"By far the most important debate about climate change is taking place among scientists, on the issue of climate sensitivity..."

"How much warming will a doubling of atmospheric carbon dioxide actually produce?"

The conclusion... is this: A doubling of CO2 will lead to a warming of 1.6°-1.7°C (2.9°-3.1°F).

This is much lower than the IPCC's current best estimate, 3°C (5.4°F)....

A cumulative change of less than 2°C by the end of this century will do no net harm. It will actually do net good... Rainfall will increase slightly, growing seasons will lengthen, Greenland's ice cap will melt only very slowly, and so on.

The difficulty has to do with water evaporating from the warmed up seas, and the way water vapor counts greenhouse gas. But how does it count? We're talking about clouds, and clouds also have cooling effects.