An international team of scientists has uncovered the mechanism that allowed Antarctica to develop a massive ice sheet approximately 34 million years ago—when global temperatures were 5°C warmer than today—whereas major ice sheets in the Northern Hemisphere did not appear until about 5 million years ago.
Published in the journal Science and led by Professor Thomas Gernon of the University of Southampton alongside colleagues from Durham University, GFZ Helmholtz, the University of Potsdam, Utrecht University, and the University of Florence, the study relies on computer models of East Antarctica's landscape evolution over the last 100 million years.
According to the findings, the rifting between Antarctica and Africa during the Jurassic period, 201–143 million years ago, played a crucial role. This process triggered "mantle waves"—slow movements of material beneath the continental crust that gradually uplifted the surface of East Antarctica.
As a result, by 45 million years ago, a significant portion of the region had risen more than 2 km above sea level. At this altitude, snow and ice could persist year-round without melting in the summer, gradually accumulating to form mountain glaciers first and then a unified ice sheet.
The researchers paid particular attention to a 2-km-high coastal escarpment in Queen Maud Land, an expansive plateau, and the ice-buried Gamburtsev Mountains. Models show that by the onset of glaciation, nearly half of the mountain range exceeded 2 km in elevation, creating the necessary conditions for sustainable ice accumulation.
Scientists note that falling atmospheric carbon dioxide levels alone cannot explain the asymmetry: if CO2 were the only driver, both poles should have glaciated at roughly the same time. Geological uplift gave Antarctica the decisive advantage.
As the ice cover expanded, the albedo effect took hold: the bright ice surface reflected more sunlight, further cooling the region. Additionally, the colder air held less water vapor, weakening the greenhouse effect and driving temperatures down even further.
Since similar high plateaus and mountain ranges did not exist in the Arctic at the time, massive ice sheets failed to form there until much later, despite the general global cooling.
The authors emphasize that Earth's internal processes predetermine the landscape, either enabling or hindering major climatic transitions. This discovery helps us better understand not only ancient glaciations but also potential tipping points in the modern climate system.
The study is based on a combination of geological reconstructions, seismic data, and numerical modeling, providing a high degree of confidence in the conclusions within the scope of currently available methods.
