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Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation

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Rahmstorf, Stefan and Box, Jason E. and Feulner, Georg and Mann, Michael E. and Robinson, Alexander James and Rutherford, Scott and Schaffernicht, Erik J. (2015) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation. Nature climate change, 5 (5). pp. 475-480. ISSN 1758-678X

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Official URL: http://dx.doi.org/10.1038/NCLIMATE2554




Abstract

Possible changes in Atlantic meridional overturning circulation (AMOC) provide a key source of uncertainty regarding future climate change. Maps of temperature trends over the twentieth century show a conspicuous region of cooling in the northern Atlantic. Here we present multiple lines of evidence suggesting that this cooling may be due to a reduction in the AMOC over the twentieth century and particularly after 1970. Since 1990 the AMOC seems to have partly recovered. This time evolution is consistently suggested by an AMOC index based on sea surface temperatures, by the hemispheric temperature difference, by coral-based proxies and by oceanic measurements. We discuss a possible contribution of the melting of the Greenland Ice Sheet to the slowdown. Using a multi-proxy temperature reconstruction for the AMOC index suggests that the AMOC weakness after 1975 is an unprecedented event in the past millennium (p > 0.99). Further melting of Greenland in the coming decades could contribute to further weakening of the AMOC.


Item Type:Article
Additional Information:

© Nature Publishing Group.
We thank O. Sherwood for providing coral data. M.E.M. acknowledges support for this work from the ATM program of the National Science Foundation (grant ATM-0902133).

Uncontrolled Keywords:Sea-surface temperature; North-Atlantic; Thermohaline circulation; Climate-change; Salinity; Variability; Millennium; Hemisphere; Discharge; Decline
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:32657
Deposited On:04 Aug 2015 09:11
Last Modified:10 Dec 2018 15:05

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