Do 97% of experts agree with the IPCC that human CO2 emissions are causing dangerous global warming?

Climate Movement activists frequently claim that "97%" of qualified experts agree with the basic premise of climate alarmism: that human emissions of carbon dioxide (CO2) are causing a dangerous warming of the earth's climate, which will have severe consequences for mankind and the Earth's ecosystems, unless CO2 emissions are quickly and drastically curtailed.

That "97%" claim is significant, not for what it what it reveals about the science of climate change, but for what it reveals about the Climate Movement spin machine. It turns out to be a classic example of the Big Lie.


  1. Articles
  2. Doran, 2009
  3. Cook, 2013
  4. Strengers, Verheggen & Vringer, 2015


  2. (or here)
  9.…/ (or here)
  23. and many more articles here:

Doran, 2009

The "97%" claim came from a January, 2009 article by Peter T. Doran about an April, 2008 survey conducted by Prof. Doran's graduate student, Margaret R. K. Zimmerman, of 10,257 Earth Scientists at academic and government institutions, of whom 3146 responded.

(A 2010 paper by Wm Anderegg claims the same conclusion, through a different but equally-flawed methodology.)

Doran's 97% claim is based on the answers to just two questions, both of which were so uncontroversial that even I, and most other climate change skeptics & "lukewarmers," would answer "yes" to them.

Worse yet, 97.5% of those who responded were excluded after their responses were received. Of 3146 responses received, only 79 responses were considered.

Plus, to reach the 97% threshold on the 2nd question, Doran excluded 40% or 50% of the remaining skeptics, i.e., 2 of the 3 respondents (out of 79) who gave "wrong" answers to the first question.

76 of 79 (96.2%) answered "risen" to the first question: "When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?"

Two of the 79 apparently answered "remained relatively constant" to the first question, so they were not asked the second question, and Doran did not count them among the skeptics when calculating his 79%. 75 of the remaining 77 (97.4%) answered "yes" to the second question: "Do you think human activity is a significant contributing factor in changing mean global temperatures?"

That means only 74 or 75 of 79 (93.7% or 94.9%) answered both "risen" to the first question and "yes" to the second question.

And that's in spite of the fact (3146-79) / 3146 = 97.5% of the respondents were excluded after the responses were received.

Plus, neither of the two questions actually addressed anthropogenic global warming!

The first question asked respondents to compare current temperatures to the depths of the Little Ice Age ("pre-1800s"), and asked whether it's warmer now. Well, of course it is! What's remarkable is that they didn't get 100% agreement. 3 of 79 apparently didn't agree even with that.

The second question asks whether any human activities significantly affect global temperatures. That encompasses both GHG-driven warming and particulate/aerosol-driven cooling. It could also be understood to include Urban Heat Island (UHI) effects.

Since just about everyone acknowledges at least one of those effects, I would have expected nearly everyone to answer "yes" to this question. Yet 2 of 77 apparently did not.

It is unfortunate that they didn't ask an actual question about Anthropogenic Global Warming. They should have asked something like, "Do you believe that emissions of CO2 from human activities, such as burning fossil fuels, are causing dangerous increases in global average temperatures?" or (para­phras­ing a pol­i­ti­cian) "Do you believe that climate change is real, man-made and dangerous?"

Doran survey details

Note:  If you read the Doran article, you might wonder whether they actually did ask a question like that, because the Doran article mentions that "up to nine" questions were asked, but never tells us about the other seven. So I bought the Zimmerman report, to find out. It turns out that other questions were mostly just about demographics. These were the nine questions:

Q1. When compared with pre-1800's levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?
1. Risen
2. Fallen
3. Remained relatively constant
4. No opinion/Don't know
Q2. Do you think human activity is a significant contributing factor in changing mean global temperatures? 
[This question wasn't asked if they answered "remained relatively constant" to Q1]
1. Yes
2. No
3. I'm not sure
Q3. What do you consider to be the most compelling argument that supports your previous answer (or, for those who were unsure, why were they unsure)? 
[This question wasn't asked if they answered "remained relatively constant" to Q1]
Q4. Please estimate the percentage of your fellow geoscientists who think human activity is a contributing factor to global climate change.
Q5. Which percentage of your papers published in peer-reviewed journals in the last 5 years have been on the subject of climate change?
Q6. Age
Q7. Gender
Q8. What is the highest level of education you have attained?
Q9. Which category best describes your area of expertise?

