As reported in the Telegraph, President Obama’s energy advisor has suggested we paint roofs white to help reflect the sun’s energy back toward space, while saving on air conditioning bills.  This could help reduce global warming, although a dark roof in winter saves on the heating bill, which saves on electricity production, which helps reduce global warming.  It is likely a white roof has greater benefit, but it probably depends upon where one lives.

How about a means of having roofs be light or white in summer, and black or dark in winter?  This idea has been suggested before, including here.

Note also that efforts are underway (as reported here) on  highly reflective roofing coatings of different non-white colors, which it is presumed people with slanted roofs would prefer for aesthetic reasons.