Runoff sensitivity to global mean temperature change in the CMIP5 Models

We estimated runoff sensitivities to global mean temperature change using climate experiments archived in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and compared with the similar CMIP3 results. We also evaluated differences in runoff sensitivity for the Earth System Models (ESMs) and Climate System Models (CSMs), which were separately identified in CMIP5 for the first time. Our results show that runoff sensitivity is relatively independent of emission scenarios in CMIP5, as in CMIP3 results. Global mean runoff would increase about 2.9% per degrees C of global warming in CMIP5, as contrasted with 1.9% in CMIP3. Although global runoff sensitivity patterns for CMIP5 and CMIP3 are roughly similar, CMIP5 suggests significant declines (increases) in runoff sensitivity over 17% (25%) of the global land area relative to CMIP3. Globally, the ESMs and CSMs have about the same model spread in runoff change projections.