Attribution of climatic changes over South America

DÍAZ, LEANDRO B.

Exeter

Workshop; WCRP EPESC/DCPP workshop on integrated attribution and prediction; 2023

Met Office Hadley Centre

Southern South America (SSA) is one of the regions of the world with the highest precipitation trends over the last 120 years. Southeastern South America (SESA), encompassing Uruguay, southern Brazil and the eastern portions of Argentina and Paraguay, has been affected by a large positive trend in austral summer precipitation. On the other hand, a significant negative trend in rainfall has been observed in the Southern Andes (SAn), encompassing the extratropical mountain region of Argentina and Chile. Despite the relevance of these trends for the region due to their impacts on regional socioeconomic activities, there are still open questions related to the attribution of them. For instance, IPCC AR6 WGI Ch.10 states that there is high confidence that SESA summer precipitation has increased and that anthropogenic forcing has contributed to the increase since 1950, but there is very low confidence on the relative contribution of each driver to the precipitation increase. The objective of this work is to assess the attribution to anthropogenic and natural forcings of the observed trends in austral summer precipitation in SSA using the Detection and Attribution Model Intercomparison Project (DAMIP) simulations from sixth phase of the Coupled Model Intercomparison Project (CMIP6).