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Infographic: 97 out of 100 climate experts think humans are causing global warming

Posted on 11 May 2011 by John Cook

I was talking about climate to my dad last week (since the book launch, he will now talk to me about the subject) and I mentioned that 97% of climate scientists are convinced that humans are causing global warming. He registered great surprise at that statistic. "I thought it was more 50/50", he said. It made me realise just how good a job both the mainstream media and the fossil fuel funded disinformation campaign have done in confusing the public about the scientific consensus on global warming. At the same time, I was working on a consensus graphic (cribbed from the Guide to Skepticism) for a video presentation. So as a tool for anyone wishing to communicate the scientific consensus, I've added the following infographic to the Climate Graphics resource:

The 97% figure comes from two independent studies, each employing different methodologies. One study surveyed all climate scientists who have publicly signed declarations supporting or rejecting the consensus (Anderegg 2010). Another study directly asked earth scientists the following question "Do you think human activity is a significant contributing factor in changing mean global temperatures?" They found 97% of actively publishing climate scientists answered yes (Doran 2009). As "climate scientists actively publishing peer-reviewed research on climate change" doesn't really roll off the tongue, I abbreviated that down to "climate experts".

One feature of Doran's survey results is that while 97% of climate expert said "yes, humans are causing global warming", only 1% said "no, we're not". The other 2% were unsure:


Response to the survey question "Do you think human activity is a significant contributing factor in changing mean global temperatures?" (Doran 2009)

I've indicated the "I'm not sure" portion in the "97 out of 100 climate experts" infographic with grey colouring.

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Comments 101 to 150 out of 179:

  1. 100, Albatross

    Interesting.

    Are you aware of any agencies that "dis-endorse" climate change?

    If 97 out of 100 scientists isn't good enough for some people, how about 100 out of 100 agencies and organizations populated by large numbers of scientists, and which in and of themselves have little to gain (financially) by supporting any one theory or another?

    How about it? Are there any real agencies out there that have publicly refuted climate change (and we're not including organizations like The Cato Heartland Freedom and Liberty Institute for Energy, Science, and Free Markets and Definitely Against Rabid Socialism and Such [a subsidiary of Exxon Mobile])?
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  2. Harry you said earlier that one problem was that:
    "First,the researchers excluded from their survey the thousands of scientists most likely to think that the Sun, or planetary movements, might have something to do with climate on Earth (i.e., solar scientists, space scientists, cosmologists, physicists, meteorologists and astronomers)."

    A quick example from my field (rheumatology, a subspecialty of internal medicine):

    Suppose you wanted to find out the current scientific consensus on how to treat patients with rheumatoid arthritis. If you surveyed rheumatologists who treat the most patients with rheumatoid arthritis, and are doing active research on rheumatoid arthritis, you would get the most scientifically sound answer to your question. You would expect a somewhat less sound answer if you surveyed, orthopedists, physical therapists, chiropracters, sports medicine doctors, or general internists, even though they might all have something to do with "arthritis". The most scientifically sound answer would come from the ones actively working in and doing research in the field in question don't you think?
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  3. @101 Sphaerica,

    I bet the "American Society of Petroleum geologists" would fit that question. Does it surprise you?
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  4. DSL @ 99.... Right! I really don't think the skeptics quite understand that no one wants AGW to be real. We would all be relieved if this weren't real. I'm a licensed general aviation pilot and I'd love to feel free to burn as much fossil fuel as my little heart desires but I've grounded myself until an adequate bio-fuel alternative is on the market. My passion for aviation takes a backseat to the future my kids will inherit.
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  5. 103, cynicus,

    And yet even they were forced to mollify their position in 2007 because (in their words) "the current policy statement is not supported by a significant number of our members and prospective members."

    The revised statement pretty much says nothing. It says that climate has changed in the past (no, really?), that the most extreme predictions of climate change aren't likely to come to pass (no, really?), and that they support alternative energy sources and conservation (with constant references to the need for it to be economically palatable).

    It's hardly a resounding refutation of current climate science.
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  6. Rob @104,

    There is always gliding :)
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  7. In fact, the AAPG have decided that it would be best if they just didn't get involved in trying to work out where they stand :


    Sunsetting the Global Climate Change Committee

    ...as a group we have no particular claim to knowledge of global atmospheric geoophysics through either our education or our daily professional work.
    For our members who want to follow the climate change discussions there are numerous, easily accessed Web sites. If there’s a demand, and if it helps us to find
    hydrocarbons or characterize potential sequestration reservoirs, AAPG can host climate-related technical sessions at our meetings – but like our other sessions, they should be composed of presenters who are doing the primary research.

