ice floating on the sea surface) around this decade.  The low bracket of their estimate has come and gone.  The central value of his estimate falls in the remaining four years of this decade, and are widely considered by sea ice experts to be utterly implausible.  The actual consensus position, as given in the IPCC AR5 is:

    "Based on the CMIP5 multi-model ensemble, projections of average reductions in Arctic sea ice extent for 2081–2100 compared to 1986–2005 range from 8% for RCP2.6 to 34% for RCP8.5 in February and from 43% for RCP2.6 to 94% for RCP8.5 in September (medium confidence).  A nearly ice-free Arctic Ocean (sea ice extent less than 1 × 106 km2 for at least 5 consecutive years) in September before mid-century is likely under RCP8.5 (medium confidence), based on an assessment of a subset of models that most closely reproduce the climatological mean state and 1979–2012 trend of the Arctic sea ice cover. Some climate projections exhibit 5- to 10-year periods of sharp summer Arctic sea ice decline—even steeper than observed over the last decade—and it is likely that such instances of rapid ice loss will occur in the future. There is little evidence in global climate models of a tipping point (or critical threshold) in the transition from a perennially ice-covered to a seasonally ice-free Arctic Ocean beyond which further sea ice loss is unstoppable and irreversible."

    (My emphasis)

    (See the upper right panel in particular.)

    So, the consensus position is for a sea ice free Arctic around mid century, approximately 30 years from now, and that being avoidable if we mitigate climate change.

    3)   "...and we would be in knee deep water in Florida".

    The IPCC AR5 predicts a likely range for sea level rice in 2081-2100 of 0.52 to 0.98 meters (ie, enough to make you shin to knee deep if you stand at the current water level) assuming RCP 8.5 (essentially business as usual.  Predictions of knee deep sea level now except as a result of storm surge are figments of your own imagination.

    4)   "Over the past 11,000 years..."

    GISP 2 represents a temperature proxy for only one location on the earths surface, and consequently does not represent Global Mean Surface Temperature (GMST).  You should at the minimum use a mean of several long term temperature proxies, such as this one from Global Warming Art:

    The recent decadal average is up around 1 C on this scale, and well above the 2004 value indicated in the graph, and hence above the mean across all decades.  These proxies do not have a annual time scale so some decades in the past 10,000 years may have been warmer than our current decade - but we do not know that any were and it is likely that very few were.  Further, the temperature rise since 1850 is almost certainly unprecedented since the end of the last glacial.

    5)  "During evolution, the CO2 was many thousands of ppm and man was definitely not around then and yet life was possible during this "catastrophic" CO2 level"

    Durring those periods with very high CO2 levels, solar activity was significantly less than it is today.  This is known because solar activity increases overtime in a very predictable pattern.  The result is that combined forcing of CO2 plus solar was not much greater than preindustrial levels, and less than likely levels of forcing with Business As Usual:

    It is interesting to note that up to 65 million years ago, land life was dominated by ectotherms and endotherms, ie, creatures much less vulnerable to heat stress than is the case for humans.  Periods of elevated temperatures in the last 65 million years have also see a dominance of smaller animals, with a higher surface to volume ratio and higher basal temperatures (both contributing to more efficient cooling).  Neither of these facts is comforting to large, homeothermic animals such as humans when facing similarly elevated temperatures.  Rodents, snakes and cockroaches, on the other hand, will do just fine.

    In summary, your "points" rely mostly on misrepresenting the claims of climate scientists, or misrepresenting what is actually known.  An argument that can only be pressed by such means (as is the case with nearly all denier arguments) are not worth pursuing, or indeed, giving any credence to. 

    If you surprise me by actually responding, please do so on the appropriate threads as indicated by the moderator.


    [JH] To make it easier for readers to disgest your posts, I suggest that you use italics font for the material you are quoting from the commenter you are responding to.  In this particular case, you may also want to put the quotes in bold-face because they essential serve as subject headers. 

