Despite marine ecosystems having recently been severely impacted by marine heatwave events, there is still a lack of marine heatwave studies in coastal areas. In this study, the researchers use a combination of four Sea Surface Temperature (SST) global products derived from satellite measurements, to provide the best estimation of marine heatwave characteristics and long‐term changes of coastal heatwaves during the past 25 years.

They found that hotspots were concentrated along the Mediterranean Sea, Japan Sea, south‐eastern Australia and the north‐eastern coast of the United States. They also found the frequency of marine heatwave events and their duration globally increased by 1–2 events per decade and 5–20 days per decade. Most of the marine heatwave hotspots identified were associated with high upward trends.

The main driver of long‐term marine heatwave increases was long‐term changes in sea-surface temperatures which, in the context of climate change, have been steadily increasing. In some regions like the south‐eastern Pacific coast, long‐term changes in marine heatwaves were driven by the local variability of the climate system.

All sea surface temperature products used in this analysis agreed well in most aspects except for average marine heatwave intensity, which was found to be well correlated to short‐term sea surface temperature variations. This last result is a reminder of the specific strengths and weaknesses of sea surface temperature products and the importance of combining them to reduce uncertainty.

  • Paper: Marin, M., Feng, M., Phillips, H. E., & Bindoff, N. L. (2021). A global, multiproduct analysis of coastal marine heatwaves: Distribution, characteristics and long‐term trends. Journal of Geophysical Research: Oceans, 126, e2020JC016708.