title: Overlooked possibility of a collapsed Atlantic Meridional Overturning Circulation in warming climate.
abstract: Changes in the Atlantic Meridional Overturning Circulation (AMOC) are moderate in most climate model projections under increasing greenhouse gas forcing. This intermodel consensus may be an artifact of common model biases that favor a stable AMOC. Observationally based freshwater budget analyses suggest that the AMOC is in an unstable regime susceptible for large changes in response to perturbations. By correcting the model biases, we show that the AMOC collapses 300 years after the atmospheric CO2concentration is abruptly doubled from the 1990 level. Compared to an uncorrected model, the AMOC collapse brings about large, markedly different climate responses: a prominent cooling over the northern North Atlantic and neighboring areas, sea ice increases over the Greenland-Iceland-Norwegian seas and to the south of Greenland, and a significant southward rain-belt migration over the tropical Atlantic. Our results highlight the need to develop dynamical metrics to constrain models and the importance of reducing model biases in long-term climate projection.
authors.affiliation: Department of Climate, Atmospheric Science and Physical Oceanography, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Climate, Atmospheric Science and Physical Oceanography, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Shang-Ping
authors.initials: SP
authors.lastname: Xie
authors.affiliation: Department of Atmospheric and Oceanic Sciences and Center for Climatic Research, University of Wisconsin-Madison, Madison, WI 53705, USA.
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Atmospheric and Oceanic Sciences and Center for Climatic Research, University of Wisconsin-Madison, Madison, WI 53705, USA.
authors.forename: Jiang
authors.identifier: 0000-0002-0908-5130
authors.initials: J
authors.lastname: Zhu
keywords: Atlantic Meridional Overturning Circulation stability bias flux adjustment global warming