  16. Hi,

    I have a question regarding the famous Cook et al. (2013) paper on scientific consensus regarding AGW, and critical responses to this paper, especially the one by Legates et al. (2015). The only response to this paper by Legates et al. that I could find was included in the '24 errors of Tol' (page 6). In their paper, Legates et al. claim that Cook et al. misrepresent the consensus since only a small minority of papers actually say that 'human activity is very likely causing most of the current GW'. The two biggest categories of papers accepting the AGW hypothesis are either of the implicit or explicit  but unquantified variety. In response to the critique, Cook et al. argue that it is an impossible expectation to expect authors to explicitly quantify the extent of global warming. I do not think that this is what Legates et al. are expecting though - they are only expecting papers to say that they are 'causing most of the current GW', which is the definition made by Cook et al. at the outset of the paper. So in so far as I'm reading the original Cook et al. paper correctly, i.e. they are querying what percentage of papers agrees with the definition of the AGW hypothesis Cook et al. establish in their paper, namely "human activity is verly likely causing most of the current GW", it appears to me that Legates et al. are correct in arguin that Cook et al. cannot show that 97% of the papers that express an opinion do express this strong of an opinion.

    I think Legates et al. do have a point in the sense that there is a clear difference between a paper saying that humans are contributing to climate change (this being the example statement in the Cook et al. paper for their category 2) and a paper saying that humans are the primary cause of climate change. 'Humans are contributing to climate change' is something that, as far as I am aware of the denialist literature, even most denialists would agree with - they would just say that the human contribution is minimal.

    Thanks in advance for any clarification on this matter!

  17. Spassapparat @741, Legates et al do not have a good point, because they apply it selectively.  We may well be interested in a comparison between the number of papers that "explicitly endorse with quantification" (65) and those that "explicitly reject with quantification" (10) which means an 86.67% endorsement rate among papers whose abstracts explicitly endorse or reject AGW, not the 0.03% used by Legates et al.  (Indeed, Legates figure is doubly wrong because 0.3% of 11,944 abstracts is 36, not the actual 65 explicit endorsements as can be determined by a simple search of the abstracts.)  We might be more interested in the 52 author rated "explicit endorse with quantification" and 9 author rated "explicit reject with quantification" (85.25% endorsement rate).  We may also be interested in the 10 rated "explicit endorse with quantification" and 0 rated "explicit reject with quantification" (100% endorsement rate) from among those abstracts that which include the term "attribute" or its cognates in the title.  We also may be interested to know that among those abstracts that include "attribute" or its cognates, the quantities in each endorsement category are:

    1: 10



    4: 366

    5: 5



    for a total endorsement rate of 97.09% among those that state a position in the abstract.

    The point is that it is not true that only those papers whose abstracts explicitly endorse with quantification actually endorse AGW.  Therefore if you are going to restrict discussion to just those abstracts with numerical attribution values, you need to compare them with just those abstracts - not the total of abstracts which have been excluded from consideration on a technicality.  Not including a specific quantification may simply occur because the quantification has been reserved for the conclusion rather than being revealed in the abstract (a common trait in scientific papers), or because the paper was not explicitly about attribution so that a more general statement was sufficient.  Pretending that is not the case to make rhetorical points is not good science.  It is pseudoscience.

  18. Mr. Curtis,

    thanks so much for your quick reply! I agree with everything you have written, and I do think that Legates et al.'s 0,03 number is completely bogus.

    What I did agree with Legates et al. is that Cook et al's wording is at least unfortunate. In my opinion, if, as is Cook et al's outset question, you want to figure out the number of papers who accept the hypothesis that 'human activity is responsible for most of current GW'  you cannot include papers that write that 'human activity is contributing to current GW' as part of the total number of papers that agree with 'human activity is responsible for most of current GW. Now the word 'attribute' is a different ballpark, since if I write 'current GW is attributed to human activity' then I actually mean, in contrast to 'contribute', that most (or all) of current GW is due to human activity. (or at least, this is my understanding, I am not a native speaker of English)


    I do believe that words matter. In my view, then, papers that use the word 'attribute' or similar should have been separated from papers that use 'contribute', 'play a part/role', 'add to', etc. If this is what is done in the analysis you posted, then this shows that Cook et al's analysis is robust to Legates et al's critique.


    I have another question: something that is also critiqued in Legates et al. as well as other critical papers is the issue of the search term used - they claim that the search term 'global warming' or 'global climate change' biases against critical research since at least some critical research does not use these terms - do you give any credence to the view that this is a significant bias?

    Thanks again!

