The collapse of the Antarctic ice shelves may be inevitable because around 300 years of thinning have predisposed them to break up, a study has found.
Researchers reconstructed the rate at which the glacier has been melting over the last 6,250 years, finding that the melt rate began to increase around 1706 AD.
As climate change drives further glacial melting in the Antarctic, researchers warn that there may be nothing we can do to prevent their collapse.
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To investigate how ice loss was driven in the past — and how such much effect the present — William Dickens of the British Antarctic Survey and colleagues analysed a core of marine sediment taken from the northeastern tip of the Antarctic Peninsula.
From this, they constructed a 6,250-year-long record of glacial meltwater discharge by studying the oxygen contained in single-celled algae preserved in the core.
Comparing the ratio of oxygen variants — or 'isotopes' — taken up by the microorganism can reveal the ratio of fresh to meltwater in which the algae lived.
Lower isotope values signal higher levels of fresh water discharged from the glaciers at the corresponding time.
'An increasing trend in glacial discharge is seen from approximately A.D. 1400 although it wasn’t until A.D. 1706 that discharge at [the core site] exceeded the levels experienced during the past 6,250 years,' the researchers wrote.
The researchers also found a second marked acceleration in glacial melting — one that began in the year 1912.
'If our interpretation is correct, one possible implication of our data is that the early onset of melting (after A.D. 1706) has contributed to the near synchronous loss of ice shelves along the eastern Antarctic Peninsula,' the researchers wrote.
This, they added, provides further support to the idea that ice shelves on the eastern Antarctic Peninsula have been predisposed to collapse by hundreds, and in some cases thousands of years of thinning.'
The authors believe that the accelerated thinning of the ice sheets was linked, at least in part, to shifts in the so-called Southern Annular Mode.
Changes in this belt of westerly winds, which oscillates between moving north- and southwards, would have led to stronger winds, atmospheric warming and ice shelf melting on the eastern Antarctic Peninsula.
At the same time, it would also have pulled warm water into the Weddell Gyre — a large circulation of water off of Antarctica's northern coastline — helping to increase the rate of melting underwater, at the base of the ice shelves.
The full findings of the study were published in the journal Scientific Reports.
This article has been adapted from its original source.
