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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

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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.


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Comments 351 to 375 out of 908:

  1. Earlier today I had a discussion with a person who described himself a "skeptic", not a denier concerning scientific consensus on ACC. His stance was that there is no consensus among climate scientists that the current climate change was due to human causes. Of course, I directed them to Anderegg 2010, Doran 2009 and Oreskes 2004; but he kept coming back with the statement, "there are climate scientists who do not believe there is a consensus among climate scientists". I kept trying to explain that yes, there are climate scientists that disagree with the consensus, but not that there is no consensus. Are there actually any practicing climate scientists that disagree that there is a consensus?
  2. Hey everyone, A climate skeptic sent me to these websites as proof that climate change is not happening and there is no scientific consensus. Help me in arguing back? Cheers, Michael.
  3. 355, mik_rosser, [snipped uncalled-for harsh reply] For information, just use the search function on this site. Searches for the following will give you more than enough ammunition to thoroughly refute each of those 1,000 times over (not to mention this very post on the consensus): climategate peer review pop tech
  4. 354, RickG, You can find climate scientists that believe that smoking does not cause cancer, and that the theory of evolution is false, so I imagine you can certainly find a few that will even claim that there is no consensus. But let me get this straight... their argument is that there is no consensus on climate change, because there is no 100% consensus on whether or not there is a consensus on climate change? Do they drink from the "Drink Me" bottle or eat the "Eat Me" cake, or both, in their special little wonderland?
  5. mik_rosser @355: Peer Review: The process of peer review if properly adhered to means that every paper published in a scientific journal has been read carefully by at least two people reasonably expert in the field, who have been able to convince a third person who is capable of understanding the argument (the editor) that: a) It contains no obvious errors; and that b) It is written well enough that somebody who wants to could reproduce the procedures and analysis used; and that c) It takes proper account of relevant scientific literature. The process is onerous, but it sets a very low bar. It requires you to convince just three people who know what they are talking about that the paper is not an obvious blunder. That does not show that the paper is not false, or that it is worthwhile or anything like that. Only that it probably does not contain an obvious blunder. The peer review process does not always work, either because reviewers miss obvious blunders (they are human and do make mistakes), or more frequently, because people with bizzare theories game the system by approaching an editor known to by sympathetic to their cause, who will shepherd the paper through to publication without proper peer review. Even creationist papers have been shepherded through in that way, and several "climate skeptic papers" which were obviously flawed have been shepherded through that way. In addition, a large number of papers, some by "skeptics", but many not, have been published which simply do not have the implications "skeptics" attach to them. In many cases, the supposed implications as stated by "skeptics" are directly contradicted by the paper itself, and a large number of scientists have complained about misrepresentation of their papers by "skeptics". Consequently I would take Poptech's list with a very large grain of salt. Because of this tendency of so-called "skeptics" to outright misrepresent the nature of research, many defenders of climate science including myself think a more appropriate label for them is "AGW deniers", in that they are not behaving skeptically, and because they are denying the descriptor of "skeptical" to the many climate scientists who do behave skeptically. However, the crucial point about peer reviewed publication is that it is just a first hurdle for science, and a very low one. It is, however, one that "skeptic's" arguments repeatedly come a cropper on. The simple test of convincing just three reasonably informed people that your argument does not contain obvious blunders is too difficult a challenge for most "skeptics" to meet. As a result they take their arguments to the internet, and to conventions organised by conservative think tanks, and to talk back radio shows. In other words, being unable to persuade even a few well informed people trained in scientific analysis, they take their arguments to people who are neither well informed, nor trained in scientific analysis. That shows clearly their agenda. If their agenda was the advance of knowledge, there would be no substitute for convincing the scientific community. I know of a number of controversial theories which do no have a scientific consensus, but whose adherents repeatedly try to break through the peer reviewed barrier and to convince scientists. That is because they believe their theory is true, and that truth matters. Consequently they think their theory can, and should face the most rigorous test possible. In contrast, AGW deniers have no such confidence or belief. What is important to them is not the truth of their theories, but the political effect of wide spread acceptance of their theories. They are playing a political game - not doing science. It is for that reason that (with rare exceptions) they give an uncritical pass to the egregious lies of some of their number, while straining at fleas in actual climate science. Finally, peer reviewed publication is just the first hurdle of peer review. After publication, papers are read by a very large number of scientists who can analyse the arguments and decide whether they are good, and well supported by evidence; largely irrelevant; or outright bad. The outright bad, ie, almost certainly false papers attract a small number of citations as scientist publish refutations. The irrelevant papers attract almost no citations as people ignore the paper. The good papers attract a large number of citations as people repeatedly reference the result in their own papers. Initial peer review is only a test to see if the paper contains an obvious blunder; citations are the true mark of a worthwhile paper. In that are, "skeptic papers" fare very poorly.
