New study warns melting ice in Antarctica could lead to dramatic rise in sea levels

Melting glaciers in Antarctica could lead to a significant rise in sea levels if greenhouse gas emissions are not reduced, a new study warns.

Over the past three decades, global sea levels already risen by more than ten centimeters. With every year that passes, the sea level creeps up nearly half a centimeter more – and that process is accelerating.

So far, Antarctica’s contribution to sea level rise has been small. By and large, the white continent has remained frozen solid.

That is likely to change, a study based on 16 separate ice sheet models warns. Regardless of the emissions scenarios used, melting ice in Antarctica alone can cause sea levels to rise by an additional 28 centimeters by the end of this century.

What happens beyond that date will strongly depend on whether governments take action to reduce greenhouse gas emissions. Under a high emissions scenario, the models predict that Antarctica can add up to 170 centimeters to sea levels by the year 2200.

To put these figures into context, nearly a quarter billion people currently live within one metre of high tide lines.

“Ice mass losses from low- and high-emission scenarios are relatively similar for this century,” said co-author Petra Langebroek from the iC3 Polar Research Hub in Tromsø, NORCE and the Bjerknes Centre for Climate Research in Bergen, who contributed to the study.

“However, the difference between scenarios grows rapidly after the year 2100. This underscores the importance of reducing emissions now to safeguard the long-term stability of the Antarctic Ice Sheet, and protect our descendants from the consequences of catastrophic sea level rise.”

Another researcher warned of potential irreversible changes ahead.

“Several basins in West Antarctica could experience a complete collapse before 2200 and all models agree that once these large changes are initiated, nothing can stop them or slow them down”, added Hélène Seroussi from Dartmouth College, lead author of the study.

“The exact timing of such collapses remains unknown and depends on future greenhouse gas emissions, so we need to respond quickly enough to reduce emissions before major basins of Antarctica are lost.”

The study notes that considerable uncertainty remains about several factors driving these projections. The rate of ice sheet loss depends on not only on air and sea temperatures, but also on how glaciers will flow over bedrock towards the ocean, and the interactions between floating ice shelves and the surrounding Southern Ocean.

To reduce these uncertainties, the iC3 Polar Research Hub is investigating how past changes in ice sheets affected ocean circulation, and conducting studies of ice sheet – ocean interactions.

The findings from these work streams will inform iC3’s future modelling work, allowing scientists to better predict what challenges people will have to cope with as the planet continues to heat up.

The study “Evolution of the Antarctic Ice Sheet over the next three centuries from an ISMIP6 model ensemble” has been published open access and is available online.