This study investigates the record high Pacific Arctic seawater temperatures in autumn 2018 and the subsequent delay in sea ice advance. Anomalous warm seawater, exceeding previous records, was observed despite a neutral Pacific Decadal Oscillation (PDO) index. This warming is attributed to southerly winds associated with episodic atmospheric blocking over the Bering Sea. The warm water significantly delayed sea ice advance, as confirmed by the R/V Mirai Arctic Expedition. Future atmospheric blocking during PDO positive phases could dramatically reduce Arctic sea ice extent.

Tsubasa Kodaira, Takuji Waseda, Takehiko Nose, Jun Inoue