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From about 1550 to 1850, a global cold wave called the small glaciers of the Ice Age in the Arctic. On Ellesmere Island in Canada, the Teardrop Glacier extended its frozen tongue across the landscape and swallowed a small tuft of moss.
Since 1850, the plant was frozen under a 100-foot thick ice sheet, while humans discovered antibiotics, visited the moon, and burned 2,000 billion tons of fossil fuels.
Thanks to this last exploit, the evolutionary biologist Catherine La Farge arrived centuries later on the edge of the melting of Teardrop to find the bunch of the species Aulacomnium turgidum finally released from its frozen landfill. The moss was faded and torn, but had a green hue – a possible sign of life.
Climate change stories often highlight the flickering fragility of Earth's ecological system. The situation became even more alarming when a United Nations report said that one million species of plants and animals on our planet are threatened with extinction. But for some exceptional species, the thaw of the ice sheets and permafrost is beginning to reveal another story, that of an astonishing biological resilience.
Researchers in a warming Arctic are discovering organisms, frozen and presumed dead for thousands of years, capable of reviving life. These ice age zombies range from simple bacteria to multicellular animals, and their endurance encourages scientists to rethink their understanding of what it means to survive.
"You would not think an object buried for hundreds of years would be viable," said La Farge, who does research on mosses at the University of Alberta. In 2009, his team was exploring the Teardrop margin to collect plant material blackened by shrinking glaciers. Their goal was to document the vegetation that once formed the base of the island's ecosystem.
"The material has always been considered dead. But seeing the green fabric, "I thought to myself," It's pretty unusual, "La Farge said about the tufts of moss that she has found for centuries.
She brought back dozens of these curious samples to Edmonton, lavishing them with nutrient-rich soil in a warm, bright laboratory. Nearly a third of the samples exploded with new shoots and leaves. "We were pretty blown away," La Farge said. The moss has shown little adverse effects from its multi-year freezer.
It is not easy to survive being frozen. Shredded ice crystals can shred cell membranes and other vital biological machines. At the beginning of winter, many plants and animals simply succumb to the cold, wanting their seeds or eggs to spawn a new generation in the spring.
Mosses have traced a more difficult path. They dry out when the temperature drops, thus avoiding the risk of ice formation in their tissues. And if parts of the plant are damaged, some cells can divide and differentiate into all types of tissues that make up a complete foam, similar to stem cells from human embryos.
With these adaptations, mosses are more likely than other plants to survive long-term frost, said Peter Convey, an ecologist with the British Antarctic Survey.
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