  6. mik_rosser @355: Consensus: I think there are two important things to understand about consensus and climate change. The first and most important is that arguments about consensus are not an argument from authority, it is an argument about who is an authority. It is an unfortunate fact of life that most things that we "know" we accept on authority. It can hardly be any other way - there is simply to much to learn, and to much to analyse for anybody to have more than a passing understanding of more than a small range of topics. Even in those topics where we claim some expertise, most of what we know we know on authority because we have not done the experiments or made the observations ourselves. To give just one example, how do I know that man has ever trod on the moon? The answer is, on authority. I was not on any trip to the moon, nor part of the effort to get man there. I have not myself seen footprints on the moon. Consequently, at some level I must accept the theory that man has walked on the moon on authority. There are those who do not accept that theory, who dispute the claims of those who could actually check for themselves (such as Neil Armstrong and Buzz Aldrin). I can, and have, looked at the evidence the lunar landing deniers present, and see that their claims are unsupported. That means I can show that they do not have a reason to believe the various films of men walking on the moon are doctored, or staged. But what I can't do is prove that they were not doctored or staged because there is no in-principle limit on how well such doctoring or staging can be done. At some point I just have to trust that the films are not fakes - but when I do, I am accepting something on authority. Now, it is obviously best to rely as little on authority as you can, especially in matters of importance. In climate science, if you don't want to rely on authority at all, you first need to get yourself a PhD in physics, making sure you are well qualified in programming and statistics. You then need to read carefully around a thousand scientific papers. That's less than a quarter of all the relevant papers, but it should get you up to speed. You then need to start a major program of experimentation that will require an annual budget of millions to sustain. Even then you will need to accept the authority of various space agencies to make use of satellite data. But you will probably then be in as good a position as anyone to not rely on authority at all in your beliefs about climate change. Of course, not everyone in the population is going to do that. Indeed, only a tiny fraction of the population will undertake the limited measure or reading multiple books, about 100 scientific papers, and several excellent essays need to become, not expert, but moderately competent in understanding the arguments about global warming. Consequently, most people will have to accept most of what they believe about global warming on authority. If anybody ever tells you different, they are lying to you*. Not only are most people going to have to accept most of what they believe about global warming on authority, it is vital that most people actually have an opinion about global warming. This is because we live in a democracy, and there is not substitute for democracy as legitimate government. Given the risks involved, is is therefore vital that people have informed opinions about global warming. But to do that, they must accept much on authority. So the essential issue for most people is this: Whose authority do you accept? So called "climate change skeptics" claim that they are the authority that you should listen to. They say that they are scientists (and some of them are); and that they have studied the issue (and some of them have even done that); and the implicit claim is that you should accept them as your authority. I disagree. If you are not very well informed on a subject, and do not intend to become so, the only rational choice is to accept on authority the consensus opinion of the people who are most informed, and who have studied the issue most closely. Recently Lord Monckton described this as a "fascist point of view", but to me it is just common sense. So common that we govern our lives by it for almost every major decision, whether that be what medicines to take, and when, or what foods to consider safe. In fact, for all their posturing, the so-called "climate skeptics" recognise that this is rational approach. They recognise it by continuously portraying the actual scientific consensus as being smaller than it is; as being perhaps a small majority at most rather than the over whelming majority that it is; and portraying there numbers as