Richard Tol apparently has a new comment about Cook et als. paper Quantifying the consensus on anthropogenic global warming in the scientific literature. The basic motivation is that

Cook et al. (2013) seem to be an outlier in the consensus literature: their results, for a large sample, are in line with other results for small samples but contradict other large samples.

This is despite Richard himself saying

The consensus is of course in the high nineties. No one ever said it was not. We don’t need Cook’s survey to tell us that.

Tol basically looks at a large number of other surveys and tries to argue that Cook et al. is some kind of outlier. Shall we provide some much needed context? For example, Tol quotes a consensus of 75% from Oreskes (2004). What does it actually say? It says

Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position.

How is that a 75% consensus?

Tol uses data from Stenhouse et al. (2013), a survey of members of the American Meteorological Society (AMS), which says explicitly

We suggest that AMS should attempt to convey the widespread scientific agreement about climate change; acknowledge and explore the uncomfortable fact that political ideology influences the climate change views of meteorology professionals

So, a survey that was partly motivated by a desire understand why some AMS members do not recognise the widespread scientific agreement, is somehow evidence that there isn’t widespread scientific agreement.

Tol quotes a maximum consensus in Verheggen et al. (2014) of 79%, despite the abstract explicitly stating

90% of respondents with more than 10 climate-related peer-reviewed publications (about half of all respondents), explicitly agreed with anthropogenic greenhouse gases (GHGs) being the dominant driver of recent global warming.

Why the difference? Tol has included all surveyed, even those who responded with “I don’t know”. Well, if I’m trying to survey relevant experts and they don’t know the answer, then they’re probably not relevant experts.

Tol also includes that Verheggen et al. has a subsample with a consensus of 7%. Who were they? They were those “unconvinced of anthropogenic climate change”. Wow, what a surprise. A vast majority of those unconvinced of anthropogenic climate change, are unconvinced of anthropogenic climate change.

What Tol also fails to highlight is that Cook et al. was a survey of the literature itself. Most other large survey were surveys of people, not surveys of the scientific literature directly. Anwyay, that’s probably enough context for now. If you want some more context, you could read this.