Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

CMIP6 Models Predict Significant 21st Century Decline of the Atlantic Meridional Overturning Circulation

TitleCMIP6 Models Predict Significant 21st Century Decline of the Atlantic Meridional Overturning Circulation
Publication TypeJournal Article
Year of Publication2020
JournalGeophysical Research Letters
Abstract / Summary

We explore the representation of the Atlantic Meridional Overturning Circulation (AMOC) in 27 models from the CMIP6 multi‐model ensemble. Comparison with RAPID and SAMBA observations suggests that the ensemble mean represents the AMOC strength and vertical profile reasonably well. Linear trends over the entire historical period (1850‐2014) are generally neutral, but many models exhibit an AMOC peak around the 1980s. Ensemble‐mean AMOC decline in future (SSP) scenarios is stronger in CMIP6 than CMIP5 models. In fact, AMOC decline in CMIP6 is surprisingly insensitive to the scenario at least up to 2060. We find an emergent relationship among a majority of models between AMOC strength and 21st-century AMOC decline. Constraining this relationship with RAPID observations suggests that the AMOC might decline between 6 and 8 Sv (34‐45%) by 2100. A smaller group of models projects much less AMOC weakening of only up to 30%.

URLhttps://doi.org/10.1029/2019GL086075
DOI10.1029/2019GL086075
Journal: Geophysical Research Letters
Year of Publication: 2020
Publication Date: 05/2020

We explore the representation of the Atlantic Meridional Overturning Circulation (AMOC) in 27 models from the CMIP6 multi‐model ensemble. Comparison with RAPID and SAMBA observations suggests that the ensemble mean represents the AMOC strength and vertical profile reasonably well. Linear trends over the entire historical period (1850‐2014) are generally neutral, but many models exhibit an AMOC peak around the 1980s. Ensemble‐mean AMOC decline in future (SSP) scenarios is stronger in CMIP6 than CMIP5 models. In fact, AMOC decline in CMIP6 is surprisingly insensitive to the scenario at least up to 2060. We find an emergent relationship among a majority of models between AMOC strength and 21st-century AMOC decline. Constraining this relationship with RAPID observations suggests that the AMOC might decline between 6 and 8 Sv (34‐45%) by 2100. A smaller group of models projects much less AMOC weakening of only up to 30%.

DOI: 10.1029/2019GL086075
Citation:
Weijer, W, W Cheng, OA Garuba, A Hu, and BT Nadiga.  2020.  "CMIP6 Models Predict Significant 21st Century Decline of the Atlantic Meridional Overturning Circulation."  Geophysical Research Letters.  https://doi.org/10.1029/2019GL086075.