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Big Survey Finds Only Minority Of Climate Scientists Agree With IPCC Keynote Statement

Fabius Maximus

Summary: In February 2014 I examined surveys of climate scientists and found (as had others) that they showed broad agreement with the IPCC’s headline statement about warming since 1950. However time brings new research, such as a major survey that digs deeper and finds that only a minority of climate scientists agree with the full keynote statement of AR5 — the most recent IPCC report. That’s important news.

In March – April 2012 the PBL Netherlands Climate Assessment Agency, with several other scientists, conducted a survey of approximately 6550 scientists studying climate change. It was published as “Scientists’ Views about Attribution of Global Warming” by Bart Verheggen et al in the 19 Aug 2014 issue of Environmental Science and Technology (peer-reviewed). In April 2015 they published a more detailed report (used in this post).

This survey covered many of the frontiers of climate science. This post examines one the questions about the keynote statement of the IPCC’s most recent work — Assessment Report 5 (AR5)…

“It is extremely likely {95%+ certainty} that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. ”

— From the Summary for Policymakers of the IPCC’s AR5 Working Group I.

The PBL survey is the first I’ve seen to test agreement with both facets of that statement. First, how much of the global surface warming is results from the anthropogenic (human-caused) emissions of greenhouse gases? (Note AR5 referred to all factors; see “Details” below). Only 1222 of 1868 (64% of respondents) agreed with AR5 that the answer was over 50%. If we exclude the 164 (8.8%) “I don’t know” respondents, 72% agree with the IPCC. So far, so good.

PBL survey: question 1a

Now for the second part of the statement: what is the certainty of this finding? That the IPCC gives these answers is one of its great strengths. Of the 1222 respondents to the PBL survey who said that the anthropogenic contribution was over 50%, 797 (65%) said it was 95%+ certain (which the IPCC defines as “virtually certain” or “extremely likely”).

PBL survey: question 1b

Those 797 respondents are 43% of all 1868 respondents (47% excluding the “don’t know” group). The PBL survey finds that only a minority (a large minority) of climate scientists agree with the AR5 keynote statement.

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