Antarctica's tropical past is revealed

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

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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.

'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.

Article continues at Planet Earth Online

Rainforest image via Shutterstock