The basic reason he jumped off, he explains is that the warmists' arguments just don't stack up. "The pieces of evidence ... just kept falling away," three pieces in particular [go and see what they are]. "There is now no observational evidence that global warming is caused by carbon emissions," says Evans, who suggests we look at "the interaction between science and politics," and at a crucial change in both at about the turn of the century.
By 2000 the political system had responded to the strong scientific case that carbon emissions caused global warming by creating thousands of bureaucratic and science jobs aimed at more research and at curbing carbon emissions.
But after 2000 the case against carbon emissions gradually got weaker. Future evidence might strengthen or further weaken it. At what stage of the weakening should the science community alert the political system that carbon emissions might not be the main cause of global warming?
...the cause of global warming is not just another political issue, subject to endless debate and distortions. The cause of global warming is an issue that falls into the realm of science, because it is falsifiable. No amount of human posturing will affect what the cause is.