New Ocean Simulations Uncover Possible Link Between Subsurface "Storms" and Antarctic Ice Loss

Dartmouth Engineering professor and study co-author Yoshihiro Nakayama. (Photo by Catha Mayor)

The study, published today in Nature Geoscience, is the first to examine ocean-induced ice shelf melting events from a weather timescale of just days versus seasonal or annual timeframes. This enabled the research team to match "ocean storm" activity with intense ice melt in West Antarctica.

"I call this ambitious use of modeling to uncover a process that has never been observed and improve our understanding of Antarctica's potential contribution to sea level rise," said study co-author Yoshihiro Nakayama, assistant professor of engineering at Dartmouth. "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 weather-like storms hitting and melting the ice."

The team relied on climate simulation modeling and moored observation tools to gain 200-meter-resolution pictures of submesoscale ocean features between 1 and 10 kilometers across, tiny in the context of the vast ocean and huge slabs of floating ice in Antarctica.

"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," said lead author Mattia Poinelli, a UC Irvine postdoctoral scholar in Earth system science and NASA JPL research affiliate. "Submesoscales cause warm water to intrude into cavities beneath the ice, melting them from below. The processes are ubiquitous year-round in the Amundsen Sea Embayment and represent a key contributor to submarine melting."

Ice front of Thwaites Glacier in Antarctica. (Photo by David Vaughan)

Poinelli said that he and his colleagues identified a positive feedback loop between submesoscale motion and ocean-induced melting: More ice shelf melting generates more ocean turbulence, which in turn causes more ice shelf melting.

"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. "This underscores the necessity to incorporate these short-term, 'weatherlike' processes into climate models for more comprehensive and accurate projections of sea level rise."

Eric Rignot, UC Irvine professor of Earth system science, who provided advice and expertise on polar ice and ocean interactions to the early-career research team, said: "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."

Joining Poinelli and Nakayama on this project—which received funding from NASA's Cryospheric Sciences Program and support from the NASA Advanced Supercomputing Division—was Lia Siegelman of Scripps Institution of Oceanography, at the University of California, San Diego.

"It's a great team," remarked Nakayama. "We like to work together, and it's very friendly. I'm good at developing the model that has close agreement with observations. Lia is good at the small scale, and Mattia does ice-ocean interaction. With our combined skills, we're able to do these things."