The 58th Japanese Antarctic Research Expedition received a rare opportunity to conduct sea
Our data show that ice directlyunder the tongue of the Shirase glacier melts at a rate of seven to 16 meters per year. This is equal to or perhaps even surpasses the rate of melting under the Totten Ice Shelf, which was believed to have the highest rate of melting in East Antarctica, at 10 to 11 meters per year.
Daisuke Hirano, associate professor at the Institute of Low Temperature Sciences at Hokkaido University.
Antarctic ice sheet, mostwhich is located in East Antarctica, is the largest reservoir of fresh water on Earth. If all of this melted, it could lead to a 60-meter rise in sea levels. Current projections suggest that global sea level will rise by one meter by 2100 and more than 15 meters by 2500. Therefore, it is important for scientists to have a clear understanding of how Antarctic continental ice is melting and to more accurately predict sea level fluctuations.
Warm water flows into the Lutzov-Kholm Bay along a deepan underwater ocean trench, and then flows up the base of the tongue, heating and melting the base of the tongue of the Shirase Glacier. (Daisuke Hirano et al., Nature Communications, August 24, 2020) Photo: Daisuke Hirano et al., Nature Communications, August 24, 2020.
Most research on ocean andice was carried out on the ice shelves of West Antarctica. The ice shelves in East Antarctica have received much less attention because the water cavities beneath most of them were believed to be cold, which protects them from melting.
During the Daisuke research expeditionHirano and his team collected data on water temperature, salt and oxygen levels at 31 points in the area between January and February 2017. They combined this information with current and wind data in the area, ice radar measurements and a computer. modeling to understand ocean circulation under the tongue of the Shirase glacier at the inner base of the glacier.
Evidence suggests that meltingoccurs as a result of the inflow of deep warm water inward, to the base of the tongue of the Shirase glacier. Warm waters carrying melted ice flow outward, mixing with glacial melt water.
The team found that this melting was taking placeall year round, but it is influenced by easterly winds along the coast, which change with the season. When the winds subside in summer, the flow of deep warm water increases, accelerating the rate of melting.
“We plan to incorporate this and future data into our computer models, which will help us develop more accurate forecasts of sea level fluctuations and climate change,” the scientists conclude.
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