Antarctica is covered by two huge ice masses: the East and West Antarctic Ice Sheets.
Two dangerous glaciers
As one of the fastest melting glaciersAntarctica, Thwaites earned the nickname “Doomsday Glacier.” Since the 1980s, Thwaites has lost about 540 billion tons of ice, contributing to a 4% rise in global sea levels. Thwaites and its northern neighbor, Pine Island Glacier, cover vast areas. Thwaites has an area of approximately 192,000 km², making it almost as large as Great Britain, while Pine Island is 162,300 km².
What did the scientists find out?
Scientists have sought to understand what is happening to the glaciers now. To do this, they studied their history.
To compare their melting rate today withmelting rates in the distant past, scientists searched Antarctic beaches for clues. By measuring the age and height of nearly two dozen coastlines, scientists hoped to find out how quickly ice disappears from land before advancing again. They found that glaciers had begun to retreat at a rapid rate, a process that had accelerated over the past 5,500 years.
Photo: British Antarctic Survey
Although these vulnerable glaciers have been relatively stable over the past few millennia, their current rate of retreat is increasing and is already raising global sea levels, the scientists noted.
The answer is in shells
The researchers estimated the age of the coastline,collecting ancient shells and tiny penguin bone fragments, and then analyzing the ancient biota using radiocarbon dating. This method determines the age of organic material by measuring the amount of carbon-14, a radioactive isotope of carbon, or a variant with a different number of neutrons. OH is found everywhere on Earth and is easily absorbed by plants and animals. When animals die, they stop storing carbon-14 in their tissues, and the amount they have already taken in starts to decay. The half-life of carbon-14 (or the time it takes for half of it to decay) is 5,730 years, and scientists can accurately determine the age of animals that died thousands of years ago by measuring its number in the remains.
After dating the bones and shells of penguins withover 20 different coastlines, scientists have found that the oldest and highest beach began to form about 5,500 years ago. The researchers reported that from then until about 30 years ago, ice melt was exposing the coastline at a rate of about 3.5 mm per year. But over the past three decades, the rate of advancement of the coastline has increased dramatically - 40 mm per year, i.e. 11 times.
Where it leads?
At the current rate of retreat, huge glaciersthat extend deep into the heart of the ice sheet could contribute to global sea level rise. So, if the entire West Antarctic ice sheet were to collapse and melt, it would raise it by about 3.4 meters.
But, as it turns out, the rate of melting is increasing.It is unclear what this means for the future of glaciers and the entire Antarctic ice sheet, as well as vulnerable coastlines around the world. The researchers' findings, while alarming, do not take into account how many times glaciers have retreated and advanced again in human history. Scientists hope to learn more about the future of the ice sheets by drilling into the ice and studying rock samples from the landmass beneath it. Then scientists can understand whether the current rate of melting is reversible or whether the glaciers have truly passed the point of no return. However, the situation is already causing concern.
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