Deep beneath the glassy surface of the oceans, a fascinating yet threatening spectacle unfolds. In the silent, dark depths where humans cannot reach, swirling currents of impressive size are constantly forming. Some of them, spanning one to ten kilometers in diameter, have a direct impact on the fate of Antarctica’s largest and most exposed glaciers.
A research team led by Mattia Poinelli at the University of California has now demonstrated just how significant these wandering water eddies really are. In their study published in Nature Geoscience, the researchers simulate how such eddies penetrate beneath the floating ice shelves of the Pine Island and Thwaites Glaciers. In doing so, they transport warm deep water precisely to the areas where it has the greatest impact, namely to the sensitive underside of the ice shelf.
These pulses of warm water often last only a few days, yet their impact is immense. The simulations show that the eddies are responsible for about one-fifth of the Thwaites Glacier’s annual melt loss this glacier being the one repeatedly referred to as the “Doomsday Glacier” due to its instability.
Particularly concerning is the feedback loop suggested by the models: As the eddies melt more ice, the resulting meltwater changes the ocean’s stratification. This altered stratification then favors the formation of new eddies, which in turn transport even more warm water toward the ice.
Despite these alarming findings, much remains uncertain. The space between the ice and the seafloor is inaccessible to research vessels, and direct measurements are extremely difficult. It is still unclear whether the simulations adequately represent reality. There are very few observations from the ocean beneath the ice. Some data obtained from probes do, however, match the model.
What is becoming clear is this: Underwater eddies are far more than fleeting oceanic phenomena. They influence ecosystems, govern energy and heat transport, and play a crucial role in determining how quickly Antarctic glaciers melt.
Research in this area is still in its early stages. But the better we understand these hidden forces, the more accurately we can predict how the fate of Antarctica and thus global sea levels will unfold in the coming decades.
Research paper: https://www.nature.com/articles/s41561-025-01860-8
Heiner Kubny, PolarJournal