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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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The 97% consensus on global warming

What the science says...

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97% of climate experts agree humans are causing global warming.

Climate Myth...

There is no consensus

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 ...". (Petition Project)

Science achieves a consensus when scientists stop arguing.  When a question is first asked – like ‘what would happen if we put a load more CO2 in the atmosphere?’ – there may be many hypotheses about cause and effect. Over a period of time, each idea is tested and retested – the processes of the scientific method – because all scientists know that reputation and kudos go to those who find the right answer (and everyone else becomes an irrelevant footnote in the history of science).  Nearly all hypotheses will fall by the wayside during this testing period, because only one is going to answer the question properly, without leaving all kinds of odd dangling bits that don’t quite add up. Bad theories are usually rather untidy.

But the testing period must come to an end. Gradually, the focus of investigation narrows down to those avenues that continue to make sense, that still add up, and quite often a good theory will reveal additional answers, or make powerful predictions, that add substance to the theory.

So a consensus in science is different from a political one. There is no vote. Scientists just give up arguing because the sheer weight of consistent evidence is too compelling, the tide too strong to swim against any longer. Scientists change their minds on the basis of the evidence, and a consensus emerges over time. Not only do scientists stop arguing, they also start relying on each other's work. All science depends on that which precedes it, and when one scientist builds on the work of another, he acknowledges the work of others through citations. The work that forms the foundation of climate change science is cited with great frequency by many other scientists, demonstrating that the theory is widely accepted - and relied upon.

In the scientific field of climate studies – which is informed by many different disciplines – the consensus is demonstrated by the number of scientists who have stopped arguing about what is causing climate change – and that’s nearly all of them.

Authors of seven climate consensus studies — including Naomi OreskesPeter DoranWilliam AndereggBart VerheggenEd MaibachJ. Stuart Carlton, and John Cook — co-authored a paper that should settle this question once and for all. The two key conclusions from the paper are:

1) Depending on exactly how you measure the expert consensus, it’s somewhere between 90% and 100% that agree humans are responsible for climate change, with most of our studies finding 97% consensus among publishing climate scientists.

2) The greater the climate expertise among those surveyed, the higher the consensus on human-caused global warming.

consensus studies

Expert consensus results on the question of human-caused global warming among the previous studies published by the co-authors of Cook et al. (2016). Illustration: John Cook.  Available on the SkS Graphics page

consensus vs expertise

Scientific consensus on human-caused global warming as compared to the expertise of the surveyed sample. There’s a strong correlation between consensus and climate science expertise. Illustration: John Cook. Available on the SkS Graphics page

Expert consensus is a powerful thing. People know we don’t have the time or capacity to learn about everything, and so we frequently defer to the conclusions of experts. It’s why we visit doctors when we’re ill. The same is true of climate change: most people defer to the expert consensus of climate scientists. Crucially, as we note in our paper:

Public perception of the scientific consensus has been found to be a gateway belief, affecting other climate beliefs and attitudes including policy support.

That’s why those who oppose taking action to curb climate change have engaged in a misinformation campaign to deny the existence of the expert consensus. They’ve been largely successful, as the public badly underestimate the expert consensus, in what we call the “consensus gap.” Only 16% of Americans realize that the consensus is above 90%.

Lead author John Cook explaining the team’s 2016 consensus paper.

 

Last updated on 8 May 2016 by BaerbelW. 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:

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 226 to 250 out of 802:

