More Frequent Warm Atmospheric Rivers Slow Regrowth of Arctic Winter Sea Ice

Nature Climate Change, 6 February 2023

Warm air currents from the tropics have caused more than one-third of the sea ice decline over the past four decades in the Barents-Kara Seas and central Arctic. “Atmospheric rivers” carry dense clouds of warm water vapor from low-latitude climates into polar regions. When they flow over newly formed sea ice, their rainfall melts any thin ice cover away. Ice will then start to regrow, but the return of another atmospheric river quickly melts it again. The increasing frequency of these rainstorms slows the formation of a stable winter sea ice cover. Rainfall also generates heat, and the dense cloud cover associated with atmospheric rivers traps this heat near the surface of the ice. Together, these conditions prevent sea ice from fully recovering during the winter and leave the ocean water open longer. Authors identify anthropogenic warming as a key reason for the worldwide increase in such atmospheric rivers; under a high-emissions scenario, nearly every part of the Arctic will experience more frequent storms generated by these tropical air currents within the next three decades. Previous studies have observed similar increases in atmospheric rivers affecting ice loss on Antarctica and Greenland as well. As temperatures continue to rise, atmospheric rivers will further intensify ice loss as well as generate wind storms, accelerating the erosion of coastal areas and making shipping routes dangerous. Loss of sea ice also increases the amount of heat absorbed by the ocean, further threatening the stability of local marine and terrestrial polar ecosystems. These findings illustrate the importance of reducing emissions to slow the further critical loss of sea ice.

https://www.nature.com/articles/s41558-023-01599-3