Future sea ice weakening amplifies wind-driven trends in surface stress and Arctic Ocean spin-up

Arctic sea ice mediates atmosphere-ocean momentum transfer, driving upper ocean circulation. This paper investigates how Arctic Ocean surface stress and velocity respond to sea ice decline and changing winds under global warming using state-of-the-art climate models. The models consistently predict increased future (2015-2100) ocean surface stress due to higher wind speeds, less sea ice, and a weaker ice pack. Winter sees the largest surface stress increase (+5.1% per decade), amplified by reduced internal ice stress. This is because less energy is dissipated by the weaker ice, leading to more momentum transfer to the ocean. Accelerated Arctic Ocean surface velocity (+31-47% by 2100) follows, increasing ocean kinetic energy and vertical mixing. The enhanced surface stress also boosts Beaufort Gyre Ekman convergence and freshwater content, impacting ecosystems and downstream ocean circulation. Model variations in atmosphere-ice-ocean momentum transfer introduce uncertainty, highlighting the need for improved model coupling.

Morven Muilwijk, Tore Hattermann, Torge Martin, Mats A. Granskog