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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 1955 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 26, 2023: The "At a glance" section was updated to improve readability.

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 archive.org)

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.

Acknowledgements

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

Update

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

Comments

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Comments 426 to 450 out of 602:

  1. Muon 424, I didn't mean to try for a higher standard, I was just trying to pull out what hit me as a clear and critical premise from IPCC so we didn't get bogged down in questions of, "well this person disagreed because of the policy issues, and this person disagreed because of something else, etc." I got that quote from here on this site and now looking back, I see I didn't give a reference, sorry for that. The quote comes from Dana1981 in the big picture post that's linked on the home page, end of the 2nd sentence in the "Humans Are Causing the Warming" section. I used that quote because I thought it reflected a reasonable summary of the opinion at this site and I thought it reflected what IPCC said as well. Sorry for the error on my part. I appreciate your comment, "That's a new, vastly higher hurdle; some no doubt can and do disagree with your words 'quantify,' 'verify' and 'essentially all'." I find it interesting that this site is promoting a statement of GWS that is stronger than the IPCC position. In that same section of Dana1981's post, he answers the question of what would it take to refute man-mad global warming theory, "it would require that our fundamental understanding of physics be wrong, because that's what the theory is based on. This fundamental physics has been scrutinized through scientific experiments for decades to centuries. It's this kind of combination of extremely strong statement of GWS linked with a claim that the evidence is so overwhelming that it's basically beyond refutation that makes me think this site is expressing more personal opinion than summary and distillation of what the scientific community would say about this topic. I'd bet everything I have that if those two sentences from Dana1981 were on the Doran survey, there wouldn't be anything near 90% acceptance of both of them. Yet those two sentences are presented in a featured article on the home page of the site. p.s. back a comment or so ago, I didn't set up the criteria from 20 publications as indicating sufficient status as a climate scientist, that comes from Anderegg
  2. Rick "At some point I'll pick an aspect of the science and get as into the detail of that as I can..." 'An aspect' encompasses many things. If you're looking at the central issue - the radiative physics of gases - all well and good. That's where the core science is, that's where the agreement is. Don't pick a side issue or a fine detail like droplet sizes affecting albedo of clouds (and dozens and dozens of similar nitpicks). The item that's been so competently put together relies on radiative physics in the atmosphere. The fine details are important for getting the best presentation possible - but the garnishes, crockery and cutlery don't change the fact that a meal is ready to serve. Changing the colours of plates or shape of forks might improve the look but not the nutritional content or the taste of the food. If, like me, you're not a scientist, concentrate on learning the basics. Be warned, basic does not mean simple or easy or quick. Science of Doom is probably the best place to start for digestible serves of serious science.
  3. And if you don't get into the science, Rickoxo, then you're going to be left relying on opinion. If I point out that some of the minority do their publication in dodgy journals, you'd have to take my word for it. Adelady's advice is good, but wear your math hat at SoD. The Miskolczi series is interesting if you like to see the in-depth interrogation of one of those 10%. If you're into the statistical side, Tamino gives statistical silliness the baseball bat treatment. It's a no-brainer over there right now, though (Joe Bastardi).
  4. Rickoxo#430: "... makes me think this site is expressing more personal opinion than summary and distillation of what the scientific community would say about this topic." No one here pretends to speak for the 'scientific community.' I doubt that many here would take issue with Dana's stronger statement ('... require that our fundamental understanding of physics be wrong'). It takes some understanding of both the physics and the intricacies of climate science to be able to say that with confidence. A statement such as the one in IPCC AR4 ('... very likely due to observed increase in anthropogenic greenhouse ...') is clearly a watered down, committee-written compromise version of what they could have (and probably should have) said. You can only see that and begin to grasp the fullness of the problem by learning something about the science. Relying on what can only be described as 3rd hand information is a very dangerous practice because there are lots of bad sources out there (and they very often come here to promote their uninformed opinions).
  5. DSL, I particularly like your post at #411. I think that anyone reading through the last fifty posts, who is still arguing against Global Climate Change is just holding a debating position. All necessary points have already been made. And anyone who doesn't want to read through everything, can find plenty in post #411. And no, I have no idea who DSL is.
  6. The topic of this thread it states: "97% of climate experts agree humans are causing global warming." Is this saying that without any man contributing CO2 the globe would not be warming?
  7. Dana69 @11:39 AM, 13 September, no. Over the course of the 20th century natural phenomenon have contributed slightly to the warming. However, over the last 30 years, natural forcings alone would have resulted in a slight global cooling. On the other hand, anthropogenic global warming would have been much stronger without the effect of human emitted aerosols which cool the Earth and have countered as much as half of the overall warming trend, and in some periods (eg 1950 to 1970) have almost completely countered the warming trend.
  8. SO it seems fair to say that there are arguments for both sides of the equation. To be sure about my skepticism: It is necessary for me to see and examine the arguments of both sides of the fence, and I then make up my own mind, based on these arguments. I am pretty sure that current climate models underestimate the role of the sun in climate variability and overestimate the role of greenhouse gases and aerosols. But I am as sure that the increase of CO2 in the atmosphere since the start of the industrial revolution is mainly from the use of fossil fuels. Appealing to authority that there is 97% consensus is a fallacy. Quick thought experiment. Lets say your a physicist that has been in a coma for the last 40 years. You wake up to the current world and the first headline you see is the shrinking arctic ice. Someone walks by and states how could anyone doubt that man is not destroying our world with CO2. You ask the person what she means and she says that 97% of all scientists claim there is a consensus regarding AGW. Would this physicist run around and defend the point by claiming 97% consensus? If his mother asked him about the proof, is his quack, consensus, consensus enough?
    Response:

