"It's a whole world of what's coming out from underneath the glaciers that really needs to be studied, " Dr La Farge said.

BBC: Centuries-old frozen plants revived

"I don't know how you deal with that one, " added Stittleburg, who's also chief of the La Farge, Wisconsin, Fire Department, an all-volunteer agency.

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They can survive being completely desiccated in long Arctic winters, returning to growth in warmer times, but Dr La Farge was surprised by an emergence of bryophytes that had been buried under ice for so long.

BBC: Centuries-old frozen plants revived

"We ended up walking along the edge of the glacier margin and we saw these huge populations coming out from underneath the glacier that seemed to have a greenish tint, " said Catherine La Farge, lead author of the study.

BBC: Centuries-old frozen plants revived