97% of Climatologists believe human activity is a significant factor in changing global mean temperature

I saw an interesting statement in the comment section of climateprogress.org: “97% of climate scientists agree that climate change is real, it’s happening now, it’s man made, and it has grave consequences.”

This statement seemed plausible, but was unsourced, so I asked for evidence. Turns out there is recent poll data on that, and I’ll try to summarize the results.

A group of 3,146 earth scientists surveyed around the world overwhelmingly agree that in the past 200-plus years, mean global temperatures have been rising, and that human activity is a significant contributing factor in changing mean global temperatures. Peter Doran, University of Illinois at Chicago associate professor of earth and environmental sciences, along with former graduate student Maggie Kendall Zimmerman, conducted the survey in late 2008. The findings of their survey were published on January 20, 2009 in EOS, the newspaper of earth and space sciences published by American Geophysical Union. Here is the PDF of the survey results.

People were asked two questions:

  1. When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?
  2. Do you think human activity is a significant contributing factor in changing mean global temperatures?

Methodology. I quote from the article:

An invitation to participate in the survey was sent to 10,257 Earth scientists. The database was built from Keane and Martinez [2007], which lists all geosciences faculty at reporting academic institutions, along with researchers at state geologic surveys associated with local universities, and researchers at U.S. federal research facilities (e.g., U.S. Geological Survey, NASA, and NOAA (U.S. National Oceanic and Atmospheric Administration) facilities; U.S. Department of Energy national laboratories; and so forth).

With 3146 individuals completing the survey, the participant response rate for the survey was 30.7%. This is a typical response rate for Web-based surveys [Cook et al., 2000; Kaplowitz et al., 2004]. Of our survey participants, 90% were from U.S. institutions and 6% were from Canadian institutions; the remaining 4% were from institutions in 21 other nations. More than 90% of participants had Ph.D.s, and 7% had master’s degrees. With survey participants asked to select a single category, the most common areas of expertise reported were geochemistry (15.5%), geophysics (12%), and oceanography (10.5%). General geology, hydrology/hydrogeology, and paleontology each accounted for 5–7% of the total respondents. Approximately 5% of the respondents were climate scientists, and 8.5% of the respondents indicated that more than 50% of their peer-reviewed publications in the past 5 years have been on the subject of climate change. While respondents’ names are kept private, the authors noted that the survey included participants with well-documented dissenting opinions on global warming theory.


Results show that overall, 90% of participants answered “risen” to question 1 and 82% answered yes to question 2. In general, as the level of active research and specialization in climate science increases, so does agreement with the two primary questions (Figure 1). In our survey, the most specialized and knowledgeable respondents (with regard to climate change) are those who listed climate science as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change (79 individuals in total). Of these specialists, 96.2% (76 of 79) answered “risen” to question 1 and 97.4% (75 of 77) answered yes to question 2.

From CNN:

Petroleum geologists and meteorologists were among the biggest doubters, with only 47 percent and 64 percent, respectively, believing in human involvement.

“The petroleum geologist response is not too surprising, but the meteorologists’ is very interesting,” said Peter Doran associate professor of earth and environmental sciences at the University of Illinois at Chicago, and one of the survey’s authors.

“Most members of the public think meteorologists know climate, but most of them actually study very short-term phenomenon.”

Biases in Selection? Of the people who responded,  most had doctorates in the physical sciences,and many of these fields were related in some way to climate science.  In other words, these people were some of the best qualified to assess the scientific validity of these two statements. These people are able to interpret scientific data and to offer counter-hypothesis and recognize methodological flaws. These are the very kind of people with the best informed and best reasoned opinions about the issue.  Climate science is a brutally interdisciplinary field; it requires being able to compare and evaluate lots of different data sets; very few people can do it passably well.  I certainly can’t do it (although I can talk a good game sometimes).

