Lake Mead could be dry by 2021

Research marine physicist Tim Barnett (right) and programmer/analyst David Pierce of the Climate, Atmospheric Science and Physical Oceanography (CASPO) division at Scripps Institution of Oceanography, UC San Diego. Click here for more information.

The Lake Mead/Lake Powell system includes the stretch of the Colorado River in northern Arizona. Aqueducts carry the water to Las Vegas, Los Angeles, San Diego, and other communities in the Southwest. Currently the system is only at half capacity because of a recent string of dry years, and the team estimates that the system has already entered an era of deficit.

“When expected changes due to global warming are included as well, currently scheduled depletions are simply not sustainable,” wrote Barnett and Pierce in the paper.

Barnett and Pierce note that a number of other studies in recent years have estimated that climate change will lead to reductions in runoff to the Colorado River system. Those analyses consistently forecast reductions of between 10 and 30 percent over the next 30 to 50 years, which could affect the water supply of between 12 and 36 million people.

The researchers estimated that there is a 10 percent chance that Lake Mead could be dry by 2014. They further predict that there is a 50 percent chance that reservoir levels will drop too low to allow hydroelectric power generation by 2017.

The researchers add that even if water agencies follow their current drought contingency plans, it might not be enough to counter natural forces, especially if the region enters a period of sustained drought and/or human-induced climate changes occur as currently predicted.

Lake Mead at Hoover Dam, October, 2007. According to Scripps researchers, Lake Mead could be dry by 2021 if climate changes as expected and future water usage is not curtailed. Click here for more information.

Barnett said that the researchers chose to go with conservative estimates of the situation in their analysis, though the water shortage is likely to be more dire in reality. The team based its findings on the premise that climate change effects only started in 2007, though most researchers consider human-caused changes in climate to have likely started decades earlier. They also based their river flow on averages over the past 100 years, even though it has dropped in recent decades. Over the past 500 years the average annual flow is even less.