News24

Antarctic mountain mystery solved

2011-11-17 08:30

London - The mystery of how a subglacial mountain range the size of the Alps formed up to 250 million years ago has finally been solved, scientists said on Wednesday, which could help map the effects of climate change.

The Gamburtsev subglacial mountains are buried 3km 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 57m 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, said Fausto Ferraccioli, lead author of the report and geophysicist at the British Antarctic Survey.

Rifting

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 upward to re-form the mountains.

The East Antarctic Ice Sheet, which covers 10 million square kilometres, 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° [Celsius] above the present day - perhaps even as much as 15°," said Ferraccioli.

Comments
  • JudithNkwe - 2011-11-17 09:39

    Absolutely fascinating - how did they know the range was there?

      Paulus - 2011-11-17 12:40

      "Scientists first realised the mountains existed more than 50 years ago when a seismic survey indicated peaks in the area but the scale of the range was only realised recently using radar." from the Telegraph.

  • Christopher - 2011-11-17 18:37

    If your ice melts in your glass does the level rise or fall. I dont have to be a scientist to figure that out.

      Phil - 2011-11-17 19:08

      I read that the article is about mountain ranges under the antarctic. Ice that melts in the ocean has no effect on levels, it is the ice that resides on land mass that will have the effect, you dont have to be a scientist to figure that out.

      Frediano - 2011-11-17 20:19

      Phil doesn't think that the solid bottom of your glass is like land when the ice melts above it. I don't know why Phil thinks that, but he does.

  • Stanley - 2011-11-17 19:08

    Actually the thing than caused Antarctica to freeze was the fact that South America and Antarctica separated in the Miocene and the Southern Circumpolar Current began to flow--Antarctica has been frozen ever since, even when the Earth was warmer (yes, it has been) than today--and will remain frozen as long as the Circumpolar Current flows. Second point--as ice floats, it occupies a greater volume while frozen than when melted, and the weight of the ice has depressed the land beneath Antarctica to well below sea level--were Antarctica to melt sea level would actually drop--there have been at least ten hot-cold cycles in the past million years alone--atmospheric gasses may contribute, but they are not causing either the cooling or the warming that has been more or less continuous in the Earth's more recent past--by the way, humans didn't cause the ice ages either.

  • jane.triegaardt - 2011-11-18 12:39

    This may seem like the MOST bog-boring story, but it is really amazing - my late father-in-law led the very first expedition to Marion Island, and he would have been delighted to read this - wonder if any other former SANAE expeditioners know if the mountains had been identified as early as the 1950's?

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