The Antarctic ice sheet formed millions of years before the Arctic froze, at a time when Earth’s temperatures were significantly higher than today. A new theory proposes an unexpected cause for this ancient deep freeze: the breakup of continents, violent currents deep within Earth’s mantle, and the slow formation of mountains.
The vast East Antarctic ice sheet, the oldest and largest ice mass on the planet, began to take shape around 34 million years ago. Scientists have long linked its formation to a drop in atmospheric CO₂ levels, which cooled the planet enough for ice to start forming.
However, this explanation does not fully align. If the cause were solely a reduction in CO₂ concentrations, we would expect both hemispheres to freeze simultaneously, rather than just the southernmost continent around the South Pole, while the Arctic remained ice-free for millions more years.
In a new study, researchers have proposed that tectonic shifts and continental uplift played a decisive role in Antarctica’s early cooling. The findings were published in the journal Science.
“If the decline in CO₂ levels occurred on its own, we might anticipate a more symmetric response from the poles. Instead, Antarctica had a major advantage because geological processes raised the land to a greater altitude, making it colder,” explained lead author Professor Thomas Gernon from the University of Southampton (UK).
The team developed computer models to trace how continental movements reshaped the landscape around Antarctica over roughly 100 million years. They discovered that the trigger was the separation of Antarctica and Africa during the Jurassic period, between 201 and 143 million years ago, when the supercontinent Gondwana fractured.
This disruption generated slowly propagating waves in Earth’s mantle, termed “mantle waves”—a phenomenon first identified by Gernon’s team while studying similar peculiar high-altitude plateaus in southern Africa.
As these waves traveled beneath East Antarctica, they gradually lifted the Earth’s crust, forming a coastal cliff, an elevated plateau, and the Gamburtsev Mountains—a mountain range now buried under more than a kilometer of ice deep within the continent.
Around 45 million years ago, much of East Antarctica’s landscape had risen approximately 1.5 to 2 kilometers above the threshold needed for year-round snow and ice, enabling the formation of a permanent ice cap.
“We found that our models could realistically replicate the evolution of a 2-kilometer-high coastal cliff, an elevated plateau, and interior mountain ranges that ultimately led to the formation of the East Antarctic ice sheet,” said co-lead researcher Thea Hincks from the University of Southampton.
“Terrain is fundamentally important for glaciation. Air temperature can drop by 10°C for every 100 meters of elevation gain,” noted study co-author Guy Paxman from the Royal Society at Durham University.
This study serves as a reminder that plate tectonics is inextricably linked to Earth’s climate, and in turn, to life.
Another classic example of this relationship is the end of the “boring billion.” During the period from 1.8 billion to 800 million years ago, Earth entered a prolonged quiet phase marked by very little change in biological evolution, geology, climate, or ocean and atmospheric chemistry.
One of the key factors that disrupted this era of sluggish stagnation was the movement of tectonic plates, which enriched the world’s oceans by lifting sediments and crust, releasing more nutrients into the water. This abundance of nutrients created a fertile environment that fostered the development of life and the evolution of new species.
Geology may appear as a slow, lifeless process operating on timescales too vast to matter for anything living. But, as this research demonstrates, it often shapes processes that we are only beginning to understand.
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