  1. #227 doug_bostrom at 10:22 AM on 2 October, 2010 10:10 needs some grownup supervision. No. They need withdrawal of corporate and government sponsorship.
  2. Perhaps an arrangement may be made wherein government sponsorship of fossil-fuel firms is withdrawn? Meanwhile, I'm wondering if 10:10 is hiding government sponsorship.
  3. #230 doug_bostrom at 10:51 AM on 2 October, 2010 I'm wondering if 10:10 is hiding government sponsorship. It does. About 35,400 results (0.06 seconds) And yes, I agree wholeheartedly, government sponsorship of all private enterprises has to be stopped, including fossil & biofuels, wind, solar, nuclear and oxen energy. Obviously some taxpayer's money should go into basic research, but only if appropriate institutions are installed to make sure politicians don't have their say in how it is distributed. And no IPR tricks, papers written on research done using public money should go into the public domain.
  4. BP #231 Your search is misleading. That's local government agencies who have decided to participate in the campaign, not providers of sponsorship. I hope your extreme libertarian statement is meant to be satirical by the way, as in any other context it makes no sense at all.
  5. BP: ...papers written on research done using public money should go into the public domain. There's broad agreement on that, at least. I'm no expert (on anything) but it looks as though the emerging model going forward is for research budgets to include boosted publication fees, those fees to cover the costs of making publications permanently accessible on a freely available basis. Trying to think of an analogy, the only one coming to mind is unfortunately that of purchasing a plot in a cemetery, where money for the plot pays for upkeep of the cemetery grounds, with no gate fee for those wishing to visit and pay their respects. Stretching the analogy past the snapping point, perhaps we may think of citations as being the equivalent of visitors leaving flowers...
  6. Doug, I tried to work with your analogy but was defeated by the straight face requirement. Perhaps it's more like roads, tunnels and bridges. The authority or other developer's costs are met out of taxes paid by everyone, as are the maintenance costs. There is no restriction on how many kms are driven on those roads by any particular driver or vehicle, taxpayer or otherwise. The current system acts more like a toll road. Not a very wonderful analogy, but you get the idea.
  7. Oh dear, BP's comments were possibly not satirical - I missed the sensible comment among all the extremism ("And no IPR tricks, papers written on research done using public money should go into the public domain."). This is tending to be a requirement in NIH and EU funded research these days. I think we're a bit behind the times here in Australia, although I have an article going into a (free to publish in, and free to retrieve) open access journal sometime soon. But that's an industry-academic partnership body who are trying to raise their profile, so it's a bit different.
  8. #232 kdkd at 13:00 PM on 2 October, 2010 That's local government agencies who have decided to participate in the campaign, not providers of sponsorship. You are kidding, are you? David Cameron announces his ambition spon·sor
    1. One who assumes responsibility for another person or a group during a period of instruction, apprenticeship, or probation.
    2. One who vouches for the suitability of a candidate for admission.
    3. A legislator who proposes and urges adoption of a bill.
    4. One who presents a candidate for baptism or confirmation; a godparent.
    5. One that finances a project or an event carried out by another person or group, especially a business enterprise that pays for radio or television programming in return for advertising time.
    The British government signs up to 10:10, assuming responsibility for the campaign and the group behind it, including a promo depicting reluctant kids to be blown up. A rather generous publicity boost for a private company while shooting themselves in the leg. Hilarious. "Further, and crucially, the solution to carbon emissions will eventually be technological not ideological. Most personal efforts to show willing will in the long-run make no meaningful difference [...] their lobbying activities encourage empty promises rather than sustainable change"
  9. My, what a political turn this thread has taken. If the scientific case against anthropogenic climate change is weak and one has ideological reasons to ignore that, I guess any opportunity for advantage must be seized.
  10. #237 doug_bostrom at 07:20 AM on 3 October, 2010 My, what a political turn this thread has taken. It's still about how to make consensus. The particular method promoted by the 10:10 team is proven to be effective in the short term multiple times throughout history, particularly here, in Central Europe. Should I say we are all too familiar with it? Unfortunately however, it may not work so well in the long run, as sooner or later people are prone to come to their senses.
  11. BP #238 Perhaps you're unaware of the immediate retraction and apology concerning the video by the 10:10 group? Certainly puts your shrill hand wringing in perspective. #236 Maybe - I'm still not convinced. But your google search was misleading as it showed participation in the campaign by a bunch of local government groups. Even adding the word "funding" or "financing" to your search doesn't clarify at all.
  12. Actually BP what's interesting is that from a cognitive perspective faulty "appeals" of the kind 10:10 demonstrated are ineffective; for efficacy, arousal of or appeal to fear must be grounded in reality w/respect to the actual risk at hand and as well must present a clear avenue to reducing the level of fear resulting from the awareness of the particular risk leading to fear. Nobody's going to blow up as a result of leaving their bathroom light on, so we're left to conclude that 10:10 were only guessing about their method of approach. Now if 10:10 were to actually show up on people's doorsteps with the threat of physical violence, different story I'm sure. They didn't do that, they're instead using a crude cognitive bludgeon not properly crafted to achieve its intended effect, akin to putting on a blindfold and a boxing glove, then rummaging in a toolbox and expecting to find the proper wrench for the job at hand. Likening 10:10 to the Ministerium für Staatssicherheit or the like is rather a ridiculous approach in itself. Again, if you're trying to inculcate fear in the audience here so as to engender an effect, you'll want to ground the risk you present in reality, not fantasy.
  13. The world is faced with two dilemmas...
    Response: This is the stump of what became an extended discussion about various alternative energy technologies; very sorry that so many people had their time wasted by a challenging question in the wrong place.

