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Global Warming Denial

Author: Muertos

Note: This page is still a work in progress and may be missing sources.

Believers in this conspiracy theory claim that the idea that the Earth's climate is warming as a result of greenhouse gases, primarily carbon dioxide, in the atmosphere, caused predominantly by human activity ("anthropogenic global warming" or "AGW"), is unsupported by science and is actually a hoax perpetrated by scientists and politicians (notably Al Gore) for economic or ideological reasons, or to "scare" populations and governments into enacting measures (such as carbon taxes) that would be difficult to implement by other means.

This is by no means the only articulation of the "global warming hoax" theory, but is one of the most common broad-based claims. This article is intended to debunk the broader themes of AGW denial, involving a few specific examples of claims that have been refuted. By no means is this article intended as a comprehensive refutation of all individual claims made by AGW deniers and conspiracy theorists, as there are thousands of them, but these are the most important and the most representative.

It is important to note that, although climate change is a contentious political issue, this article is not intended as a political statement. does not take any stand on the political issues involved with global warming, such as cap-and-trade, carbon taxes etc., nor is this article intended as a statement of political agreement with Al Gore or political disagreement with AGW deniers who are also politicians, such as Ron Paul. This article is concerned with answering three questions: is global warming happening as a factual matter, is it primarily caused by human activity, and is it a conspiracy or hoax? The answers to these questions are, respectively: yes, yes, and no.

Notable AGW Deniers and/or Conspiracy Theorists:

Rebuttal of Specific Claims

Claim: "There is no scientific consensus either that (1) climate change is happening, or (2) that humans are causing it."

Rebuttal: False. The consensus that AGW is real is overwhelming. In 2009, a poll organized by Dr. Peter Doran of the University of Illinois, whose results were published in EOS, the journal of the American Geophysical Union, questioned 10,257 scientists on whether they believe that human activity is a contributing factor in changing global temperatures. Eighty-two percent of all scientists polled said yes, but among climatologists who have published research on climate change, 97.5% said yes. (Source:

Furthermore, a 2004 survey of peer-reviewed scientific literature considered 928 peer-review articles on climate change published between 1993 and 2003. Of those nearly 1000 papers, not a single one rejected the consensus position that AGW is happening. A skeptic, Benny Peisner, attempted to discredit this survey, and claimed to have found 34 peer-reviewed papers rejecting the AGW theory; in fact, after it was revealed that this claim was not true, Peisner retracted his criticism of the survey.

(Sources: (Survey: (Peiser's retraction: (Further discussion on survey results:

Claim: "The 'hockey stick' is broken."

Rebuttal: False. The "hockey stick" is a famous graph reconstructing global temperature from extant records as set forth in a 1999 paper by Michael Mann (no, not the movie director; he's a scientist at University of Massachusetts). (The paper is here: The projections of rising global temperatures resemble a hockey stick in that they swing dramatically upwards in recent years. Since then there have been various critiques of the study, focusing mainly on the methods Mann used to reconstruct global temperature from hundreds of years ago, a doctrine known as palaeoclimatology which uses tree rings, ice cores and other indicators to project what temperatures actually were in times before weather records were kept reliably. Although Mann's methods were primitive by modern standards, every new method used to reinvestigate historical temperatures since 1999 has resulted in the exact same hockey stick-shaped graph, for example, boreholes ('00.pdf) and stalagmites ( All of these studies confirm the "hockey stick" phenomenon. Not some of them. All of them.

Further discussion on this issue, with links to various studies:

Claim: "Far greater levels of carbon dioxide (CO2) are emitted by natural processes such as plants and the ocean than by human's ludicrous to think that it's harmful!"

Rebuttal: It's not about the amount of CO2 in the atmosphere, but the rate of absorption. Natural emissions of CO2, such as from plants, are absorbed by natural processes (also oceans and plants) in rough balance. It's the human emission of CO2 that is the problem--because it's overwhelming the planet's ability to absorb the additional CO2. In fact, only about 40% of human CO2 emissions are being absorbed at all--the rest is going into the atmosphere and staying there.


Claim: "Al Gore's movie An Inconvenient Truth is deceptive and exaggerated."

Related Claim: "The movie Inconvenient Truth was judged to be fraudulent by a British court."

