Data come from an expedition using the underwater robot Icefin under remote Thwaites Glacier in Antarctica.
The rapid retreat of Thwaites Glacier in West Antarctica appears to be driven by processes under its floating ice shelf that are different than researchers realized. It is known as the “Doomsday Glacier” because of the potential threat it poses to global sea level rise, according to SciTech Daily.
Two papers published in the journal Nature provide a clearer picture of the changes taking place under the glacier, which is the size of Florida and is one of the fastest-changing ice-ocean systems in Antarctica.
The results show that, although melting has increased beneath the floating ice shelf, the present rate of melting is slower than many computer models currently estimate.
New observations determining where the ice enters the ocean show that, while melting beneath much of the ice shelf is weaker than expected, melting in cracks and crevasses is happening much faster. The findings are an important step in understanding the glacier’s contribution to future sea-level rise, scientists say.
A layer of fresher water between the bottom of the ice shelf and the underlying ocean slows the rate of melting along flat parts of the ice shelf. However, scientists were surprised to see that the melting had formed a staircase-like topography across the bottom of the ice shelf. In these areas, as well as in cracks in the ice, rapid melting is occurring.
Thwaites Glacier’s grounding zone – the point where it meets the seafloor – has retreated 14 kilometers since the late 1990s. Much of the ice sheet is below sea level and susceptible to rapid, irreversible ice loss that could raise global sea level by more than half a meter  in centuries.