Antarctic Ice sheet loses over 3,000 billion tonnes of ice - enough to bury Empire State Building 137 times

The amount of ice lost from the 20 major glaciers is enough to bury the Empire State Building 137 times - and there is “no sign” the process will reverse

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The fastest changing Antarctic region, the Amundsen Sea Embayment, has lost more than 3,000 billion tonnes of ice over a 25-year period, scientists have announced.

If the lost ice was piled on London, it would stand more than 2km tall - seven times the height of the Shard.

If it were to cover Manhattan, the Empire State Building would be buried 137 times over standing at 61km, research by the University of Leeds suggests.

The university study shows that West Antarctica saw a net decline of 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.

The Amundsen Sea Embayment comprises 20 major glaciers, which altogether are more than four times the surface area of the UK. They play a key role in contributing to the level of the world’s oceans as so much water is held in the snow and ice - if it were to drain into the sea global sea levels could increase by more than one metre.

The research, led by Dr Benjamin Davison at the University of Leeds, calculated the “mass balance” of the Amundsen Sea Embayment. This describes the balance between 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, the Embayment loses mass overall and contributes to global sea level rise.

Dr Davison, a Research Fellow at the Institute for Climate and Atmospheric Science at Leeds, said: “The 20 glaciers in West Antarctica have lost an awful lot of ice over the last quarter of a century.”

Iceberg floating from the Amundsen Sea Embayment. (Image by the University of Leeds) Iceberg floating from the Amundsen Sea Embayment. (Image by the University of Leeds)
Iceberg floating from the Amundsen Sea Embayment. (Image by the University of Leeds)

He added: “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.

“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.”

The research published in the scientific journal Nature Communications also identified that the Amundsen Sea Embayment had experienced several extreme snowfall events over the 25-year period including heavy snowfall, very little snowfall and “snow droughts”.

The researchers found that between 2009 and 2013 there was a period of a persistent snow drought. The lack of snowfall starved the ice sheet and caused it to lose ice which caused sea levels to rise 25% more than in the years of average snowfall.

But during the winters of 2019 and 2020 there was very heavy snowfall.  Scientists estimated that this mitigated the sea level contribution from the Amundsen Sea Embayment, reducing it to about half of what it would have been in an average year.

Dr Davison said: “Changes in ocean temperature and circulation appear to be driving the long-term, large-scale changes in West Antarctica ice sheet mass.  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.”

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