A paddle wheeler and a small motorboat sail on Lake Mead, North America's largest man-made reservoir. The water is at its lowest level since the Hoover Dam was built in the 1930s. The white "bathtub ring" of mineral deposits on the rocks marks past water levels. (Photograph by Ethan Miller, Getty Images)
Large parts of the U.S. are in for a drought of epic proportions in the second half of this century, scientists warn in a new study that provides the highest degree of certainty yet on the impact of global warming on water supplies in the region.
The chances of a 35-year or longer "megadrought" striking the Southwest and central Great Plains by 2100 are above 80 percent if the world stays on its current trajectory of greenhouse gas emissions, scientists from NASA, Columbia University, and Cornell University report in a study published Thursday in the new open-access journal Science Advances.
If countries reduce their emissions to current "middle of the road" targets, the chances of a megadrought hitting the Great Plains drop to between 60 and 70 percent. But they remain nearly 80 percent for the Southwest.
National Geographic - see link below