If the Antarctic ice sheet melts completely, it could lead to a 60-meter rise in global sea level.
Scientists at the Hokkaido University, Japan, have identified a sub-glacier melting hotspot in East Antarctica. Their findings were recently published in the journal Nature Communications.
The 58th Japanese Antarctic Research Expedition analyzed the East Antarctic Shirase Glacier when large areas of ice broke up, giving them access to the Lützow-Holm bay. The new data will allow for more accurate predictions of sea-level fluctuations.
“Our data suggests that the ice directly beneath the Shirase Glacier Tongue is melting at a rate of 7–16 meters per year,” said Daisuke Hirano, Assistant Professor at Hokkaido University.
The Antarctic ice sheet is the largest freshwater reservoir on Earth and, if it melts completely, could lead to a 60-meter rise in global sea level. Current forecasts estimate that sea levels will rise by one meter by 2100 and by more than 15 meters by 2500.
The recent expedition collected data on water temperature, salinity, and oxygen levels from 31 spots in East Antarctica between January and February 2017. Then, scientists combined the data with information on ocean currents and wind in Antarctica.
Using a computational model, they were able to conclude that the melting is the result of deep, hot water flowing towards the Shirase Glacier.
As the researchers explain, most studies of the interaction between ocean and ice have been conducted on ice platforms in West Antarctica, while the eastern region of the continent has received much less attention.
This is because researchers thought that water below the ice in East Antarctica was cold, preventing the glaciers from melting.
The new study, however, shows that hot water flows along a deep underwater oceanic valley and then flows upward towards the Shirase Glacier. This upward movement carries the melted ice out of the glacier, mixing it with the glacial meltwater.
The team also found that this melt occurs year-round, but is affected by winds from the east, along the coast, which vary seasonally. When the wind decreases in intensity during the summer, the influx of deep warm waters increases, accelerating the melting rate.
“We plan to incorporate this and future data into our computer models,” Hirano said. “[This] will help us develop more accurate predictions of sea level fluctuations and climate change.”