being much larger than they actually are by misleading comparisons. They compare, for example, the total number of scientists involved in the IPCC (which they drastically and deceitfully understate) with a list of "scientists" by which they mean anyone with a medical or engineering degree a if that where the appropriate comparison. In fact, comparing like with like, deniers make up around 3% of actively publishing (and hence researching) scientists of any type, and just 1% of actively publishing climate scientists. But they want you to ignore the reasoning and evidence that has raised acceptance of AGW among climate scientists from around 40% two decades ago to around 97% today. The argument from consensus points out that ignoring that evidence is not a reasonable thing to do. So, while I definitely encourage anyone interested to become genuinely familiar with the science of climate change (which is fascinating in its own right), if you are not willing to do so, don't be conned into accepting a false authority by inaccurate comparisons with Galileo. * Lord Monckton actually begins his seminars by saying he will not ask anyone to accept anything on authority. He then proceeds to tell whopper after whopper secure in the knowledge that most of his audience won't check. In other words, he is banking on their accepting his authority, and the disclaimer is a sham. This is a common tactic among deniers, and is equivalent to the "cockroach trap" mail order scam. In that scam a cockroach trap is advertised with a money back guarantee. It turns out the "trap" is just two bricks and instructions to bang them together with the cockroach between. The business is legit in that the money is give back to those who apply, but the scammers make a fortune because most people don't make the effort.
  7. Sorry, forgot to cover the important thing, but two essays is enough or one day. Very briefly, it is the nature of the IPCC consensus. The positions taken by the IPCC are the position that nearly all scientists have least disagreement with. Some might disagree significantly with some points, but an equal number will disagree just as much in the opposite direction. A rough measure the level of disagreement is the statement of the likelihood of the claim (which should be paid careful attention to.) If something is considered very likely, there is very little disagreement, and those who disagree do not disagree by much. If something is "more likely than not" then there is wide disagreement, but the IPCC position is still the position from which there is least disagreement.
  8. Anyone reviewing this site that assigns a percentage for each chapter and working group of the IPCC? No
  9. PS: It seems to be getting promoted out there in the Denialosphere, and has a 'score card' in which this photographer somehow rates the % of peer-review for each chapter of the IPCC report.
  10. It is nonsense. Indeed, it is OBVIOUSLY nonsense. The first massive flaw in their methodology which I noticed is that they treated every reference in the IPCC reports as a 'scientific reference' with which to dispute the IPCC claim that its scientific findings were based solely on peer reviewed research. Thus, reports on progress of various countries towards meeting the Kyoto targets, economic impact estimates, and even citations of objections from 'skeptics' (e.g. Bjorn Lomborg's book 'Global Crises, Global Solutions') are counted against the IPCC's 'score'. In short, no effort whatsoever was made to review WHAT the citation referred to in the text or whether it had anything to do with the case for AGW. The second ridiculous flaw is that their determination of whether something was peer-reviewed or not was entirely based on whether an obvious scientific journal was cited in the reference. Thus, for instance, dozens of references citing "Cambridge University Press" were marked as NOT peer reviewed... demonstrating that no attempt whatsoever was made to track down any of these papers - which appeared in the multiple peer reviewed academic journals which Cambridge publishes. Ditto various other major universities. Ditto anything in the references which people with no apparent knowledge of academic publishing did not immediately recognize as a peer reviewed journal. In short, the 'grades' they present do NOT measure the accuracy of the IPCC's claim that its scientific findings are based on peer reviewed research. Rather, they are measuring the percentages of references on any subject in the IPCC reports which they could determine to be peer reviewed with a cursory inspection by people who don't know what they are doing. A meaningless statistic... which they get completely wrong.
