The Colorado River system supplies water to tens of millions of people and millions of acres of farmland, and has never experienced a delivery shortage. But if human-caused climate change continues to make the region drier, scheduled deliveries will be missed 60-90 percent of the time by the middle of this century, according to a pair of climate researchers at Scripps Institution of Oceanography, UC San Diego.
“All water-use planning is based on the idea that the next 100 years will be like the last 100,” said Scripps research marine physicist Tim Barnett, a co-author of the report. “We considered the question: Can the river deliver water at the levels currently scheduled if the climate changes as we expect it to. The answer is no.”
Even under conservative climate change scenarios, Barnett and Scripps climate researcher David Pierce found that reductions in the runoff that feeds the Colorado River mean that it could short the Southwest of a half-billion cubic meters (400,000 acre feet) of water per year 40 percent of the time by 2025. (An acre foot of water is typically considered adequate to meet the annual water needs of two households.) By the later part of this century, those numbers double.
The paper, “Sustainable water deliveries from the Colorado River in a changing climate,” appears in the April 20 edition of the journal Proceedings of the National Academy of Sciences.
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