Multidecadal 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.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/621966 |
| Date | 28 September 2016 |
| Creators | Coats, S., Smerdon, J. E., Cook, B. I., Seager, R., Cook, E. R., Anchukaitis, K. J. |
| Contributors | Univ Arizona, Sch Geog & Dev, Univ Arizona, Tree Ring Res Lab, Cooperative Institute for Research in Environmental Sciences; University of Colorado Boulder; Boulder Colorado USA, Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA, Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA, Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA, Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA, School of Geography and Development and Laboratory of Tree Ring Research; University of Arizona; Tucson Arizona USA |
| Publisher | AMER GEOPHYSICAL UNION |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | ©2016. American Geophysical Union. All Rights Reserved. |
| Relation | http://doi.wiley.com/10.1002/2016GL070105 |
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