Human-induced climate change disrupted a natural cooling trend that had quietly set the stage for Earth’s next ice age, according to a study published Thursday in the journal Science.
Researchers analyzing ancient vegetation and rock isotopes on Canada’s remote Baffin Island discovered that the Delaware-sized Barnes Ice Cap had begun steadily re-expanding roughly 2,000 years ago. That gradual advance marked what scientists describe as the infant stage of a new glacial cycle. However, around 1960, the trend abruptly reversed as industrial greenhouse gas emissions accelerated global warming, causing the ice to rapidly melt instead.
“It was just getting started, everything was normal, the next glaciation was about to happen — and yet it stopped,” said Nicolás Young, the study’s lead author and a geochemist at Columbia University’s Lamont-Doherty Earth Observatory. “It’s a very powerful example of how we have jolted the system.”
Unlocking Clues Under the Ice
The Barnes Ice Cap is the final surviving fragment of the vast Laurentide Ice Sheet, which blanketed Canada and stretched south to Illinois and New York before retreating 12,000 years ago. Unlike many fast-moving glaciers that crush the terrain beneath them, the Barnes Ice Cap remains frozen to the bedrock. That unique characteristic preserved fragile tundra plants that were buried alive when the ice advanced centuries ago.
By collecting long-dead mosses emerging along the margins of the receding glacier and performing radiocarbon dating on 88 samples, researchers reconstructed an exact timeline of the ice’s historical movements, CNN reported. The scientists also measured concentrations of beryllium-10, an isotope that builds up in rock when exposed to cosmic rays, to determine when the surrounding stone was last free of ice. The tests indicated the ice sheet hit its modern minimum size roughly 3,600 years ago before cooling temperatures prompted it to expand again around 2,000 years ago.
Historical aerial photographs show that the expansion came to an abrupt halt around 1960. Driven by hotter summers, the ice cap has retreated at an average rate of four meters annually since the 1980s, effectively wiping out two millennia of ice gains in just a few decades, according to Wired.
Scientific Debate and 1970s Climate Warnings
Young emphasized that while global warming averted the glacial cycle, the findings should not be celebrated. Continental ice sheets require thousands of years to grow large enough to alter human civilization, whereas rapid global heating poses immediate risks to ecosystems and modern infrastructure. Furthermore, emissions have likely deferred any future natural glaciation for tens of thousands of years.
The study also offers a new perspective on a disputed chapter in climate science. During the early 1970s, a group of scientists gathered at Brown University and later warned President Richard Nixon that an ice age might be approaching—a hypothesis publicized in mainstream media that climate change skeptics later cited to cast doubt on global warming research. Young noted the new data indicates natural forces had indeed begun moving the planet toward glaciation until industrial pollution overpowered the cycle.
Outside experts caution that evidence from a single Arctic site cannot definitively prove a global ice age was underway. Andrey Ganopolski, a climate physicist at the Potsdam Institute for Climate Impact Research who was not involved in the work, told CNN that orbital modeling suggests an ice age would not naturally arrive for another 50,000 years, arguing the Baffin Island growth alone is insufficient to conclude a glacial cycle had formally begun.
Meredith Kelly, an earth sciences professor at Dartmouth College, praised the dating methods but noted that broader comparisons to glaciers in other parts of the world are necessary to verify the planetary mechanisms at work. Meanwhile, the Barnes Ice Cap lost its high-elevation snow accumulation zone around 2010, and scientists project the ancient remnant may melt away entirely over the coming centuries.
