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The last drop: climate change and the southwest water crisis

Frank Ackerman, Elizabeth A. Stanton / Published on 10 February 2011

Ackerman, F., and Stanton, E.A. (2011). The last drop: climate change and the southwest water crisis. SEI-U.S. report, funded by the Kresge Foundation.

Rings on the water

Rings on the water

Water is already a major concern in the Southwest, where homes, businesses and farms use far more water than is produced by rain and snowfall, and groundwater reserves are shrinking.

This study quantifies the impact of climate change on the problem. It finds that without prompt action to reduce water usage, Arizona, California, Nevada, New Mexico, and Utah will face a combined shortfall of 1,815 million acre feet from population and income growth alone, plus 282 million to 439 million more from climate change – at a combined cost of as much as $5 trillion.

And that’s if the shortfall can be made up at all. As conventional water sources dry up, the Southwest could find itself facing serious water crises in dry years, with unexpected disruptions that could devastate agriculture and affect homes and businesses as well.

“Climate change is affecting Americans in many areas; the water crisis in the Southwest is one of the clearest examples,” said Frank Ackerman, director of the Climate Economics Group at SEI-U.S. and lead author of the study. “Climate policy choices we make today are not just about exotic environments and far-future generations – they will help determine how easy or hard it is to create a sustainable water system in the most arid region of the country.”

The authors also evaluate potential ways to meet the shortfall, including water imports, desalination and additional groundwater extraction, and conclude that none can solve the problem. To avoid serious water crises, they recommend, the Southwestern states should promptly implement substantial conservation and efficiency measures as well as price increases for both urban and agricultural users. They also advise phasing out low-value crops, some of which are worth less than the water used to grow them.

This report is part of a package that also includes California Water Supply and Demand: Technical Report and The Water-Energy Nexus in the Western States: Projections to 2100.

Download the report (pdf, 906kb)


Note: A citation was corrected in this document on Feb. 22, 2011.

In the Media:

“Economists: Smarter Water Use by Farmers Key to Solving Southwest Water Woes,” by Brendon Bosworth, New West Development, March 8, 2011.
“Report: Southwest water use surpasses supplies,” by Staci Matlock, The New Mexican (Santa Fe, NM), Feb. 18, 2011.
“The Central Valley’s Giant Sucking Sound,” by Craig Miller, KQED (San Francisco, CA, public radio) Climate Watch blog, Feb. 13, 2011.
“Southwestern Water: Going, Going, Gone?” by Felicity Barringer, Green blog,, Feb. 11, 2011.
“Climate Change to Worsen Severe Water Shortages in US Southwest,” by Brian Merchant, Treehugger, Feb. 11, 2011.
“Will warming worsen state water crisis?” by Pat Brennan, The Orange County Register (CA), Feb. 11, 2011.
“Southwest’s water usage must change, or region faces severe shortages – report,” by Debra Kahn, ClimateWire (subscription required), Feb. 11, 2011.
“Climate: A New Study Finds That Global Warming Could Dry Out the Southwest,” by Bryan Walsh, Ecocentric on, Feb. 10, 2011.
“Longterm water projections dismal for Southwest,” by Mike Lee, The San Diego Union-Tribune, Feb. 10, 2011.
“Study suggests water in southwestern U.S. may dry up sooner than expected,”by Eric English, ABC-15 Phoenix, Feb. 10, 2011.

Frank Ackerman and Liz Stanton also wrote an opinion article based on the report:
“Securing enough water will challenge Southwest,” The Arizona Republic, Feb. 12, 2011.
“Viewpoints: Changing climate will make coming water crisis even worse,” The Sacramento Bee (CA), Feb. 11, 2011.

Another article on the report, by Frank Ackerman, appeared March 1, 2011, on the TripleCrisis blog and was reprinted on Grist and Truthout, among others.

In addition, “The Costs of Inaction: Southwest Water Crisis,” an article based on The Last Drop and The Water-Energy Nexus, appeared Feb. 24, 2011, on the RealClimateEconomics blog.

Selected blog coverage:

“Water shortages: Act before the river runs dry,” by Marc Albert, Understanding Government, Feb. 15, 2011.
“Report Warns of Worsening Western Water Crisis,” by Andrew Freedman, Climate Central, Feb. 14, 2011.
“Drying Out in the West,” by Hillary Rosner, Tooth and Claw, PLoS Blogs, Feb. 14, 2011.
“Studies predict water shortfall in Southwest,” Freshwater Society blog, Feb. 14, 2011.
“Running out of water,” by John Fleck, jfleck at inkstain (NM) blog, Feb. 13, 2011.
“Study of Climate Change Impacts on Water Shortages in U.S. Southwest,”Climate Change Attorney Blog, Feb. 12, 2011.
“Is the Southwest on Borrowed Time?” by Keith Kloor, Collide-a-scape, Feb. 11, 2011.
“Changing climate will make coming water crisis even worse, says commentary,” Aquafornia: The California Water Blog, Feb. 11, 2011 (one of several posts on the report on this blog).

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