Antarctica developed a massive continental-scale ice sheet 34 million years ago while global temperatures remained roughly five degrees Celsius warmer than today. A new study published in Science
reveals that slow-moving mantle waves spent more than 100 million years lifting the interior landscape high enough for permanent ice to survive.
Tectonic Forces and Mantle Waves That Built Antarctica
The long-standing puzzle of how Antarctica froze long before the Arctic has finally found a geological explanation. Researchers investigated the forces deep inside Earth that gradually transformed the southern continent. The process began after Antarctica and Africa started separating during the Jurassic breakup of Antarctica and Africa, a continental rift that altered thick plates and the mantle underneath them.
According to computational models reconstructing 100 million years of landscape evolution, dense material at the plate’s underside detached in coordinated drips. That loss made the surface above buoyant, launching a propagating process researchers call mantle waves. These slow-moving waves travel beneath continents after tectonic plates separate. As they passed beneath East Antarctica, they raised a vast plateau topped by the Gamburtsev Mountains.
Reaching the Critical Two-Kilometer Elevation Threshold
Topography played a fundamental role in the timing of the glaciation. Before 50 million years ago, most of the Gamburtsev landscape stood below 1.5 kilometers in elevation. By roughly 45 million years ago, broad areas had risen beyond the critical height of two kilometers. Air temperatures drop by up to one degree Celsius for every 100 meters of altitude gained, radically altering the annual snow budget.
“Antarctica’s land surface was gradually lifted to the point where ice could gain a permanent foothold, even while the surrounding polar oceans as well as global temperatures remained surprisingly warm.”
Thomas Gernon, Professor of Earth Science at the University of Southampton
By 34 million years ago, nearly half of the Gamburtsev range stood above two kilometers. At those heights, snow and ice survived summer warming and accumulated year after year, eventually forming the East Antarctic Ice Sheet. The international study was led by researchers at the University of Southampton alongside scientists from Durham University, the GFZ Helmholtz Centre for Geosciences, the University of Potsdam, Utrecht University, and the University of Florence.
Why Antarctica Froze Before the Arctic
While falling atmospheric carbon dioxide levels remain a principal trigger for the transition from Eocene greenhouse conditions to the colder Oligocene, CO₂ drops alone fail to explain why the poles responded with extreme asymmetry. Large ice sheets in the Northern Hemisphere did not form until approximately the past five million years, leaving the Arctic ice-free for nearly another 30 million years.
The delayed northern response highlights the unique role of tectonic uplift. Because geological processes raised the southern landmass to higher elevations, Antarctica crossed its glaciation threshold long before global climate reached modern temperatures. Once the ice sheet began expanding, ice-albedo feedback kicked in, with the bright surface reflecting more sunlight back into space and lowering global temperatures by about one degree Celsius in the simulations.
“We found that our models can realistically capture the evolution of the two-kilometer-high coastal escarpment, elevated plateau and inland mountains, eventually seeding the East Antarctic Ice Sheet.”
Dr. Thea Hincks, Senior Research Fellow at the University of Southampton
Global Climate Reorganization and Future Sea-Level Stakes
The Eocene-Oligocene transition marked one of the largest climate reorganizations of the Cenozoic Era. Sea levels fell sharply as a continental-scale ice sheet assembled. Today, that same ice sheet holds profound implications for global stability. The East Antarctic Ice Sheet stands as the largest ice sheet on Earth, containing enough frozen water to raise global sea levels by around 52 meters if it were to melt completely.
Researchers emphasize that the modeled cause-and-effect chain bridges geology and climate science. The findings demonstrate how deep interior processes operating across tens of millions of years can ultimately dictate surface climate thresholds. Understanding how ancient ice sheets first established themselves provides crucial baseline data for interpreting modern polar ice stability in a warming world.
