Three major ice sheets are being closely watched by scientists as global temperatures increase, glaciers melt and sea levels rise. Of the three, the East Antarctic Ice Sheet is the largest potential contributor to sea-level rise.
But efforts to predict the East Antarctic鈥檚 role in future sea-level rise have been hindered by an absence of data about the ice sheet鈥檚 response to warming periods in the past. The geological history of the massive ice sheet 鈥 frozen both above and, in many places, below the ocean鈥檚 surface 鈥 has been difficult to pinpoint.

Using ultra-sensitive analytical measurements that have helped to reveal the history of other ice sheets, a team of researchers has found that the East Antarctic Ice Sheet did not retreat significantly over land during the warm Pliocene epoch, approximately 5.3 to 2.6 million years ago, when atmospheric carbon dioxide concentrations were similar to today鈥檚 levels, a team of scientists reports in the journal Nature.
The findings suggest that some ice on the southern continent could be stable in a warming climate, but do not signal that Antarctica can somehow backstop the impact of climate change, the researchers caution. Ongoing emissions mean that atmospheric carbon dioxide levels will soon surpass the benchmark set during the Pliocene, the last time Earth experienced carbon dioxide levels higher than 400 parts per million.
The study focused on terrestrial ice, the portion of the ice sheet that sits above the ocean and sequesters enough water to account for more than 110 feet of sea level rise were the ice sheet to melt away in response to rising air temperature. The other component of the East Antarctic Ice Sheet is so-called marine-based ice, which sits below sea level and is thus directly affected by the ocean.
鈥淏ased on this evidence from the Pliocene, today鈥檚 current carbon dioxide levels are not enough to destabilize the land-based ice on the Antarctic continent,鈥 said Boston College Assistant Professor of Earth and Environmental Science Jeremy Shakun, a lead author of the report.
鈥淭his does not mean that at current atmospheric carbon dioxide levels, Antarctica won鈥檛 contribute to sea-level rise," Shakun said. "Marine-based ice very well could, and in fact is already starting to鈥攁nd that alone holds an estimated 65 feet of sea-level rise. We鈥檙e saying that the terrestrial segment of the ice sheet is resilient at current carbon dioxide levels.鈥