    [DB] "It is necessary for me to see and examine the arguments of both sides of the fence, and I then make up my own mind, based on these arguments."

    Try starting here and reading up on all of the argument rebuttals that interest you.

    "I am pretty sure that current climate models underestimate the role of the sun in climate variability and overestimate the role of greenhouse gases and aerosols."

    Is that based on anything scientific or...?

  9. Dana69 - based on the questions you are asking, sitting down with the IPCC AR4 would be a good first step. Know what the published science is and then take it from there. I'm looking forward to you presenting evidence for science underestimating the sun. Perhaps you should look at Benestad & Schmidt 2009 found.
  10. dana69#437: "a physicist that has been in a coma for the last 40 years." I suspect there are a few of those around. However, the flip side of your question is equally valid. Does Rip Van Physicist side with the dissenting 3%? Or does he infer that there must be an enormous weight of evidence behind the opinions of the 97%?
  11. Dana69, Being skeptical is certainly the right approach, but giving equal weight to all arguments is not. You will find that there is a very clear correct answer to almost every issue in climate science, no matter how much doubt certain people attempt to sow. A lot of people will lead you astray with seemingly sensible but incomplete analyses (such as your chemist friend's discussion of how CO2 warms the atmosphere). To begin with you will very quickly learn that (a) it absolutely is not the sun and (b) there is absolutely no question that the rise in CO2 is 100% the result of human activity, and the majority of it is from burning fossil fuels. I would also point out that argument from authority itself is not a fallacy. The fallacy occurs when the authority is not qualified in the area in question, or when the point is expected to be taken as 100% true because of the authority's position. But it is perfectly valid and common to use the position of an actual, qualified authority when one is not and cannot become completely educated in a matter themselves. As with much of science, very little is ever taken as 100% true, but much like the consensus discussed on this thread, for all intents and purposes the probability of truth must govern reason. It's simply not logical to say "it seems almost certain that what I'm doing will kill me, but it's not 100% certain, so I'm going to go ahead and ignore the risks." BTW, did you ever see the response I posted on this comment on the CO2 trace gas thread to your chemist friend's mistakes concerning the ability of greenhouse gases to warm the atmosphere?
  12. ... or does Rip Van Physicist (assuming his 40-year coma has not had too many ill effects) actually go and read some of the key papers and get to grips with the overwhelming nature of the evidence, rather than basing it on somebody else's survey-based opinion? I'm also interested to hear where solar activity has been underestimated and CO2 been overestimated.
  13. Dana69 wrote: "It is necessary for me to see and examine the arguments of both sides of the fence, and I then make up my own mind, based on these arguments." well quite, that is what we should all do. Have you read the IPCC WG1 report (or at least used it to check whether claims are true)? However Dana69 then wrote: "I am pretty sure that current climate models underestimate the role of the sun in climate variability and overestimate the role of greenhouse gases and aerosols." I suspect that you have not done enough reading to have a balanced view on this one. Please go to "Its the sun" and give a list of the sources for and against on which you base your opinion and then give an explanation of why you think the models do not sufficiently account for the role of the sun. I will happily discuss this with you if you can show that you have followed the procedure you have set out in the first quote. As for Rip van Scientist, he wouldn't defend any position until he had had a chance to get up to date with the science (fortunately the IPCC has produced a report which sets out the mainstream scientific position, the NIPCC have similarly produced a report setting out the contrarian view). He (being a scientist) would then base his arguments on the science. The importance of a concensus is not of any relevance to the scientists, who are capable of grasping the scientific arguments. Its importance is for the rest of us who can't accurately weigh the scientific arguments becase we don't have the necessary background. Then like seeking second (and third, and fourth and ... n-1th and nth) opinons for a medical problem, the fact that a strong majority recommend a particular course of treatment is a fairly reliable indication that it would be a wise course of action. Good science generates broad (but never complete) concensus, not the other way round.
  14. 77/79 is a 97% out of 0.77% of climate scientists. I assume we are using the Doran study. A 30% turn-out may be typical in internet polls but 70% of views are not here. 70% is too large. I'm not claiming that the 70% are skeptics but when 70% don't show up it is not legiminate. And in the Oreskes report he took a poll in 'refered journals'. There has been rejection of skeptic papers in the journal as it 'goes againt the consensus'.
    Response:

