By Paul Homewood
h/t Bishop Hill
Mark Walport, the government’s chief scientist and expert in immunology, has been submitting evidence to the Energy & Climate Change Select Committee. Asked about Matt Ridley’s view, (backed up by Richard Tol’s analysis), that global warming would bring net benefits over the next 40-50 years, he replied:
I understand the point [Ridley] is trying to make but I think he’s completely wrong unfortunately. While there might be trivial benefits in some parts of the world for some of the time the long term direction for all of us is a negative direction. And frankly I think he is…he described himself as a “rational optimist”. I’m not sure about the rational bit.
He has obviously forgotten what proper scientists were saying during the 1970’s, after three decades of cooling.
Scientists like Walter Orr Roberts, atmospheric physicist and first director of NCAR, the National Center for…
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CraigM350 
Do you really think Walport is ignorant? Ridley seems to base his optimism on Richard Tol’s work, specifically on a graph shown on the Bishop Hill page you linked to. In the graph (Tol’s figure 1 from http://www.econstor.eu/bitstream/10419/50039/1/584378270.pdf), the benefit from rising temperatures is seen to go up, peaking at around 1C and then down thereafter. You’ll see that there 14 ‘observations’, two at 1C, two at 3C and the rest at 2.5C. Only 3 of the 14 are above zero (ie. net positive impact) and the rest negative. The rising and then falling shape of the curve is determined almost entirely by the single data point at 1C, showing an impact of +2.3% of GDP. Guess who wrote the study responsible for that one point – right, Richard Tol. If you ignore Tol’s 2005 study and re-plot the curve, the result would be almost entirely negative. Would you accept the conclusion of any other climate related study (or any study for that matter) if that conclusion relied on just one data point? Acceptance of the curve comes down to the question of whether Tol’s 2002 study correct.
I wonder whether Ridley did more than glance at that curve. It is remarkably weak evidence upon which to argue for 40 years net benefit.
So Walport, far from being ignorant, shows that he knows rather more about the basis of Ridley’s optimistic prediction than Ridley himself.
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