#2. Southeast U.S. Droughts

Water experts like to call drought the Rodney Dangerfield of natural disasters: It gets no respect. But the long dry that gripped much of the American Southeast this year is making everyone take notice. Normally verdant, Georgia and several neighboring states are suffering through their worst dry spell in recorded history. At one point the city of Atlanta, one of the fastest-growing metro areas in the U.S., had just three months of water left. As the drought worsened, it triggered a nasty legal fight between Florida, Georgia and Alabama over declining water supplies. The chief legacy of the 2007 drought will be this: It could well be water, not energy or oil, which finally constrains American growth.