    The topic of the thread is scientific consensus on the reality of climate change.
  14. Roger #244: Several of your assumptions are false. 1: Even taking the high end estimates of future population and economic growth fossil fuels would not run out within 50-100 years. If we squeezed out every last bit we might get 200 years of continual expansion. Prices might rise (barring more cost efficient extraction technologies) to the point that these energy sources would be replaced by others, but they aren't going to run out any time soon. 2: Ditto nuclear power. We'd get less than a hundred years of power in 'once through' type reactors, but with more modern breeder reactors nuclear power could last for thousands of years. 3: Most projections DON'T have population and energy use growing continuously. Indeed, the mainstream view is that both will level off sometime during this century. 4: It is simply false that 'green technology' cannot match the power generated by fossil fuels and uranium. Indeed, potential wind power dwarfs all of those others combined and potential solar power makes wind power look minuscule. Thus, once we have dispensed with the fictions we have considerably more options than 'die off' or 'institute population controls'... aka 'kill off'.
  15. Roger #247: Solar and wind prices are declining while fossil fuel prices are increasing. If we assume these trends will continue then the cost of solar or wind power with an assumed 30 year lifespan is actually ALREADY lower than the cost of a fossil fuel plant (yes, even coal) with an assumed 30 year lifespan and the average projected cost of coal over those 30 years. The point at which the CURRENT price of solar and wind is lower than the CURRENT price of coal for most of the world (it already is in some places, e.g. Hawaii) is still a decade or so off, but since we know the price of coal will rise (as you yourself argue) waiting until that point is short-sighted. "CO2 is at 390 ppmv now and could easily be at 500 ppmv before coal even peaks. Experts say CO2 must be pushed back to 350 ppmv to be safe. Green thinking won't get us there; only downsizing will." Another complete falsity. You could end all human industry and indeed kill off the entire human race and that wouldn't cause the atmospheric CO2 level to drop from the current 390 ppm down to 350 ppm any faster than switching over to 100% nuclear and renewable power. As to BP's 'renewable uses up too much land' argument... in addition to already mentioned offshore wind and space based solar there are; high altitude wind, geothermal, hydropower, tidal, ocean heat flux, and simply citing wind and solar on 'dual use' land... e.g. wind in cornfields and solar over parking lots - more than enough available land.
  16. The AGW arguments rely heavily on feedback loops, and the concensus argument is just about the biggest. A concensus IS a feedback loop. Especially if it exists in a scientific community. How many new students in the climate science field come into the subject without an opinion on global warming? And what it the overwhelming opinion going to be? Pro, of course. If you didn't believe in global warming, you would be crazy to choose climate science as a career. So every new intake is already convinced of AGW, generally because of the concensus. There is your feedback loop, concensus naturally reinforces concensus and actually increases it. In fact, in any field, most "experts" are understandaby apologists for the concensus. There is an incredibly similar situation in the field of Bible study. The huge majority of people entering the profession are already believers. What happens when they study in depth, and maybe experience some doubts? Here's a good article "Biblical Scholars Here's another well written piece on why most "experts" are apologists for the concensus: Most experts are apologists for the concensus .
  17. Mistermack, The difference in religious studies and science is that science is self-correcting, using the most rigorous methodology of discovery humans have ever invented. Providing links to arguments about religious experts tells us absolutely nothing about science or the field of climatology. Your statements regarding a "consensus" are yet another Argument by Assertion, a logical fallacy. I strongly suggest you spend some time at the Fallacy Files before posting here again. You'll be able to make a stronger case for your point of view.
  18. Truevoice, firstly, are you saying then that the scientific consensus is never wrong? I'm afraid I have to disagree. And you don't attempt to refute my points, you are simply argueing by assertion yourself. I think you should reread your own link, and look up "irony".
  19. Mistermack @242 says: A concensus IS a feedback loop. Especially if it exists in a scientific community. There is scientific consensus on General Relativity and Quantum Mechanics and Darwinian Evolution ... Does that mean they're wrong ? Why should it for climate science ? There is an incredibly similar situation in the field of Bible study. I had a friend that lost her faith studying Theology. Her view was that the lecturers threw every argument against religion at the students to ensure students could overcome any "doubts". For her the doubts got the better of her. She was quite bitter about it :-(
