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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 451 to 475 out of 602:

  1. Dana69, if I do some research, and independently come to the same conclusion as a great many scientists carrying out similar research before me, then I am following the consensus. I'm not doing it blindly, and I would be doing so absolutely based on my own views. Let's say, on the hypothesis that an apple released at shoulder height will go down, rather than up, I carry out the experiment. I find the same answer as the scientific consensus on the matter. Am I blindly following the consensus? When you (indirectly) accuse others of being sheep, be careful your argument is not wooly.
  2. I posted this on RealClimate a few days ago: "Los Alamos National Laboratory is hosting the Third Santa Fe Conference on Global and Regional Climate Change Oct. 31 thru Nov. 4. A lot of good science has come out of LANL, but the conference program is dismaying. I’m not familiar with many of the names on it, but I do know a few of them, e.g. Lindzen, Singer and Monckton! What can the conference organizers be thinking?" In response, Gavin pointed out that one of the organizers is Petr Chylek, who leads a Remote Sensing team at LANL. It appears Chylek is attempting to bolster the scientific credibility of AGW denial, as he has done this kind of thing before. His strategy may backfire, by diminishing LANL's reputation for producing high-quality science.
  3. From a debate on another thread where Jonathon argued: "For the record, I do not believe that a large range of values (whether it be climate sensitivity, projected warming, etc.) indicates that there is a consensus on the issue. On the contrary, it argues the opposite." I do think 'consensus' that some variable is changing can apply to a wide range of estimated values so long as that range does not include zero. There has been for many years a large range on estimated climate sensitivity (e.g. the oft-quoted 2C-4.5C per doubling CO2). I want to give another example where there was, for a great many years, a lot of uncertainty in the magnitude of a value, yet the existence of the change it implied was not questioned. For many years, there was a large range for estimated values of H0, the expansion rate of the Universe, which only recently has been narrowed down considerably. As recently as 1996, there were estimates as low as 40km/s/Mpc and as high as 100km/s/Mpc, it is now closer to 74km/s/Mpc. Edwin Hubble's initial estimate in 1929, after he first measured the redshift of spectral lines in Cepheid variables, was 500km/s/Mpc. Was there consensus in 1996 that the Universe is expanding? There certainly was. Was that based on a tightly-constrained value for the expansion rate? Absolutely not.
  4. Skywatcher, I disagree that just because a value is not zero, that there is a consensus among all players. Do you really believe that Lindzen, who published that the climate sensitivity is 0.5, Link - 1.1, Spencer - 1.3, Annan - 3, Hansen - 6, and Pagani - 9.4 are all in agreement? This seems odd to me, especially since there are many from this site who constantly argue against Lindzen and Spencer (and anyone else who claims a low climate sensitivity). Do you really believe that they are part of the "consensus" just because their values are nonzero?
  5. Jonathon The individual scientists may not agree on the most likely value of equilibrium climate sensitivity, but that does not mean there is not consensus on the distribution of plausible values for equilibrium climate sensitivity, which is what the IPCC actually presents. The scientists are well aware that there are different ways of estimating climate sensitivity and each will give a different answer, thus there is uncertainty involved, and there is no good reason to think of any of the point estimates as the truth, but instead look how the various estimate constrain the values that can be considered plausible according to what we do know. Of course Spencer won't agree, but that is becuase his estimate of climate senistivity lies outside the range considered plausible by the mainstream consensus view. Note Spencer would have a hard time explaining many paleoclimate events with such a low sensitivity, which is why the concenssu is that a value that ow isn't plausible.
  6. While I agree that there is agreement that CO2 has contributed to the observed warming (i.e. climate sensitivity is greater than zero), I disagree that there is agreement as to the value of the climate sensitivity. Posts made on the other thread claimed that any sensitivity greater than zero was part of a consensus about the climate sensitivity. There is little agreement on the range of climate sensitivity values (the most commonly quoted ranges are 2-4.5, 1.5-4.5, and 1.5-5). With the exception of James Annan, the five scientists I mentioned in my earlier post are all outside this range, and there are others which make claims of even higher and lower values. Sure, Spencer will not agree, but I doubt that Hansen will either. There appears to be a misconception on the other thread that since scientists agree that CO2 has contributed to warming, that there is a consensus as to how much.
