Climate change impacts on an alpine watershed in Chile: Do new model projections change the story?

• We evaluate differences in CMIP3 and CMIP5 climate projections.
• We evaluate climate-attributed changes in the Mataquito river basin Chile, South America.
• The location of snow line will shift to higher elevations.
• Reduction in the number of days with precipitation falling as snow.
• Extreme precipitation and streamflow events expected to become more frequent in 21st century.

SummaryDue to global warming the climate of central Chile is expected to experience dramatic changes in the 21st century including declining precipitation, earlier streamflow peaks, and a greater proportion of precipitation falling as rain. We used 12-member ensembles of General Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phase 3 (CMIP3) and Phase 5 (CMIP5) to evaluate climate-attributed changes in the hydrology of the Mataquito river basin in central Chile, South America. Simulations using the Variable Infiltration Capacity (VIC) hydrology model indicate that a drier and warmer future will shift the location of snow line to higher elevations and reduce the number of days with precipitation falling as snow. Extreme precipitation and streamflow events are expected to become more frequent. Conversely, low flow conditions will intensify during the warm months. The changes in the mean of hydrologic states and fluxes by the end of the 21st century are statistically robust, whereas changes in the variance are not found to be statistically significant. Results of the ensembles for CMIP3 and CMIP5 are generally indistinguishable regarding projected impacts on hydrology.