Plate Nº 53 · recorded October 10, 2026
Earth & ClimateReported finding
Slow waves deep inside Earth helped Antarctica freeze first
A study in Science points to mantle waves deep below East Antarctica as the reason the continent froze 34 million years ago, long before the Arctic.
By Marcus Bennett4 min read825 words
In brief
- Antarctica's ice sheet began forming about 34 million years ago; Arctic ice sheets only formed within the past 5 million years
- By roughly 45 million years ago, large parts of East Antarctica had risen above the 2-kilometer threshold for mountain glaciation
- The Gamburstsev range climbed from below 1.5 km to over 2 km in the 16 million years before the ice age began
- The ice-albedo feedback cooled Earth by an estimated 1°C, with air temperatures dropping roughly 1°C per 100 meters of altitude
- The East Antarctic Ice Sheet holds enough water to raise global sea levels by about 52 meters
Antarctica began to freeze about 34 million years ago — roughly 29 million years before large ice sheets formed in the Arctic, according to a study published on August 25, 2026, in Science.
The new research points to slow-moving "mantle waves" deep inside Earth as the mechanism that lifted East Antarctica high above sea level, allowing ice to take permanent hold while the planet was still about 5°C warmer than today.
How did Antarctica freeze before the Arctic?
The answer, researchers say, lies in geology rather than the atmosphere. An international team led by the University of Southampton reconstructed 100 million years of landscape evolution using computational models. The simulations show that after Antarctica and Africa began separating during the Jurassic Period, 201 to 143 million years ago, deep-Earth mantle waves gradually raised East Antarctica.
By about 45 million years ago, the models indicate, large parts of East Antarctica had climbed above roughly 2 kilometers in elevation. That altitude is the threshold for mountain glaciers to form and expand.
What are mantle waves?
Mantle waves are a recently identified phenomenon first described by lead author Thomas Gernon, a Professor of Earth Science at the University of Southampton. They are slow ripples of hot rock that travel beneath continents after tectonic plates begin to separate. The same waves have previously been linked to diamond-volcano eruptions and unexplained phases of continental uplift.
As mantle waves passed beneath East Antarctica, they helped raise a vast plateau topped by the Gamburtsev Mountains. Until now, researchers lacked a mechanism that could explain how Antarctica reached elevations high enough to begin freezing.
"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," Gernon said.
Why did topography matter so much?
Topography controls whether snow survives summer. Air temperatures drop by about 1°C for every 100 meters of altitude gained, according to co-author Guy Paxman, a Royal Society University Research Fellow at Durham University.
Before 50 million years ago, most of the Gamburtsev range stood lower than 1.5 km. By 34 million years ago, nearly half of the mountains had risen above 2 km. At those heights, snow and ice could survive year-round.
"Topography is fundamentally important for glaciation," Paxman said.
Once the ice cap formed, it cooled the planet further. Bright ice reflects sunlight back into space in what scientists call the ice-albedo effect. The team estimates this feedback reduced global temperatures by about 1°C — not enough, on its own, to freeze the Arctic.
What stopped the Arctic from freezing at the same time?
Arctic landmasses sat at lower elevations, leaving them too warm for permanent ice. Antarctica's geological head start of tens of millions of years let the southern continent build a critical mass of ice first. Large Northern Hemisphere ice sheets did not form until roughly the past 5 million years.
"If falling levels of CO2 acted alone, you would expect the poles to respond more symmetrically," Gernon said. "Instead, Antarctica gained a major head start because geological processes had raised land to higher elevations, making it colder."
What feedback loops cemented the cooling?
Two reinforcing feedbacks helped Antarctic ice spread beyond the mountains:
- The ice-albedo effect, in which bright ice reflected more sunlight and lowered regional temperatures further.
- A drier atmosphere. Colder air holds less water vapor, weakening Earth's natural greenhouse effect.
"Together, these feedbacks allowed the Antarctic ice sheet to spread from the mountains across the continent, eventually reaching the coast," said co-author Philip Goodwin, a climate physicist at the University of Southampton.
How big is the East Antarctic Ice Sheet today?
The East Antarctic Ice Sheet is now the largest ice sheet on Earth. It holds enough frozen water to raise global sea levels by about 52 meters if it melted completely.
What does this change for climate research?
The findings reframe how scientists think about the origins of ice ages. Climate alone does not decide when ice sheets form — deep-Earth forces may first have to prepare the land by raising it to elevations where permanent ice can survive.
"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," Gernon said. "That's incredibly important for understanding Earth's ancient ice ages as well as future tipping points in the climate system."
The study involved researchers from Durham University, the GFZ Helmholtz Centre for Geosciences in Germany, the University of Potsdam in Germany, Utrecht University in the Netherlands, and the University of Florence in Italy. Funding came from the WoodNext Foundation. The study is preliminary in nature — it is a single modeling-based reconstruction, and direct geological evidence of the proposed mantle-wave uplift in East Antarctica still needs to be verified in the field.
via dx.doi.org (Original)
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