Here are some variables that might call into question the validity of the poll:

  • what percentage of full-time scientists work in academia or government bodies? Is it a significant amount?
  • Are there ways in which nonscientists or people without PhDs  have a deeper understanding about climate change research? For example, would a geologist who works for  Exxon have access to more reliable data or have  a business need to uncover the truth?
  • Does academia discourage people with alternative (but scientifically credible) viewpoints from   staying in academia? (Do departments deny tenure, etc?)
  • To the extent that all educated people see things only from the perspective they are familiar with,  are  biases in academia stronger or weaker than  biases in the private sector?
  • Do academics have more or less time to study the data and become better informed about a topic?
  • Does the availability of more research money in the private sector lead to more money and time to do research of a basic nature?
  • Which kind of scientist is more likely to have a broad interdisciplinary understanding of a complex issue like climate change?
  • As I said before, I do not have a scientific background (much less a Phd). Also, I’ve been outside of academia for  a while – even though I follow aspects of the academic world online. But I can make intelligent guesses about each of these questions.

    1. I suspect that among people with PhDs, a high percentage are working in academia or governmental jobs. When you pursue a PhD, you want your investment in time and money to bring the ability to do more research and with fewer strings attached. Making money is no longer really an important motivator for these people (although certainly they would request a reasonably good salary).  People with Phds are attracted to research for its own sake, and the private sector rarely provides enough independence to pursue their research goals.
    2. My guess is that people in industry could have a deeper understanding about a specific area that concerns global warming, but would be significantly disadvantaged in trying to see the big picture. The business world sets priorities differently from research institutions, and so it would be impractical for a qualified scientist working for Exxon to spend time on areas outside of their field of interest at the company. Perhaps a nutrition researcher has done a study demonstrating that eating Cheerios reduces cholesterol. This study may be valid and interesting, but of trivial importance in nutritional research.
    3. Academia has a long tradition of dissent and listening to opposing viewpoints. Academics are incredibly open-minded to new research areas. On the other hand, a groupthink does emerge in some academic disciplines  (like other  places). But it’s more subtle. Departments define legitimate areas for research, and younger academics typically are trained to produce research topics along  the paths previously established by their colleagues. In the humanities, the key thing is having original analysis and being the first to discover something new. In the sciences, I suspect the key thing is not being original but producing research papers which lack flaws and can be easily replicated in another context.  Scientists definitely  value the gadfly and outside-the-box thinker, but only if that thinker’s research can be replicated and is methodologically sound. As it stands, most climate change denial research has serious methodological flaws.   Very little has been vetted in peer reviewed journals, and they have yet to come up with accurate climate models with predictive value.
    4. I think tenured professors have freedom and objectivity to adopt controversial positions, but often by the time they have reached tenure, they are no longer as committed to doing cutting edge research. When you are an 40+ year old academic, you have a family to maintain, are more committed to  mentoring and have less lofty ambitions (i.e., you are no longer aiming to win the Nobel Prize).  Grad students have more time and dedication and are not significantly invested in academia (though they feel a lot of pressure to publish).  They have more recent tools of analysis and have no qualms about pursuing new avenues of research. PhD candidates are not really “biased” about anything. Instead, they have deep knowledge and specialized training about certain topics and are careful not to make statements which cannot be factually supported.  But the defect of these people is in not seeing the big picture. They tend to assume that  their specialized knowledge is applicable to many other areas and that their kind of analysis is superior.
    5. I doubt that academics have more time overall (although the situation must improve with the gaining of tenure). But they have more control about how to set their research agenda. Private sector scientists on the other hand have an agenda set for them.  Their only way to control the agenda is to quit the company and find another job. That does not mean that the person must compromise his scientific integrity – only that his or her focus will be on things not necessarily in the public interest.
    6. Private sector is awash with research money, but it is available for applied research and not really for basic research (which climate science badly needs). A soil scientist may have a lot of money and resources to understand the impact of corn farming, but if his funding source comes from big agriculture,  he or she may not be able to use the money to do a study of more general relevance.  Also, private sector research may not necessarily be published or accessible (especially if it is concerned with the development of a new product).
    7. I am inclined to say that academia tolerates the interdisciplinary generalist, but only after the scientist has received tenure (and that usually requires pursuing a narrow topic to reach that goal).  As I said above, people in industry may tend to see things only from the point of view of their own industry (i.e., petroleum engineering), but that doesn’t mean they can’t see the big picture. If anything, when you are in industry, you see how something like petroleum impacts not just geology, but business processes, politics and economics. Your perspective is not limited merely by what one kind of scientist sees. A scientist in industry might more inclined to come in contact with workers with a practical understanding of the problem. But it seems mandatory that anyone studying global warming have the ability to analyze different kinds of data and to know how they relate and whether they contradict one another.

