biostudies-literatureMorales MSChilean Research CouncilBNP Paribas | Fondation BNP ParibasConsejo Nacional de Investigaciones Científicas y TécnicasMINCyT | Agencia Nacional de Promoción Científica y TecnológicaRussian State Assignment ProjectFondo Nacional de Desarrollo Cientifico, Tecnologico y de Innovacion Tecnologica, PerúInter-American Institute for Global Change ResearchNational Agency for Research and Development ChileNational Science Foundation16816-16823https://www.ebi.ac.uk/biostudies/studies/S-EPMC7382209biostudies-literatureUnknown117(29)South American (SA) societies are highly vulnerable to droughts and pluvials, but lack of long-term climate observations severely limits our understanding of the global processes driving climatic variability in the region. The number and quality of SA climate-sensitive tree ring chronologies have significantly increased in recent decades, now providing a robust network of 286 records for characterizing hydroclimate variability since 1400 CE. We combine this network with a self-calibrated Palmer Drought Severity Index (scPDSI) dataset to derive the South American Drought Atlas (SADA) over the continent south of 12°S. The gridded annual reconstruction of austral summer scPDSI is the most spatially complete estimate of SA hydroclimate to date, and well matches past historical dry/wet events. Proceedings of the National Academy of Sciences of the United States of AmericaSix hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century.PMC7382209AGS-16025810148-2019-0004ANID/PAI/77190101ANID/FONDAP/15110009GEO-0452325AGS-1805490CRN03; CRN027PICT2013-1880PIP11220130100584OISE-1743738FONDECYT-BM-INC.INV 039-20191161381; 1201411; 1181956 and 11161061THEMES projectGonzalez-Reyes AWilliams APBoninsegna JALeQuesne CFerrero MEMorales MSBianchi LOFlores FMasiokas MHAliste DUrrutia-Jalabert RLopez LCouvreux FMatskovsky VLister DLara AAguilera-Betti ISmerdon JEVelazquez GCook ERChristie DARodriguez-Caton MSrur AMAravena JCRojas-Badilla MCuq ERojas FPrieto MRVillalba RMunoz TAlvarez CBarichivich JLuckman BHMarcotti EMunoz AAMundo IAHarris IJones PDfalseSix hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century.South American (SA) societies are highly vulnerable to droughts and pluvials, but lack of long-term climate observations severely limits our understanding of the global processes driving climatic variability in the region. The number and quality of SA climate-sensitive tree ring chronologies have significantly increased in recent decades, now providing a robust network of 286 records for characterizing hydroclimate variability since 1400 CE. We combine this network with a self-calibrated Palmer Drought Severity Index (scPDSI) dataset to derive the South American Drought Atlas (SADA) over the continent south of 12°S. The gridded annual reconstruction of austral summer scPDSI is the most spatially complete estimate of SA hydroclimate to date, and well matches past historical dry/wet events. 2020-01-01T00:00:00Z2020 Jul2025-04-05T15:19:08.053Z2025-04-05T15:19:08.053ZS-EPMC73822093263200310.1073/pnas.2002411117