  19. I have now dabbled with the search tool you posted a bit and looked up papers whose abstracts include 'attribute'. Just on the first page, I found several papers that use the word attribute, but in association with someting other than climate change attributed to human impact. Did your analysis of the word attribute and its cognates only include such papers that used the word attribute and its cognates specifically for this purpose?


    Also, I was wondering about what the paper is actually saying. If we include category 2 and 3, don't we have to dial down what we are saying to what is included in the weakest category (category 3), i.e. all we can say is 97% of papers agree that humans are causing global warming to some extent. That is decidedly not how this paper is used in public discourse though, I think in many instances this paper is used to say that not only do humans cause global warming, but they are also the major cause and the degree of effect on nature/climate is in some way dangerous and needs to be mitigated. This only is true for a minority of the papers though. Would you agree with this assessment?


  20. Spassapparat @744 & prior :

    two points for your consideration, are (A) the design of the Cook-2013 study included a second part where the scientific paper authors were surveyed to discover their assessments of their own papers, regarding attribution ... and this second part confirmed the accuracy of the first part

    and (B) the average "age" of the papers equalled approx. 2005 ... so 10 years or more ago.   Reading the Cook et al. study shows that later papers were more "attributive" than earlier papers.   This result is exactly what one would expect, in view of scientific research subsequent to 2005 all indicating the high [ approx. 100% ] attribution to human-causation of global warming.  (See the latest IPCC summaries)

    Additionally, if you look around the world today, you find almost no genuine climate scientists who attempt to support a contrary [ =non-human ] attribution for the present & continuing rapid warming.

    We can enjoy having Spass with words & rhetoric, but it is our duty to look at the Realitaet — the physical reality of atoms & energies which underlie the words.  That reality is experiencing major warming, and the causation is scientifically very clear and obvious.

  21. Eclectic @745 , thanks for your response!

    Since the chair of the science committee in today's hearing on climate change brought the papers critiquing the Cook et al study into public record, this brought me back here.

    I am aware of (A), but one should note that even there we still do not get close to a 97% consensus on category (1). I've looked into the data, and it suggests that 17% of the authors of papers that do express an opinion on climate change self-identify their paper as a category 1 paper. This is substantially higher than the rating by Cook et al. themselves, but still a farcry from the 97%.

    If Cook et al. are now saying that many papers do not make a definite statement because it is obvious that most of global warming is human-made, I am inclined to agree with this assumption, not least because of other research referenced on this page showing a similar degree of consensus. However it is still just that, an assumption.

    I do not think it is just Spass to play with words, I do think there is a substantial difference between saying "Cook et al. show that there is a 97% consensus that most of global warming is human made" (which, in my opinion, is an untrue statement) and "Cook et al. show there is a 97% consensus that some global warming is human made".

    I wonder why, since there are half a dozen other studies showing a similar agreement, this site in particular and the climate science  community in public discourse in general chooses to use a study whose proclaimed findings are so easily attackable.

  22. Spassapparat @746, in Cook et al, endorsement or rejection is explicitly stated to be endorsement or rejection of the theory of AGW.  That is, it is endorsement or rejection of a specific theory which states, in part, that anthropogenic factors are responsible for greater than 50% of warming since 1950.  If you interpret the different categories of endorsement (implicit, explicit, and explicit with quantification) as applying to successively stronger theories, you have misinterpreted the paper and misunderstood the methodology in the paper.

    You say (@744):

    "Also, I was wondering about what the paper is actually saying. If we include category 2 and 3, don't we have to dial down what we are saying to what is included in the weakest category (category 3)"

    However, category 3 is not endorsement of a weaker theory, but a less strong endorsement of the same theory.  In category 1, endorsement is explicit, and a quantification is give so there can be no doubt that AGW is endorsed.  In category 3, endorsement is implicit, so while the theory endorsed is the same, the possibility of error in assessing whether or not the paper endorses the theory is greater.

    I am aware that climate "skeptics" reject this understanding of the paper, but it was the understanding of the authors, and it was the understanding of the raters.  More importantly, if the endorsements are not understood in that way, it makes the paper inconsistent.  That means critics are rejecting a consistent understanding of the paper, which was held by the authors and raters, in order that a criticism they have should be valid.  Another way of putting that is that they are raising a straw man.

  23. Spassapparat @746 ,

    the purpose of science is to discover the truths of our universe.

    And the purpose of surveys such as Cook et al., 2013 , is to discover the truth about what scientists hold to be factual.

