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 CO2 emissions are causing a dangerous warming of the earth's climate, which will have catastrophic 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. Here are some articles about it:

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The 97% claim comes from a January, 2009 article by Peter T. Doran about an April, 2008 survey by 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 an equally-flawed methodology.)

The 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, 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, they excluded two more skeptics, 2 of the 3 respondents (out of 79) who gave a "wrong" answer to the first question.

76 of 79 (96.2%) answered "risen" to this 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," and they were not asked the second question:

75 of the remaining 77 (97.4%) answered "yes" to this 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.

Since just about everyone acknowledges that anthropogenic particulate/aerosol air pollution causes cooling, I would have expected just about everyone to answer "yes" to this question. Yet 2 of 77 apparently did not.

Why do you suppose they didn't ask an actual question about Anthropogenic Global Warming? Why didn't they ask 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?"

Note #1:  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?


Note #2:  There's also a very fundamental flaw in the Doran/Zimmerman 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

A "neighboring discipline" of climatology is meteorology (and meteorologists are particularly well-equipped to recognize the difference between climate and mere weather).

From the Bulletin of the American Meteorological Society we learn that most broadcast meteorologists say that they disagree with the IPPC claim that humans are primarily responsible for recent global warming. A newer survey of all American broadcast meteorologists by researchers at George Mason University confirms that result.

Even back in 2007, when Harris polled 500 leading American Meteorological and Geophysical scientists (a broader category; details here), there was no consensus -- and that was before the Climategate revelations! Harris found that: "97% agree that 'global average temperatures have increased' during the past century. But not everyone attributes that rise to human activity. A slight majority (52%) believe this warming was human-induced, 30% see it as the result of natural temperature fluctuations and the rest are unsure."

UPDATE: 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, Dr. Cook had to discard over 2/3 of the climatology papers he examined, and mischaracterize many of the rest. More details here:

Dave Burton
March 1, 2012
revised and extended 7/23/2012, 10/24/2012, 4/7/2013, 6/18/2013, 12/10/2013, 2/4/2014 & 3/3/2014.