This is fairly big news. Richard Tol, him of the freaky hair, and, to his credit, one of the first wave of economists to study the economics of climate change, has long argued that--until global warming pushed the planet's average temperature above the two degree C threshold proscribed by the IPCC as an acceptable upside limit--AGW's economic effects would be, when you combined all the local pluses and minuses, beneficial to the planet as as whole. After some fierce criticism from Bob Ward of the Grantham Research Institute on Climate Change and the Environment, Mr. Tol has admitted he was wrong: the economics of global warming start to suck before we reach the U.N.'s two degree maximum:
Good on Richard for issuing the correction. That's how science is supposed to work.
Update: First "this" above now goes through to full text of Tol's correction.