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: In his first paper on the matter, he estimated that global temperature would rise by around 5 to 6 °C ( 9.0 to 10.8 °F ) if the quantity of CO 2 was doubled.