Bering Sea marine heatwaves: Patterns, trends and connections with the Arctic

The conterminous marine system of the Bering Sea serves as an important connection between the Pacific and the Arctic. Surface water temperatures of the Northern Pacific have been rising over the past decades with associated changes in extremes: marine heatwaves (MHWs). This study aims to explore the spatiotemporal evolution characteristics and occurrence mechanisms of MHWs in the Bering Sea. Our findings reveal that MHW metrics are above average in most parts of the Bering Sea, with the number of days being more than 50 a year. Frequencies of MHWs are relatively high in the western sectors while durations and intensities are high in the eastern and southern sectors of the Bering Sea. Increasing trends in the MHW days are noticed almost everywhere while similar increases in MHW intensities are found in the northern Bering Sea. In addition, Chukchi Sea ice concentrations show a negative correlation with heatwave frequencies and days while the Arctic Oscillation has no significant connection. Positive correlations are observed between Chukchi sea temperatures and Alaskan air temperatures, implying influences on the MHW frequencies and days. While the annual trends in the MHW frequencies and days peak over several periods, the latest decade (2010–2019) has seen the highest of both. Our findings suggest that the spatiotemporal distribution of MHW metrics is connected with underlying physical processes in the Bering Sea and neighbouring climatic patterns such as the Pacific teleconnections, sea ice extent, air temperature, and its location within the Arctic.