A new study led by the University of Leeds in the UK has found that the Amundsen Sea Embayment – the fastest changing region in Antarctica – has lost over 3,000 billion tons of ice during a 25-year period. If all this lost ice were to cover Manhattan, it would reach a height of 61 kilometers, or 137 Empire State Buildings placed on top of one another.
To estimate the fluctuations of sea ice in that region, the experts calculated a variable called “mass balance,” referring to the balance between the mass of ice gain due to snowfall and mass lost through calving, a process in which icebergs form at the end of a glacier and drift out to sea. When this phenomenon happens faster than the replacement of the lost ice through snowfall – or when the snowfall supply drops – the Embayment loses mass overall, contributing to sea level rise.
The analysis revealed that, between 1996 and 2021, West Antarctica lost 3,331 billion tons of ice, contributing more than nine millimeters to global sea level rise. According to the experts, changes in ocean temperature and currents were the most important drivers of ice loss.
“The 20 glaciers in West Antarctica have lost an awful lot of ice over the last quarter of a century and there is no sign that the process is going to reverse anytime soon although there were periods where the rate of mass loss did ease slightly,” said study lead author Benjamin Davison, a research fellow in Climate and Atmospheric Science at Leeds.
“Scientists are monitoring what is happening in the Amundsen Sea Embayment because of the crucial role it plays in sea-level rise. If ocean levels were to rise significantly in future years, there are communities around the world who would experience extreme flooding.”
By using climate models showing how air currents move across the globe, the researchers found that the Embayment had experienced several extreme snowfall events over the 25-year study period – such as during the winters of 2019 and 2020 – as well as “snow droughts” or periods of very little snowfall that characterized the 2009-2013 period. Although the massive snowfalls managed to replace part of the ice lost during snow droughts, overall, the ice mass declined significantly over the past quarter of a century.
“We were really surprised to see just how much periods of extremely low or high snowfall could affect the ice sheet over two to five-year periods – so much so that we think they could play an important, albeit secondary role, in controlling rates of West Antarctic ice loss,” Davison explained.
“Ocean temperature changes and glacial dynamics appear strongly connected in this part of the world, but this work highlights the large variability and unexpected processes by which snowfall also plays a direct role in modulating glacier mass,” concluded co-author Pierre Dutrieux, a scientist at the British Antarctic Survey.
The study is published in the journal Nature Communications.
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