Marine heatwaves, prolonged spells of abnormally warm ocean water, have grown stronger and more frequent as the planet warms, with serious consequences for marine ecosystems and fisheries. A NASA-funded study from Duke's Nicholas School of the Environment, published in Nature Communications, is the first to analyse their connection to atmospheric rivers, the long, narrow bands of moisture that stream through the sky and deliver much of the extratropical world's rain.
Shineng Hu, assistant professor of climate dynamics, and postdoctoral associate Suqiong Hu combined satellite, ship and other instrument records covering the extratropical North Pacific and North Atlantic from 1982 to 2023. Their statistical analysis revealed a strong association between the two phenomena: in winter, unusually active atmospheric rivers tend to occur a couple of days before marine heatwaves reach their peak, a sequence that suggests the rivers help drive the ocean events.
The physics cuts both ways. Atmospheric rivers bring cloud cover that shades and cools the sea surface, but also warm, moist air that heats it, and the net effect varies by season and region; in summer, marine heatwaves tend to follow periods of fewer atmospheric rivers. With both phenomena intensifying as the atmosphere warms and moistens, understanding how they interact has become a pressing question for climate science.