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If an ice age is coming and you are a lichen in Antarctica, you better hope you live near a volcano.

A new study suggests organisms native to the South Pole survived ice ages by huddling in pockets of warmth created by the heat of underground volcanoes.

“These slightly warmer areas would have kept some parts of the continent ice free and let organisms survive on that land,” said Peter Convey, of the British Antarctic Survey. “Then, when the ice receded, the plants and animals spread out from that refuge to occupy other places.”

Antarctica is a difficult place for terrestrial organisms to live, with scant patches of dry land. But during the Earth’s periodic ice ages, it becomes all but uninhabitable as nearly all of the ice-free land disappears.

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Many scientists thought it was impossible for the Antarctic’s lichens, moss, primitive insects and roundworms to survive an ice age. Instead, they proposed that the plants and animals living there must be relatively recent colonizers — arriving since the last ice age receded about 20,000 years ago.

But further study revealed that can’t be the case. A third to a half of the organisms in the Antarctic are found there and only there. Since it would have taken these organisms millions of years to evolve to their present forms, they had to have been living on the continent through several ice ages.

Enter the “geothermia glacial refugia” hypothesis that suggests plants and animals native to the Antarctic survived ice ages only when they were lucky enough to live near geothermal heat. To test this theory, the researchers turned to the largest record of Antarctic fauna and flora available and found that the highest diversity of animals and plants were indeed found around volcanoes that either are or have been active since the last great ice age.

The results of the study were published recently in the Proceedings of the National Academy of Sciences. The study, led by Ceridwen Fraser of the Australian National University and Aleks Terauds from the Australian Antarctic Division, also has implications beyond Antarctica.

“In the last ice age in the Northern Hemisphere, we think plants and animals moved south as the ice moved south, and then when the ice moved north they moved back with it,” said Convey, one of the authors of the paper. “But this study opens up the possibility that hidden in there are things that survived in high latitude, up in the Arctic, thanks to geothermal heat.”

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