The western United States is warming nearly twice as fast than the average global rate, according to a new synthesis study by the Rocky Mountain Climate Organization.

A review of 50 published scientific papers concludes that while the global average increase is around 1 degree C over the past five years, the West is now 1.7 degrees hotter. Inland Western states, such as Arizona, Utah, and Montana, have warmed as much as 2 degrees C, while coastal states have only gained 1.1 degree C.

The trend is expected to accelerate in the future, with the West warming at 1.5 times the global average rate. While snowpack in the Rocky Mountains is at normal levels, that snowpack is expected to melt as much as two weeks earlier than in the past.

A region known for its tenuous water supplies, extreme aridity, and total dependence on the dams that control its rivers to support its cities and agriculture, the West is intimately tied to the climate, and disproportionately affected by global warming.

For most of the West, climate change is not just a meaningless idea or a removed abstraction. Lakes Powell and Mead are below 50 percent of their normal capacity, due to a record drought. Those reservoirs supply a lion's share of the water consumed by Phoenix, Los Angeles, San Diego, Tucson, and Las Vegas -- some of the fastest-growing cities in America.

The Colorado River and other Western rivers are running at abnormally low rates of flow, threatening water supplies to irrigate the Central Valley of California, the source of one third of the fresh produce consumed in the US. As the Ancestral Puebloan and Hohokam cultures might tell us were they still extant, drought and climate change can spell doom for a desert culture, and the cities of the West today are desert cultures no less than the pueblo-builders who came before. Let's hope we don't make the same mistakes they did.