LOS ANGELES, March 27 (Reuters) - The U.S. West is heating up at nearly twice the rate of the rest of the world and is likely to face more drought conditions in many of its fast-growing cities, an environmental group said on Thursday.

By analyzing federal government temperature data, the Natural Resources Defense Council concluded that the average temperature in the 11-state Western region from 2003-07 was 1.7 degrees Fahrenheit (0.94 degrees Celsius) higher than the historical average of the 20th century.

The global average increase for the same period was 1.0 degrees Fahrenheit (0.55 degrees Celsius).

In the Colorado River Basin, which supplies water to big and fast-growing cities like Los Angeles, San Diego, Las Vegas and Denver, the average temperature rose 2.2 degrees Fahrenheit (1.21 degrees Celsius), the U.S. group said.

Most of the river's water comes from melting snow in the mountains, and climate scientists predict hotter temperatures will reduce the snowpack and increase evaporation, the NRDC said in a statement.

"Global warming is hitting the West hard," said Theo Spencer of the NRDC. "It is already taking an economic toll on the region's tourism, recreation, skiing, hunting and fishing activities."

Study author Stephen Saunders of the Rocky Mountain Climate Organization said there were signs of the economic impacts throughout the West.

"Since 2000 we have seen $2.7 billion in crop loss claims due to drought. Global warming is harming valuable commercial salmon fisheries, reducing hunting activity and revenues, and threatening shorter and less profitable seasons for ski resorts," he said.

The report is available online at www.nrdc.org/globalWarming/west/contents.asp. (Reporting by Mary Milliken; Editing by Bernie Woodall)

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