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Oceanic and Radiative Forcing of Medieval Megadroughts in the American SouthwestMultidecadal "megadroughts" were a notable feature of the climate of the American Southwest over the Common era, yet we still lack a comprehensive theory for what caused these megadroughts and why they curiously only occurred before about 1600 CE. Here, we use the Paleo Hydrodynamics Data Assimilation product, in conjunction with radiative forcing estimates, to demonstrate that megadroughts in the American Southwest were driven by unusually frequent and cold central tropical Pacific sea surface temperature (SST) excursions in conjunction with anomalously warm Atlantic SSTs and a locally positive radiative forcing. This assessment of past megadroughts provides the first comprehensive theory for the causes of megadroughts and their clustering particularly during the Medieval era. This work also provides the first paleoclimatic support for the prediction that the risk of American Southwest megadroughts will markedly increase with global warming.
Document ID
20190029204
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1126/sciadv.aax0087
Authors
Steiger, Nathan J. (Lamont-Doherty Earth Observatory Palisades, NY, United States)
Smerdon, Jason E. (Lamont-Doherty Earth Observatory Palisades, NY, United States)
Cook, Benjamin I. (NASA Goddard Inst. for Space Studies New York, NY, United States)
Seager, Richard (Lamont-Doherty Earth Observatory Palisades, NY, United States)
Williams, A. Park (Lamont-Doherty Earth Observatory Palisades, NY, United States)
Cook, Edward R. (Lamont-Doherty Earth Observatory Palisades, NY, United States)
Date Acquired
August 20, 2019
Publication Date
July 24, 2019
Publication Information
Publication: Science Advances
Publisher: American Association for the Advancement of Science
Volume: 5
Issue: 7
Subject Category
Meteorology And Climatology
Report/Patent Number
GSFC-E-DAA-TN71642
Distribution Limits
Public
Copyright
Use by or on behalf of the US Gov. Permitted.
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