    Which kind of scientist is more likely to act in the public interest? I think people in private industry are just as capable of doing that – but practically speaking will they do so? Will they let subtle biases cloud their judgment? Scientists at government agencies seem more geared to the public interest, but first they have to justify their own job. They need to show that they are fulfilling the mandate of the position, and that the public needs his expertise to understand the problem. Academics have career concerns (obviously), but they are more concerned about academic reputation and revealing new things boldly.

    This is why surveys like this are good reflections of where the science is and whether it approaches a consensus.

    Finally, the paper presented an interested graphic that contrasted the view of scientists with that of nonscientists.

    Question: Do you think human activity is a significant contributing factor in changing mean global temperatures?


    The Public response comes from a Gallup poll and shows the divergence between the opinion of scientists and nonscientists.

    A final point. It goes without saying that surveys are not a good way to analyze scientific questions. For one thing, it is a kind of subtle appeal to authority. But global warming is an important issue for many scientists, and for the nonexpert, it can be hard to tell the difference between a well-informed scientist and a bad one. For an example of what I mean, see this  video by Lord Monckton.  If you don’t have an in-depth understanding of the topic, it’s easy to be confused by misleading scientific information. Lord Monckton appeared to win the debate, but in fact almost every single statement he made was wrong or misleading. (He tried to publish one scientific paper, and it was so incompetent and error-ridden with errors  that  it was a proper subject of ridiculemore here and these videos: #1 and #2).

    Lord Monckton’s tactic is to challenge younger and less informed people and to score trivial rhetorical points. Obviously serious scientists have no tolerance for his antics, and yet Monckton is invited over and over on TV.  (I don’t regard Monckton as a credible scientist, merely a caricature; surely more qualified people exist to question APG and the harmful effects; I’m just using Monckton as an egregious example of what I mean).

    I can think of 4 responses to the person who says: scientists disagree or throws unfamiliar details to the nonscientist as a way to “refute” AGW:

    1. if the climate models by IPCC (and others) are wrong, which climate model is the least wrong? (Denialists need to make a statement which can be tested and compared against other explanations).
    2. I will bet anybody (up to  $1000)  that the global mean temperature in the second decade of this century (2010-9) will be higher than the global mean temperature in the first decade of the century (2000-9). Would you take that bet? If you won’t won’t take this bet that the effects of  global warming are real and measurable,  why do you insist that the rest of the world ought to?
    3. If your child were sick, and 97% of the world’s doctors said the child would die unless he take a certain medicine, should you give him this medicine or do nothing until the autopsy confirms the original diagnosis? (This shifts the debate to that of legacy and future generations).
    4. If my child wanders on to a road I can’t be certain that they will be hit by a car, but I am certain that I need to get them off the road as quickly as I can. (An elegant formulation because it acknowledges that the real question is not whether the danger actually exists but whether we should take steps to minimize risk in any event).

    Skeptical Science has addressed the argument about consensus.

    The following scientific organisations endorse the consensus position that “most of the global warming in recent decades can be attributed to human activities”:

    The Academies of Science from 19 different countries all endorse the consensus. 11 countries have signed a joint statement endorsing the consensus position:

    • Academia Brasiliera de Ciencias (Brazil)
    • Royal Society of Canada
    • Chinese Academy of Sciences
    • Academie des Sciences (France)
    • Deutsche Akademie der Naturforscher Leopoldina (Germany)
    • Indian National Science Academy
    • Accademia dei Lincei (Italy)
    • Science Council of Japan
    • Russian Academy of Sciences
    • Royal Society (United Kingdom)
    • National Academy of Sciences (USA) (12 Mar 2009 news release)

    A letter from 18 scientific organisations to US Congress states:

    “Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science.”

