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The Arctic Beaufort Gyre in CMIP6 Models: Present and Future
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  • Marylou Athanase,
  • Raphael Harry Köhler,
  • Xavier J. Levine,
  • Ryan Scott Williams,
  • Céline Heuzé
Marylou Athanase
Alfred-Wegener-Institute

Corresponding Author:[email protected]

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Raphael Harry Köhler
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research

Corresponding Author:[email protected]

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Xavier J. Levine
NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
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Ryan Scott Williams
British Antarctic Survey, UK Research and Innovation
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Céline Heuzé
University of Gothenburg
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Abstract

The Beaufort Gyre is an important feature of the Arctic Ocean. By accumulating or releasing freshwater, it influences ocean properties both within the Arctic and as far as the North Atlantic. Yet, its future remains uncertain: the gyre could strengthen as sea ice declines and allows increased wind stress on the ocean, or weaken along with the Beaufort High pressure system. Here, we provide a first evaluation of the Beaufort Gyre in historical and climate-change simulations from 27 available global climate models. We find that the vast majority of models overestimate the gyre area, strength, and northward extent. After discarding the models with too inaccurate a gyre and its drivers – namely, the sea ice cover and Beaufort High – we quantify changes in the Beaufort Gyre under two emission scenarios: the intermediate SSP2–4.5 and the high-warming SSP5–8.5. By the end of the 21st century, most models simulate a significant decline or even disappearance of the Beaufort Gyre, especially under SSP5–8.5. We show that this decline is mainly driven by a simulated future weakening of the Beaufort High, whose influence on the Beaufort Gyre variations is enhanced by the transition to a thin-ice Arctic. The simulated gyre decline is associated with an expected decrease in freshwater storage, with reduced salinity contrasts between the gyre and both Arctic subsurface waters and freshwater outflow regions. While model biases and unresolved processes remain, such possible stratification changes could shift the Atlantic-Arctic Meridional Overturning Circulation northward.
30 Sep 2024Submitted to ESS Open Archive
30 Sep 2024Published in ESS Open Archive