  7. Jonathon If say Annan publishes an estimate of climate sensitivity of 3, that does not mean that he thinks Hansen's estimate of 6 (I'll take your word for it that is Hansens most probable value rather than a bound) is implausible, and vice versa. This is not at all unlikely as scientists know that estimates made via different methods, with different sources of uncertainty, will have different results, without that meaning that one s right and the other is wrong. It just means that the plausible range for the true value, given what we actually know, lies somewhere in beteen the two estimates. Thus they would have a concensus opinion that climate sensitivity lies in the range 3-6. As the new estimates are considered, if they are considered plausible (even if not very likely) then the concensus range will increase. The point is that the concensus is on the range of plausible values, not on the individual point estimates. This is actually a good way to narrow down the uncertainty of the estimate of climate sensitivity by performing research that places constraints on climate sensitivity, beyond which they are not plausible (or inconsistent with the observations). I rather suspect that the Pagani value for instance is not a estimate of the most likely value, but an upper bound resulting from some physical constraint. BTW, climate sensitivity is not specific to CO2 radiative forcing, it applies more or less equally to any other forcing.
  8. Dikran, Using ranges is a very good way to narrow down uncertainties in many instances. For such a complicated scenario, different methods are used in an attempt to ascertain the most likely value (or range of values). In genetics, significant research has been able to narrow down the genes responsible for specific traits. Initially, there would be no consensus, but as pieces were placed together, a general picture appeared, resulting in an agreement among the scientists involved. At some point, you could say a consensus occurs, because the scientists agree that certain genes are responsible, without nailing down the specifics. The point at which that occurs may be somewhat nebulous. The same could be said for climate science. At what point can we say there is a consensus on climate sensitivity? My conclusion is that the range is still too wide to claim a general agreement. Some have tried to narrow the range, but then lose enough scientists to preclude calling it a consensus. BTW, the Pagani value was determined from paleo measurements, and Hansen and Sato (2011) recently stated that fast climate sensitivity was 3, while equilibrium climate sensitivity was 6. Excluding the Pagani value, with may not e relevant to today anyway, to claim a consensus opinion on the range of climate sensitivity, one would have to choose values from ~1-7! IMO, this does not constitute a consensus.
  9. Jonathon As I said, there is a concensus, the concensus is on the range of plausible values because at this stage there is insufficient evidence to make a stronger statement given out current state of knowledge. Of course there is no agreement on a specific value for climate sensitivity, nobody is claiming that there is, and indeed it is an unreasonable expectation. However that doesn't mean we can't have a concensus on the spread of plausible values. Note that a spread of plausible values is what we need for impacts studies, so that the distribution of plausible loss properly incorporates our uncertainty regarding climate sensitivity. You need to get away from the idea that we need to know the exact value of climate sensitivity. I note that your comment regarding the Pagani value does not address the question as to whether it is a most probable value or a bound.
  10. Dikran, I guess it comes down to what we understand to be the range of plausible values, and if that range is sufficient to state that there exists a consensus. I am not comfortable making that claim at this time, as I would prefer to see a narrower range of plausible values before making that assertion. Also, I do not believe that scientists would agree on the range. This does not mean that a consensus could not be formed in the future. I do not need to know the exact value, but the concept that the high end of the range is a factor of three higher than the low end implies that we still have a long way to go. Given the EPA range of atmospheric CO2 to lie between 535 and 983 by 2100, the resultant temperature increase lies in the range is 0.5 - 7.0 C (low-low to high-high). The pagani value was a calculated number for three different times in the recent geological past: 7.1 +/- 1.0, 8.7 +/- 1.3, and 9.6 +/- 1.4 C/doubling. http://earth.geology.yale.edu/~mp364/data/2009%20Pagani%20et%20al.pdf
  11. Jonathon, you appear to be missing the point. Nobody is claiming there is consensus on the exact value of climate sensitivity. There is however consensus on the range of values that would be plausible. If you want to claim that the scientists don't agree on the range of plausible values then please provide some evidence to support that assertion. Your comment on the Pagani estimate(s) still doesn't clarify whether it is a bound or an estimate of the most likely value.
  12. Jonathon, you're treating the extremes of the possible range as if they were equally probable as the mid range values. I doubt it is the case. The Pagani numbers should certainly give us cause for great concern.