    In the meantime, the Executive Committee saw no advantage and several significant potential pitfalls in maintaining an AAPG Global Climate Change Committee. The AAPG Global Climate Change Committee has fulfilled its mission with passion and energy, providing lively debate. The members are sincerely thanked for a job well done.

    The Professional Geologist

    And that is pretty good, coming as it does from such a group (geologists), some of whom are die-hard so-called skeptics - *cough* Plimer...
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  8. 106, Albatross,

    Except to do any gliding you need power to get the glider aloft (or for a hang glider something to lug you and the glider up to a launch point, and then go pick you up where ever you wind up landing).

    One of the big sins (I think) about how we're wasting fossil fuels today is that they're the only practical solution to powered flight. We're wasting it all puttering around to the corner store, when a hundred years from today people are going to regret all the things that can't be done because flying is so prohibitively expensive (because there's so little fuel left to meet the needs of aviation).
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  9. Rob @104, I have always wondered about the viability of an electrically powered ducted fan based on a glider frame and with PV cells in the wings.

    Sphaerica, most air transport needs could be met with derigibles again propelled by ducted fans and powered from battery power with PV cells recharging the batteries during daylight hours. Granted it would take five days to cross the atlantic, but that is almost irrelevant for freight; and if you need a faster personal meeting, there is skype.
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  10. Sphaerica - There's a lot going on in terms of electric airplanes, which can address at least small craft in the forseeable future. I believe there were several present at Sun-and-Fun this spring, and more to appear at Oshkosh. But battery recharge times limit distance traveled per day, which means even the best won't be replacements.

    For general and commercial aviation, however, we're more likely to end up with either biofuels or solar/wind generated (carbon neutral) liquid fuels. For example, there's a pretty serious effort by Swift Enterprises to certify their 100LL replacement (propeller driven planes), which is a biofuel, for FAA approved use. They're in testing now, and should have that cleared fairly soon - and it appears to be price competitive. I expect some kerosene/jet fuel replacements hitting the market in <5-10 years as well.
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  11. Sphaerica wrote : "Except to do any gliding you need power to get the glider aloft (or for a hang glider something to lug you and the glider up to a launch point, and then go pick you up where ever you wind up landing)."


    The last time I went gliding, I was launched by a winch, which is like launching a kite. I suppose the winch still needs fuel for the motor but, apart from that, and presuming a landing back on the airfield where you start, the carbon footprint should be very small !
    Best way to fly, unless you need to get somewhere...
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  12. Tom Curtis, Rob, etc. - Take a look at the Sunseeker, a solar powered glider which crossed the US on solar power in August 1990.

    See also the Sunseeker II and other projects on that page, including the Sunship - a solar powered dirigible.
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  13. Albatross @100, I believe Harry Seaward was playing coy. Your statement was:

    "Please list for us all the professional scientific societies of the same standing as the American Meteorological Society (for example) who state that human emissions of GHGs are not contributing to global warming."


    You would not agree with that statement, and neither would Lindzen or Christie (although I know of some scientists who would). I believe the question should be:

    "Please list for us all the professional scientific societies of the same standing as the American Meteorological Society (for example) who state that human emissions of GHGs are not the major contributing factor to global warming."


    All of the scientific societies you listed endorse that human emissions of GHG is the major contributing factor, as of course, do you.
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  14. funglestrumpet @82, quoting Tyndale is all very well, but their are deniers who believe that the climate response for a doubling of CO2 is around 0.5 degrees C after feedbacks. Indeed, I recently came across one who claimed increasing CO2 reduces the temperature. There is no way that you will convince such deniers and their gratefully hoodwinked political allies that reducing CO2 emissions will be a cost effective means of combating rising global temperatures. This is particularly the case seeing the same people also tend to believe that the major drivers of increasing temperatures is natural, and is in the process of reversing, ie, entering a sustained cooling period.

    You certainly would not convince me, if I believed those falsehoods, to reduce CO2 emissions without first convincing me that those beliefs were false. That is because I am rational.

    Further, Stephen Baines @85 is entirely correct.

    This is my last comment on this topic which is OT on this thread. I recommend, however, that you become familiar with the arguments deniers actually present before you recommend how we can overcome their political effect.
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  15. Stephen Baines @84:

    "What I would like to see someday is a historical perspective of how the level of consensus has changed over time."


