Actually, I do believe that the book was either co-authored by Robert Silverburg, or written entirely by him based off Issac Asimov’s short story. Probably the latter. Either way it was an awesome story and well written.
Um, no. Suns. Small suns, but suns nonetheless.
Epimetheus is correct: it was a short story by Asimov that was later re-written by Robert Silverberg with Asimov as a full-length novel.
Considering the size of the Earth’s population and the rythm it is increasing a greenhouse effect could possibly create famine in a scale unseen before.
Breakdown in international commerce and banking could lead to drastic drops in GDPs and subsequent riots, poverty and disaster that could be "tagged" dark ages if compared to our present moment. A major stockmarket bubble burst followed by a massive 1928 style market crash could do quite some damage to "civilization".
Bush getting reelected for me sounds ominous enough to give the present moment the name dark ages too.