Science Source

Anthropogenic and natural contributions to the Southeast Pacific precipitation decline and recent megadrought in central Chile

States that the Southeast Pacific drying stands out as a robust signature within climate models, within large uncertainties in the precipitation response to greenhouse gas forcing
States there has been an observed decline in precipitation in central Chile since the late 1970s of consistent direction but of larger amplitude than obtained in simulations with historical climate forcing
To attribute the causes of this trend, this study analyzes local rain gauge data and contrasts them to a large ensemble of both fully coupled and sea surface temperature-forced simulations It shows that in concomitance with large-scale circulation changes, the Pacific Decadal Oscillation explains about half of the precipitation trend observed in central Chile
Finds that the remaining fraction is unlikely to be driven exclusively by natural phenomena but rather consistent with the simulated regional effect of anthropogenic climate change
Estimates that a quarter of the rainfall deficit affecting this region since 2010 is of anthropogenic origin
Finds an increased persistence and recurrence of droughts in central Chile emerges then as a realistic scenario under the current socioeconomic pathway