As the country sizzles from Phoenix to Las Vegas, scientists and environmentalists are saying, "I told you so."
Although it's hard to judge long-term trends from individual seasons, a study co-written by researchers at Columbia and Princeton universities confirms that long-term drought is already under way in the American Southwest — one that may last the rest of this century, if not longer.
These scientists attribute this new climatology in one of the fastest-growing regions of the United States to global warming.
"It's already on the way," said senior researcher and geophysicist Richard Seager of the Lamont-Doherty Earth Institute at Columbia University. "Even if we intervene, it will persist for a few more decades. It takes that long to respond."
Seager and his colleagues at Lamont-Doherty, and at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Lab at Princeton, looked at 19 different computerized climate models from around the world.
Similar to those used for weather forecasting, the models dated back to 1860 and projected to 2100. The models showed a marked increase in arid climate beginning around now and worsening through the current century.
The team reported its findings this year at the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, often called the supreme court of climate science. Its research was also published in April in the journal Science.
Temperatures 10-15 Degrees Higher
Today, temperatures climbed to 115 degrees in parts of Arizona and as high as 125 degrees in Baker, Calif. Power plants failed in the now week-old heat wave.
Meteorologists report that summer temperatures are running 10 to 15 degrees above normal in states like Utah and Nevada.
"It's dangerously hot," said Rob Smith, whose thermometer reached 104 degrees in the shade this morning at his Sonora Desert home in Arizona. "This is what global warming looks like."
As regional staff director of the Sierra Club, Smith has watched trees die of insect infestations and reservoirs for power and drinking water dwindle. For the second year in a row, fireworks were cancelled in Flagstaff near the Grand Canyon because of threat of fire.
The study predicts that the drought could be as severe as the Dust Bowl of the 1930s. Unlike historical droughts, this climate change seems linked to the overall warming of the oceans and atmosphere caused by rising greenhouse gases, according to the Columbia study.
The Colorado River is the "lifeblood" of the Southwest and supplies most of the water to the region. Its levels have dropped by about 15 percent. About 90 percent of its water is used for agriculture, but as the population swells, so will the need for drinking water.
A Million Moved to Southwest
Five of the 10 fastest-growing states are in the Southwest, and nearly 1 million newcomers moved to Arizona, Nevada, Texas, Utah and Texas last year, according to 2006 census data.
"It is certainly consistent with what scientists have projected," said Dan Becker, director of the global warming program at the Sierra Club. "We're certainly seeing worse drought in the Southwest as a harbinger of things to come."
The searing heat of the Southwest means people largely stay indoors and jack up their air conditioners. When they do go out, they drive everywhere, according to Becker.
"Running air conditioners is not a formula for sustainable living," said Becker. "It's not good news for the planet that people are choosing a lifestyle that is dependent on more energy."
If these scientists and their models are correct, severe drought could ignite conflicts over water that will have epic effects on development, immigration and even international politics.
"Being in the desert is unnatural," said Seager. "The whole Southwest is dependent on massive works of engineering, all of which were built assuming there would be more water available than there really is. How is that whole system going to stand up to this kind of stress? Who gets the water?"
Droughts as far back as the medieval period have devastated populations across the United States. During the medieval period, a series of megadroughts of multi-decadal length struck the West and one of these, at the end of the 13th century, has been linked to the demise of the Anasazi culture.
The Dust Bowl on the Plains in the 1930s and droughts in 1950s had catastrophic effects on agriculture, migration and employment. Since the recent drought of the 1990s and 2000s, the water levels in Nevada's Lake Mead and Arizona's Lake Powell are only half full.
Without smart growth and good planning, says Seager, a long-lasting modern drought could stretch water resources to the "point of social conflict."
Border and immigration conflicts could flare as drought in Mexico pushes thousands more poor, rural migrants into the United States looking for work. International treaties with that country may also be strained in the quest for water.
Lamont Doherty scientists said adjustments can be made to deal with the change, perhaps by withdrawing some land from production and by conserving water in urban areas. But green policies often collide with green backs.
"We like to think that a developed country can adjust to these things," said Seager. "But look at the catastrophic response to Katrina.That doesn't inspire confidence at all."