    Bray, 2010, "The scientific consensus of climate change revisited" draws on three surveys by Bray and Storch, the first in 1996 and the last in 2008, to answer your question. It turns out that:

    1) In 1996, just over 60% of climate scientists believed the Earth was warming; just under 40% believed humans where responsible; and just under 60% believed the IPCC was an accurate reflection of the science.

    2) In 2003, just over 80% of climate scientists believed the Earth was warming; around 55% believed humans were responsible; and around 75% believed the IPCC reports accurately reflected the science.

    3) In 2008, around 95% of climate scientists believed the Earth was warming; just under 90% believed humans where responsible; and 80% believed the IPCC reports accurately reflected the science, or understated the risks.

    Based on Doran and Zimmerman, Bray indicates that the proportion of climate scientists believing humans where responsible for global warming had risen to around 95% by 2009. (All data from Figure 1 in the paper.)

    Robert Lichter (2008) also compares the results of a 1991 Gallup Poll of climate scientists to his 2007 Survey:

    "We repeated several of their questions verbatim, in order to measure changes in scientific opinion over time. On a variety of questions, opinion has consistently shifted toward increased belief in and concern about global warming. Among the changes:

    In 1991 only 60% of climate scientists believed that average global temperatures were up, compared to 97% today.
    In 1991 only a minority (41%) of climate scientists agreed that then-current scientific evidence “substantiates the occurrence of human-induced warming,” compared to three out of four (74%) today.
    The proportion of those who see at least a 50-50 chance that global temperatures will rise two degrees Celsius has increased from 47% to 56% since 1991.
    The proportion of scientists who have a great deal of confidence in our understanding of the human-induced sources of global climate change rose from 22% in 1991 to 29% in 2007. Similarly, the proportion voicing confidence in our understanding of the archeological climate evidence rose from 20% to 32%.
    Despite these expressions of uncertainty, however, the proportion which rating the chances at 50-50 or better that the role of human behavior will be settled in the near future rose from 47% in 1991 to 69% in 2007."


    There is a clear pattern of a rising consensus as scientist by scientist is driven by the evidence to conclude that temperatures are rising, we are responsible, and it is dangerous.
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  16. Bud @87:

    "It is irrelevant how many scientists there are in total nor how many are "climate" scientists. It only takes one experiment by scientist or non-scientist to prove them all wrong. Consensus is not part of scientific method.

    Consensus is a political process."


    Consensus does not make anything true, but it was (and is) a fundamental assumption of the enlightenment and of science (which grew out of it) that close examination of the evidence with an open mind will lead people to the same opinion. The will converge on truth. So, arriving at a consensus by negotiation is a political process; but arriving at a consensus by independently examining the evidence is the hallmark of science. It is a sign that the consensus theory accurately represents the available evidence, which in turn means any superior theory is not likely to be very different in its predictions.

    As can be seen from the evidence in my preceding post, the consensus on global warming was reached slowly and arduously. Slowly, one scientist after another has moved from rejection or agnosticism about the theory to endorsement, and what has moved them is the accumulation of evidence. You would be arrogant indeed to think that you no better without a full and detailed knowledge of the evidence; and any politician who bases their policy on the consensus being wrong is a fool.
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  17. 111, JMurphy,

    Back in the 80s (in hang gliders in Chicago) I launched two ways, from the Indian Dunes by foot, or by tow off the back of a station wagon on an abandoned army air strip (basically, a long, straight dirt road through the fields).

    The dunes were low, so I could carry the glider the 100 feet up. The north wind coming in over a smooth-as-glass Lake Michigan, hitting the sand dunes that had been built over the millenia by that same wind, produced tremendous lift, especially in the natural "bowl" where we launched. Landing was actually a problem, because the lift was so strong in the bowl, but it was the only safe place to land. The shore line itself was too narrow, crowded with beach goers, and you were likely to drown if you ever had to try to come down there.

    Of course, it was over an hour and a half drive to the dunes from Chicago, with the glider on the roof.

    And launching at Lookout Mountain in Tennessee required an SUV to get up the mountain (after having driven 6-8 hours to get there).

    Basically, the hobby used a lot of fuel, even if the actual flying was "emissions free" (not counting the energy expended in constructing the high-tech glider to begin with, of course).
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  18. Albatross @ 100
    You are so intent on making your point that you are not reading what I posted. I knew you had your list waiting and to clarify my response to that let me state the following: "the organizations may be endorsing their support of catastrophic AGW, but there are individuals within those organizations who do not."

    Your task was: "Please list for us all the professional scientific societies of the same standing as the American Meteorological Society (for example) who state that human emissions of GHGs are not contributing to global warming."

    I replied: "I don't know of any scientists period that would make that statment."

