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Antarctica's tropical past is revealed

2 August 2012, by Marion O'Sullivan

Antarctica was once home to a diverse range of tropical plants including ferns, palms and rainforest trees, say scientists.

The stump of a once-majestic rainforest tree

They have uncovered the first direct evidence of a much warmer, greener continent in the Southern Ocean. They publish their findings today in Nature.

The researchers took a research ship to Wilkes Land off Antarctica's eastern coast, where they drilled a kilometre deep into the ocean floor. The layers of sediment they extracted contain tiny fossils and chemicals, trapped in a snapshot of time.

Dr James Bendle from the University of Glasgow was one of the team who took part in the study. He says, 'In the sediments we found fossilised pollen representing two distinct environments with different climatic conditions - a lowland, warm rainforest dominated by tree-ferns, palm trees and baobab trees; and a cooler mountainous region dominated by beech trees and conifers.'

Baobab trees are native to Madagascar and are also known as the 'tree of life', because their swollen trunks can store water.

52 million-year-old palm pollen grain from Antarctica.

52 million-year-old palm pollen grain from Antarctica.

'Several of the rainforest pollen types come from trees which are insect-pollinated – including the palms and baobab – but also Macadamia, which produce the delicious nuts we enjoy today,' adds Bendle. 'Pollen from both environments would have been washed, blown or transported by insects into the shallow coastal shelf, where it settled in the mud and was preserved for the past 50 million years or so.'

The pollen shows that temperatures around the Antarctic coast would have been around 16°C, with summers reaching a balmy 21°C and winters staying over 10°C even during the three months of darkness. Further evidence of these mild temperatures came from preserved organic molecules, produced by soil bacteria that would have lived in soils along the coast.

Bendle warns that their work carries a sobering message, though. In the 'Greenhouse World' of the Eocene period, which lasted between 48 and 55 million years ago, carbon dioxide (CO2) levels in the atmosphere would have been more than twice as high as they are today.

'But CO2 levels are rising rapidly through our burning of fossil fuels and deforestation,' says Bendle. 'We haven't reached Eocene levels yet, but we are increasing faster than any time in Earth's history.'

'The CO2 content of the atmosphere as assumed for that time interval is not enough on its own to explain the almost tropical conditions in the Antarctic,' adds Professor Jörg Pross, a paleoclimatologist at the Goethe University in Frankfurt. 'Another important factor was the transfer of heat via warm ocean currents that reached Antarctica.'

When the warm ocean current collapsed and the Antarctic coast came under the influence of cooler ocean currents, the tropical rainforests, palms and baobab trees also disappeared.

Persistent near-tropical warmth on the Antarctic continent during the early Eocene epoch by Jörg Pross and colleagues is published in Nature

Dr James Bendle is funded by the Natural Environment Research Council.

The research was carried out as part of the 2010 Integrated Ocean Drilling Program.

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Your comments

As per "Antarctica's tropical past is revealed". I believe it might still exist inside the earth as reported by Admiral Byrd in hid diary and eyewitness Olaf Jansen in his personal account (The Hollow Earth: Olaf Jansen & The Smoky God.

Kenzo Breaze, Malta
Sunday, 5 August 2012 - 13:55

So, if Antarctica had a tropical past, does this seem to indicate that the cold and ice are not natural; and that "global warming" is a natural way to help restore environmental normalcy?

Italics Mine, Boston, Mass
Sunday, 5 August 2012 - 15:57

Good thing the global warming activists got that under control.

Roddy Pfeiffer, Earth
Sunday, 5 August 2012 - 18:57

Antartica was warmer because it was further north 50million years ago! Also pollen travels large distances.

Malcolm Jones, wales
Monday, 6 August 2012 - 22:54

Do we know that there were 3 months of darkness back then?

jack Work, manton
Tuesday, 14 August 2012 - 02:44

Fifty million years ago, Antarctica was not as isolated as today.
At present, a ring of cold sea currents prevents warm water from reaching its coast.
Then, however, Drake Passage was closed - ie Antarctica was linked to South America - while Madagascar, India and Australia were farther south.
That arrangement forced tropical currents to reach Antarctica and provide enough heat to avoid sea ice formation in winter, like today north of Norway.
CO2 in excess kept the whole Earth warmer.

Massimo Roscio, Legnano, Italy
Wednesday, 10 October 2012 - 10:17

Fifty million years ago the earth didn't exist, Pangea was split up during the world flood. Radio metric dating isn't a good way to know things since it is flawed without all the variables as well as its method. But I would presume since it used to be close to the equator a tropical setting would be logical.

Dr Pepper, Everywhere
Thursday, 28 February 2013 - 06:28

Did you ever study any modern physics?
Please stop writing nonsense, abusing of religious belief.

Massimo Roscio, Italy
Monday, 8 April 2013 - 09:02


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