The bare bones climate change consensus is that it is happening, will continue to happen, and is mainly caused by human activity. By 'consensus', I mean a majority of scientists considered sufficiently qualified to render an opinion on the matter. Although the 97% figure is bogus (see Climate Change: Exploring the Consensus for more on that), it's safe to say that a large majority of qualified scientists believe the earth has been undergoing anthropogenic global warming for some time and will continue to do so for the foreseeable future.

We tend to approach beliefs as discrete things: either you have a belief or not. But beliefs are not static or irreducible.  Beliefs are passing summations of changeable inputs, including current assumptions, points of reference, and degree of certainty. I'm going to focus on the latter.

If you're relying on experts for guidance on 'x', you don't just want to know their position on 'x'. You also want to know how much confidence they have in that position. Same goes with climate change. Luckily, we have the Bray and von Storch 5th International Survey of Climate Scientists to address this very issue. This survey was sent to scientists who worked directly in climate-related fields, such as atmospheric modelling and paleoclimatology, or affiliated fields, such as socio-economic impact assessment and ecological impact assessment. More on the survey from the authors:

The survey ran from mid-December 2015 until the end of January 2016. There were 651 returns (complete and partial) for a response rate of approximately 17%, exceeding the response rates of our previous online surveys. A set of statements was presented to which the respondent was asked to indicate his or her level of agreement or disagreement...

Responses were forthcoming from some 53 countries. The majority of respondents claimed to have worked in climate science for more than 10 years. Over 90% of the respondents were employed in academic degree granting institutes or publicly funded research non-degree granting institutes.

So what did the survey reveal? Ninety-one percent of 642 respondents* were convinced or very confident climate change is occurring and 5% were modestly confident climate change is occurring.** Forty-eight percent of 640 respondents were convinced that most of recent or near future climate change is the result of anthropogenic causes; 26% were very confident of this; and 14% were modestly confident.

So far, so good: about 88% of the respondents endorsed anthropogenic global warming. Not 97% but an impressive majority nonetheless. However, other survey responses were less one-sided. For instance, just 24% of the scientists were convinced or very confident about the ability of current climate models to simulate future climatic conditions. More on that in the next post. Plus charts.

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* About a third of the respondents were involved (as author, reviewer, etc.) with the United Nations Intergovernmental Panel on Climate Change Fifth Assessment Report (2014 IPCC AR5 Report).

**All the responses were on a scale of 1-7. I interpreted ‘7’ as convinced, ‘6’ as very confident, and ‘5’ as modestly confident.  In their introduction, the authors represent a response of ‘4’ as basically being on the fence.