#Arizona starts talks on addressing dwindling #ColoradoRiver — The Rock Springs Rocket-Miner #COriver #aridification

From The Associated Press (Felicia Fonseca) via The Rock Springs Rocket-Miner:

Arizona is getting a jump start on what will be a yearslong process to address a dwindling but key water source in the U.S. West…

Arizona water officials are gathering Thursday to start talking about what comes next, while other states have had more informal discussions.

Meanwhile, the U.S. Bureau of Reclamation is reviewing the effectiveness of the 2007 guidelines. The report is expected later this year.

Climate change is causing the Southwest aridify. (Left) Since the 1930s, increasing temperatures have caused the percentage of precipitation going to evapotranspiration (ET) to increase at the expense of precipitation going to Colorado River flow, resulting in an unprecedented and still ongoing megadrought (shading) starting in 1999 (8). (Right) Higher temperatures have already reduced Colorado River flow by 13%, and projected additional warming, assuming continued high emissions of greenhouse gases, will increase ET while reducing river flow even more through the 21st century. Data on Left are 20-y running means from ref. 5, and data on Right are calculated from Representative Concentration Pathways (RCP) 8.5 multimodel Coupled Model Intercomparison Project–Phase 5 (CMIP5) ensemble temperature increases projected for the Upper Colorado River Basin combined with temperature sensitivity of −9.3%/°C estimated by ref. 5, assuming no change in precipitation. Graphic credit: Jonathan Overpeck/Brad Udall

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