Simulation finds East Antarctic ice sheet mostly intact above 10 degrees of warming

A 100,000-year run with climate and ice interacting

The findings appeared in Nature Climate Change on 30 October. The 100,000-year simulation was led by Axel Timmermann, director of the IBS Center for Climate Physics, and Yoon Kyung-sook, a research fellow at the center. The team combined a global climate model with an ice sheet model. The researchers set atmospheric carbon dioxide at a range of levels and analyzed how the climate and the Antarctic and Greenland ice sheets changed while influencing one another. Earlier studies fed predetermined atmospheric and ocean conditions into ice sheet models. This run let the climate and the ice respond to each other, the team reported.

The East Antarctic Ice Sheet remained mostly intact even when the temperature increase topped 10 degrees Celsius. The analysis found that warming affects ice sheets very differently by region.

West Antarctica and Greenland lose more

If global average temperatures stay more than 2 degrees Celsius above pre-industrial levels, West Antarctica would lose a substantial amount of ice over the long term. The Greenland Ice Sheet would shrink gradually as warming proceeds and could vanish completely once the increase exceeds about 6 degrees Celsius. The East Antarctic Ice Sheet sits largely on land. The team attributed the regional difference to warming-driven changes in atmospheric circulation, snowfall and cloud cover.

Snow and cloud slow the loss

Warmer air holds more water vapor. Shifting Southern Hemisphere air flows carry more of it toward Antarctica, where it falls as snow on the high interior plateau of East Antarctica and builds new ice. Additional cloud cover produced by warming also blocks sunlight from reaching the ice surface, suppressing melt.

Under the strongest warming scenario, the volume of the Antarctic ice sheet shrank by about 70% when changes in precipitation and solar radiation were left out. In the coupled model that included those atmospheric responses, the decline was only about 20%. Long-term projections of ice loss can therefore differ widely depending on how the interaction between climate and ice is represented.

Yoon said the results show the long-term future of ice sheets cannot be understood from temperature alone. "We need to consider together how changes in snowfall, clouds, winds and ocean temperatures interact with the ice sheet surface," she said.

What the model cannot settle

The team stressed that the results do not mean Antarctica is safe from climate change. Sustained warming could still trigger large-scale ice loss in West Antarctica and accelerate global sea level rise. Ice retreat is already under way in parts of East Antarctica. The model's relatively coarse spatial resolution could not fully reproduce detailed changes beneath ice shelves or along the ice sheet margins.