Collapse of Antarctic Ice Shelves Likely Centuries in the Making

(CN) – Ice shelves in the eastern Antarctic Peninsula have been thinning for hundreds of years, leaving them vulnerable to collapse in the face of climate change, according to research released Thursday.

In a study published in the journal Scientific Reports, 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.

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