Antarctic landscape

Antarctica has lost over 3000 billion tonnes of ice since 1996

Image credit: Dreamstime

Scientists have calculated the amount of ice that melted from Antarctica's Amundsen Sea Embayment over a period of 25 years.

University of Leeds scientists have found that West Antarctica lost 3,331 billion tonnes of ice between 1996 and 2021, contributing over nine millimetres to global sea levels.  

Changes in ocean temperature and currents are thought to have been the most important factors driving the loss of ice.  

In order to estimate the calculated the amount of ice lost in the region, the researchers calculated the 'mass balance' of the Amundsen Sea Embayment, using climate models that show how air currents move around the world.

The region hosts 20 major glaciers and is considered the fastest-changing Antarctic region.

The researchers calculated the balance between the mass of snow and ice gain due to snowfall and mass lost through calving, where icebergs form at the end of a glacier and drift out to sea. When calving happens faster than the ice is replaced by snowfall or when the snowfall supply drops, the Embayment loses mass overall and contributes to global sea level rise.

“Changes in ocean temperature and circulation appear to be driving the long-term, large-scale changes in West Antarctica ice-sheet mass," said Dr Benjamin Davison, one of the study's authors. "We absolutely need to research those more because they are likely to control the overall sea-level contribution from West Antarctica.   

“However, 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.”  

If the total amount of ice lost - over 3,000 billion tonnes - was piled on top of London, it would stand over 2km tall. If it were to cover Manhattan, it would stand at 61km – or 137 Empire State Buildings placed on top of one another.  

In total, the Amundsen Sea Embayment is more than four times the size of the UK. So much water is held in its snow and ice, that if it were to all to drain into the sea, global sea levels could increase by more than one metre.   

“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 any time soon, although there were periods where the rate of mass loss did ease slightly," said Dr Davison, a research fellow at the Institute for 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.”  

The ice loss from the region over the past 25 years has seen the retreat of the Pine Island Glacier (PIG). As it retreated, one of its tributary glaciers became detached from the main glacier, and has now been named Piglet Glacier. 

“As well as shedding new light on the role of extreme snowfall variability on ice sheet mass changes, this research also provides new estimates of how quickly this important region of Antarctica is contributing to sea level rise," said Dr Anna Hogg, one of the authors of the paper. 

“Satellite observations have showed that the newly named Piglet Glacier accelerated its ice speed by 40 per cent, as the larger PIG retreated to its smallest extent since records began.”   

Satellites such as the European Space Agency's Copernicus Sentinel-1 satellite, which uses sensors that ‘see’ through clouds, have transformed the ability of scientists to monitor  the incredibly rapid change taking place in Antarctica

The research has been published in the scientific journal Nature Communications

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