  11. Eclipse @10, I just reviewed the Working Group III references, only to find that CBDunkerson has stolen my thunder with an excellent response. I will add to his points just three more: First, in order to get the "failing grade", the "No consensus" website has obviously had to include as "grey literature" sources as diverse as IPCC reports, the Stern Review, papers presented at academic conferences, and chapters of books by reputed academic publishing houses. While many of these sources have not been through a standard journal type peer review, there is no doubt that they have been extensively reviewed to a far more rigorous standard than would be implied by such peer review. In other words, their ideosyncratic standard of "peer reviewed" is artificially restricted, and exclude much material of the highest academic quality. Second, even with this highly artificial standard, the Working Group 1 chapters nearly all get an A, with only two falling below that standard to get a B. Based on that assessment, if they took their own measure seriously, they would not question the essential results of WG 1. Clearly they do not do that, which reveals what a hypocritical exercise they are indulging in. Three, what is entirely absent is any assessment using their standard of the work of deniers. That assessment would, of course, show the deniers work in a very poor light indeed.
  12. I'm not sure if this is the right thread for this post, but I'm asking whether there is any material addressing this new theory? It's really doing the rounds in Australia. It's all about heat exchange in the upper atmosphere — Douglas Cotton Lastly, how do I subscribe to a thread? I'm not getting emails when someone answers me?

    [DB] You should be getting those now.  You may have to log out of SkS and then re-log back in for the changes I made to take effect.

  13. Eclipse @366, I am not sure of the correct thread, so I'll make my response here. First I should say, what a load of tripe Douglas Cotton has produced. He persistently claims that the IPCC "assumes" values which have been measured, while asserting without measurement "facts" to be true simply on the basis that they are convenient to his theory. Like many deniers, he obviously has no idea what goes into a General Circulation Model, assuming that they have the properties of a one dimensional model, while he himself employs an unphysical model of radiative transfer, the most obvious flaw of which is that he assumes any upward transmitted radiation from the atmosphere is immediately emitted to space (whereas most of it is simply absorbed by higher levels of the atmosphere). His core assumption is that:
    "The IPCC models assume far too much radiation from the Earth's surface instead of convection with air molecules which do not emit photons that can be captured by CO2"
    He defends that claim with this illustration: The defense consists of simply reasserting his claim, and an analogy based on a cooking pot. Of course, the IPCC (actually Kiehl and Trenberth 1997, which has since been updated with Trenberth, Fasullo and Kiehl 2008 [PDF]) based their conclusions on actual measurement. The difficulty arises because it is not possible to measure the upward surface IR radiation at all, or even many locations around the globe. Rather, detailed measurements have been done over particular land surface types under various conditions. These measurements produce results like these: Note that the upward IR radiation is consistently greater than 400 W/m^2. (It is shown as a negative number to distinguish energy leaving from energy entering the surface. For comparison, consider these measurements of Net radiation, Q*, (Incoming shortwave plus incoming longwave minus outgoing shortwave minus outgoing longwave), latent energy, LW, and sensible heat, H. Sensible Heat, Cotton's "conduction" does not rise above 200 W/m^2 except over a dry lake bed, and is negative for much of the time. Clearly, averaged across the twenty four hour day, and across a variety of locations, it is a much smaller component than the outgoing surface IR radiation. Khiel and Trenberth's figures where generated by taking a great number of measurements such as these, and using them together with knowledge of the proportion of the Earth's surface covered by each surface type to estimate a global figure. In contrast, Cotton's alternative estimate was made by waving his hand near a cooking pot. The difference in procedure is a true indicator of the difference in value of the two works.
  14. Well, I had to read it carefully to make sure this guy was serious and not a Poe. So many unphysical things, so little time. You might like to look also at Greenhouse theory violates 2nd Law thread too. Unfortunately, there are a great many "papers" like this around. Appinsys and are full of them (often mutually contradictory). The question is ask is "has it been published in a peer-reviewed journal?" (and E&E doesnt count). There is a Nobel prize waiting for someone who can get humanity off the global warming hook. I'd cheer them all the way, but Cotton isn't the man.