    You replied: "Bad news, I'm a scientist and I made that statement. But then again, you don't know me ;)"

    If you would slow down and read what is posted instead of anxiously waiting to cut and paste your trump card, you might finally understand that we really aren't that far apart.

    I've said it before and I will say it again - human activities do have impact on the global climate. We disagree on the level of impact, future ramifications, and current strategies to cope with those anticipated changes.
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  19. This is utter nonsense.

    Science advances primarily through falsification and paradigm shifts. So-called 'consensus' has nothing to do with science.

    'Consensus' is pure propaganda. The bottom line is you don't use consensus if you have proof.
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  20. This question may not be that well thought out, but I am asking mercy. I ruptured my Achilles tendon and recently had surgery and the Lortab sometimes REALLY has an effect.

    Let's take 3 situations: AGW, evolution, and the existence of Bigfoot.

    I believe in AGW (to a limited effect). Definitely believe in evolution. And, I think the existence of Bigfoot MIGHT be a possibility.

    All have multiple lines of evidence and the first 2 have scientific consensus. All are currently a theory or maybe hypothesis. What would it take to prove or disprove any of the 3?
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  21. 119, RW1,

    You have it upside-down.

    We don't have a consensus because we need proof, we have a consensus because we have proof.

    There is also a consensus on lung cancer, ozone and CFCs, the right ways to construct buildings, fly planes, prepare food, etc.

    The only reason we don't discuss the consensus on those issues is because there aren't masses of people who have been fooled into thinking there's actually any question in those matters.

    The only reason we do discuss the consensus behind climate change is because of the number of people who so adamantly refuse to look at, understand, and accept the science that proves the facts behind climate change.
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  22. 120, apiratelooksat50,

    Sorry about your Achilles. That's got a long recovery time, but I know a few people who have done it, and they were all fine (eventually).

    Prove/Disprove:

    1) Bigfoot
    • Prove: Find physical evidence, such as a carcass, skeleton, DNA, or live specimen
    • Disprove: can't ever be done (unless maybe you can program an army of surveillance robots capable of scouring the entire northwestern part of the continent, leaving no stone unturned).
    2) Evolution
    • Prove: This is a case where real science comes in, because one can rarely ever "prove" anything, and even when you do, that "proof" is founded on other "proven" hypotheses, so if one of them is overturned, everything else collapses as well. But after a while, a compilation of confirming evidence and a paucity of contradictory evidence strengthens the case to the point where one no longer feels that "proof" is needed.
    • Disprove: First you need an alternative hypothesis, whether it be a variation on or complete refutation of evolution. Then you need a compelling body of evidence supporting that hypothesis and unambiguously contradicting that of evolution. As an example, Intelligent Design will never be proven or disproven, unless God comes down and interrupts a science lecture at MIT to assume the role of guest speaker.
    3) Climate Theory
    • Prove: We already have substantial evidence, but this can no more be "proven" than one can "prove" evolution. It's better to speak in terms of "confidence" than "proof."
    • Disprove: The answer is the same as with evolution: a feasible hypothesis with supporting (but unambiguous) evidence.
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  23. 115 @Tom Curtis

    Thanks for the link! Exactly what I was asking for. That matches my memory pretty well. I wonder if there would be a way to turn that info into a nice graphic.

    119 @ RW1 "Science advances primarily through falsification and paradigm shifts. So-called 'consensus' has nothing to do with science."

    And what happens when scientific propositions survive attempts to falsify them? You get consensus. Without it you cannot have establish settled scientific propositions upon which to build future work and science essentially stops. I'm not sure how you can say consensus has no role in science.

    The fact is there used to be plenty of scientists skeptical about the proposition that the earth was warming and that humans were responsible. They have slowly been convinced by the evidence over time. Only a few diehards still remain concerning those two central issues.
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  24. Sphaerica (RE: 121),

    "You have it upside-down.

    We don't have a consensus because we need proof, we have a consensus because we have proof."


    I don't think you understand. There is no such thing as 'consensus' on anything in science.

    Scientific theories generally become 'accepted' after rigorous falsification testing fails repeatedly and when all the existing evidence is in strict accordance with the theory (i.e. no pieces of contradictory evidence exist). When any such theories become accepted, there is never a 'consensus'. There is more or less a cessation of further testing and research on the theories.

    This is certainly no where near the case with climate science, as there is more still unknown than known and significant uncertainties and contradictory pieces of evidence abound. Significant research on the subjects' many facets continues from all perspectives.
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  25. Stephen Baines (RE: 123),

    "And what happens when scientific propositions survive attempts to falsify them?

