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

Previous studies have indicated that blocking anticyclones around Europe to the Ural Mountains enhances moisture transport to the Barents-Kara Seas (BKS), leading to sea ice loss. However, the extent to which this moisture transport explains the sea ice decline trend remains unknown. In this study, we seek to address this question in terms of atmospheric rivers (ARs), given that ARs contribute to more than half of the total water vapor transport into the Arctic. Our investigation reveals a significant increase in the frequency of ARs reaching the BKS region, accounting for at least 34% of winter sea ice cover decline in the past several decades. The moisture carried by more frequent ARs intensifies surface downward longwave radiation and rainfall, resulting in the melting of thin, fragile ice cover and slowing the seasonal recovery of sea ice. 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 changes in Arctic ARs.