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Susceptibility of Colorado River basin to megadroughts in a warming climate. Dennis Lettenmaier Dept of Civil and Env Engineering, Univ of Washington April 9, 2009, Abrupt Climate Change Session, CCPP Meeting.
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Susceptibility of Colorado River basin to megadroughts in a warming climate Dennis Lettenmaier Dept of Civil and Env Engineering, Univ of Washington April 9, 2009, Abrupt Climate Change Session, CCPP Meeting • Multimodel averages over Colorado River basin, 19 IPCC AR4 GCMs, A2 emissions scenario • Drastic decline P-E by 2100 Model output courtesy Richard Seager Motivation: Will the Colorado River basin, and the U.S. Southwest more generally, transition to a permanent megadrought state over the next century, and what role will land-atmosphere feedbacks play relative to remote climate forcings if such changes occur?
Preliminary Results Precipitation Elasticity and Temp Sensitivity • Annual discharge at Lees Ferry, three models • Precipitation elasticities quite similar, temperature sensitivities vary • Composite seasonal runoff for the Colorado basin • 25% basin produces most (about 75%) runoff Seasonal Runoff
Next Steps Spatial Distribution of Temperature Sensitivities • Upper Colorado River basin VIC simulations: • Explore why in specific locations (red) increases in temperature result in increases in runoff • Implement the coupled WRF- VIC model over the NARCCAP domain to simulate 20th and 21st century GCM climate scenarios
