Over 3,000 billion tonnes of ice lost from West Antarctica in 25 years: Study
New Delhi, March 22: Scientists have calculated the loss of ice from the Amundsen Sea Embayment located in West Antarctica to be more than 3,000 billion tonnes in the fastest changing Antarctic region over a period of 25 years.
The study by the University of Leeds, UK, shows that West Antarctica could see a net loss of 3,331 billion tonnes of ice between 1996 and 2021, contributing more than nine millimeters to global sea level rise.
The study says that if all this lost ice were piled up on London, it would be more than 2 km long. If it were to cover Manhattan, it would be as tall as 137 Empire State Buildings stacked on top of each other.
“Changes in ocean temperature and circulation appear to be driving long-term, large-scale changes in the mass of the West Antarctica ice sheet. We absolutely need to know more about them,” said study lead researcher Benjamin Davison, from the University of Leeds. The research needs to be done because they are likely to control the overall sea level contribution from West Antarctica.
Twenty major glaciers, which form the Amundsen Sea Causeway in West Antarctica, play a significant role in contributing to the level of the world’s oceans. Together they are more than four times the size of the UK.
Global sea levels could rise by more than a meter if all the water stored in ice and snow drained into the ocean, the study said.
The findings are published in the journal Nature Communications.
Davison calculated the “mass balance” of the Amundsen Sea embankment, which describes the balance between the mass of ice gained from calving and the mass lost through calving, where icebergs form at the end of a glacier and get washed away in the sea.
When calving rates are greater than the amount of ice being replaced by glaciers, the levee loses mass overall, contributing to global sea level rise.
Similarly, when the supply of snowfall is reduced, the embayment may lose mass overall, contributing to sea level rise.
“The 20 glaciers in West Antarctica have lost a great deal of ice in the last quarter of a century and there is no sign that this process is going to reverse anytime soon, although there were periods when the rate of mass loss was slightly higher.” decreased,” Davison said.
The scientists further found that the Amundsen Sea Embayment experienced several extreme glaciation events over the 25-year study period, playing a significant role in the Embayment’s contribution to sea level rise during the given time period.
This is because these events contributed to half the ice change at a given time.
The researchers included these extreme events of heavy snowfall and “ice drought” in their calculations.
For example, between 2009 and 2013, the model revealed a period of persistently low snowfall, or “ice drought”. The lack of nutritious snowfall starved the ice sheet and caused it to lose less snow, therefore contributing to sea level rise by about 25 percent more than in years of average snowfall.
In contrast, there was very heavy snowfall during the winters of 2019 and 2020. Scientists estimate that this heavy snowmelt reduced the sea level contribution from the Amundsen Sea Levee, which reduces it by about half in an average year.
“We were really surprised to see how much low or high snowfall over a two- to five-year period can affect the ice sheet – so much so that we think they may play an important, albeit secondary, role in controlling rates.” West Antarctic ice loss,” Davison said.
“Scientists are monitoring what is happening in the Amundsen Sea Basin because it plays an important role in sea level rise. If sea level rises significantly in future years, there are communities around the world that would be extremely will experience flooding,” Davison said.