During the Little Ice Age, a period from about 1550 to 1850, temperatures were significantly cooler than they are now, and glaciers crept in to cover parts of the Northern Hemisphere. The ice has gradually retreated over the past century -- and even faster in the past 10 years -- thereby revealing plants that haven't thrived since the reign of Henry VIII (or thereabouts).
In 2007, biologist Catherine La Farge from the University of Alberta encountered these ancient mosses -- they're called bryophytes, a category that includes liverworts and hornworts -- on a trip to a glacier near Ellesmere Island, in Canada's far north:
Much to her surprise, the vegetation peeking out from under the receding ice looked like it still might have some life left in it.
"We were looking around and walking in the glacier, and coming out from underneath are huge populations of these bryophytes," she explained "You pick up a chunk of this moss in your hand. And it's looking kind of green, and you think, 'Hmm, that's interesting that it's so green when it's coming from the last ice age.'"
La Farge and her team took some samples back to her lab, where they ground them up, plopped them in some soil, and watered them regularly.
"We let them do their thing," La Farge explained. "And as it happened, they grew."
In fact, the authors grew 11 cultures from seven specimens representing four distinct species, transforming them from the brownish clumps to bright green, fresh, new moss -- with 400 years of history to catch up on.
La Farge said the study shows just how resilient and robust bryophytes are: They're a great "pioneer species" that can provide moisture and protection for other organisms and vascular plants.
The experiment also revealed that glaciers are fantastic biological reservoirs, and as they continue to recede, they might reveal increasingly more plant life that had been laying dormant. We don't yet know the full extent of what might be preserved underneath them -- or how these mosses might play a role in re-populating the centuries-old habitats the retreating ice leaves behind.
Or as La Farge put it,
"It was like taking a blanket off the Little Ice Age."