A hidden threat is melting Antarctic ice from within, and it's happening faster than we thought! Researchers from the University of California, Irvine, and NASA's Jet Propulsion Laboratory have uncovered a startling phenomenon: storm-like ocean currents churning beneath the Antarctic ice shelves, causing them to melt at an alarming rate. This discovery has significant implications for how we predict global sea level rise.
In a recent paper published in Nature Geoscience, scientists detailed their groundbreaking study. They were able to examine ocean-induced ice shelf melting on a timescale of mere days, unlike previous studies that looked at seasonal or annual changes. This allowed them to link these "ocean storms" directly to intense ice melt at the Thwaites Glacier and Pine Island Glacier, both located in the Amundsen Sea Embayment in West Antarctica – an area already under threat from climate change.
The team utilized sophisticated climate simulation models and moored observation tools to capture detailed pictures of submesoscale ocean features. These features, ranging from 1 to 10 kilometers across, are tiny in the vastness of the ocean, yet they pack a powerful punch.
"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," explained lead author Mattia Poinelli. These submesoscales cause warm water to invade the cavities beneath the ice, melting them from the bottom up. This process is a year-round occurrence in the Amundsen Sea Embayment and is a major contributor to submarine melting.
But here's where it gets controversial... Poinelli and his colleagues identified a positive feedback loop. More ice melting leads to more ocean turbulence, which in turn accelerates the melting process. "Submesoscale activity within the ice cavity serves both as a cause and a consequence of submarine melting," he elaborated. The melting creates unstable meltwater fronts that intensify these storm-like ocean features, driving even more melting through upward vertical heat fluxes.
The study found that these short-lived, high-frequency processes account for nearly a fifth of the total submarine melt variation over an entire seasonal cycle. During extreme events, submarine melting can increase by up to threefold within hours as these features collide with ice fronts and penetrate beneath the ice base.
These findings align with high-resolution observational data, confirming the presence of intermittent warming and increased salinity at depths, mirroring the extreme melting events described in the study.
"The region between the Crosson and Thwaites ice shelves is a submesoscale hot spot," Poinelli noted. The unique topography of the area, with the floating tongue of the Thwaites ice shelf and the shallow seafloor, enhances submesoscale activity, making it particularly vulnerable.
And this is the part most people miss... These findings are especially critical given the changing climate. The West Antarctic Ice Sheet, if it were to collapse, could raise global sea levels by up to 3 meters. The research suggests that in future scenarios with warmer waters, longer periods of open water (polynyas), and less sea ice, these energetic submesoscale fronts could become even more prevalent, with potentially devastating effects on ice shelf stability and global sea level rise.
"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 stated. This underscores the need to incorporate these short-term, "weatherlike" processes into climate models for more accurate projections of sea level rise.
Co-author Yoshihiro Nakayama added, "Initially, I was just trying to understand the observations using model output so we can say, 'This is how you explain the data.' But now that our model matches the data so well, we can go an extra step. We can extrapolate further to say there’s weatherlike storms hitting and melting the ice.”
Eric Rignot, a professor at UC Irvine, emphasized the urgent need for better observation tools, including advanced oceangoing robots, to measure these suboceanic processes.
This research highlights the complex and dynamic nature of our planet's climate system. Do you think these findings will change how we approach climate modeling and sea level rise predictions? What other factors do you believe contribute to the melting of Antarctic ice? Share your thoughts in the comments below!
