Antarctica became covered by a massive ice sheet roughly 34 million years ago, millions of years before permanent ice sheets developed in the Arctic. New research published in Science suggests the explanation may lie not only in global cooling, but in a dramatic transformation of Antarctica's landscape.

After Antarctica and Africa began separating during the Jurassic Period, deep geological processes gradually lifted large portions of East Antarctica. Researchers believe slow-moving “mantle waves” beneath the continent helped raise the terrain, eventually creating a vast plateau, escarpment, and the Gamburtsev Mountains.

By about 45 million years ago, large areas had reached elevations near 1.2 miles (2 km). Because temperatures decline with altitude, those higher elevations became cold enough for snow to survive through summer. By roughly 34 million years ago, nearly half of the Gamburtsev Mountains had risen above that threshold, allowing glaciers to form and gradually merge into the East Antarctic Ice Sheet.

The elevated landscape then helped trigger additional climate feedbacks. Expanding ice and snow reflected more sunlight back into space, producing further cooling through the ice-albedo effect. Colder air also holds less water vapor, weakening the atmosphere's greenhouse effect and allowing additional heat to escape.

Declining atmospheric carbon dioxide likely contributed to the broader cooling of the planet, but the new study suggests it was not enough by itself to explain why Antarctica froze so much earlier than the Arctic. Higher Antarctic terrain gave the Southern Hemisphere a crucial geographical advantage.

The findings demonstrate that major climate transitions can depend on both atmospheric conditions and geological change. Earth's interior may first reshape the landscape, creating the elevation and environmental conditions that allow a seemingly gradual cooling trend to trigger a much larger and more lasting transformation.