Rebuttal: There are errors in Al Gore's film, two of which stand out. The first is the film's assertion that the disappearance of snow on Africa's Mt. Kilimanjaro can be directly attributable to AGW. The second is where Gore asserts that CO2 projections and temperature graphs are an exact fit. As to Kilimanjaro, the cause of glacial retreat is subject to fierce debate in the scientific community.  Suffice it to say, while it may be caused by AGW, it may not be, and thus Kilimanjaro's glaciers should not be used as direct evidence of AGW.  (Lengthy discussion of this issue here: As to the temperature graphs, Gore conflated the 1999 Mann "hockey stick" graph with the East Anglia CRU's surface temperature measurements.

Neither of these errors affect the basic thrust of Gore's film: that global temperatures are rising and human activity is the cause. Indeed, very much like the CRU email hacking incident (discussed below), AGW deniers seized upon the errors to denounce the basic thesis of the film as a whole--entirely without evidence.

Because Al Gore is so publicly and universally associated with AGW and efforts to mitigate it, AGW deniers and conspiracy theorists often believe that attacking and discrediting Al Gore and An Inconvenient Truth is tantamount to discrediting the science behind AGW itself. Of course this is silly. Al Gore is not a scientist, and the scientific basis of AGW did not originate with him. Even if An Inconvenient Truth was a total fabrication, the science behind AGW would still be overwhelmingly convincing.

Discussion of Inconvenient Truth errors is available here:

Related Rebuttal: The UK High Court of Justice, in an October 2007 decision (which is available in full here:, did not find Gore's film to be "fraudulent." The issue was whether, under UK law, An Inconvenient Truth was a science film, suitable for presentation in public schools, or a political film, which would require an accompanying guide clarifying certain points if it was shown in schools. That was the only issue. The court found it was a political film and that it must be accompanied by a guide--but that its science was sound. In fact, the court found that:
"It is substantially founded upon scientific research and fact, albeit that the science is used, in the hands of a talented politician and communicator, to make a political statement and to support a political programme."

This is hardly surprising, considering Al Gore is a politician, not a scientist; I think very few people would disagree that An Inconvenient Truth is, and was always intended to be, a political film. Clearly it is.

The court also found:
"The Film advances four main scientific hypotheses, each of which is very well supported by research published in respected, peer-reviewed journals and accords with the latest conclusions of the IPCC: (1) global average temperatures have been rising significantly over the past half century and are likely to continue to rise ('climate change'); (2) climate change is mainly attributable to man-made emissions of carbon dioxide, methane and nitrous oxide ('greenhouse gases'); (3) climate change will, if unchecked, have significant adverse effects on the world and its populations; and (4) there are measures which individuals and governments can take which will help to reduce climate change or mitigate its effects.' These propositions, Mr. Chamberlain submits (and I accept), are supported by a vast quantity of research published in peer-reviewed journals worldwide and by the great majority of the world's climate scientists."

So, in other words, the British court ruled that the four main scientific bases of An Inconvenient Truth were accurately presented, and the nine specific errors discussed in the judgment (for a list of them, go here: do not impugn the basic scientific integrity of the film.

Claim: "Emails from the University of East Anglia's Climate Research Unit (CRU) prove that AGW is a fraud and that scientists are trying to hide it!"

Rebuttal: False. Conspiracy theorists love to engage in "quote-mining," that being the taking of particular quotes out of context to support a predetermined conclusion, and this is exactly what happened in the CRU case. This conclusion has been validated by an independent investigation by the British House of Commons.

Here's what happened. In November 2009, just before the United Nations Copenhagen summit on climate change, somebody hacked into the CRU's computer system and illegally downloaded emails from the database that had passed between prominent climate scientists. The emails were posted on an Internet blog for AGW deniers. Taken out of context, the quotes appear to indicate the scientists are hiding something. This is the most famous of them, from Phil Jones, then head of the CRU:
"I've just completed Mike's Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith's to hide the decline."

