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(Paper) Abrupt cooling over the North Atlantic in modern climate models **

Scientific documentation
2017-03-10

Giovanni Sgubin, Didier Swingedouw, Sybren Drijfhout, Yannick Mary & Amine Bennab (2017), Abrupt cooling over the North Atlantic in modern climate models, NATURE COMMUNICATIONS | 8:14375 | DOI: 10.1038/ncomms14375 |www.nature.com/naturecommunications

Link
http://www.nature.com/articles/ncomms14375

Abstract
Observations over the 20th century evidence no long-term warming in the subpolar North
Atlantic (SPG). This region even experienced a rapid cooling around 1970, raising a debate
over its potential reoccurrence. Here we assess the risk of future abrupt SPG cooling in 40
climate models from the fifth Coupled Model Intercomparison Project (CMIP5). Contrary to
the long-term SPG warming trend evidenced by most of the models, 17.5% of the models
(7/40) project a rapid SPG cooling, consistent with a collapse of the local deep-ocean
convection. Uncertainty in projections is associated with the models’ varying capability in
simulating the present-day SPG stratification, whose realistic reproduction appears a
necessary condition for the onset of a convection collapse. This event occurs in 45.5% of the 11 models best able to simulate the observed SPG stratification. Thus, due to systematic
model biases, the CMIP5 ensemble as a whole underestimates the chance of future abrupt
SPG cooling, entailing crucial implications for observation and adaptation policy.

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Sgubin_NC_2017.pdf (2 MB) Sgubin_NC_2017.pdf Full version paper Chiara Bearzotti, 2017-03-10 09:17