    What is/are the primary falsification tests for AGW?
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  26. 124, RW1,

    I don't think you understand. "Consensus" is just a word, which describes the situation where scientific theories generally become 'accepted' after rigorous falsification testing fails repeatedly and when all the existing evidence is in strict accordance with the theory (i.e. no pieces of contradictory evidence exist).

    This has pretty much happened, and the only case where there is more still unknown than known and significant uncertainties and contradictory pieces of evidence abound is in the minds of those who desperately want such uncertainties and evidence to exist, to the point that they are in complete denial, and turn everything upside-down.

    You are correct in saying that significant research on the subjects' many facets continues from all perspectives, but that research is being done by the real scientists, not the skeptics in denial, and the goal is to learn more, wherever the truth may not, and not to simply prove it wrong at all costs.

    In the meantime, we're digging ourselves a deeper and deeper hole.
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  27. RW1:
    Wow. You show me a list of what you would call "accepted theories" and I'll show you a list of what I would call "laws of nature."

    But then, what would you call a theory that is a synthesis of known physics that does meet your "accepted theories" criteria (but also includes elements that involve some uncertainty), has good predictive value, has no competing theories that come anywhere close to explaining the data as well, and that has survived decades of spirited challenges?

    And what word would you use to express the idea that, among those most familiar with the evidence in the field, almost all are persuaded by this theory?
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  28. RW1 @119:

    "Science advances primarily through falsification and paradigm shifts. So-called 'consensus' has nothing to do with science."


    What an incoherent statement. Falsification is an idea from Popper about how science advances. It is in fact a false idea. As has been frequently pointed out, you cannot test any theory in isolation, but only in together with a number of auxiliary hypotheses (Duhem-Quine thesis). If the test fails, what is falsified is not the theory, but the conjunction of the theory and all those auxiliary hypothesis. That is, if the test fails, we know that at either the theory is false, or that least one of the auxiliary hypotheses is false - but we don't know which one. Nor do we know if the change required to the theory or auxiliary hypotheses to make them true are minor, or radical. Naive falsificationists, if consistent, would insist that Newton abandon his theory of gravity when it was first formulated because it included the (known falsehood) that astronomical bodies are point masses; and his theory of motion because canon balls never match a parabola in their flight. Popper was far more sensible than his interpreters and maintained that whether something was falsified or not was largely a matter of convention.

    Paradigms are the invention of Thomas Kuhn, a historian of science who knew Popper's account simply did not match actual scientific practise (nor can because of the Duhem-Quine hypothesis. He therefore proposed his theory of scientific revolutions and paradigm shifts in opposition to falsificationism. Saying that science advances by falsification and paradigm shifts is like saying wood burns by oxidation and by emitting phlogiston. It shows RW1 to be illiterate on the philosophy of science.

    What is more puzzling (if we assumed that he knew what he was talking about, is that a paradigm shift only occurs when a new consensus forms around a particular theory. RW1 has just claimed that science doesn't work by consensus, but rather it works by falsification and an incommensurable scientific consensus forming around new theories.

    In fact, both theories are false. Science advances by the empirical testing of theories, with rational support being given to those theories which have the best track record, and show the best prospects of fruitful prediction. Currently there exist an incoherent hodgepodge of theories that agree about nothing except that humans are not responsible for the majority of 20th century climate change, and that we couldn't do anything about it if we were; and the theory of AGW. The former hodgepodge of ideas have an almost uniform record of predictive failure, while the theory of AGW has a solid record of predictive success. Naturally this record has attracted knowledgeable scientists who gravitate to that theory as a result.

    Despite this, deniers keep on trying their little two-step.

    1) They claim that because two dentists in Woking disagree with AGW, there is a significant scientific debate on AGW (or AGW has been falsified) and therefore it is too early to act against future warming.

    2) And when this appeal to authority is challenged by pointing out that the overwhelming majority of climate scientists accept the evidence for AGW, they claim that science is not settled by consensus (true) and that we are resorting to argument by authority (false).
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    Moderator Response: Martin Gardner wrote a good critique of Popper. Here is quote he reprinted: "'Sir Karl Popper / Perpetrated a whopper / When he boasted to the world that he and he alone / Had toppled Rudolf Carnap from his Vienna Circle throne.' —a clerihew by Armand T. Ringer"
  29. RW1 @ 125

    What you fail to accept is that most of the evidence for climate change, and the human impact on it was generated by multiple and multifarious attempts to test those predictions. It was not assembled post facto.