Sounds suspicious, doesn't it? Especially when he uses words like "trick" and "hide." However, he is not referring to "trick" in the sense of a deception. What he is referring to is the method of correlating data from various sources that use incompatible phenomenon into an intelligible picture. The "trick" that Jones is referring to is set out in a 1998 paper, again by Michael Mann and published in Nature (hence the "Nature trick"), discussing how to do precisely this--and it's not deceptive at all. (The paper is here: The British House of Commons report, released in March 2010 (read it here: is very clear in stating:
"Critics of CRU have suggested that Professor Jones's use of the word 'trick' is evidence that he was part of a conspiracy to hide evidence that did not fit his view that recent global warming is predominately caused by human activity. The balance of evidence patently fails to support this view. It appears to be a colloquialism for a 'neat' method of handling data."

And what about that "decline?" AGW deniers insist he means a decline in temperatures; in fact he is referring to the decline in the sensitivity of data culled from tree rings (called dendrochronology) to indicate temperatures in more recent years, because (ironically) of climate change. In other words, the more recent the tree-ring records you're looking at, the less accurate they are going to be, which means that if you're plotting tree-ring temperature records from recently against those from hundreds of years ago, you will have to recalibrate one set of figures or the other so that they're measuring the same thing. This is what "hiding the decline" means. But don't take my word for it. The House of Commons report addresses this specific point:
"Critics of CRU have suggested that Professor Jones's use of the words "hide the decline" is evidence that he was part of a conspiracy to hide evidence that did not fit his view that recent global warming is predominantly caused by human activity. That he has published papers--including a paper in Nature--dealing with this aspect of the science clearly refutes this allegation. In our view, it was shorthand for the practice of discarding data known to be erroneous. We expect that this is a matter the Scientific Appraisal Panel will address."

Another hacked email from Kevin Trenberth, who wrote much of the IPCC report, contains a statement, "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't." Again, this sounds very suspicious, doesn't it? In fact what Trenberth is talking about is not that it's a "travesty" that the planet isn't as warm as he would like it to be; in fact what he's actually expressing is the exact opposite--that scientific measurements can't explain why the Earth isn't already warmer than it is! This has to do with the planet's "energy budget." We know the Earth is getting hotter, but, calculating all the warming sources all over the planet, mathematically the Earth should be trapping more heat via the greenhouse effect than it already is. Trenberth is not certain why that is, but he feels it extremely important that the answer be found--a conclusion I doubt anyone would disagree with. Again, do not take my word for it. Trenberth already published a peer-reviewed paper on this subject. (It's here: Thus, it is clear that he is not part of a conspiracy to "fudge" data showing AGW. All of the emails pointed to by AGW deniers are quote-mined. Not some of them. All of them.

The House of Commons report made several good points, such as calling for greater transparency in the sharing of climate change data by the CRU, especially given the political and economic importance of the AGW issue. The House also criticized the CRU's handling of Freedom of Information Act requests. Those appear to be quite reasonable criticisms. But as far as the CRU emails showing a conspiracy, the House of Commons is extremely clear that they do not:
"In addition, insofar as we have been able to consider accusations of dishonesty--for example, Professor Jones's alleged attempt to 'hide the decline'--we consider that there is no case to answer. Within our limited inquiry and the evidence we took, the scientific reputation of Professor Jones and CRU remains intact. We have found no reason in this unfortunate episode to challenge the scientific consensus as expressed by Professor Beddington, that 'global warming is happening [and] that it is induced by human activity'."

More discussion on the CRU email issues, and other issues raised in this rebuttal, here:

Claim: "Over 31,000 scientists have signed a petition disputing that AGW is real. This clearly represents a significant lack of consensus in the scientific community regarding AGW."

Rebuttal: No, clearly it does not. Furthermore, the petition itself is misleading and in many respects an outright fraud.

The petition in question was once known as the "Oregon Petition," the first time it surfaced in 1998. It's called that because it was the brainchild of an organization called the Oregon Institute of Science and Medicine, which embarked on a project with Dr. Frederick Seitz to circulate a petition to get as many scientists as possible to sign off on opposition to AGW. [Note: I live in Oregon, and I find it interesting that the "Institute" that created the petition has the acronym OISM, which is a letter-switch for another organization called OMSI, the Oregon Museum of Science and Industry. Whether this was a deliberate attempt to invite confusion I have no idea, though as you will see in the next paragraph, there was evidently a deliberate attempt to invite confusion as to whether the petition was connected to the National Academy of Sciences]. Basically, OISM shotgunned the petition to thousands of scientists of various disciplines, hoping for as many positive responses as possible. This was done while the U.S. government was considering ratification of the 1997 Kyoto Accords which impose voluntary caps on greenhouse gases.

