Fuseworks Media

Colder seas and nearly 200 years of increased snowfall needed to rebuild Antarctic ice loss

A new study exploring ways to slow retreat of ice loss in the Amundsen Sea Embayment-the biggest contributor to sea level rise from Antarctica-suggests that even if melting stopped, it would take nearly two centuries of increased snowfall to rebuild the ice that’s already disappeared.

“The Pine Island and Thwaites glaciers in the Amundsen Sea Embayment are the ‘weak underbelly’ of the West Antarctic Ice Sheet. 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,” said lead author Dr Alanna Alevropoulos-Borrill, a research fellow at Te Herenga Waka-Victoria University of Wellington.

Using computer modelling, the study investigated the conditions required to slow retreat of ice in the Embayment and reverse sea-level rise.

“We explored nearly 200 different scenarios, including the use of geoengineering proposals to slow melting. These proposals are based on building submarine walls or curtains that could prevent warm water from the Southern Ocean reaching and rapidly melting vulnerable parts of the ice sheet.

“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.”

Dr Alevropoulos-Borrill said the findings paint “a gloomy image” for the future of the Amundsen Sea Embayment and highlight the need for immediate action.

“Current melting is already pushing the Embayment to a point of no return. The collapse of its two biggest glaciers and four smaller ice streams could contribute up to 1.2 metres of global sea-level rise, or as much as 3 metres if the whole of the West Antarctic Ice Sheet collapsed.”

Relying on expensive geoengineering options to protect the Antarctic ice sheet from warm water was unlikely to provide a solution, she said.

“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.”

Geoengineering options remained “very controversial,” said Dr Alevropoulos-Borrill.

“Recent research suggests they could even 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.”

 

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