Venu Menon
Wellington, May 17,2024
If the Antarctic ice sheet stopped melting, it would take nearly 200 years to rebuild the lost ice, researchers say.
This startling finding comes in the wake of a study into ways of slowing the retreat of the major Antarctic glaciers leading to global sea-level rise.
The study, published last month in Communications Earth and Environment and titled: ‘Sustained ocean cooling insufficient to reverse sea-level rise from Antarctica’, explored ways of slowing the retreat of ice in the Amundsen Sea Embayment of the West Antarctic Ice Sheet.
“The Pine Island and Thwaites glaciers in the Amundsen Sea Embayment are the ‘weak underbelly’ of the West Antarctic Ice Sheet,” said lead author Alanna Alevropoulos-Borrill, a research fellow at Victoria University of Wellington.
“These glaciers make the Embayment the largest contributor to sea-level rise from Antarctica and rates of ice loss are expected to increase in a warming climate,” Alevropoulos-Borrill added.
The study relied on computer modelling to understand the conditions needed to arrest or slow the retreat of ice in the Embayment and reverse sea-level rise.
Nearly 200 different scenarios were examined to slow the melting of the ice. These included proposals based on building undersea walls to keep warm water from the Southern Ocean reaching and accelerating the melting rate of the ice sheet.
While the modelling indicated a cooler ocean would result in reduced ice loss, reversing sea-level rise presented a formidable challenge .
Alevropoulos-Borrill noted: “Our modelling showed cooler water conditions would reduce the maximum amount of ice lost. However, we also found that entirely offsetting or reversing the region’s contribution to sea-level rise would need more than ocean cooling – it would also require nearly two centuries of increased snowfall to build up the mass of ice that has so far been lost.”
She said current melting was “already pushing the Embayment to a point of no return.”
The collapse of Antarctica’s two biggest glaciers, and “four smaller ice streams,” could contribute to a rise in global sea-level.
The study estimates that sea-level rise could be up to 1.2 metres globally, “or as much as 3m if the whole of the West Antarctic Ice Sheet collapsed.”
Alevropoulos-Borrill was sceptical about how effective the construction of undersea walls to cordon off the ice sheet from warm water would be.
“Our modelling suggests that building submarine walls to prevent warm waters reaching the Embayment might be sufficient – if it worked – to mitigate effects of the worst-case scenario. However, there will still be ongoing ice loss and global sea-level rise for decades, if not centuries, to come.”
Alevropoulos-Borrill cited recent research to point out that these submarine walls could “cause more harm than good by redirecting warmer ocean water to other vulnerable areas, causing these areas to melt faster and accelerating sea-level rise.”
The research findings painted a gloomy future for the West Antarctic Ice Sheet and highlighted the need for urgent action.
Venu Menon is an Indian Newslink reporter based in Wellington
