Catastrophic collapse of West Antarctic ice sheet not inevitable, scientists say

The runaway collapse of the West Antarctic Ice Sheet – which would trigger catastrophic sea level rise – is not inevitable.

Pine Island Glacier in Antarctica, nicknamed the Doomsday Glacier. Picture: NASA

The runaway collapse of the West Antarctic Ice Sheet – which would trigger catastrophic sea level rise – is not inevitable, scientists say, following research that tracked the region’s recent response to climate change.

As global temperatures rise, there is mounting concern that warming could trigger tipping points that set off irreversible melting of the world’s massive ice sheets and ultimately lift oceans enough to redraw the world map.

New research published in the journal Nature Communications suggests a complex interaction of factors affecting the melting of the West Antarctic Ice Sheet, which is home to the enormous and unstable Pine Island and Thwaites glaciers – nicknamed the “Doomsday glacier” – that together could raise global sea levels by more than three metres.

Using satellite imagery as well as ocean and climate records between 2003 and 2015, an international team of researchers found that while the West Antarctic Ice Sheet continued to retreat, the pace of ice loss slowed across a vulnerable region of the coastline.

Their study concluded that this slowdown was caused by changes in ocean temperatures that were caused by offshore winds, with pronounced differences in the ­impact depending on the region.

Researchers said this raises questions about how rising ­temperatures would affect the Antarctic with ocean and atmospheric conditions playing a key role. Co-author Eric Steig from the University of Washington in Seattle, said that meant that ice-sheet collapse was not inevitable. “It depends on how climate changes over the next few decades, which we could influence in a positive way by reducing greenhouse gas emissions,” Professor Steig said.

The researchers observed that, while in one region, in the Bellingshausen Sea, the pace of ice retreat accelerated after 2003, it slowed in the Amundsen Sea. They concluded this was down to changes in the strength and direction of offshore surface winds, which can change the ocean currents and disturb the layer of cold water around Antarctica and flush warmer water towards the ice.

Both the North and South pole regions have warmed by roughly 3C compared with late 19th-century levels, nearly three times the global average.

Scientists are increasingly concerned that the Pine Island and Thwaites glaciers have reached a “tipping point” that could see irreversible melting irrespective of cuts to greenhouse gas emissions.

AFP