Publication Abstracts
Romanou et al. 2023
, , , , , , , , , and , 2023: Stochastic bifurcation of the North Atlantic Circulation under a mid-range future climate scenario with the NASA-GISS ModelE. J. Climate, 36, no. 18, 6141-6161, doi:10.1175/JCLI-D-22-0536.1.
A 10-member ensemble simulation with the NASA GISS-E2-1-G climate model shows a clear bifurcation in the Atlantic Meridional Overturning Circulation (AMOC) strength under the SSP2-4.5 extended scenario. At 26°N, the bifurcation leads to 8 strong AMOC and 2 much weaker AMOC states, while at 48°N, it leads to 8 stable AMOC-on and 2 nearly AMOC-off states, the latter lasting approximately 800 years. A variety of fully coupled models have demonstrated tipping points in AMOC through hosing experiments, i.e. prescribing sufficient fresh water inputs in the subpolar North Atlantic. In the GISS simulations, there are no external fresh water perturbations. The bifurcation arises freely in the coupled system and is the result of stochastic variability (noise-induced bifurcation) associated with sea ice transport and melting in the Irminger Sea after a slowing of the GHG forcing. While the AMOC strength follows the near shut-down of the Labrador Sea deep convection initially, the Irminger Sea salinity and deep mixing determine the timing of the AMOC recovery or near collapse at 48°N, which varies widely across the ensemble members. Other feedbacks such as ice-albedo, ice-evaporation, E-P, and the overturning salt-advection feedback play a secondary role that may enhance or reduce the primary mechanism which is ice melt. We believe this is the first time that a coupled climate model has shown such a bifurcation across an initial condition ensemble and might imply that there is a chance for significant and prolonged AMOC slow down due to internal variability of the system.
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BibTeX Citation
@article{ro00910i,
author={Romanou, A. and Rind, D. and Jonas, J. A. and Miller, R. L. and Kelley, M. and Russell, G. and Orbe, C. and Nazarenko, L. and Latto, R. and Schmidt, G. A.},
title={Stochastic bifurcation of the North Atlantic Circulation under a mid-range future climate scenario with the NASA-GISS ModelE},
year={2023},
journal={Journal of Climate},
volume={36},
number={18},
pages={6141--6161},
doi={10.1175/JCLI-D-22-0536.1},
}
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RIS Citation
TY - JOUR ID - ro00910i AU - Romanou, A. AU - Rind, D. AU - Jonas, J. A. AU - Miller, R. L. AU - Kelley, M. AU - Russell, G. AU - Orbe, C. AU - Nazarenko, L. AU - Latto, R. AU - Schmidt, G. A. PY - 2023 TI - Stochastic bifurcation of the North Atlantic Circulation under a mid-range future climate scenario with the NASA-GISS ModelE JA - J. Climate JO - Journal of Climate VL - 36 IS - 18 SP - 6141 EP - 6161 DO - 10.1175/JCLI-D-22-0536.1 ER -
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