According to a study conducted by the University of Leeds in the United Kingdom, West Antarctica saw a net loss of 3,331 billion tonnes of ice between 1996 and 2021, contributing more than nine millimetres to world sea levels.
According to the study, if all of the lost ice was stacked on London, it would be over 2 kilometres tall. If it covered Manhattan, it would be as tall as 137 Empire State Buildings stacked on top of each other.
"Long-term, large-scale fluctuations in West Antarctica ice sheet mass appear to be driven by changes in ocean temperature and circulation. We must conduct additional research on these topics since they are likely to limit the overall sea level contribution from West Antarctica "said Benjamin Davison, the study's principal researcher at the University of Leeds.
The twenty large glaciers that comprise the Amundsen Sea Embayment in West Antarctica have an important role in contributing to global ocean levels. They are more than four times the size of the United Kingdom. According to the study, if all of the water trapped in the snow and ice were to drain into the sea, global sea levels may rise by more than one metre.
The findings were published in Nature Communications. Davison estimated the Amundsen Sea Embayment's "mass balance," which represents the balance between the quantity of snow and ice gained from snowfall and the mass lost through calving, which occurs when icebergs form at the terminal of a glacier and float out to sea.
When the pace of calving exceeds the rate of ice replacement by snowfall, the Embayment loses mass overall, leading to global sea level rise. Similarly, if the supply of snowfall falls, the Embayment may lose mass overall, contributing to sea level rise.
"The 20 glaciers in West Antarctica have lost a lot of ice over the previous quarter-century, and there is little suggestion that the process will reverse very soon, though there have been moments when the rate of mass loss did slow significantly," Davison said. The scientists also discovered that certain exceptional snowfall events that occurred in the Amundsen Sea Embayment across the 25-year study period played a significant influence in the Embayment's contribution to sea level rise during specific time periods.
This is due to the fact that these events generated up to 50% of the ice change at various times. The researchers accounted for excessive snowfall and "snow drought" in their calculations. For example, the models revealed a period of persistently low snowfall, or "snow drought," between 2009 and 2013. The lack of nutritious snowfall impoverished the ice sheet and caused it to lose ice, causing around 25% more to sea level rise than ordinary snowfall years.
In contrast, considerable snowfall fell during the winters of 2019 and 2020. The scientists concluded that the significant snowfall reduced the Amundsen Sea Embayment's sea level contribution to around half of what it would have been in a normal year. "We were genuinely astonished to discover how much periods of exceptionally low or high snowfall may influence the ice sheet across two to five-year intervals," Davison said.
"Scientists are keeping an eye on what's going on in the Amundsen Sea Embayment because of the critical role it plays in sea-level rise. If sea levels rise dramatically in the coming years, communities all across the world will face severe flooding, " Davison stated.
