Ice shelf that could be next to collapse ‘has been stable for 10,000 years’ say British Antarctic Survey scientists
The last remaining ice shelf on the eastern Antarctic peninsula has been stable for the past 10,000 years, a new study has shown, but there are signs that it may be next in line to collapse.
Scientists at the Madingley-based British Antarctic Survey have used geological records to reconstruct the history of the Larsen C Ice Shelf.
Twice the size of Wales, the ice shelf is the biggest remnant of a much more extensive area of ice on the Antarctic peninsula that began to break up in the 1990s.
The disintegration of the northernmost region, known as Larsen A, in January 1995 was followed by the dramatic collapse of Larsen B in 2002.
Then after a huge rift developed in Larsen C, a vast 5,800 square kilometre iceberg weighing more than a trillion tonnes calved in 2017. It broke up completely in April 2021, after three years drifting from the Antarctic Peninsula to the sub-Antarctic island of South Georgia.
Several of the region’s ice shelves have collapsed over the past 25 years. This sequential break-up along the eastern Antarctic peninsula has been linked to global warming, with higher atmospheric temperatures moving southwards over the last half a century.
Warm ocean currents have increased over the same period, which has weakened the ice shelves from below.
Scientists collected seabed sediment cores from beneath Larsen C back in 2011, using hot water drilling technology to penetrate through the 300-metre thick ice shelf.
For their new study, the team combined the findings with data from sediment cores recovered offshore a decade earlier.
This enabled them to reconstruct a detailed history of the ice shelf for the first time.
The study’s lead author, marine geologist Dr James Smith, from British Antarctic Survey, said: “There is a huge international scientific effort under way to get a better understanding of what’s happening to Antarctica’s ice shelves.
“If we can understand what happened in the past we will have a sense of what might happen in the future.
“We can perhaps differentiate natural events that affect the ice shelves from environmental change related to human activity.
This new study provides the final piece of the puzzle to the history of this last remaining ice shelf on the eastern Peninsula.”
“Their findings are concerning, for the researchers conclude that despite modest retreat and advances of the ice shelf front, there has been no significant collapse during the past 10,000 years.
The longevity of Larsen C, and Larsen B, suggests these ice shelves were more resilient to past climate warming because they were thicker or may indicate the heat from the atmosphere and ocean did not penetrate this far south.
The 2002 collapse of Larsen B provides a clue that contemporary ice shelf break-ups are now being seen further south than at any point in the past 10,000 years.
And there is good scientific evidence that climate change has caused a thinning of the ice shelf.
“We now have a much clearer picture of the pattern and extent of ice shelf break-ups, both past and present,” said Dr Smith. “It starts in the north and progresses southward as the atmosphere and ocean warms.
“Should collapse of Larsen C happen, it would confirm that the magnitudes of ice loss along the eastern Antarctic Peninsula and underlying climate change are unprecedented during the past 10,000 years.”
The study was published in the journal Geology.
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