CONICET | Buscador de Institutos y Recursos Humanos

Due to their heavy dependence on naturalresources, the South American societies are highly vulnerable to severedroughts and pluvials. However, the absence of a complete spatial coverage oflong-term climate observations across the continent prevents the modeling and predictionof the dynamical processes that drive its complex spatiotemporal climaticvariability. Herein, we combine 290 annually-resolved tree-ring chronologieswith gridded self-calibrated Palmer Drought Severity Index (scPDSI) to derive aSouth American Drought Atlas (SADA) over the continent south of 12ºS. The SADAprovides spatially-gridded (0.5° x 0.5°) annual maps of summer (DJF) moisture from1400 to 2000 CE, and indicates that severe droughts have become more spatiallywidespread since the mid-20th century. Maximum-shared covariance between thereconstructed scPDSI from the combined SADA-ANZDA (Australia-New ZealandDrought Atlas) with sea surface temperatures and atmospheric pressures suggest that ENSO and SAM largely explain mostextreme hydroclimate variability in the Southern Hemisphere over the past 500years. The SADA provides the spatio-temporal context for recentdrought/pluvial variability, information critically needed for benchmarking climatemodels and predictions.