The materials enclosed with the original 1998 petition included a paper--which was not peer-reviewed--arguing that more CO2 is actually good for the environment. The paper was printed in the same format and typeface as used by the National Academy of Sciences' official journal and accompanied by a cover letter signed by Dr. Seitz, who had been NAS president years before (in the 1960s). The confusion was significant enough to cause the NAS to issue a press release (you can read it here: bluntly dissociating itself from Dr. Seitz's efforts. The NAS stated:
"The Council of the National Academy of Sciences is concerned about the confusion caused by a petition being circulated via a letter from a former president of this Academy. This petition criticizes the science underlying the Kyoto treaty on carbon dioxide emissions (the Kyoto Protocol to the Framework Convention on Climate Change), and it asks scientists to recommend rejection of this treaty by the U.S. Senate. The petition was mailed with an op-ed article from The Wall Street Journal and a manuscript in a format that is nearly identical to that of scientific articles published in the Proceedings of the National Academy of Sciences ( The NAS Council would like to make it clear that this petition has nothing to do with the National Academy of Sciences and that the manuscript was not published in the Proceedings of the National Academy of Sciences or in any other peer-reviewed journal."

Over the years the "Oregon Petition" has surfaced again and again, and gained new traction in 2009 when it was featured on Congressman Ron Paul's website (scroll to where Ron Paul is listed above for a link to that site). However impressive the "31,000" figure seems, three things are evident about it:

  1. There is no independently verifiable method to determine the qualifications of the 31,000 people who have signed it; OISM refuses to release information that would make it clear. In fact only 39 have actually been identified as climatologists.

  2. The number 31,000 represents a tiny minority of the 10.6 million "scientists" (as defined according to OISM's original and very broad qualification statement) who have graduated from U.S. universities since 1970.

  3. OISM has a serious problem with vetting who has signed the petition, as numerous demonstrably fake names have been successfully added to the petition in an attempt to test how open the qualifications really are.

These points in turn. The first two are closely related. OISM called for "scientists" to sign the petition, but it defined "scientist" as "obtained formal educational degrees at the level of Bachelor of Science or higher in appropriate scientific fields." The scientific fields that are listed as "appropriate" include such things as computer science, aerospace engineering, zoology, electrical engineering or metallurgy as well as climate science and more appropriate studies. (Source: But the OISM does not indicate the qualifications of the individual signers--just their names and the states they live in. (Example: How many zoologists in California have signed the petition? We don't know. How many electrical engineers in Delaware? No idea. What does seem clear is that the number of signers is far less impressive when one realizes that they include experts on chimpanzee behavior or silicon circuit designers who have not studied climate science. What is also clear is that 31,000 is a drop in the bucket when you're talking about people who have "obtained formal educational degrees at the level of Bachelor of Science or higher" in the fields identified by the OISM as their target demographic. According to U.S. Department of Education statistics (have fun searching them here:, nearly eleven million people have done this in the United States since 1970. Thirty-one thousand people--almost all of whom are not climatologists--out of almost eleven million science graduates does not seem particularly impressive, especially when one considers that the petition has been collecting signatures for 12 years.

Furthermore, the Oregon Petition's qualification and gatekeeping functions are clearly deficient. Environmental groups have snuck names such as "B.J. Hunnicutt" (Mike Farrell's character from the old M*A*S*H TV show) and one of the Spice Girls onto the list with success. They have since been removed, but we have no idea how many other fake names that might not be so recognizable are on the list.  How many real climate scientists are there who are willing to go on record as supporting the Oregon Petition? Thirty-nine. (Source:

At the risk of committing what conspiracy theorists love to call an "ad hominem attack," it should be noted that the independent scientific credibility of Dr. Seitz, whose brainchild the Oregon Petition was, is open to serious question. After Seitz retired from the National Academy of Sciences, he did a good deal of work for the nice fellows at the Philip Morris Tobacco Company, who paid him to spearhead a project to inject officially-tinged doubt into the debate about whether secondhand tobacco smoke causes cancer. The effort was funded by Philip Morris. (You can see a 1994 document indicating Seitz's involvement in tobacco lobbying efforts here:;jsessionid=2E3191CCAB06867DF3D6D7226CD4DE49) It would seem that during his lifetime Dr. Seitz was not adverse to selling his scientific credentials to a well-paying source.