Neighboring disciplines

There's also a very fundamental flaw in Doran's approach:

“To test consensus position on a particular topic of science, correct methodology requires genuine experts of that very field to be excluded from the poll.

“If you wanted to know, for example, [whether] homeopathy was science or pseudoscience, [to decide if] it deserved financial support from government on taxpayer's money, you’d never ask a group of homeopaths if they believed substances diluted until not a single molecule of the supposed agent remained in them had still beneficial effect, would you? Even if you would and found 98% consensus on this issue among them, it would be utterly meaningless.

“On the other hand, asking experts of neighboring disciplines like doctors, pharmacologists, biologists, nurses and the like makes sense.

“It is the same with climatology. As soon as the scientific value of the basic paradigm of a field, in this case fitting multiple computational models of high complexity to a single run of a unique physical instance, is questioned, it is up to experts of neighboring fields to decide its validity. They may not be able to do their own research in that field, but they do have ample background to understand and evaluate the methods applied in the field in question.”
- Berényi Péter  2/17/2013

“Neighboring disciplines” of climatology are fields like meteorology, physics and geology. (Meteorologists are particularly well-equipped to recognize the difference between climate and mere weather.) So what do scientists in neighboring disciplines think of the climate scare?

Outside of academia and government institutions, surveys of scientists reveal widespread skepticism toward climate alarmism. Here are some examples:

Cook, 2013

May, 2013 brought another attempt by Climate Movement activists to revive their discredited "97% consensus" claim. But this time, the author, John Cook, didn't count scientists, he counted papers, and announced that 97% of relevant climate science papers “endorsed the consensus position that humans are causing global warming.”

But to reach that conclusion, Mr. Cook had to use an overly broad definition of the “consensus,” discard over 2/3 of the climatology papers he examined, and mischaracterize many of the rest, among other irregularities. Jo Nova has written a very good summary, and Richard Tol a more thorough examination of the problems in that dicredited paper.

Mr. Cook's main data file is here (in various formats):
pdftxt/csv (original)csvExcel spreadsheet and HTML spreadsheet.

H/t to Brandon Shollenberger (old blog here) for saving & mirroring 59 internal "ratings files" before Mr. Cook deleted them from his server; I've saved copies of them here.

For more details see:

Strengers, Verheggen & Vringer, 2015

In 2015 researchers in The Netherlands and Australia actually made a serious attempt to survey scientists about their views on climate change, rather than simply conduct an exercise in propaganda generation.

Unfortunately, they made a glaring methodological error: they biased their sample by restricting it to practicing climate scientists, rather than including scientists from neighboring disciplines. Nevertheless, their survey is the most comprehensive and informative to date.

Their first question asked to what extent human greenhouse gas emissions are responsible for the Earth's warming trend since the mid-20th century. They found that 65.9% of the respondents believe that human GHG emissions are responsible for at least 51% of the warming trend since the mid-20th century.

Their survey was very long; for more details you may read their report, here.

Dave Burton
March 1, 2012
Revised & extended 7/23/2012, 10/24/2012, 4/7/2013, 6/18/2013, 12/10/2013, 2/4/2014, 3/3/2014, 5/19/2014, 6/6/2014, 7/4/2014, 7/11/2014, 7/12/2014, 7/22/2014, 7/27/2014, 9/8/2014, 10/16/2014, 1/7/2015, 3/26/2015, 4/15/2015, 4/18/2015, 11/3/2015 & 1/20/2017.


Permalink: or