Melting Arctic ice bolstering North Atlantic Ocean currents, for now
Charles Blue
contributing writer
Sadie Harley
scientific editor
Andrew Zinin
lead editor
From more frequent wildfires to rising sea levels, climate change is disrupting ecosystems and upending once-stable weather patterns. One particularly alarming consequence of rising global temperatures is the potential collapse of the Atlantic Meridional Overturning Circulation (AMOC), a conveyor-belt-like system of ocean currents driven by the sinking of cold, salty waters in the North Atlantic.
Despite rising temperatures and receding Arctic sea ice, however, measurements suggest that the AMOC has endured and even strengthened in recent decades. This is in spite of less briny, and therefore less dense, waters in the Nordic Seas, and an increase in ocean temperatures, and an influx of fresh water from the melting of the Greenland and Arctic ice sheets.
Shedding light on these welcome but counterintuitive observations, new research published in the journal , reveals that the AMOC has been able to compensate for the encroachment of warmer waters (Atlantification) by migrating north to previously ice-covered regions.
As Arctic ocean ice retreats, the newly exposed surface water, which has lost its insulating layer of ice, now comes in direct contact with the colder airmass above it. This lowers the temperature of the water, which then plunges and travels south along the ocean floor until it rises again near the Antarctic.
From there, it travels north to start the cycle again. Along the way, it brings warmer waters to the Northern Hemisphere, which is essential to maintaining warmer temperatures in Europe.
The authors of the paper based their conclusions on data from a high-resolution (1/12掳) ocean reanalysis (). They further validated these data with direct observations and compared them with other reanalyses. They then compared trends in surface-forced water mass transformation, mixing, and dense water export.
This approach, the authors acknowledge, could be affected by artifacts in the original data. Also, the estimates of Arctic overturning are limited to the time range of the observations.
These findings help explain why the system of ocean currents, which includes the Gulf Stream, has been able to remain stable while ocean temperatures continue to rise. How long this process is able to compensate for a warming climate, however, is unclear.
"Atlantic water is eating its way into the Arctic, but it can't do so indefinitely," said Marius 脜rthun, lead author from the University of Bergen, in a statement.
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More information: Marius 脜rthun et al, Atlantification drives recent strengthening of the Arctic overturning circulation, Science Advances (2025).
Journal information: Science Advances
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