Posts Tagged ‘survey’

Rick Santorum misrepresents our climate survey results on Bill Maher show

September 2, 2015

In our survey of more than 1800 scientists we found that the large majority agree that recent climate change is predominantly human induced. The article where we discuss our results is publicly available and a brief rundown of the main conclusions is provided in this blogpost.

We were quite surprised to hear a US Presidential candidate, Rick Santorum, make the opposite claim based on our survey. On the Bill Maher show he said:

The most recent survey of climate scientists said about 57 percent don’t agree with the idea that 95 percent of the change in the climate is caused by CO2. (…) There was a survey done of 1,800 scientists, and 57 percent said they don’t buy off on the idea that CO2 is the knob that’s turning the climate. There’s hundreds of reasons the climate’s changed.

What did we actually find in our survey?

In our survey of 1868 scientists studying various aspects of climate change, we asked two questions about the causes of recent global warming. Of all scientists who provided an estimate ~85% think that the influence of human greenhouse gases is dominant, i.e. responsible for more than half of the observed warming. ~15% think greenhouse gases are responsible for less than half of the observed warming. If you zoom in to those respondents with arguably more expertise, the percentage agreeing with human dominated warming becomes 90% or larger.

The existence of a strong scientific consensus about climate change is also clear from previous surveys of scientists and of the scientific literature and from statements of scientific societies. A scientific consensus is a logical consequence of the evidence for a certain position becoming stronger over time.

Rick Santorum’s claim is misleading and wrong because:

1) it is based on a wrong interpretation of just one of the two survey questions about the causes of recent climate change.

2) it is based on the argument that respondents who didn’t provide a specific estimate for the contribution of greenhouse gases (22% of the total number) think that this contribution is small. That is a wrong inference.

3) it is based on the argument that respondents who think it is “very likely” or “likely” or “more likely than not” that greenhouse gases are the dominant cause of recent warming disagree with this dominant influence. That is a wrong inference.

Politifact also did a fact-check of Santorum’s claim and found it to be false. It gives a very good overview of what’s wrong with Santorum’s claim. Several people are quoted in their article, myself included as well as the blogger Fabius Maximus who came up with the 43% consensus figure used by Santorum to claim a 57% dissensus:


Climate Science Survey – the questions

October 8, 2012

In the spring of 2012, a large scale climate science survey was held amongst 6500 scientists studying various aspects of global warming. The survey was spearheaded by the Netherlands Environmental Assessment Agency (PBL), where I was responsible for the execution and analysis during the first half of 2012.

The objective of this study is to gain insight into how climate scientists perceive the public debate on the physical scientific aspects of climate change. More info about the survey was posted on the PBL website at the time, which has recently been updated to include a link to the survey questionnaire. Please note that the survey is no longer active.

Some confusion has arisen over the status of this survey. I responded at WUWT in an attempt to clarify:

We undertook a survey in March/April of this year (which, as Hans Labohm mentioned in a comment on WUWT, had been previewed by a variety of people with different viewpoints). Some respondents, e.g. Timothy Ball, asked to see the questions again. After internal consultation, we decided to publish the survey questions on the institute’s website, so that they are viewable to all. We contacted the survey respondents to inform them of the questions being available to view. I informed Dr Ball of this as well, to follow-up on my earlier email to him.

Our email to all respondents, informing them of the fact that the survey questions are available on the web, was apparently misunderstood to mean that we were again soliciting responses to a survey; this is however not the case. Roger Pielke Sr had already put a notice about the survey on his blog, which he has since updated after an email clarifying that this is an inactive survey, to which he had previously responded.

Below we (Bart Verheggen and Bart Strengers) reply to some of the more substantive questions regarding the survey questions raised on WUWT. However, we will not discuss results or the survey sample at this point in time. We will do so when our manuscript has been accepted.


Climate survey discussion

January 3, 2012

On the previous post a discussion about climate surveys erupted. Please continue here. I’ll chime in when I habe more time.

I’m curious to hear what you find good or not so good about a particular survey and why. If you have contributed to the discussion on the previous thread, perhaps you want to condense your main arguments in one comment so that we can start a more structured discussion. If succesful, I’ll follow up with a post including the various contributions. Call it crowdsourced blogging if you wish.

A noteworthy survey that has not been discussed much is the one by Brown, Pielke Sr and Annan that I wrote about before:

A recent survey of scientists having authored a recent journal article on climate change found that the majority concurred with the IPCC position. A sizeable minority was of the opinion that the IPCC reports overstate the importance of and/or certainty regarding CO2 compared to other forcings (both natural and anthropogenic!). Only very few respondents were of the “skeptical” opinion that warming is predominantly natural. Nobody denied that the globe is warming. A large minority found the IPCC too cautious, understating the human influence on climate and/or the seriousness of the problem. Note that the authors do not claim that their survey is representative; less then 10% of the 1800 scientists contacted replied. Moreover, the positions that respondents had to choose between were sometimes a little ambiguous.

Others that have been discussed a lot include those by Bray and von Storch and the recent one by Doran and Kendal-Zimmerman.


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