claim: His best estimate is that the  warming in response to a doubling of CO2 concentration, which may happen  this century unless the usual suspects get away with shutting down the  economies of the West, will be a harmless 1 Fahrenheit degree, not the 6  F predicted by the IPCC.
evidence: The 1990 IPCC First Assessment Report estimated that equilibrium climate sensitivity to a doubling of CO 2 lay between 1.5 and 4.5 °C ( 2.7 and 8.1 °F ), with a best guess in the light of current knowledge of 2.5 °C ( 4.5 °F ).