  13. Jonathon - Looking at the Pagani paper, they are estimating equilibrium sensitivity, not transient sensitivity (the number usually listed as ~3°C/doubling of CO2.). Hansen estimated equilibrium sensitivity at ~6°C? So while the Pagani numbers are rather higher, they are really not directly relevant to the short term transient sensitivity of 3°C. Also, keep in mind that the high end of the sensitivity tail is much less determined than the low end. --- This is all smoke and mirrors on your part anyway, Jonathon. The consensus on values and ranges come from the evidence - if you wish to assert a climate sensitivity outside that range, present some evidence, not a petition.
  14. Dikran, I am not missing the point. I never said that there is a consensus on the exact value, so you can stop repeating yourself on this issue. I have yet to see anything that support a consensus on the range of plausible values, and highly doubt that one exists. Typically the evidence against a consensus is to present data which does not conform, which I have already done. The Pagani estimates are estimates of the value, not a bound. The uncertainties listed after each value are his calculated range. Clear? Philippe, When assembling a range of value such as this, each individual measurement is assigned the same probability, assuming they were determined independently, just like rolling the dice. If additional research yields values which begin to cluster around a specific range, then we can assign higher probability to those values. In the case of climate sensitivity, we see values clustered not around a mid-range value, but at the high and low ends, but still yielding a similar mid-range value. This anti-Gaussian distribution would indicate that the mid-range value is less likely than either end.
  15. Jonathon, I am curious. What is your reference for Hansen believing sensitivity to be 6? Wasnt what he said in public meeting I attended. Also, in consensus. Am I correct in assuming that in your mind, if there is a published value outside a consensus range, even in a refuted paper, then consensus doesn't exist?
  16. Continued sensitivity discussion is better suited to the existing sensitivity thread. The consensus there is 3.5 deg C per doubling.
  17. Scaddenp, (-Snip-). The Hansen value can be found here among other places: http://www.skepticalscience.com/Climate-emergency-time-to-slam-on-the-brakes.html Muon, We are discussing the range, not a value.
    Response:

    [DB] Inflammatory snipped.

  18. Jonathon, two very simple questions. If the range of plausible climate sensitivty values is 1.5C to 5C per doubling CO2, is there a consensus that the climate warms with added CO2? Yes or no? If the range of plausible values for the Hubble Constant is 55-80km/s/Mpc, is there a consensus that the Universe is expanding? Yes or no?
  19. Johathon, "climate sensitivity" = short-term transient sensitivity = fast feedbacks = 3 deg C The 6 deg C figure you keep providing is for long-term sensitivity / slow feedbacks.
  20. Sky, We already answered that on the other thread - yes. The discussion here is about whether we can say that there is a consensus among scientists as to the sensitivity of the temperature to CO2. We have already agreed that exact value in unknown, and that there is a plausible range of values. The disagreement is about what is that range, and is it narrow enough to constitute a consensus. Your range for the Hubble is much narrower, and not being a cosmologist, I cannot appropriately answer your question. Biblio, If we are talking about short-term transient sensitivity, then the plausible values are much lower, and Hansen's value of 3 is still on the high side. The following might help clear this up for you. http://profmandia.wordpress.com/2011/01/18/clearing-up-the-confusion-about-climate-sensitivity/ http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI3989.1
  21. Jonathan wrote: "The disagreement is about what is that range," as far as I can see you have provided no evidence that there is substantial disagreement regarding the range of plausible values, just that there are point estimates that are not in close agreement.. "and is it narrow enough to constitute a consensus." The spread of the range of plausible values has no bearing whatsoever on whether there can be a concensus on what the range actually is. If we had some dimensionless quantity that physics constrained to be strictly positive, but otherwise we knew nothing about it, then it would be perfectly reasonable for the concensus to be that the plausible range were from 0 to +infinity.
  22. The article you posted states that the most likely climate sensitivity is 3 deg C. How is 3 on the high side of 3?
  23. Biblio. That is for equilibrium climate sensitivity. I though you were talking abobut transient sensitivity, which the first article states as 1-3, while the second says 1.3-2.6. In either case, 3 is on the high side for transient sensitivity. Please read more carefully.
  24. Bibliovermis, 3 is on the high side of 3, but only for large values of 3 ;o)
  25. Dikran, The argument that everyone is in agreement, because we all think that the value is positive, is nice, but does not tell us much. If that is the extent of the consensus, then we should just drop it altogether. Since no one wishes to go beyond that issue, there is really no point arguing any further.

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