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Stability of the Atlantic meridional overturning circulation: A model intercomparison
Author(s) -
Weaver Andrew J.,
Sedláček Jan,
Eby Michael,
Alexander Kaitlin,
Crespin Elisabeth,
Fichefet Thierry,
PhilipponBerthier Gwenaëlle,
Joos Fortunat,
Kawamiya Michio,
Matsumoto Katsumi,
Steinacher Marco,
Tachiiri Kaoru,
Tokos Kathy,
Yoshimori Masakazu,
Zickfeld Kirsten
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl053763
Subject(s) - coupled model intercomparison project , climatology , environmental science , thermohaline circulation , general circulation model , climate model , ocean current , flux (metallurgy) , climate change , zonal and meridional , atmospheric sciences , geology , oceanography , chemistry , organic chemistry
The evolution of the Atlantic Meridional Overturning Circulation (MOC) in 30 models of varying complexity is examined under four distinct Representative Concentration Pathways. The models include 25 Atmosphere‐Ocean General Circulation Models (AOGCMs) or Earth System Models (ESMs) that submitted simulations in support of the 5th phase of the Coupled Model Intercomparison Project (CMIP5) and 5 Earth System Models of Intermediate Complexity (EMICs). While none of the models incorporated the additional effects of ice sheet melting, they all projected very similar behaviour during the 21st century. Over this period the strength of MOC reduced by a best estimate of 22% (18%–25%; 5%–95% confidence limits) for RCP2.6, 26% (23%–30%) for RCP4.5, 29% (23%–35%) for RCP6.0 and 40% (36%–44%) for RCP8.5. Two of the models eventually realized a slow shutdown of the MOC under RCP8.5, although no model exhibited an abrupt change of the MOC. Through analysis of the freshwater flux across 30°–32°S into the Atlantic, it was found that 56% of the CMIP5 models were in a bistable regime of the MOC for at least part of their RCP integrations. The results support previous assessments that it is very unlikely that the MOC will undergo an abrupt change to an off state as a consequence of global warming.