Stability of the largest piece of ice on Earth at risk of ocean warming

The drastically increasing influence of human beings on the earth’s climate causes a melting of the polar ice caps and therefore a rise in the global sea level. A team of international scientists led by Heidelberg University’s Institute of Earth Sciences and which includes the University of Southampton has now analyzed the response of Earth’s largest ice sheet, the East Antarctic Ice Sheet, to a hot weather.

Based on geochemical data obtained from deep-sea sediments, the study sheds new light on the factors that determine the stability of the East Antarctic ice sheet. It suggests that in an increasingly warm climate, as predicted for the foreseeable future, the East Antarctic ice sheet may be less stable than previously thought.

“The future melting of the polar ice caps and the resulting global sea level rise as a result of climate change will have a substantial impact on low-altitude coastal areas,” emphasizes Dr Kim Jakob of the University of Heidelberg. To better understand the behavior of the East Antarctic ice sheet in a world warmer than it is today, scientists performed geochemical analyzes of deep-sea sediments from the Atlantic Ocean obtained through the Integrated International Ocean Drilling Program.

The study focuses on the time span from about 2.8 to 2.4 million years ago, a period in which atmospheric CO₂ the levels were similar to those of today. The results show an increase in the stability of the East Antarctic ice sheet compared to about 2.5 million years ago. This stability has lasted to the present day, with only brief interruptions during the exceptionally hot phases.

The factors that are generally accepted to have controlled the growth and decay of polar ice caps throughout the history of the Earth are solar radiation and CO₂ content of the atmosphere. However, this new study found that another factor played a decisive role in stabilizing the East Antarctic ice sheet: the formation of large ice sheets in the Northern Hemisphere, which caused global sea level to drop. This drop in sea level has reduced the East Antarctic ice sheet’s exposure to relatively warm ocean waters that have the potential to melt underwater parts of the ice sheet.

Professor Paul Wilson of the Department of Earth and Ocean Sciences at the University of Southampton said: “Our data provide an unusually high resolution picture of changes in ocean temperature, ice volume and sea level. sea ​​for an interval in which atmospheric CO₂ the levels were as high as they are today. We can see that before 2.5 million years ago, in our records, sea level peaks were so high that even the largest mass of ice on Earth, the East Antarctic Ice Sheet, melted.

These findings shed light on the behavior of polar ice caps under higher atmospheric greenhouse gas concentrations, as expected for the foreseeable future. The result of their study highlights the vulnerability of the East Antarctic ice sheet to global warming and the risk of renewed destabilization of the East Antarctic ice sheets triggered by continued sea level rise.

Professor Wilson added: ‘We suspect that the melting occurred in areas where the Antarctic ice sheet was in contact with a rising and warming ocean driven by the retreat of other ice sheets in the Northern Hemisphere; a kind of vicious circle.’ .

Their study titled “A new sea level record for the Neogene / Quaternary boundary reveals the transition to a more stable Eastern Antarctic ice sheet” was published today in the journal Proceedings of the National Academy of Sciences.