Ocean storms under Antarctic ice found to rapidly boost melting

Scientists have uncovered a new threat hiding under the floating edges of Antarctica: fast moving, stormlike swirls of water that attack the ice from below. These secretive currents, spinning in the dark beneath vast ice shelves, are melting glacier fronts far more aggressively than anyone realized.

The new research, led by the University of California, Irvine and NASA’s Jet Propulsion Laboratory, focuses on West Antarctica’s Amundsen Sea Embayment. This remote region holds Thwaites and Pine Island glaciers, two giants that already lose ice at alarming rates.

Instead of looking at slow, seasonal changes, the team zoomed in on “weather scale” events that unfold over days. That shift in focus let them track short lived bursts of activity in the ocean and match them directly to sudden spikes in ice shelf melting.

Beneath the ice, they found something that behaves a lot like a storm. Small, intense circulation patterns in the upper ocean race toward the ice front, shove warm water into the narrow space under the shelves, and carve them from below.

In ocean science, these features are called submesoscale motions. They are swirling structures between 1 and 10 kilometers across. To the human eye, that sounds large. In the Southern Ocean, it is tiny.

These whirling filaments twist, fold and stretch water masses, a bit like wind shears clouds in the sky. When they form near Antarctic ice shelves, they act as delivery systems. They grab slightly warmer, saltier water from offshore, then push it sideways and upward into the hidden cavities under the ice.

Lead author Mattia Poinelli, a postdoctoral scholar in Earth system science at UC Irvine and a research affiliate at NASA JPL, draws a sharp comparison. “In the same way hurricanes and other large storms threaten vulnerable coastal regions around the world, submesoscale features in the open ocean propagate toward ice shelves to cause substantial damage,” he said.

To see these processes, the team combined high resolution computer simulations with moored instruments anchored in front of the ice. The model resolved ocean motions down to 200 meters, fine enough to capture the narrow submesoscale fronts that most climate models blur out.

They then tracked how quickly ice shelves thinned from below as these features swept by. During calm periods, melt rates followed familiar patterns linked to broader currents and background heat. During an “ocean storm,” the story changed fast.

The study shows that when these features slam into the ice front and slip under the shelf, submarine melting can triple within hours. Over an entire seasonal cycle, these short, violent bursts explain nearly one fifth of the total variation in melt from below.

The scientists also found that these currents do not only cause melting; they respond to it. As warm water eats into ice, it produces a layer of fresher, colder meltwater that spreads along the base of the shelf.

That light meltwater sits on top of heavier salt water and creates sharp fronts in temperature and salinity. Those fronts are exactly the kind of structure that fuels more submesoscale activity. The result is a powerful feedback.

“Submesoscale activity within the ice cavity serves both as a cause and a consequence of submarine melting,” Poinelli explained. “The melting creates unstable meltwater fronts that intensify these stormlike ocean features, which then drive even more melting through upward vertical heat fluxes.”

Not all parts of the Antarctic coast respond in the same way. The study highlights one particularly vulnerable corridor between Crosson and Thwaites ice shelves. In that narrow space, the floating tongue of Thwaites and a shallow seabed form a natural barrier that reshapes passing currents.

Those underwater hills and ridges steer swirling water into tighter paths and amplify submesoscale motions. Poinelli calls the area “a submesoscale hot spot,” where the topography and the ice shelf geometry work together to boost turbulence.

For you, that means parts of the coastline that already worry scientists, such as Thwaites Glacier, face not just slow erosion but recurring assaults from below. Each “storm” weakens the ice support that helps hold back inland ice.

The research team did not rely on models alone. They checked their simulations against real world data from moorings in the Amundsen Sea and from autonomous floats in another Antarctic sector.

Those instruments recorded sudden pulses of warmth and salinity at depth, lasting hours to days, with magnitudes similar to what the model predicted during extreme melt events. That agreement gave the scientists confidence that the simulated “ocean storms” reflect real physics rather than model artifacts.

Eric Rignot, a UC Irvine professor of Earth system science who advised the early career team, sees a bigger message in that match. “This study and its findings highlight the urgent need to fund and develop better observation tools, including advanced oceangoing robots that are capable of measuring suboceanic processes and associated dynamics,” he said.

Up to now, many large scale climate models have treated the ocean around Antarctica in broad strokes. They track seasonal warming, major currents and sea ice cover, but they cannot see motions on the order of a few kilometers, let alone a few hundred meters.

The new work shows that those fine features are not just background noise. “These findings demonstrate that fine oceanic features at the submesoscale, despite being largely overlooked in the context of ice ocean interactions, are among the primary drivers of ice loss,” Poinelli said.

The study was funded by NASA’s Cryospheric Sciences Program, with support from the NASA Advanced Supercomputing Division. Co authors include Lia Siegelman of the Scripps Institution of Oceanography at UC San Diego and Yoshihiro Nakayama of Dartmouth College. Together, the team has made a strong case that short lived, small scale ocean “weather” needs to sit alongside long term climate trends in any serious picture of Antarctic change.

Over the coming decades, the behavior of glaciers in West Antarctica will help decide how much global sea level rises. The West Antarctic Ice Sheet holds enough ice to lift oceans by up to 3 meters. If submesoscale “ocean storms” become more active as waters warm, then ice shelves that now buttress this ice sheet could thin or break apart sooner than expected.

For coastal communities, that matters in very direct ways. Stronger and more frequent underwater melt events could speed up glacier retreat, alter timelines for sea level rise, and reshape when you might see more frequent flooding. Updating those timelines helps governments plan sea walls, zoning rules and adaptation strategies with fewer surprises.

The study also gives climate modelers a clear target. To offer reliable projections, future Earth system models must resolve, or at least realistically represent, submesoscale motions under ice shelves. That will likely require higher resolution grids, smarter parameterizations and more computing power.

Finally, the research makes a strong case for new observing systems. Robotic vehicles, smart moorings and under ice floats that can track small scale currents will let scientists test and refine these ideas. Better measurements will reduce uncertainty, sharpen sea level forecasts and give people more time to prepare for the changes that are already under way.

Research findings are available online in the journal Nature Geoscience.

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