    Thus we have evidence that temperature has increased not only over land but in the oceans and in the troposphere, that sea levels has risen, that CO2 has increased, that CO2 is human in origin, that it has influenced radiative transfer, that changes in distribution of heating geographically, vertically in the atmosphere and in time correspond to predicted effects of CO2 on warming (fingerprinting). Finally, we currently have no physically realistic model of climate that can recreate the current pattern without CO2 forcing.

    The effect of human produced CO2 was on climate has past multiple tests, sometimes repeatedly. What more could you want?
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  30. RW1 @124:
    "Scientific theories generally become 'accepted' after rigorous falsification testing fails repeatedly and when all the existing evidence is in strict accordance with the theory (i.e. no pieces of contradictory evidence exist). When any such theories become accepted, there is never a 'consensus'."


    Translated: the theory becomes 'accepted' by all, or nearly all scientists; but there is no 'consensus' amongst scientists about that theory.

    So your whole argument is based on an empty word game. (Worse than empty, because the meaning of the word consensus is well known, and has been clearly explained several times in this thread, so you 'misunderstanding' of its meaning cannot be simple ignorance.)
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  31. Tom Curtis,

    And you accuse me of playing semantics?

    I know exactly what I'm talking about. Perhaps I better way to put it would be falsification testing. The point is for a theory to be sound it must be thoroughly testable, which means it must be falsifiable or have a clear idea of what evidence would be sufficient to prove it untrue.

    The only 'consensus' or accepted aspect of climate science is that anthropogenic CO2 will perturb the climate system. The AGW theory of a 3 C rise in the next 100 years is not falsifiable in the way other 'accepted' scientific theories are. Given that it requires a response so much greater than the measured response of the system to surface incident energy makes it an extraordinary claim requiring extraordinary proof. At best it's an educated guess - more so it's an unfalsifiable series of heuristic assumptions.
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  32. 131, RW1,
    The AGW theory of a 3 C rise in the next 100 years is not falsifiable in the way other 'accepted' scientific theories are.
    For the eighth time now, the evidence that you have refused to acknowledge, address or understand, going back to the "negative cloud feedback" debate, is the multiple lines of evidence that demonstrate a climate sensitivity of 3˚C or more per doubling of CO2.
    Given that it requires a response so much greater than the measured response of the system to surface incident energy makes it an extraordinary claim requiring extraordinary proof.
    And that proof is more than there for anyone who doesn't simply shut their eyes, cover their ears, and sing "nah nah nah."
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  33. Of the many extraordinary things that deniers manage to believe before breakfast, the idea that "consensus" is a kind of political order imposed upon scientists from above forcing them to confess, in some kind of Stalinist or McCarthyist show trial, to things they don't believe in so they won't be killed or purged, must be the most extraordinary.

    Does "consensus" in this field have some other meaning than "The great majority of climate scientists believe that global warming is occurring as a result of increasing ghg production from human activities"; just as "the great majority of biologists believe evolution is occurring as a result of natural selection" has only one meaning?

    How can you not understand that the effectively 100% of climate scientists who are in fundamental agreement on the basic facts of climate science represent the separately reached conclusions, based on evidence, of thousands of scientists?

    How do deniers imagine that you would impose "consensus", in the sense they mean, on those thousands of scientists in various sub-disciplines (and indeed other disciplines like ecology providing evidence that agrees with the consensus) in countries all round the world, both in the present and retrospectively on research carried out on the past?

    Just a rhetorical question. Or it should be.
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  34. RW1 @131, yes, I am accusing you of semantics. Anybody who can say that a theory can be so widely accepted in science that nobody even bothers to test it any more, but that at the same time there is no scientific consensus in favour of that theory as you have clearly done is playing semantics. Given your statement in @124, consistent with your use of the word, 100% of climate scientists could believe AGW and you would still deny that there was a consensus. Ergo your denial is just so much empty posturing.
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  35. Thought of making this into a t-shirt?

    I'd buy one if it were available.
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  36. I'll admit that I haven't had time to read through all of the large list of comments here so this point may have already been raised.

    I do not dispute that there is sufficient evidence to prove the existence of a consensus in climate change science - Anderegg, Oreskes are good surveys in this matter. However Doran's survey, as I know has been commented, only 79 specialised climate scientists were present in the sample of 3146. The 97% comes from that small sample. I think it is only fair and wise that this article should mention it. I Believe it is an excellent survey and shows the strength of the consensus within the related natural sciences and that is sufficient as climate science is a subfield of this. I am from the field of social science and study climate change receptiveness of the public. Trust is a vital part of that response. To not mention the figure of 79 appears as disingenuous. Trust can be very hard to build but extremely easy to break.

