Ancient Earth Movements Set the Stage for Antarctica's Deep Freeze

A Mystery Solved Deep Beneath the Ice

Some 34 million years ago, when Earth was significantly warmer than it is today, Antarctica froze over — and it would take another 25 million years for ice to cover the Arctic. The question of how the South Pole got such an enormous head start has puzzled scientists for decades. Now, a landmark study published in the journal Science has found a surprising answer buried not in the ice itself, but deep in the planet's interior.

A new study found that slow-moving mantle waves set in motion more than 120 million years ago may have given Antarctica a head start — triggered by the separation of Africa and Antarctica. Mantle waves are slow-moving disturbances deep within Earth. Recently identified by the research team, they form when tectonic plates break apart, then move beneath a continent, stripping material from its base and pushing the land above higher.

How a Jurassic Breakup Shaped a Frozen Continent

Africa and Antarctica broke apart during the Jurassic period, around 170 million years ago. When continents break apart, hot material from Earth's mantle wells up beneath them, cools, and then sinks. This swirling motion destabilises the base of the neighbouring continent, triggering a series of lava lamp-like instabilities that remove chunks of its deep roots, one by one. These disturbances, called "mantle waves," sweep below continents over millions of years, travelling more than 1,000 kilometres as they ripple through the hot, sticky rock beneath the landmass.

Hundreds of kilometres inland, the mantle wave stripped away rock deep beneath the continent. Like a hot air balloon rising after dropping its ballast, the land above slowly lifted, creating a vast plateau and triggering a wave of erosion across the landscape. The uplift didn't stop there — it kept migrating inland, taking roughly 100 million years to reach the Gamburtsev Mountains, over 1,500 km from the coast. Before 50 million years ago, most of the Gamburtsev Mountains stood below 1.5 km. By the time Antarctica's major glaciation began around 34 million years ago, nearly half of the range had risen above 2 km — an increase that allowed snow to remain through the summer and accumulate into permanent ice caps.

Elevation: The Hidden Key to Ice

Elevation matters enormously for ice. Air temperature drops by roughly 1°C for every 100 metres of elevation gained, so even a modest additional uplift can tip a mountain range from losing its snow each summer to keeping it year round. The simulations indicate that by about 45 million years ago, large parts of East Antarctica had climbed above the critical elevation — about 2 km — required for mountain glaciers to develop and expand. Over time, those glaciers grew together to form the East Antarctic Ice Sheet.

Once the ice began spreading, it helped create conditions for even more ice. "As the ice sheet expanded, its bright surface reflected more sunlight back into space, cooling the region further," said Dr. Philip Goodwin, a climate physicist at the University of Southampton and study co-author. The study is careful to note that falling CO₂ levels were still a critical ingredient — as lead author Prof. Gernon explained: "If falling levels of CO₂ acted alone, you would expect the poles to respond more symmetrically. Instead, Antarctica gained a major head start because geological processes had raised land to higher elevations, making it colder."

What This Means for Understanding Our Climate Future

The results may also explain why the two polar regions followed very different paths. Antarctica became heavily glaciated around 34 million years ago, while large ice sheets in the Northern Hemisphere did not form until approximately the past five million years. That asymmetry, long unexplained, now has a geologic foundation rooted in the slow, grinding machinery of the planet itself.

"Our findings reveal that the Earth's interior preconditions landscapes to glaciation, determining when and where major climate transitions like the glaciation of Antarctica become possible," said lead author Thomas Gernon. "That's incredibly important for understanding Earth's ancient ice ages as well as future tipping points in the climate system." In other words, the story of Antarctica's ice didn't begin with a cold snap — it began with a continental divorce 170 million years in the making, and the slow, invisible waves that followed.