Painting roofs (or even all man-made surfaces) white wouldn't do much globally at all, but it might reduce the urban heat island effect. But probably (speculati

Painting roofs (or even all man-made surfaces) white wouldn't do much globally at all, but it might reduce the urban heat island effect. But probably (speculating a bit here) not quite so much as creating more green spaces (or green roofs, for that matter).