    A further point - although I am a big fan of this blog it follows the model of information-deficit where what is needed to move the public is more accurate knowledge. However in the social sciences there is plenty of evidence where knowledge doesn't lead to change. It is far more complicated than that. However despite this I see this info-deficit model repeatedly trundled out in uncritical style - The Paul Nurse Horizon programme is a classic example of this. No real change will occur until we move beyond this blind-spot into the very depths of the structures of our societies. It is a contradiction that climate scientists keep saying listen to the experts but when it comes to the social element of climate change they continually snub the experts in societal dynamics (Sociologists, human geographers etc (I exclude social psychology as it is too individualist a science and thus reduces society to the myth of individuals) If you really want to know about changing the public's mind we need to understand how they encounter climate change in their everyday lives - two books I would highly recommend in this regard is Hulme "Why We Disagree About Climate Change" and Norgaard "Living in Denial". If climate change teaches us anything it is of the complex and systemic nature of the earth systems to which only an interdisciplinary response is sufficient.
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  37. Tom Curtis@128 Interesting points. It seems to me that Popper is trying to define what science is, whereas Kuhn seems more concerned with how science actually happens. Since scientists are human beings, rather than vulcans, it isn't that surprising that the way science actually happens isn't necessarily always completely scientific.

    However the point about concensus is that (i) concensus is a consequence of science, not a cause, and can also occurr for sociological reasons and (ii) as no group of scienctists every agree completely on anything some common sense has to be applied as to what is meant by a concensus.

    At the end of the day, the fact that a very broad concensus does exist in climatology, is good evidence that the science is solid. This is especially true given that the dissenters from the concensus are not ignored, they get their papers published in the journals, where their work is discussed. If the dissenters had some solid evidence behind them, they would eventually break down the concensus and there would be a paradigm shift. But such shifts only occurr where there is good reason.
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  38. Bud wrote : "Consensus is a political process."


    This seems to be the definition of 'consensus' that the so-called skeptics are using : Consensus has been decided by politicians (presumably led by Al Gore ?), who have somehow forced the science to comply.
    It is a very ideological meaning which is totally opposed to the actual meaning of consensus, i.e. general, widespread, majority agreement.
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  39. RW1 @131

    You are playing semantics here too:

    The AGW theory of a 3 C rise in the next 100 years is not falsifiable in the way other 'accepted' scientific theories are.

    A 3C rise in global temperatures is not a theory, it is a prediction made by applying the theories of climate physics (along with a guestimate of projected fossil fuel use). Those theories are typically not only applicable to the planetary atmosphere and so can be independently verified by experimentation. (An obvious example is fluid dynamics which can be studied in the lab). Other theories of climate physics can be verified either by direct observation or by hindcast.

    The fact that the prediction is not falsifiable is obvious - if it were it would not be a prediction, and would therefore be of no use to us.
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  40. Phil at 139
    What if the 3 C rise doesn't happen?
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  41. Let's make sure we are using terms properly.

    The predicted 3C rise is a hypothesis, not a theory. It could be stated: If atmospheric CO2 levels continue to rise at current rates, then we can expect a 3C rise in temperature over the next years.

    A hypothesis attempts to answer questions by putting forth a plausible explanation that has yet to be rigorously tested.

    A theory, on the other hand, has already undergone extensive testing by various scientists and is generally accepted as being an accurate explanation of an observation. This doesn’t mean the theory is correct; only that current testing has not yet been able to disprove it, and the evidence as it is understood, appears to support it.

    A theory will often start out as a hypothesis -- an educated guess to explain observable phenomenon. The scientist will attempt to poke holes in his or her hypothesis. If it survives the applied methodologies of science, it begins to take on the significance of a theory to the scientist. The next step is to present the findings to the scientific community for further, independent testing. The more a hypothesis is tested and holds up, the better accepted it becomes as a theory.

    By the way, what is the historic observation that led to the formation of the AGW hypothesis?
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  42. 136, EFox,

    I don't think climate scientists snub the social sciences, so much as it's just not their thing, so they don't ask.

    That said... I am sure John would put up some relevant social sciences posts if he got them. You could submit something yourself.
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  43. 141, Harry Seaward,
    The predicted 3C rise is a hypothesis, not a theory.
    At this point, the evidence supporting a 3˚C rise is pretty darn strong. Attempts to paint it as otherwise are just demonstrations of ignorance.

