Slowdown and Recovery of the Atlantic Meridional Overturning Circulation and a Persistent North Atlantic Warming Hole Induced by Arctic Sea Ice Decline

• Published in: Geophysical Research Letters
• Main Authors: Ferster, Brady, Simon, Amélie, Fedorov, Alexey V., Mignot, Juliette, Guilyardi, Éric
• Other Authors: Océan et variabilité du climat (VARCLIM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Instituto Dom Luiz, Universidade de Lisboa = University of Lisbon (ULISBOA), Department of Earth and Planetary Sciences New Haven, Yale University New Haven, ANR-18-MPGA-0001,ARCHANGE,Changement climatique et Arctique et circulation océanique globale(2018), European Project: 727852,Blue-Action(2016), European Project: 776613,Fighting and adapting to climate change,H2020-EU.3.5.1,EUCP(2017)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Arctic sea ice; AMOC; subpolar North Atlantic; NAO; [SDU]Sciences of the Universe [physics]; Arctic; Iceland; North Atlantic; Sea ice
• Online Access: https://insu.hal.science/insu-03778097; https://insu.hal.science/insu-03778097/document; https://insu.hal.science/insu-03778097/file/Geophysical%20Research%20Letters%20-%202022%20-%20Ferster%20-%20Slowdown%20and%20Recovery%20of%20the%20Atlantic%20Meridional%20Overturning%20Circulation.pdf; https://doi.org/10.1029/2022GL097967

International audience We investigate the impact of Arctic sea ice loss on the Atlantic meridional overturning circulation (AMOC) and North Atlantic climate in a coupled general circulation model (IPSL-CM5A2) perturbation experiment, wherein Arctic sea ice is reduced until reaching an equilibrium of an ice-free summer. After several decades we observe AMOC weakening caused by reduced dense water formation in the Iceland basin due to the warming of surface waters, and later compensated by intensification of dense water formation in the Western Subpolar North Atlantic. Consequently, AMOC slightly weakens in deep, dense waters but recovers through shallower, less dense waters overturning. In parallel, wind-driven intensification and southeastward expansion of the subpolar gyre cause a depth-extended cold anomaly ∼2°C around 50°N that resembles the North Atlantic "warming hole." We conclude that compensating dense water formations drive AMOC changes following sea ice retreat and that a warming hole can develop independently of the AMOC modulation.