Internal ocean-atmosphere variability drives megadroughts in Western North America
AffiliationUniv Arizona, Sch Geog & Dev
Univ Arizona, Tree Ring Res Lab
MetadataShow full item record
PublisherAMER GEOPHYSICAL UNION
CitationInternal ocean-atmosphere variability drives megadroughts in Western North America 2016, 43 (18):9886 Geophysical Research Letters
JournalGeophysical Research Letters
Rights©2016. American Geophysical Union. All Rights Reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractMultidecadal droughts that occurred during the Medieval Climate Anomaly represent an important target for validating the ability of climate models to adequately characterize drought risk over the near-term future. A prominent hypothesis is that these megadroughts were driven by a centuries-long radiatively forced shift in the mean state of the tropical Pacific Ocean. Here we use a novel combination of spatiotemporal tree ring reconstructions of Northern Hemisphere hydroclimate to infer the atmosphere-ocean dynamics that coincide with megadroughts over the American West and find that these features are consistently associated with 10-30 year periods of frequent cold El Nino-Southern Oscillation conditions and not a centuries-long shift in the mean of the tropical Pacific Ocean. These results suggest an important role for internal variability in driving past megadroughts. State-of-the-art climate models from the Coupled Model Intercomparison Project Phase 5, however, do not simulate a consistent association between megadroughts and internal variability of the tropical Pacific Ocean, with implications for our confidence in megadrought risk projections.
NoteFirst published: 28 September 2016; 6 Month Embargo.
VersionFinal published version
SponsorsNSF [AGS-1243204, AGS-1401400, ATM-0402474, AGS-1304245]; NASA; [AGS-1338734]