Humans may have already called off the next ice age. A new study, published in Science, finds that the Barnes Ice Cap on Canada’s Baffin Island — the last remnant of the Laurentide Ice Sheet that once smothered much of North America — grew for roughly 2,000 years before reversing course in the 1960s, just as carbon emissions took off, as Wired’s Molly Taft reports.
Because the Delaware-sized ice cap is frozen to bedrock rather than sliding like a glacier, it preserves a record of what grew at its edges. Using beryllium-10 exposure dating on nearby rocks, researchers found the ice reached its modern size about 3,600 years ago.
Dead mosses, killed when the ice re-advanced and now exposed again, showed it began growing around 2,000 years ago — a possible sign Earth was edging toward a new, naturally driven glaciation.
Then came the reversal. Historic aerial photos show the ice cap shrinking since the 1960s, and its margins have retreated an average of 4 meters per year since the 1980s.
“Modern retreat of this glacier has reversed 2,000 years of net expansion—that’s a pretty decent chunk of time,” said lead author Nicolás Young, a paleoclimatologist at Columbia University’s Lamont-Doherty Earth Observatory.
Andrew Wickert, an associate professor of environmental science at the University of Minnesota Twin Cities who wasn’t involved, put it bluntly: “even as we were just starting to ramp up emissions, we’ve already done enough damage to cause the major North American ice sheet to already start retreating. That’s significant.”
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Meredith Kelly, a professor of earth sciences at Dartmouth, called the data “awesome” but wants comparisons with other sites worldwide to confirm how Earth was trending before human warming intervened.
There’s an ironic twist, too. Climate skeptics have long mocked a 1970s Brown University meeting where scientists warned President Nixon of an imminent ice age. “I think this study actually helps show that scientists were right about a pending glaciation,” Young said
