Reply #2: He's right - sort of

[Waistdeep]

It's true that a dark roof reflects less visible light than a light roof. It heats up more and emits more infrared radiation which is absorbed by the various greenhouse gases. The overall reflectivity of the earth is called the albedo and is definitely lowered by dark roofs ( as opposed to a roof made out of mirrors, for example).

HOWEVER, I expect that the overall effect is pretty damn small. Where's my envelope, I need to do a calculation........

The Bushco solution will be to make sure there are fewer roofs.