The Arctic Beaufort Gyre in CMIP6 Models: Present and Future

Abstract

The Beaufort Gyre (BG) 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 (BH) pressure system. Here, we provide a first evaluation of the BG 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 BH—we quantify changes in the BG 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 BG, especially under SSP5–8.5. We show that this decline is mainly driven by a simulated future weakening of the BH, whose influence on the BG 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.