    Of course, we should also look for further evidence that may corroborate what the surveys do find (they find that, for expert climate scientists, a percentage figure in the high 90's is holding AGW theory to be factual).

    These survey results are (unsurprisingly) supported by word-of-mouth opinion from expert scientists about their colleagues — and Spassapparat, this is a matter which you can rather easily ascertain for yourself, by questioning some genuine climate-related scientists.  I am confident you will find it difficult, indeed almost impossible, to find any genuine "contrarian" scientist.  And any such, that you can find, will be unable to provide any real evidence to support their contrarian viewpoints.

    For the year 2013, it is reported that over 2000 climate-related scientific papers were published (totalling 9000 authors).  And yet in that period, only one paper made a contrarian claim [i.e. that modern global warming is caused by an alteration of cosmic ray bombardment of the atmosphere].  This single paper was by a Russian astronomer, and was published in a Russian journal of proceedings.  The paper was vaguely-worded; it did not measure the claimed effect; and it failed to dispose of the well-measured and well-understood CO2 mechanism known to produce AGW.  This cosmic ray hypothesis had already been debunked before 2013 : and in addition, since 2013 there has been more evidence (from cloud-chamber experiments by CERN scientists) showing that this cosmic ray hypothesis is false.  In short, the Russian paper was Dreck.

    So in reality, Null out of 2000 papers could support a non-AGW position.  To me this seems excellent corroboration that the "over 97%" Cook et al. study is the correct representation of the truth — and that the Cook 97% figure very much understates the current status.

    In seeking truth, it is our duty to use complete Ehrlichkeit, and to avoid word-games which are unsupported by the general evidence, and to avoid unredlich conclusions (even when these unredlich conclusions are politically fashionable in some quarters).

  24. This page needs to be updated because denialists are using a new strategy: rather than deny the consensus itself, they deny what the consensus view is. One guy that I debated at length repeatedly ignored the words "most" and "mostly" present in many of the survey questions, instead summarizing the survey questions as asking whether warming is affected by humans "at all" so that scientists' views would not be in conflict with his (he and the 3 followers 'liking' all his posts ignored me as I repeatedly pointed out the ridiculousness of claiming "most" = "any at all".)

    Also, this page should give the EXACT wording of each survey question and the percentage of publishing climate scientists in agreement. According to the "consensus on consensus" paper, for instance, I noticed that 88% of members of the AMS surveyed whose area of expertise was climate science, agreed in 2014 that half or more of the warming was caused by human activities, including 78% who agreed that “the cause of global warming over the past 150 years was mostly human”. “An additional 6% answered ‘I do not believe we know enough to determine the degree of human causation.’” (Stenhouse 2014)

    Notice the window on this question: 150 years. Now, it’s clear the numbers on this very web site that humans caused substantially less than half of global warming in the early 20th century and before. Why, then, do 88% of American climate scientists still agree, despite this, that the roughly 1°C of global warming over the last 150 years was half-or-more human-caused? The obvious answer: although the human contribution was below half before 1940, it was far more than half in the last 50–65 years. So on average, in aggregate, humans are responsible for 50% or more, and much more than that if we limit the window to 50–65 years.

    Smart climate deniers may ignore this reasoning and focus on numbers like 78%, saying 22% disagreed and that's not a consensus. (The one I spoke with will simply change the subject and dazzle you with his encyclopedic knowledge of contrarian claims, never admitting that he holds a minority opinion or disagrees with scientists.) Yet if the question had asked about the most recent 50-65 years instead of 150 years, the consensus might have been 97%.

    We can't stop denialists from twisting words around, but if the survey questions and methodology are not easily discoverable to the public then it is harder to counter their claims.

  25. Oh, and specifically it's no longer useful to cite Doran 2009 which asked if "human activity is a significant contributing factor in changing mean global temperatures". Denialists will interpret "significant" as "anything above zero" and claim to be "in" the 97%. Instead be sure to quote one of the other 97% surveys that uses the word "most" or "mostly".

Prev  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  Next

Post a Comment

Political, off-topic or ad hominem comments will be deleted. Comments Policy...

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

Link to this page

The Consensus Project Website


(free to republish)

© Copyright 2024 John Cook
Home | Translations | About Us | Privacy | Contact Us