The study, led by researchers at the University of Southampton and completed by an international team, traces the origin of East Antarctica's ice sheet to the uplift of the Transantarctic Mountains and the Gamburtsev Mountains — a subglacial range buried under 1 to 3 kilometers of ice. The key finding is that these mountains and the adjacent Dronning Maud Land escarpment created the high ground necessary for snow to accumulate and persist, even when the planet was significantly warmer than today.
Why high ground matters for ice sheets
Ice sheets do not form at sea level in a warm world. Snow must fall and survive the summer melt season. Higher elevations are colder, and the air above a mountain range holds less moisture, which means less rain and more snow. The Dronning Maud Land escarpment rises to nearly 2 kilometers above sea level, and the Gamburtsev Mountains, though now buried, reach heights comparable to the European Alps. That altitude was the critical difference: it allowed snow to survive year-round, compact into firn, and eventually transform into glacial ice.
The Arctic, by contrast, is a frozen ocean surrounded by low-lying land. There was no equivalent high ground to kick-start ice formation. Only when global carbon dioxide levels dropped below a critical threshold roughly 3 million years ago did the Arctic Ocean begin to freeze over. The sequence, therefore, was not simultaneous. Antarctica's ice grew because of topography; the Arctic's ice grew because of atmosphere.
How the puzzle was solved
The team used a combination of geological field data, thermochronology — measuring the cooling history of rocks to determine when they were uplifted — and climate modeling. They traced landscape features from the coastal escarpment inland to the subglacial Gamburtsev Mountains, reconstructing the uplift timeline. The data showed that the East Antarctic highlands were already in place well before the Eocene-Oligocene boundary, about 34 million years ago, when the first continental-scale ice appeared.
The modeling then confirmed that those elevations, paired with the drop in atmospheric CO2 that occurred at that time, were sufficient to trigger runaway ice accumulation. In the Arctic, the same CO2 drop was not enough to form permanent ice because the land around the Arctic Ocean lacked comparable elevation.
What this means for understanding past and future climate
One of the implications is that ice-sheet formation is not purely a function of global temperature. Topography can act as a geological on-off switch, determining when and where ice can take hold. The finding also refines how scientists reconstruct past CO2 thresholds: the same CO2 level that produced glaciation in Antarctica would have been harmless in the Arctic, because the geographical starting conditions were different.
For modern climate science, the study reinforces a less comforting point. Once an ice sheet is established, it reshapes the landscape beneath it, eroding valleys and depressing the crust. The result is that the ice sheet becomes partly self-sustaining — and partly self-defeating. The East Antarctic Ice Sheet sits in a basin that, if the ice were to melt, would fill with water, creating an inland sea. That geography means the ice sheet may be more vulnerable to warming than once assumed, because the basin topography funnels warm ocean water toward the ice margins.
Knowledge takeaway: the East Antarctic Ice Sheet formed 34 million years ago because the Transantarctic Mountains and Gamburtsev Mountains created high ground that trapped snow, even when Earth was 5 °C warmer than today; the Arctic only froze 3 million years ago when CO2 dropped further, because the Arctic lacks equivalent high ground; the finding solves a long-standing puzzle in climate science and shows that topography is as important as temperature in determining when ice sheets form.