SAN DIEGO, Feb. 13 (UPI) -- U.S. scientists have issued an urgent warning that Lake Mead, which supplies water to millions of people in southwestern states, might be dry by 2021.

LIVERMORE, Calif., Feb. 1 (UPI) -- California scientists said humans are to blame for diminishing water flow in the western United States.

WASHINGTON, Jan. 31 (UPI) -- Computer modeling suggests the decline in the snowpack in the Western United States is caused by global warming, scientists said Thursday.

BOULDER, Colo., June 6 (UPI) -- New research shows clear evidence of human-produced warming in the oceans and verifies some of the most important predictions of climate models, suggesting it is time for action instead of argument about the existence of greenhouse warming.