Deserts in the American Southwest and around the globe are creeping toward heavily populated areas as the jet streams shift, researchers reported Thursday. The result: Areas already stressed by drought may get even drier. Satellite measurements made from 1979 to 2005 show that the atmosphere in the subtropical regions both north and south of the equator is heating up. As the atmosphere warms, it bulges out at the altitudes where the northern and southern jet streams slip past like swift and massive rivers of air. That bulging has pushed both jet streams about 70 miles closer to the Earth's poles....