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A new threat is rapidly eroding Antarctica from below: fast-moving, storm-like swirls of water are attacking the edges of the ice shelves, melting glacier fronts far more aggressively than previously understood. These previously undetected currents, operating in the dark beneath vast ice formations, are dramatically reshaping our understanding of ice loss and accelerating the timeline for potential sea level rise.
Scientists have, for the first time, zoomed in on “weather scale” events – unfolding over days rather than seasons – to track short-lived bursts of ocean activity directly linked to sudden spikes in ice shelf melting. The research reveals that these underwater phenomena behave much like storms, carving away at the ice from beneath.
Unmasking Submesoscale “Ocean Storms”
In ocean science, these swirling structures are known as submesoscale motions. they range in size from 1 to 10 kilometers across. While seemingly large to the human eye, these features are considered tiny in the vastness of the Southern Ocean.
these whirling filaments twist,fold,and stretch water masses,similar to wind shears in the atmosphere. When they form near Antarctic ice shelves, they act as conduits, delivering slightly warmer, saltier water from offshore into the hidden cavities under the ice.
“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 considerable damage,” explained a lead researcher from UC Irvine and NASA JPL.
Melting Spikes Observed in Hours
To observe these processes, the team combined high-resolution computer simulations with data from instruments anchored in front of the ice. The model was able to resolve ocean motions down to 200 meters, capturing the narrow submesoscale fronts that are typically blurred out in larger-scale climate models.
Tracking the rate of ice shelf thinning revealed a startling pattern. During calm periods, melt rates aligned with established patterns linked to broader currents and background heat. Though,during an “ocean storm,” the melting process accelerated dramatically.
The study demonstrates that when these features collide with the ice front and slip underneath the shelf, submarine melting can triple within hours. Over an entire seasonal cycle, these short, violent bursts account for nearly one-fifth of the total variation in melt from below.
A Destructive Feedback Loop
The research also uncovered a concerning feedback loop.These currents don’t just cause melting; they respond to it.As warm water erodes the ice, it produces a layer of fresher, colder meltwater that spreads along the base of the shelf.
This lighter meltwater sits atop the saltier, denser water, creating a stratification that further enhances the formation of submesoscale “ocean storms”. The more the ice melts, the more these destructive currents are likely to form, creating a vicious cycle of accelerated ice loss. “These currents, along with warming ocean temperatures, are among the primary drivers of ice loss,” the researcher said.
The behavior of glaciers in West Antarctica will be a critical factor in determining the extent of global sea level rise in the coming decades. The West Antarctic Ice Sheet holds enough ice to raise oceans by up to 3 meters. If submesoscale “ocean storms” become more frequent or intense as waters warm, ice shelves that currently buttress this ice sheet could thin or break apart sooner than expected.
For coastal communities, this translates to potentially faster glacier retreat, altered timelines for sea level rise, and increased frequency of flooding. Updating these timelines is crucial for governments to effectively plan for sea walls,zoning regulations,and adaptation strategies.
The study also provides a clear target for climate modelers: future Earth system models must resolve, or at least realistically represent, submesoscale motions under ice shelves. this will likely require higher-resolution grids, smarter parameterizations, and increased computing power.
the research underscores the need for new observing systems – robotic vehicles, smart moorings, and under-ice floats – to track these small-scale currents and refine our understanding of these critical processes. Better measurements will reduce uncertainty, sharpen sea level forecasts, and provide communities with more time to prepare for the changes already underway.