PP038-07
Aerosol-forced AMOC changes in CMIP6 historical simulations.

Monday, 14 December 2020: 10:24
Virtual
Matthew Menary1, Jon Robson2, Richard Philip Allan3, Ben Booth4, Christophe Cassou5, Guillaume Gastineau1, Jonathan M Gregory2,4, Dan Hodson2, Colin Jones6, Juliette Mignot1, Mark Ringer4, Rowan Sutton2, Laura Wilcox2 and Rong Zhang7, (1)LOCEAN-IPSL, CNRS-IRD-MNHN-Sorbonne Université, Paris, France, (2)University of Reading, National Centre for Atmospheric Science, Reading, United Kingdom, (3)University of Reading, Reading, United Kingdom, (4)Met Office Hadley Centre, Exeter, United Kingdom, (5)CECI CNRS-Cerfacs, Toulouse, France, (6)University of Leeds, National Centre for Atmospheric Science, Leeds, United Kingdom, (7)Princeton University, Program in Atmospheric and Oceanic Sciences, Princeton, NJ, United States
Recorded Presentation
Abstract:
The Atlantic Meridional Overturning Circulation (AMOC) has been, and will continue to be, a key factor in the modulation of climate change both locally and globally. However, there remains considerable uncertainty in recent AMOC evolution. Here, we show that the multi-model mean AMOC strengthened by approximately 10% from 1850-1985 in new simulations from the 6th Coupled Model Inter-comparison Project (CMIP6), a larger change than was seen in CMIP5. Across the models, the strength of the AMOC trend up to 1985 is related to a proxy for the strength of the aerosol forcing. Therefore, the multi-model difference is a result of stronger anthropogenic aerosol forcing on average in CMIP6 than CMIP5, which is primarily due to more models including aerosol-cloud interactions. However, observational constraints - including a historical sea surface temperature fingerprint and shortwave radiative forcing in recent decades - suggest that anthropogenic forcing and/or the AMOC response may be overestimated.
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