In remote West Antarctica, two glaciers are melting.
The Thwaites and Pine Island glaciers account for more than a third of the total ice loss in Antarctica. Thwaites, roughly the size of Florida, is nicknamed the “doomsday glacier,” because of its potential impact on sea level rise.
But exactly how these glaciers are melting is still a mystery.
Dartmouth professor Yoshihiro Nakayama, an oceanographer who studies changing polar regions, set out to help solve that mystery. He created a high-resolution model of the area, a super-detailed 200-meter resolution rendering of the glaciers and ocean, that allowed researchers to see melting as it happens on smaller scales, like looking at daily weather instead of seasonal or yearly trends.
“In oceanography, we normally look at time scales like months or years, because these processes are not super fast,” Nakayama said. “But when we look into these processes over a few days, we realize that there are some processes that pick up the melt.”
That high resolution model allowed researchers to see that underwater “storms” could be a significant source of the ice melt.
In a study published in the journal Nature Geoscience, Nakayama and two other scientists describe how small eddies form in the open ocean, move towards the glaciers, intrude into cavities below their ice shelves, and melt the ice from below.
Using his model, Nakayama says his team saw that the ice melt would peak for a few days, and then go back to normal. During those times, they saw those small eddies forming, acting like underwater storms that interacted with the ice shelf.
“Like atmospheric storms hitting the continent, damaging the coastline,” he said, “small eddies that formed just outside of the ice in Antarctica can hit into the ice and melt the ice.”
In their paper, the team says they see a feedback loop: more melting creates more ocean storms, which creates more melting. In a warming climate, that loop could become more intense.
Nakayama is hopeful that his research team’s work will deepen scientists’ understanding of the physics of ice melt in Western Antarctica, which could make it easier to understand what to expect from melting in the future.
In their paper, researchers say the day-to-day melting from those underwater “storms” should be incorporated into climate models, to more accurately project sea-level rise.
Thwaites and Pine Island are in one of the most remote places on earth, and observing their melt is difficult. But the researchers say their findings emphasize the need to develop better observational tools that could capture these “storms” and how they contribute to ice melt.
Nakayama said from his modeling, the impact of these “storms” seems significant.
“But we need to confirm with observations and we need to further extend this to other regions of the Antarctic,” Nakayama said.
