'Alps under the ice' give clues to global warming

The mystery of how a subglacial mountain range the size of the Alps formed up to 250 million years ago has finally been solved and could help map the effects of climate change, scientists say.

The Gamburtsev subglacial mountains are buried 3 km below the East Antarctic Ice Sheet, the largest remaining body of ice on the planet.

Experts are trying to learn more about the frozen continent as even a small thaw could swamp low-lying coastal areas and cities. Antarctica contains enough ice to raise world sea levels by about 57 metres (187 ft) if it ever all melted.

Discovered in 1958, the mountains' origin has largely been an enigma until now.

Around 34 million years ago, there was an abrupt decline in levels of carbon dioxide in the atmosphere which prompted the glaciation of Antarctica. The process began over the Gamburtsev mountains, Fausto Ferraccioli, lead author of the report and geophysicist at the British Antarctic Survey, told Reuters.

On top of the mountain range, there is a strong possibility of finding the oldest ice on the planet, which could be 1.2 million years old or more, he said. Until now, scientists have only been able to study ice from up to 800,000 years ago.

Based on radar, gravity and magnetic data, scientists from seven countries found a tectonic process called rifting was the trigger that lifted up the Gamburtsev mountains.

The findings, published in the journal Nature, showed that several continents collided around one billion years ago, crushing the mountain's rocks together. This formed a huge root which extended deep beneath the mountain range. Although the mountains eroded over time, the root was left behind.

When rifting occurred up to 250 million years ago, the root warmed up, which forced land upwards to re-form the mountains.

The East Antarctic Ice Sheet, which covers 10 million sq km, protected the mountains from erosion.

"In particular, the fluvial and glacial valleys were responsible for uplifting the peaks and making the mountains look like the Alps. Their present day aspect is strongly influenced by climate and ice sheet evolution," said Ferraccioli.

"Understanding long-term ice sheet evolution is critical in order to develop more realistic models of variations of the ice sheet to climate change," he said.

The mountains could also contribute to the long-term stability of the ice sheet.

"The ice sheet and climate models would suggest you can still maintain an ice sheet in the interior of East Antartica over the mountains even if the temperature rise were 10 degrees (Celsius) above the present day -- perhaps even as much as 15 degrees," said Ferraccioli.


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