Misconceptions and mislabellings
Nov 16, 2015
Bishop Hill in Climate: other, Economics, Matt Ridley

So, some minor brouhaha this morning over Roger Harrabin's piece about Richard Tol this morning. In it, Richard is quoted as follows:

Prof Richard Tol predicts the downsides of warming will outweigh the advantages with a global warming of 1.1C - which has nearly been reached already.

This is contrasted with Matt Ridley, quoted as follows:

Matt Ridley, the influential Conservative science writer, said he believed the world would probably benefit from a temperature rise of up to 2C.

And if you refer to the transcript, which Roger has helpfully made available at Joe Smith's Climate Creativity site (!) you can read this:

RH: I mean I’m intrigued on this because other contrarians are talking about, ‘Oh well, we’ll have benefits up to two Celsius.’ Matt Ridley, for instance, says, ‘Oh, anything up to two Celsius of warming, the earth will probably benefit.’ Do you disagree with that? [CB: Matt Ridley and Richard Tol are both advisors to the Global Warming Policy Foundation, a climate skeptic lobby group based in the UK]

RT: I think that’s a bit too optimistic, yes.

RH: But I think he references you in order to make that conclusion.

RT: All sorts of people put all sorts of things in my mouth. I would not hold it against Matt Ridley. I mean compared to what other people have put in my mouth, Matt is actually a good guy.

I get the impression that Richard has subsequently thought about this and has realised where this misunderstanding arises.

Ridley and I agree if you insert the word "incremental" before my "impact", as accidentally omitted by @RHarrabin https://t.co/Sj3dse8Iki

— Richard Tol (@RichardTol) November 16, 2015



Take a look at the well-known Figure 1 from Richard's 2009 paper.

As you can see, Matt is talking about where the line crosses zero again, and Richard about the maximum. So no, there's not really a difference of opinion here at all. Indeed Richard has said that he misspoke...


then I misspoke -- I referred to incremental impacts, rather impacts https://t.co/O6YzPz1lIC

— Richard Tol (@RichardTol) November 16, 2015

This is a bit unfortunate for Roger, who has an article under his byline describing a difference of opinion between Matt and Richard that doesn't actually exist. You can see why he would have written what he did though.  It's a bit of a car crash really. A lot of correction of the record is going to be required.

But there's one other wrinkle here that bears looking at. Just read the first sentence of the caption [emphasis added].

Figure 1 shows 14 estimates of the global economic impact of climate change, expressed as the welfare-equivalent income gain or loss, as a function of the increase in global mean temperature relative to today.

So how does this equate to the "nearly reached" in Roger's article? Is the caption wrong? I'm confused.

[Update: In the comments, ATTP says that the figure caption has been amended in a correction to "relative to preindustrial"]

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