What’s the consensus of climate scientists? Why do we care?

chartHere’s a briefing about climate change, prepared for Politifact at their request. Unused, of course, since the reporter was just fishing for smears (here’s an analysis of what they published). However, it’s a useful introduction to this complex subject. What do we know about the consensus of climate scientists, and why does it matter? These are unedited emails, and so roughly written and unproofed. (2nd of 2 posts today.)

Initial Inquiry by Linda Qiu of Politifact, and my response

I’m a reporter with PolitiFact, the fact-checking website of the Tampa Bay Times. I’m currently looking into something Rick Santorum said: 57% of scientists “don’t buy into the idea that CO2 is the knob that’s turning the climate.” His campaign hasn’t gotten back to me on his source but one of your posts also has the figure, but it’s not quite what Santorum said. So I was hoping for your take on Santorum’s reading on your analysis — how accurate is it?

I have a lot of data about this. Here’s a quick data dump. I’m in the middle of something about this very subject, so don’t have time to compose. Tell me what more you’d like. I can provide links and cites for all of this. I work late, so deadlines are not a problem.

There have been many surveys seeking to determine the consensus of scientists and the subgroup of climate scientists (neither group having a clear definition) about the headline attribution statements of the IPCC. That is, how much of the warming since 1950 is attributed to us.  The IPCC states its findings in two parts: the finding, and the IPCC’s confidence in that finding. The latter is off little relevance to science, but obviously of great importance when taking public policy action. For example, it’s nice to know that all scientists believe “X”, but what if they have little confidence in that belief?

The standard measure of confidence is 95% (defining what this means is both complex and controversial, especially now with the replication crisis). The IPCC defines 90%+ as “very likely” and 95%+ as “extremely likely”.

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