Jose Luis, right, an illegal immigrant who was deported to Mexico, gets dressed as he and other deportees gather near the Nogales Port of Entry in Nogales, Sonora, Mexico, Wednesday, July 28, 2010. A report by a think tank released Wednesday, Sept. 1, 2010, says global warming will increase illegal migration into the United States across the Mexican border. (AP Photo/Jae C. Hong)

Photo by: Jae C. Hong

Jose Luis, right, an illegal immigrant who was deported to Mexico, gets dressed as he and other deportees gather near the Nogales Port of Entry in Nogales, Sonora, Mexico, Wednesday, July 28, 2010. A report by a think tank released Wednesday, Sept. 1, 2010, says global warming will increase illegal migration into the United States across the Mexican border. (AP Photo/Jae C. Hong)