Another entertaining episode in the hearings this morning was where Mark Walport was asked about Matt Ridley's suggestion that global warming would bring net benefits over 40-50 years. This conclusion is based on Richard Tol's metaanalysis of mainstream economic studies into such questions (see key figure below).
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.
I wonder if Walport has any actual evidence to support his position that Ridley is wrong. The words read like our chief scientist substituting name-calling for a lack of evidence.
In the comments, Matt Ridley reveals that he has written to Walport, who is signally failing to substantiate his remarks.