    [DB] As a new participant here, please take the time to acquaint yourself with the Comments Policy.  Posting comments here at SkS is a privilege, not a right. 

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  15. Roh: "And in the Oreskes report he took a poll in 'refered journals'. There has been rejection of skeptic papers in the journal as it 'goes againt the consensus'." Roh, you really don't understand how journals work, do you? You assume there's pressure on journals to adhere to the consensus. Why? What's the mechanism? If anything, there's pressure not to adhere to the consensus. Who would want to reject a paper because it "blows a hole" in the dominant theory? That's the kind of stuff that Science and Nature salivate for. In reality, though, there's simply pressure to get the science right, whatever it might mean for our understandings. Don't you agree?
  16. Consensus is based on science, but science is not based on consensus. Consensus is a political argument, not a scientific argument. The scientific process is based on evidence, not consensus. Scientific evidence does not care about any consensus. Consensus does not imply that the science is correct. To argue otherwise is to commit these two fallacies: http://en.wikipedia.org/wiki/Argumentum_ad_populum http://en.wikipedia.org/wiki/Appeal_to_authority That, in a nutshell, is why scientific "truth" is not determined by consensus, but rather by evidence. Here are some recent examples of the scientific consensus being wrong. Each of the following examples were initially rejected by the consensus, but the consensus changed based on evidence. the theory of continental drift the theory of symbiogenesis the theory of punctuated equilibria the theory of prions the theory of Helicobacter pylori as the cause of stomach ulcers. Consensus is based on scientific evidence, but consensus itself is not scientific evidence. Consensus is merely a statistical survey of scientific opinion. It is not a guarantee that the scientific opinion is correct. Settled science claims are inductive arguments which assumes the number of scientists who agree strengthen then argument. While induction does not strengthen the argument scientifically,it does strengthen the argument in a rhetorical sense. Consensus is a rhetorical (political) argument, not a scientific argument. Politics relies heavily on consensus. Science does not. Policy decisions ought to be made on the best available information,and in that sense only is consensus valuable.
  17. For the record -- in anticipation of possible misinterpretations of my position on global warming -- I have not attacked the scientific consensus. I have not denied there is a consensus where there truly is a consensus. I have however, attacked claims of consensus where there is no actual consensus. And I have simply pointed out that the consensus argument is not a valid scientific argument. And that it depends on which scientists you choose to believe. But I am not attacking the consensus that the Earth is warming. I believe the earth is warming.....
  18. Dan69, Let us cut to the chase here. 1) Do you agree that most of the observed warming the past 100 years is from humans burning fossil fuels? 2) Do you deny the theory (it is no longer a hypothesis) of AGW? That is, do you deny the physics behind it? 3) Do you deny the body of evidence consistent with the theory across many scientific disciplines? Please make your position very clear, and perhaps the best way to do this is for you to state what you believe the equilibrium climate sensitivity is for doubling CO2. A number please with 95% confidence limits. Dana69 "And I have simply pointed out that the consensus argument is not a valid scientific argument. And that it depends on which scientists you choose to believe." Nature does not choose to believe any opinion, it is physics, chemistry, biology etc. And the observations, across many disciplines are perfectly consistent with the theory of AGW. So on that note, instead of railing against "consensus", you should really be railing against "consilience". As for consensus, you know what is intriguing Dana69? The reason that consensus on AGW came to the fore was because "skeptics" and those who deny AGW were claiming that scientists do not agree on the subject. How does one address that? You show them that scientists are in agreement, that the body of evidence and observations across many scientific disciplines are consistent with the theory of AGW. What does the "skeptics" then say, "Well, consensus is based on scientific evidence, but consensus itself is not scientific evidence. Consensus is merely a statistical survey of scientific opinion. It is not a guarantee that the scientific opinion is correct." And so the faux debate continues. "Skeptics" have had since the days of Fourier, Tyndall and Arrhenius to overturn the building blocks of AGW, and have not...so in lieu of making substantive scientific arguments they have to resort to playing games.