    Jan 20 2010 Update. Here’s a great essay by Steve Dutch about why industrial scientists tend to see scientific questions incorrectly:

    Although an industrial scientist may be intimately familiar with real-world phenomena that interfere with theories from being completely fulfilled in reality, that person’s perspective may also be limited to a very narrow range of phenomena that bear on his or her work. It would be quite possible for such a person to perform competently in a specific field and still have very poor theoretical understanding, or be quite unaware of the broader theoretical implications of an idea. In his own work, Ransom may spend his entire professional life without encountering a fact that refutes Velikovsky, but he may be completely unaware that there are other fields where workers encounter such facts every day.

    This “tunnel vision” can lead some applied scientists to overestimate their own competence and underestimate the difficulties of other fields. The geologists who opposed continental drift in the late 1960’s and early 1970’s were perfectly competent at finding oil; they failed to recognize that much of their experience was simply irrelevant to the evidence and techniques that were involved in the confirmation of continental drift. Essentially, they drilled the same oil well for decades without broadening their experience in the slightest. A good general rule here: if you can’t get a paper published in some field, you are not qualified to reject the consensus of workers in that field. If you can get papers published in astronomy, you can advocate for Velikovsky, but not until.

    May 10, 2010 Update.  Scientist Rafe Sagarin  comments on how an academic setting influences climate change research:

    I am a scientist who does some of my work on the climate change issue. I published some of the first work documenting that climate warming is affecting natural systems now.

    I have never, and will never get rich or even modestly wealthy doing this science that I love (I graduated Stanford in the early 1990’s – I had abundant opportunities to cash in on dot com 1.0 and 2.0 and many of my classmates took that route and are very wealthy). Scientists do not get wealthy off of grants on climate change or anything else – typically we put one or two months salary on a grant and the rest to graduate students, equipment and university overhead. Granting rates are about 10%, so there’s not oodles of money out there in any event.

    Every climate scientist I know is out there trying to disprove, not prove, the theory of global warming, because that’s what scientists do. Unlike, say, Glenn Beck or Rachel Maddow (classmate of mine), we cannot decide what we want to prove and present the facts in a light to make that case. We observe and use the observations to disprove a set of alternative hypotheses.

    Moreover, the reward system in science, which is not financial but based on reputation based on strong publications is fully loaded against finding something that helps “prove” global warming. For example, the first few papers showing that plants and animals are showing earlier signs of spring made it into the top journals – Science and Nature. But if you’re the guy who found the 25th case or the 275th case (and there are that many, at least) of earlier signs of spring associated with climate warming, you have little chance of getting that finding published in a top journal.

    So far, of the thousands of scientists working hard (with very little pay) to disprove part or all of the theory of climate warming, all have failed. That is why there is said to be a “consensus”, not because Gore or Obama or the UN said it should be. The consensus emerges from the balance of observable data, presented in the clearest and most transparent light possible. That allows mistakes to be discovered and corrected. The mistake in the IPCC about the Himalayan glacier melt rate was discovered by a scientist and reported by scientists. We thrive on correcting mistakes by our peers.

    Finally, if you are an intellectually honest person and you want to go about saying that climate change isn’t happening or that it’s not human created, you yourself have a huge amount of facts to clear out of the way before you can then construct a counter argument to explain why all of the things you would expect from an increase in greenhouse gases in the atmosphere–which have been observed–were actually caused by something completely different. So, before you respond on this forum or in your own head, you need to go to RealClimate.org and read through the articles and the thoughtful comment boards. See if the arguments of the climate deniers really hold up. See if your own arguments that you’ve made here or at dinner parties or on the bus hold up. “Climategate” is discussed there. The role of sunspots is discussed there. The “Hockey Stick” graph is discussed there. Read through it with an open mind and see if it still makes sense to deny what we can and have clearly seen going on all around us. Thanks.