  15. Tom wrote: "In contrast, Cotton's alternative estimate was made by waving his hand near a cooking pot." LOL! That's taking 'hand waving' arguments to a whole new level. :]
  16. The gravitational warmth theory seems to be making the rounds these days. The idea that the Earth would heat itself through gravity in the absense of the sun boggles the mind. Especially after going to great lengths to show how the incoming solar radiation has fluctuated throuhgout history. While some people like his hand waving over the cooking pot, it does show how some scientists are placing to much emphasis on outgoing radiation effects in the atmosphere as opposed to convection. Of course, this is due to the much larger difficulty in measuring the convection effects.
  17. EtR#370: "gravitational warmth theory" We heard that one over and over on the 2nd Law threads; its all due to the potential energy released by air molecules falling from the upper atmosphere. That does not rise to the level of 'theory'; call it an idea, a notion, a delusion. "some people like his hand waving over the cooking pot," It's easier than doing actual research. Fewer annoying things like 'data' to worry about.
  18. Eric the Red @370, which scientists are "...placing to much emphasis on outgoing radiation effects in the atmosphere as opposed to convection"? It is certainly not the mainstream climate scientists. The importance of convection as a distributor of heat has been central to the theory of the greenhouse effect since Manabe and Wetherald 1967, and is a central feature of GCMs.
  19. 370, Eric the Red, does show how some scientists are placing to much emphasis on outgoing radiation effects in the atmosphere as opposed to convection.
    Evidence, please. This is mere assertion. At the same time, please reference Trenberth's energy budget, which is a careful accounting of exactly how energy is transferred, backed by actual measurements. Coming down: 517 W/m2. Going up (in W/m2)...
    Convection (thermals):17
    Total: 517 Everything balances as measured (in/out/retained). Gee, whiz, those dang scientists really do know what they are talking about... precisely, and without simple assertions and hand waving.
  20. Michael Pidwirney of NASA has some different values: Incoming radiation: 340 W/m2 Reflected: 99 W/m2 Absorbed by Atmosphere: 78 W/m2 Absorbed by Surfase: 163 W/m2 Of that absorbed by the surface, his ebergy transfer numbers are: Thermal radiation: 61 W/m2 Convection: 17 W/m2 Evaporation: 85 W/m2 You can stop waving your hands now.
  21. 374, Eric the Red, If you are getting your numbers from Pidwirny's article on energy balance of the earth where this diagram is just a revision of Trenberth's, substituting percentages for W/m2, then I'm afraid you are reading it incorrectly. In any event your numbers are incomplete. You are only accounting for incoming radiation (340) and not the greenhouse effect (which adds additional energy to the surface that must be accounted for). Either way, how does this in any way support your original contention that "scientists are placing too much emphasis on outgoing radiation effects in the atmosphere as opposed to convection"? Or are you openly withdrawing that comment?
  22. Eric the Red @374, I am going to need a citation for that claim. I have googled several articles articles written by Pidwirny, and none of them have the figures you show. Further, as Sphaerica points out, your quoted figure was for net thermal radiation (Surface Radiation minus Back Radiation), whereas Cotton and I where clearly discussing the Surface Radiation alone.
  23. Tom, Try here.
  24. 377, Eric the Red, Yes, we know. That's where we looked. That site is not only in complete agreement with Trenberth, but it got its data from Trenberth. Follow the citations at the end of the article. You have greatly misinterpreted what you found there. You need to read it much, much more carefully. And where exactly in that did you get your numbers from? I don't find your particular numbers anywhere there.
  25. 377, Eric the Red, You also avoided my salient questions from post 375:
    Either way, how does this in any way support your original contention that "scientists are placing too much emphasis on outgoing radiation effects in the atmosphere as opposed to convection"? Or are you openly withdrawing that comment?

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