  19. Dana69 Pointing out that mainstream science has been wrong on occasions before where there has been concensus does not mean that the existence of a concensus on AGW tells us nothing about the likelihood of AGW being correct. To make such an inference you would also need to consider the number of occasions where there has been a scientific concensus on some issue where the concensus has been correct. The solidity of the science is what causes the concensus, not the other way round, you are correct to point that out. However a corrolary of that is that the existence of a concensus is usually a pretty good indication that the science is solid. Thus while the existence of a concensus has no bearing on whether the science is actually correct or not, it is completely rational to take the existence of a concensus amongst the experts as strong evidence that the science is solid, and that it would be wise to be primarily guided by mainstream science rather than scientific "outliers" when deciding on a course of action.
  20. Dikran Marsupial, First off, let me tell you I have been very impressed with your posts here,and in forums off this site. I am not sure what your background is, but it appears to be solid in statistics. Please understand my post. I have indicated agreement that the climate is warming. This notion of consensus to validate a point is useless. If the consensus hasn't done the work then it is simply appealing to Argumentum_ad_populum. If the argument can be made scientifically, then appealing to the fallacy of consensus is unnecessary and irrelevant. Scientists do not need to point to a consensus, they simply point to the facts and the evidence. So why bother using consensus as an argument at all? Since most of the scientists signing on to the AGW "consensus" are not climate experts -- in fact even among climate experts they are not all expert in each others specialty -- Dr. Trenberth for example is not a hurricane expert -- it appears that the consensus is saying it is not based on the scientific method but rather on popularity. Consensus seems to mean, "I have looked at your results and even though I have not personally verified those results or even looked at all your data, it is my personal opinion they are probably valid." I'm sorry, but that is not the scientific method. Basing one’s beliefs on the scientific consensus is rational. I do it often. It is not the only rational response, however. It is not irrational to be skeptical of an argument based only on consensus. Secondly, and perhaps most importantly, there is no scientific consensus on what the political response to AGW should be. Respectfully,
  21. Dana69 I think you are missing the point of the significance of the concensus. The science doesn't stand and fall on the existence of a concensus. Similary those who can reliably understand the science can happily ignore the existence of the concensus. What about the rest of us who are not capable of reliably understanding the science at the level of detail required to form an opinion of our own (I most certainly fall into that category). We have to decide where the truth is likely to lie via other means, and the existence of a concensus is a useful indicator of reliability of expert opinion. If you are ill, do you trust your doctor or do you go and do the research you need to do to diagnose yourself? Most of us do a mixture of the two, but heavily biased in favour of the doctors opinion because he has earned hid credibility, we haven't. Now logically this is "argument from authority" and thus a fallacy; however it is also perfectly reasonable and rational. No it isn't science, but like the AGW debate we are fooling ourselves if we think we are doing science. We aren't, merely trying to understand and interpret the science of others so that we can hold an informed opinion. It would be a logical falacy to say that the science is right because there is a concensus. That would indeed be "argumentum ad populum". However, it would be perfectly correct, to say that it was more rational to have confidence in the concensus position than in the skeptics; on the balance of probabilities (not certainties) you are very likely to be right. The concensus says nothing about the actual correctness of the science; it says plenty on how we (as non-experts) should rationally apportion our belief to the competing hypotheses.
