Pockets of warm sub-surface water in the Arctic Ocean are accelerating the rate at which Arctic sea ice is melting, joining other global warming-driven mechanisms affecting the decline of this “source of global climate stability,” according to research published Friday.

According to the study by physical oceanographers at Scripps Institution of Oceanography at the University of California San Diego published Friday in the journal Nature Communications, water from the Pacific Ocean has been creating warm sub-surface pockets in the Arctic, which have been strengthening over the past decade.

These pockets known as “heat bombs” can be stable enough to last for years and are positioned beneath the Arctic surface water layer due to the Pacific water’s increased salinity, according to researchers, melting the ice as the heat diffuses upwards over time.

Previously, it was uncertain how the warmer water was subducting — or positioning beneath — the surface water, preventing this effect from being included in climate scientists’ forecast models and leading to an under- prediction of the true acceleration of sea ice melt rates, according to Scripps.

“The rate of accelerating sea ice melt in the Arctic has been hard to predict accurately, in part because of all of the complex local feedbacks between ice, ocean and atmosphere; this work showcases the large role in warming that ocean water plays as part of those feedbacks,” said Jennifer MacKinnon, a physical oceanographer at Scripps, chief scientist of the expedition, and lead author of the paper.

Given the influx of warm Pacific origin water over the past decade, Scripps said, “This work adds to a growing body of evidence that Arctic sea ice, a source of global climate stability, could disappear for large portions of the year.”

The research was primarily funded by the Office of Naval Research, which also funded a 2018 expedition that reportedly caught a subduction event in the act for the first time.

“The group’s success highlights the new perspectives we can see on the natural world when we look at it in new ways,” said Scripps oceanographer Matthew Alford. “This detailed view of the complicated processes governing Arctic heat transport would not have been possible without multiple simultaneous instrument suites, including remote sensing and custom shipboard and autonomous profilers developed at Scripps.”

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