    For more information, see the thread on the evidence behind a 3˚C climate sensitivity.
    By the way, what is the historic observation that led to the formation of the AGW hypothesis?
    In addition to the above link on climate sensitivity, it is suggested that you read Spencer Weart's A Discovery of Global Warming (unless you don't really want answers, and just like the idea of implying that the foundations of climate theory don't actually exist).
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  44. "The predicted 3C rise is a hypothesis, not a theory. It could be stated: If atmospheric CO2 levels continue to rise at current rates, then we can expect a 3C rise in temperature over the next years"

    It is a prediction based on theory.

    "By the way, what is the historic observation that led to the formation of the AGW hypothesis?"

    There is no such thing as the "AGW hypothesis".

    On the slight chance that what you're asking is what observation led to the theory describing the climate response to differing concentrations of CO2, it all started with observations made by Tyndall a long time ago. I'll let you do the google to determine exactly how many years ago this was.
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  45. Sphaerica at 143

    The 3C rise is a prediction, or more accurately a projection (which is less precise). You can't slice it any other way.

    Read the definitions from the IPCC Glossary. The last line is a doozy.

    Climate prediction
    A climate prediction or climate forecast is the result of an attempt to produce a most likely description or estimate of the actual evolution of the climate in the future, e.g. at seasonal, interannual or long-term time scales. See also: Climate projection and Climate (change) scenario.

    Climate projection
    A projection of the response of the climate system to emission or concentration scenarios of greenhouse gases and aerosols, or radiative forcing scenarios, often based upon simulations by climate models. Climate projections are distinguished from climate predictions in order to emphasise that climate projections depend upon the emission/concentration/ radiative forcing scenario used, which are based on assumptions, concerning, e.g., future socio-economic and technological developments, that may or may not be realised, and are therefore subject to substantial uncertainty.
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  46. Sphaerica at 143
    Your statement: "At this point, the evidence supporting a 3˚C rise is pretty darn strong. Attempts to paint it as otherwise are just demonstrations of ignorance."

    You could make the first sentence more accurate by inserting the word projected in front of the number 3.

    And, is the second sentence really necessary in a scientific discussion?

    "In addition to the above link on climate sensitivity, it is suggested that you read Spencer Weart's A Discovery of Global Warming (unless you don't really want answers, and just like the idea of implying that the foundations of climate theory don't actually exist)."

    Thanks for the link, and, again, you could have left out the words within the parantheses.
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  47. dhogaza at 144
    "It is a prediction based on theory."
    Prediction or projection, but I agree with your statement.

    "On the slight chance that what you're asking is what observation led to the theory describing the climate response to differing concentrations of CO2, it all started with observations made by Tyndall a long time ago. I'll let you do the google to determine exactly how many years ago this was."

    Thank you. I really am curious about that.
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  48. Harry Seaward:

    "The last line is a doozy."

    Why?

    The physical theory regarding the change in climate due to changes in concentration of GHGs comes with error bounds, but is reasonably complete.

    Our ability to predict the future of human history is not. We don't really have a clue as to what life will be like a century from now, nor how much CO2 society will spew into the atmosphere over the next 100 years. Perhaps there will be a fusion breakthrough and electricity will be too cheap to meter and generation will be free of any negative environmental effects at all! (cough cough.)
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  49. "And, is the second sentence really necessary in a scientific discussion? "

    At the risk of seeming rude ... a discussion about something like "the AGW hypothesis" is not a discussion about science, so you shouldn't be too surprised at the kind of responses your posts elicit.
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  50. 145, Harry Seaward,

    You're playing word games, and you obviously didn't bother to read anything I pointed you toward before you replied. I'm not sure how serious anyone should take the posts of someone who wants to expound but refuses to learn.

    The 3˚C rise is neither a projection nor a prediction. It is a theory which is close to a law (i.e. "any forcing X will result in a temperature change of 3X") and is backed by a substantial body of evidence that spans an unbelievable variety of methods and sources. The strength behind the statement is very, very strong.

    There is still uncertainty involved, but with every new study that uncertainty diminishes.

    Your weak grasp of the IPCC Glossary, on the other hand, highlights much of your problem. I see nothing whatsoever wrong with the text you quoted, and in particular I see nothing "doozyish" about the last line.

    Their point is that climate science can make predictions based on climate facts. But since one of those facts is actual greenhouse emissions, which in turn are based not on scientific or natural factors but rather on socio-economic factors, then climate projections are difficult to make.

    In fact, a related debate just finished "raging" over on the Linzen Illision #2 thread over the difference between a projection in future temperatures, and the emissions scenario used to make the projection.
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