  22. Dana69 @445, "So why bother using consensus as an argument at all?" I've explained why to you above @443. I'm sorry Dana69, but you really are saying an awful lot without really saying anything. That is why I was asking you to answer some specific questions to try and determine where you are coming from. You say "it appears that the consensus is saying it is not based on the scientific method but rather on popularity." Let me remind you about the purpose of this post, the main post was made to address this claim made in a petition: "The Petition Project features over 31,000 scientists signing the petition stating "there is no convincing scientific evidence that human release of carbon dioxide will, in the forseeable future, cause catastrophic heating of the Earth's atmosphere" The goal of that petition is to advance the claim that there is "no convincing evidence" for AGW and that that opinion is held by many people with credentials. Well there is compelling evidence, from multiple, independent lines of evidence in fact. You talk above about "popularity", well such petitions are just that, and worse yet, signed by people not qualified to speak to the subject. Do you endorse such petitions as a refutation of the theory of AGW? I hope you agree that such an approach is not the scientific method, unlike how the theory of AGW was arrived at. "Since most of the scientists signing on to the AGW "consensus" are not climate experts" Not true. Please read Anderegg et al. (2010) a link is provided in the body text. Please note the tiny fraction of people who sign petitions wishing away the theory of AGW are qualified to speak to climate science. Is that OK by you? "Since most of the scientists signing on to the AGW "consensus" are not climate experts -- in fact even among climate experts they are not all expert in each others specialty -- Dr. Trenberth for example is not a hurricane expert" I'm sorry, this is an absurd point. But it does underscore why consilience is so important. Trenberth has shown that the water vapour content of the atmosphere is increasing as temperatures increase, that is a positive feedback that is key to the theory of AGW and perfectly consistent with the Clausius-Clapeyron equation. Whether or not he has experience to speak to how hurricanes will respond to a warming planet is not relevant, and besides, how hurricanes respond to a warmer planet has nothing to do with the validity of theory of AGW. So I'm sensing some strong one-sided skepticism here by you Dana69. Lindzen is a meteorologist by training, so by your logic he is simply subscribing to popular opinion when he agrees that doubling CO2, in theory, will warm the planet by 1.1 C or so.
  23. Dana69 wrote : Each of the following examples were initially rejected by the consensus, but the consensus changed based on evidence. the theory of continental drift... Well, it's hardly surprising that it was rejected, when Wegener believed that the physical processes involved were to do with the rotation of the earth or gravitational attraction involving the sun and moon. Would you have believed that ? I doubt it, because the calculations didn't add up. It was only when the theory of Plate Tectonics was refined and provable, and the forces involved were undestood to be thermal convection currents within the mantle, that the original theory (albeit adapted) could be accepted and proved. How does that compare with the theory of AGW ? Is there another theory out there that you think might be better ?
  24. Dana69: "even among climate experts they are not all expert in each others specialty ... it appears that the consensus is saying it is not based on the scientific method but rather on popularity." This argument is very strange. Would it be better if most climate scientists - whatever their specialty - disagreed with the important elements of a theory? Seems to me that if that were the case, you'd be arguing 'there's no agreement among scientists!' It is also most often the 'pseudo-skeptics' who bring up this consensus issue. Those who have looked at evidence objectively seem content that many independent lines of evidence point in the same direction. That's the consensus worth talking about.
  25. Albotross, Sorry for taking so long to answer your questions posed @447. Just for the record this thread is regarding consensus; my views regarding any particular point is not relative to this topic. If I am to follow the conclusions of the so called "consensus", any meaningful result would have naturally stemmed from the consensus itself, and not my own views. It becomes circular.

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