More frequent atmospheric rivers slow the seasonal recovery of Arctic sea ice

During the winter season, Arctic sea ice recovers from summer melt, but this winter sea-ice growth has weakened over recent decades. Here the authors show that atmospheric rivers reach the Arctic more frequently with warming, which in turn slows down the seasonal recovery of sea ice. In recent decades, Arctic sea-ice coverage underwent a drastic decline in winter, when sea ice is expected to recover following the melting season. It is unclear to what extent atmospheric processes such as atmospheric rivers (ARs), intense corridors of moisture transport, contribute to this reduced recovery of sea ice. Here, using observations and climate model simulations, we find a robust frequency increase in ARs in early winter over the Barents-Kara Seas and the central Arctic for 1979-2021. The moisture carried by more frequent ARs has intensified surface downward longwave radiation and rainfall, caused stronger melting of thin, fragile ice cover and slowed the seasonal recovery of sea ice, accounting for 34% of the sea-ice cover decline in the Barents-Kara Seas and central Arctic. A series of model ensemble experiments suggests that, in addition to a uniform AR increase in response to anthropogenic warming, tropical Pacific variability also contributes to the observed Arctic AR changes.

Automated summary

The frequency of atmospheric rivers reaching the Arctic has increased in recent decades, which has slowed down the recovery of sea ice during the winter season. This is due to intensified precipitation and melting caused by the more frequent atmospheric rivers. Additionally, tropical Pacific variability also contributes to the observed changes in Arctic atmospheric rivers.