In the headwall scarp of a landslide on Bylot Island in northeastern Canada, researchers uncovered the remnant ice of an ancient glacier that could be over a million years old.
Stéphanie Coulombe
On a remote island in the Canadian Arctic, researchers have discovered the remains of an ancient glacier that could be over a million years old. The discovery represents what may be the oldest glacier ice ever found buried in permafrost — ground that has been frozen for at least 2 years straight — in the Arctic, researchers report in the January 1 Geology. For researchers keen on studying the glacier, the clock is ticking, as human-caused climate change has exposed the long-preserved ice to melting.
Like notes in the pages of a logbook, the gas bubbles, compounds and particulates trapped in a glacier’s icy layers can yield information about the atmospheres and climates of bygone millennia. But there are precious few reports of such ice older than the last great expansion of the ice sheets, 26,000 to 20,000 years ago. The newfound ice could thus provide researchers with a rare chance to study the climate of the early Pleistocene epoch, during which the Earth underwent episodic ice ages separated by warm periods known as interglacial periods. “These [Pleistocene climate shifts] are analogs for what we can see in the future,” says geomorphologist Daniel Fortier of the University of Montreal.
In 2009, Fortier and colleagues were studying a buried fossilized forest on Bylot Island, in Canada’s Nunavut Territory, when they stumbled across the sites of some recent landslides that had been triggered by the thawing of permafrost. The slides had exposed translucent, layered bodies of ice that had been buried a few meters underground, just above the fossil forest. Much to Fortier’s surprise, radiocarbon dating of organic matter in the ice revealed it was over 60,000 years old. “I was not expecting that at all,” he says.
What’s more, in the sediment layers overlying the ice, the researchers discovered a flip in the alignment of magnetic minerals that corresponded with a reversal of Earth’s magnetic field roughly 770,000 years old, indicating the ice was at least that old. And previous research had dated the fossil forest upon which the glacier rested to around 2.8 to 2.4 million years ago, providing a maximum possible age for the ice.
The discovery is a testament to the resilience of permafrost, Fortier says. While climate projections suggest permafrost will completely thaw in many regions by the end of the century, this preserved glacier has persisted through interglacial periods that were warmer than today, he notes. “I don’t think permafrost will disappear so fast. The system is more resilient than we think.”
