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.
In a study William Dickens of the British Antarctic Survey and his team analyzed isotopes in single-cell algae to compose a 6,250-year record of glacial meltwater discharge.
These algae found in the northeastern tip of the Antarctic Peninsula were perfectly preserved in pieces of marine sediment core, which are known to provide a glimpse into ecosystems of the past. The algae showed that the lower the isotope value, the higher the glacial discharge.
This record depicted an increasing trend in glacial discharge beginning after the year 1400 and reaching its peak in 1912. Researchers deduced from these findings that the ice shelves in the region have been thinning at an increasing rate for the past 300 years, predisposing the massive bodies of ice to collapse from increased climate warming.
The authors suggest that a possible reason for this accelerated thinning could be from a shift in the Southern Annular Mode, the belt of westerly winds that circles Antarctica. Over time, this wind belt has brought stronger westerly winds, atmospheric warming, and ice shelf melting on the eastern Antarctic Peninsula.
It has also pulled warm water into the Weddell Gyre – a cyclone formed between surrounding currents and the Antarctic Ice Shelf. Unfortunately, warming of this gyre increases the chances of underside melting of the ice shelves, contributing to the possibility of collapse.
Recently, the Southern Annular Mode has experienced more frequent shifts suspected to be caused by increasing levels of greenhouse gases in the atmosphere, as well as ozone layer depletion. The authors add that these frequent shifts could lead to accelerated ice mass loss in the future.