Further discussion of the Oregon Petition here:

Claim: "AGW can't exist because the idea of the greenhouse effect violates the Second Law of Thermodynamics."

Rebuttal: False. This issue, which arises out of one poorly-researched paper that fundamentally misunderstands climate science, has recently become hot (excuse the expression) because of its extremely technical nature. AGW deniers and conspiracy theorists love it because only those with a very fluent vocabulary in scientific concepts can debunk it; consequently, to the uninformed, it appears official and convincing.

This is a complicated issue because of the technical concepts involved. Basically the Second Law of Thermodynamics states that in an isolated system which is not in equilibrium, entropy will tend to increase, basically irreversibly. What is this supposed to mean in terms of climate change? AGW deniers argue that it means that heat must flow from warmer areas of the atmosphere to colder ones, and because the greenhouse effect holds that greenhouse gases absorb radiation from the surface and re-radiate it back, warming the Earth, this (supposedly) cannot happen.

Sounds definitive, right? Well, the problem is that the Second Law applies to systems as a whole--not individual molecules. When a CO2 molecule releases a particle of energy, that particle can flow anywhere, up or down; the Second Law does not mean it will always flow upwards. What this means is that energy is constantly being exchanged in both directions in the atmosphere. (There is a good layman's explanation of this phenomenon here:  Furthermore, if this theory was correct, the Earth would not be able to retain enough heat to support life.  Since we're obviously here, there must be something fundamentally wrong with this argument.  (Discussion of this issue, among others surrounding the 2009 paper referenced below, is here:

The "AGW violates the Second Law" argument has been around for a while, but it gained traction in 2009 when a paper by two German scientists, Gerlich and Tscheuschner, was published in a physics journal. The paper was titled On Falsification of the Atmospheric CO2 Greenhouse Effects. The title seems to have been carefully chosen: like the CRU emails incident, the word "falsification" would tend to raise a red flag in the uninitiated, but in fact falsification is a common tenet of the scientific method and has nothing whatsoever to do with deception. Gerlich and Tscheuscher's paper has been widely refuted and it is clear that their modeling of the greenhouse effect is faulty--but, as the best technical and scientific refutation of the paper is in German and has not yet been translated into English (if you sprechen sie Deutsch, you can see it here:, lay people in the English-speaking world are generally limited to scientific blogs that attempt to reduce the gibberish into terms understandable by a non-scientific audience. (Examples:,, That in itself lends AGW deniers and conspiracy theorists the argument that "this refutation is not scientific" and thus not creditable. AGW deniers will also often use hostile comments posted on these blogs to try to refute them, but naturally blog comments can be made by anyone and there's no guarantee the commentator knows what he or she is talking about.

Suffice it to say that no reputable climate scientists agree with Gerlich and Tscheuscher, and many have expressed shock that their paper managed to find publication in the first place. AGW does not violate the Second Law of Thermodynamics, and the notion that the multitudes of scientists who do believe in AGW do so in violation of one of the most basic scientific principles is utterly fantastic.

Claim: "It's cold today! That proves global warming isn't happening!"

Rebuttal: This claim is so nonsensical that ordinarily it shouldn't be accorded the dignity of a response. However, in my experience this is the single most common argument used by AGW deniers, as amazing as that sounds. Therefore, it must be addressed.

Coby Beck, who wrote a terrific blog for lay people (link here: aimed at refuting AGW denial, refers to this as the "It's Cold Today in Wagga Wagga" argument. It fails for two reasons. First, there is a difference between weather and climate. Weather is what's happening outside your window at this moment. As TV meteorologists well know, it's often difficult to predict. Climate is the aggregation of long-term atmospheric and hydrospheric trends. It can be predicted with scientific accuracy. "It's Cold Today in Wagga Wagga" deliberately confuses the two. It also plays on the connotation of the words "global warming." To those who do not understand climate change, the words "global warming" suggest that climate change means it will always be getting hotter everywhere on Earth all the time, forever. Naturally that's absurd.

