Mariah: I work for a publishers purchase erectinol Another key area of conjecture is what is known as ''climate sensitivity'': the expected warming that would come from doubling the concentration of carbon dioxide in the atmosphere. The 2007 report projected that this would increase temperatures by between 2 degrees and 4.5 degrees. Drafts of the new report drop the lower end of that range to 1.5 degrees, but maintain the 4.5 degrees high end.