Under‑ice 'Storms' Pull Warm Water Under Antarctica — Could Accelerate Ice Loss

The West Antarctic Ice Sheet covers roughly 760,000 square miles and reaches depths up to about 1.2 miles. If it were to vanish completely, global sea levels would rise by roughly 10 feet — a change that would normally unfold over centuries given the enormous volume of ice involved. Recent research, however, suggests some processes under and around the ice could speed that timeline.

Small vortices, big consequences

Scientists have identified intense, storm‑like vortices beneath ice shelves — the floating extensions of grounded glaciers — that can pull relatively warm deep water up against the ice. These flows are driven by changes in seawater density: when seawater freezes it expels salt; when ice melts it freshens the surface. Those salinity shifts create spinning, vertical currents that draw heat upward toward the ice undersides.

“They look exactly like a storm,” said Mattia Poinelli, a glaciologist at the University of California, Irvine and an affiliate of NASA’s Jet Propulsion Laboratory, describing the results published in Nature Geoscience. “They're strongly energetic, so there is a very vertical and turbulent motion that happens near the surface.”

This turbulence can displace the cold, insulating layer of water that normally clings to the bottom of ice shelves and shields them from warmer ocean currents. The undersides of ice shelves are often uneven — with ridges and troughs — which can create channels and currents that further expose ice to warmth. Researchers are only recently able to observe many of these processes directly because of advances in underwater robots and sensors.

Feedbacks that amplify melt

The condition of ice shelves matters because they act like corks that slow the flow of grounded glaciers behind them. If melting and mechanical breakup thin or remove those corks, grounded ice can accelerate into the ocean and raise sea levels. Compounding the risk is the dramatic loss of surrounding sea ice. Floating sea ice normally absorbs wave energy and reflects sunlight, helping keep the ocean surface cooler. As sea ice declines and darker water is exposed, the ocean absorbs more heat — which produces more meltwater and more density‑driven vortices, creating a reinforcing feedback loop.

“We’re really trying to understand: where is warm water getting in, how’s it getting in, and what are the processes by which the ice is melting from below?” said Clare Eayrs, a climate scientist at the Korea Polar Research Institute, who was not involved in the new study.

Links to grounding‑line retreat

These under‑ice storms may also help explain observed retreats of grounding lines — the places where ice lifts off bedrock and begins to float. Other research using 25 years of observations found grounding‑line retreat of up to about 2,300 feet per year in some regions. Fresh meltwater flowing beneath grounded ice can stir warm deep water upward, accelerating basal melt and allowing the ocean to access previously protected ice.

“This study provides a compelling mechanism of tiny but powerful storms that punch beneath the ice and accelerate melt,” said Pietro Milillo, a physicist at the University of Houston, who co‑authored the grounding‑line study but was not part of the vortex research. “The kind of retreats that we see in our dataset can be partially explained with these underwater storms.”

So far, the vortices were identified in a model, though researchers say similar dynamics have been observed in at least one Antarctic region. Quantifying how much additional melting these vortices cause remains an open question. Scientists emphasize the urgent need for more direct observations — more instruments, targeted fieldwork, and sustained monitoring — to better constrain how rapidly Antarctic ice may respond.

Bottom line: Turbulent, density‑driven vortices beneath ice shelves can pull warm water against ice, undermining the insulating cold layer and potentially accelerating grounded ice loss. If widespread, these under‑ice storms would strengthen feedbacks that make parts of Antarctica more vulnerable and increase the urgency of monitoring the ice undersides.