The second reason that the argument fails is because data from a single point source cannot be extrapolated to a conclusion about the climate of the whole Earth. A day of record-breaking cold temperatures in Fargo, North Dakota has nothing whatsoever to do with desertification in Africa or the shrinking of the Antarctic ice sheet. Climate change isn't that simple.

This is by no means a comprehensive list of AGW deniers' arguments, and I'm quite certain comments on this article or hate mail to its author (you can send it to will invariably raise one of the hundreds of other memes used by AGW deniers and conspiracy theorists that are not addressed here. "But they predicted global cooling in the 1970s!" "The hottest year on record was 1934!" "Antarctic ice is growing, not shrinking!" I'm sure we'll get responses along these lines. There are handy resources on the web, and even an iPhone app, that collect and refute AGW deniers' arguments. The best ones in my opinion are here:, I would request that AGW deniers and conspiracy theorists please check these resources and look up the refutation of your argument there before bringing them to


Anthropogenic global warming is really happening. It is not a hoax or a conspiracy. Al Gore's movie An Inconvenient Truth, while containing some errors, generally states coherently and correctly the science behind AGW. The consensus of scientists regarding AGW is virtually total. The minority that does deny AGW is extremely noisy and the media is eager to cover them because global warming denial is the classic example of a "dog bites man" story: the opposite story is so mainstream and accepted that it doesn't make news, while going against the tide is by definition newsworthy. Many of the motives behind attacks on AGW science and its proponents are political, due in no small measure to the association of a divisive political figure, Al Gore, with the AGW issue. Those who feel a need to attack AGW for political reasons are eager to keep up the drumbeat of propaganda against it, which is why the global warming hoax conspiracy theory is so prominent and popular on the Internet. But the science is not in question.

When dealing with conspiracy theories it's always helpful to take a step back and consider what would have to happen if the conspiracy theory was true. If AGW is a hoax, you must accept that someone (who? Margaret Mead?) came up with an erroneous scientific idea, whether willfully or innocently, and then a critical mass of the world's scientists fell in line behind it. You must accept that those legions of scientists must themselves either be innocently mistaken or have made a conscious choice to push a spurious theory for ideological or economic reasons, or to preserve grant funding or avoid academic ridicule. You must accept that all of the following organizations which have explicitly and publicly endorsed AGW science are necessarily in on the conspiracy: the American Geophysical Union, the British Antarctic Survey, the European Geosciences Union, Geological Society of Australia, National Center for Atmospheric Research, NASA, the Chinese Academy of Sciences, the Royal Society of Canada, the Science Council of Japan, the Russian Academy of Sciences, the United Nations, the Polish Academy of Sciences, the Academy of Science of South Africa, the presidential administrations of Bill Clinton, George W. Bush and Barack Obama, and even the Royal Society of New Zealand. You must accept that the governments of small island nations such as Kiribati and Vanuatu, who are undertaking wide-ranging and costly efforts to relocate their entire populations in the coming decades because of rising sea levels caused by AGW, are either in on the conspiracy or have been duped by it. These are among the poorest countries on Earth. If there was a credible excuse for them not to spend resources they don't have on reacting to climate change by literally abandoning their territory, they most definitely would do so.

And why is this all being done? To make Al Gore rich? To punish oil companies? To pass carbon taxes? (The United States Congress can't even pass cap-and-trade legislation. How on Earth are they ever going to pass a carbon tax?) The existence of a truly global conspiracy backed by millions of scientists and scores of governments around the world--a hoax so large that even the Chinese, the Poles and the president of Kiribati have been taken in by it--is one of the most incredible notions ever conceived, far more incredible than the wildest conspiracy about the 9/11 attacks or the New World Order. In terms of sheer scale, the "global warming is a hoax" conspiracy theory has to qualify as the single largest conspiracy theory that has ever taken on.

The scientific facts are clear and persuasive: AGW is happening. But again, do not take my word for it. Do your own investigation--all the science is out there in the open and no one is hiding it. A good place to start is with the report of the International Panel on Climate Change (IPCC), which most AGW deniers haven't even read. It's here: