Andean drought and glacial retreat tied to Greenland warming during the last glacial period

Arielle Woods,Joseph S Stoner,Sophie B Lehmann,Christine Y Chen,Donald T Rodbell,Pedro M Tapia,Blas L Valero-Garcés,Robert G Hatfield,Mark B Bush,Nicholas C Weidhaas,Mark B Abbott,David Mcgee

doi:10.1038/s41467-020-19000-8

Abstract

Abrupt warming events recorded in Greenland ice cores known as Dansgaard-Oeschger (DO) interstadials are linked to changes in tropical circulation during the last glacial cycle. Corresponding variations in South American summer monsoon (SASM) strength are documented, most commonly, in isotopic records from speleothems, but less is known about how these changes affected precipitation and Andean glacier mass balance. Here we present a sediment record spanning the last ~50 ka from Lake Junín (Peru) in the tropical Andes that has sufficient chronologic precision to document abrupt climatic events on a centennial-millennial time scale. DO events involved the near-complete disappearance of glaciers below 4700 masl in the eastern Andean cordillera and major reductions in the level of Peru’s second largest lake. Our results reveal the magnitude of the hydroclimatic disruptions in the highest reaches of the Amazon Basin that were caused by a weakening of the SASM during abrupt arctic warming. Accentuated warming in the Arctic could lead to significant reductions in the precipitation-evaporation balance of the southern tropical Andes with deleterious effects on this densely populated region of South America.

Highlights

Abrupt warming events recorded in Greenland ice cores known as Dansgaard-Oeschger (DO) interstadials are linked to changes in tropical circulation during the last glacial cycle
South American low-latitude paleoclimate proxy records are sensitive to high-latitude forcing via the strength of the South American summer monsoon (SASM), which increased during cold stadial periods such as Heinrich events[4,5,6,7], and weakened during the abrupt warmings recorded in Greenland ice cores associated with Dansgaard–Oeschger (DO) interstadials[5,8,9]
We show that the DO interstadials between 50 and 15 ka, which are recorded isotopically both in Greenland ice[20,21] and speleothem δ18O from Pacupahuain Cave in the upper Amazon Basin[5], were associated with rapid and large reductions in Andean precipitation amount recorded by multiple independent proxies in Lake Junín sediments

Summary

Introduction

Abrupt warming events recorded in Greenland ice cores known as Dansgaard-Oeschger (DO) interstadials are linked to changes in tropical circulation during the last glacial cycle. We show that the DO interstadials between 50 and 15 ka, which are recorded isotopically both in Greenland ice[20,21] and speleothem δ18O from Pacupahuain Cave in the upper Amazon Basin[5], were associated with rapid and large reductions in Andean precipitation amount recorded by multiple independent proxies in Lake Junín sediments.

Results

Conclusion