  20. Hi Phil, from the little I know, QM and GR contradict each other in places, and both fail when applied to the very beginning of the big bang. However, my real argument would be that most science can be verified by experiment, and maths by proof. Climate science is brand new, with no track record, and has a record of NO correct predictions so far. ( I mean real predictions, not retro ).
    Response: You are wrong. In the Search field type "Models are Unreliable."
  21. @mistermack: "How many new students in the climate science field come into the subject without an opinion on global warming? And what it the overwhelming opinion going to be? Pro, of course." This is irrelevant. Most people believe in AGW because the evidence is there, and the science is convincing. One has to be pretty arrogant to assume that the majority of people going into climate science are led by irrational belief rather than actual scientific knowledge. "If you didn't believe in global warming, you would be crazy to choose climate science as a career." It's not a matter of belief, but of logical reasoning. We accept AGW as very likely true because the evidence clearly suggests it is. "So every new intake is already convinced of AGW, generally because of the concensus." The consensus exists because the science is pretty compelling. The fact the science is so compelling is the reason many contrarians choose not to debate the science, but rather attack the integrity of those who understand it by claiming (without evidence) they are victim of groupthink. This is what you're trying to do now. It's insulting, not to mention factually wrong. "In fact, in any field, most "experts" are understandaby apologists for the concensus." And that means they are wrong? Is a doctor an apologist for treatment because he's an expert in it? Is a general an apologist for good military strategy because he's an expert? Your position seems to be that the more someone knows about something, the less we should trust that person. That's nothing more than ole' fashioned anti-intellectualism. the bane of scientific thought. You assume the experts are wrong simply because you don't agree with the conclusion...that's not a logical position. "There is an incredibly similar situation in the field of Bible study. The huge majority of people entering the profession are already believers." Actually, the situation is very different, because Bible study isn't empirical science. It's simply the study of Christian religious texts. Again, you try to attack the reputation of those you disagree with, this time by likening them to religious people. The sad thing is that, by espousing false ideas not based on logic and trying to discredit honest scientists, *you* are the one acting like the anti-sciece fanatical religious fringe.
  22. Mistermack @246 most science can be verified by experiment No, science is verified by observation. Experimentation is, of course, just a "fast track" way of making observations. For some sciences, (Astronomy, Ethology, Geology) experimentation is difficult, if not impossible; for others (Economics, Human Development) experimentation can be considered immoral. Climate science is actually largely, if not entirely, the application of physics and a little bit of chemistry to a specific system - the Earth and its atmosphere. Experiments pertaining to climate science, and indeed think about the effects of CO2 on the energy balance have been going on for about 150 years.
  23. Actually the first relatively back-of-the-envelope style calculations of the net effects of CO2 forcing were remarkably close to what we're seeing, mistermack. The earlier model predictions also produced results that can be considered reasonably useful in light of how things have since progressed. Early calculations were done some 50 years ago or more, model runs were first being done over 30 years in the past, so this is hardly "brand new." One can of course say, "oh, they were just lucky" but that's really not sufficient.
  24. Archie, if the evidence was as overwhelming as you say, I wouldn't waste my time looking. I know for a fact that the evidence is debateable, because I've done a lot of looking, much more that the average student intake. I think I am therefore well justified in my conclusion that most people are initially convinced by the "consensus" rather than evidence. You mention doctors, but many doctors are also homeopaths, and many are "experts" in homeopathy. The concencus of experts in homeopathy would be overwhelmingly supporting the effectiveness of homeopathic remedies. Same applies to Chirpractic. I'm not saying that climate science is as silly as these, I'm just pointing out that a consensus is naturally self perpetuating, till it's disproved. That's why the consensus on AGW is totally valueless, as evidence.
  25. Phil, you can talk up climate science all you like, it involves physics and chemistry, but that's where the similarity ends. You can make predictions in physics and chemistry, and verify them. In climate science, you can't even predict next year's trend. But you can grandly predict the trend for the next century. Without the slightest risk of being proved wrong.
    Response: You are solidly in the topic of a different thread now: "Models are Unreliable." Use the Search field at the top left of this page.

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