Six hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century

MORALES, M.S; COOK, E.R; BARICHIVICH, J; CHRISTIE, D.A.; VILLALBA, R.; LEQUESNE, C.; SRUR, A.M; FERRERO, E.M; GONZALEZ-REYES, A.; COUVREUX, F; MATSKOVSKY, V.; ARAVENA, J.C; LARA, A.; MUNDO, I.A; ROJAS, F.; PRIETO, M.R; SMERDON, J.E; BIANCHI, L.O; MASIOKAS, M.H; URRUTIA, R.; RODRIGGUEZ-CATÓN. M; MUÑOZ, A.A; ROJAS-BADILLA, M.; ALVAREZ CLAUDIO; LÓPEZ, L.; LUCKMAN, B.; LISTER, D.; HARRIS, I.; JONES, P.D.; WILLIAMS, P.; VELAZQUEZ, D.; ALISTE, D.; AGUILERA-BETTI, A.; MARCOTTI, E.; FLORES, F.; MUÑOZ, T.; CUQ, E.; BONINSEGNA, J. A.

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA

NATL ACAD SCIENCES

Lugar: Washington DC, USA; Año: 2020

0027-8424

South American (SA) societies are highly vulnerable to severe droughts and pluvials, but the absence of long-term climate observations across the continent prevents a complete understanding of the global processes that drive climatic variability in the region. The number and quality of climate sensitive tree-ring records in SA have significantly increased during the past few decades, now providing a robust network for assessing the range of hydroclimate variabilityduring the past several centuries. We combine 288 annually-resolved tree-ring chronologies with a self-calibrated Palmer Drought Severity Index (scPDSI) dataset to derive the South American Drought Atlas (SADA) over the continent south of 12ºS. The reconstructed gridded annual-maps of summer scPDSI from 1400-2000 CE are the most spatially complete estimates of SA hydroclimate to date, and regions of the reconstruction are shown match well the dry and wet events characterized by documentary evidence. The SADA is shown to characterize morewidespread severe droughts and extreme pluvials since the mid-20th century. Relating the SADA to the Australia-New Zealand Drought Atlas (ANZDA), sea surface temperatures and atmospheric pressures, we determine that the El Niño-Southern Oscillation and the Southern Annular Mode explain much of the occurrence of spatially extend droughts and pluvials over the SADA domainfor the past several centuries.