The study predicts that precipitation would quadruple in the tropical Pacific, while it would be reduced by up to third in the Americas and a factor of two over parts of Australia, the Mediterranean, southern Africa, and the Amazon.
Allen says not only could tropical rain forest systems collapse, but drought in southern Europe and the United States would be "completely catastrophic for agriculture." Wealthy nations might maintain food supply, but not places like southern Africa. "A lot of people would have to leave, or a lot of people would die," Allen says.