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Coverage from around the web: Study says drought & global warming in the Western U. S. are man-made

Posted by: Aqua Blog Maven on January 31, 2008 at 5:09 pm

From National Geographic News:

The U.S. West will see devastating droughts as global warming reduces the amount of mountain snow and causes the snow that does fall to melt earlier in the year, a new study says. By storing moisture in the form of snow, mountains act as huge natural reservoirs, releasing water into rivers long into the summer dry season. “We’re losing that reservoir,” said research leader Tim Barnett, an oceanographer and climate researcher at the University of California, San Diego.

“Spring runoff is getting earlier and earlier in the year, so you have to let water go over the dams into the ocean.” Summers are also becoming hotter and longer. “That dries things out more and leads to fires,” Barnett added.

“Our results are not good news for those living in the western United States,” the scientists write in their report, which appears in today’s online edition of the journal Science.

But wait a minute, some of you are thinking, there’s so much snow this year! Whatever do you mean?

Those findings may come as a surprise this year, when the West is getting so much snow that skiers and snowmobilers are dying in avalanches in places that normally don’t get that much snow. But that doesn’t mean the future won’t see significantly less snowfall. “We’ll still have wet years and dry years,” Barnett said. “People have a problem distinguishing weather events and things that happen on a long scale. … It’s important to think of climate on time scales of a decade or more.”

Sadly, he said, residents of states like California, Utah, and Arizona are in line for some rude surprises. “Global warming is an abstraction to most people,” he said. “Well, the people who live in the West, if they haven’t already, are going to very shortly find out what global warming really means to them.”

Barnett predicts a crisis in water management that will require not only government action but individual sacrifices.

To read the full text of this story from National Geographic News, click here.

The National Geographic News article does see some positives in climate change, and the Pacific Institute’s Peter Gleick does as well, in this article from the New Scientist:

Hopes that the drought is temporary have been dashed by the analysis, prompting leading researchers to intensify their calls for policy change.

Peter Gleick, a water policy expert at the Pacific Institute, an independent think tank based on Oakland, California, says that water use in his state could be reduced by a fifth by 2030, even if the population and economy continue to grow.

Many sectors need to change to achieve that goal. Agriculture would have to shift towards drip irrigation, in which small amounts of water are focused on individual plants, rather than whole areas being sprayed. Home owners would also have to adopt toilets and washing machines that use less water, he says.

Gleick is cautiously optimistic about the chances about the willingness of politicians to make the necessary changes. New standards for water-saving toilets were adopted in 2007, for example. “We can do the things we want for less water,” he says. “But we need more federal and state legislation.”

To read the full text of the article from New Scientist, click here.

From Wired News, which is also reporting on the same study:

The new research comes as Western states are already struggling to supply water for both their farms and cities. Increased migration to the water-poor regions of the Southwest into cities like Los Angeles, Phoenix and Las Vegas has increased the amount of water necessary to support the rising U.S. population. With such a constrained supply and rising demand, the cost of water is likely to rise, experts said. Some California farmers, responding to a record water shortage, are even beginning to consider selling their water rights, instead of their crops.

Barnett’s team worked with climate models to simulate the impact of greenhouse gases on the Western water cycle. If their models for the future prove as accurate as their modeling of the past, the paper predicts unprecedented water shortages.

“We’re already at a level that can’t be sustained,” said Barnett. “Climate models show there will be less water supply while we continue to grow more cities out in the desert.”

Under the new conditions, what to do with the water we do have will become increasingly important, said Erik Straser, a partner at the venture capital firm Mohr Davidow Ventures, a firm that invests in clean technologies.

“Four out of five gallons of water go to agriculture,” Straser said. “We have to make hard choices and the choices are going to be between agriculture and people.”

To read the full text from Wired News, click here.

The U.K.’s Nature.com adds this:

“What they’ve got is quite scary,” comments Ian Cluckie, a hydrologist at the University of Bristol, UK. The trend looks likely to make water shortages even more severe for residents of southern California, Arizona and New Mexico, he says. These naturally arid regions already receive a lot of their water by ‘north–south transfer’ — careful manipulation of water flow through damming and aquifer management — from wetter regions to the north, Cluckie says. “This area only survives by major water transfer and it’s going to get much, much worse,” he adds.

Just how much worse is difficult to say. Much of the rainfall in the region occurs through thunderstorms and these are too localized to be predicted accurately by climate models, which are usually organized in grids with squares several hundred kilometres across.

Other regions likely to suffer similar problems include the entire area surrounding the Mediterranean Sea, and the southern parts of Africa, says Chris Milly, of the US Geological Survey. Syria, for example, looks set to suffer a more than 40% drop in freshwater runoff by 2050, according to computer models based on IPCC emissions predictions (see Map).

To read the rest of this story from Nature.com, click here.

January 31, 2008 · Filed Under Climate change & water supply

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