    Sept 8 2010 Update. Skepticalscience.com has a discussion about this study and what it means.






    6 responses to “97% of Climatologists believe human activity is a significant factor in changing global mean temperature”

    1. Preston Avatar

      Robert, I have to laugh at your comment in #3 about the tradition of dissent and listening to ideas. To the contrary, academia has a long tradition of deeply bitter and divisive power struggles, “groupthink”, and general unseemly shenanigans. It’s only human nature that when someone spends five years (or more) in research and stakes his reputation on a theory he will fight tooth and nail to preserve that theory (and thus his reputation) even in the face of evidence to the contrary.

      Further, with the dramatic decline in state funding for research universities, academic researchers are increasingly dependent on grant money to maintain their positions. Thus our “independent” academia is increasingly being steered by the types of grants being written. In this scenario and with so much at stake, I think it would be a wise policy move to set aside 10% of research grants for lines of research that attempt to challenge prevailing theory. (Not just of climate change, but in any field.) When too many people start looking the same direction, other valuable science can get overlooked.

    2. Robert Nagle Avatar

      The amount of funding available to disprove global warming far outweighs that of academic or even government funding. That is an unfortunate reality. I really do not worry one bit about the American Petroleum Institute or AEI or ACCCE or Competitive Enterprise Institute (more here ) lacking the funds to fund research. Nor do I worry about denialists getting their message out. There is a massive amount of greenwashing on the airwaves these days (overt and covert). The most dramatic example I can think was a 2 hour episode about global warming on ABC last year. It was cutting edge and actually a bit alarmist. But immediately following the TV show, TXU ran several commercials about being a good Texas energy company. Unsurprisingly, the ABC special pinned the blame on leaders for failing to come to an agreement and NOT on specific industries, nor did it call for lifestyle changes or boycotts of specific products or services. The TV show was still excellent, but it indicated how hard it can be for a TV station to broadcast an anti-commercial message like global warming.

      I’m not denying groupthink at the academia. I just don’t think it is any worse than groupthink in other areas.

      By now the key questions are no longer scientific; they are political and economic. What is the most workable way to mitigate the harms? What is the most fair way to share the burden? What is the cost-benefit analysis of various mitigation strategies? I don’t scientists are especially qualified to answer that question (but the McKinsey report tried to do this).

      Climate change is more than a scientific question. But so far in the US we haven’t really progressed beyond the basic scientific facts.

    3. Klem Avatar

      “97% of Climatologists believe human activity is a significant factor in changing global mean temperature”

      Fortunatly, these sceintists don’t write policy. Public opinion will determine policy for climate change, and right now public opinion has flipped. Now a majority do not believe in AGW, so the skeptics have won. Wahoo!

    4. Tom Black Avatar
      Tom Black

      Its 97% of 79 climatologists, a tiny tiny tiny tiny fraction of the worlds geoscientists.
      Its misleading, typical alarmists, you just cant quit lying.

    5. Xenomorph Avatar

      Hmm, 30.7% of 3,146 equals… 965 people that replied. Of those people, about 48% were geoscientists (geochemists, geophysicists, oceanographers, climatologists, etc). That amounts fo about 460 qualified individuals. Doesn’t sound much like lying to me.

    6. litesong Avatar

      You state, ‘Petroleum geologists and meteorologists were among the biggest doubters, with only 47 percent and 64 percent, respectively, believing in human involvement.’

      Wow! Said geologists & meteorologists believe that the companies for which they work, are causing AGW!…..at least, near a majority…..& likely considerably more! Wow……& wow, again!

      Your uncontrolled bias shows dramatically, that you think that ‘only’ 47% of petroleum geologists & 64% of petroleum meteorologists believing in AGW are small numbers!

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