Human-driven greenhouse gas emissions reversed the expansion of the Barnes Ice Cap on Baffin Island, effectively halting the early phase of a new ice age that began some 2,000 years ago. Scientists studying the ice cap published their findings in Science, revealing how industrial warming overpowered Earth’s ancient Milankovitch cycles.
For billions of years, periodic glacial cycles governed by Earth’s orbit around the Sun shaped the planet’s climate. But new research published in Science demonstrates that industrial activity has profoundly altered that natural rhythm. Scientists investigating the Barnes Ice Cap in Canada’s Nunavut territory found that warming driven by fossil fuels reversed an advancing cold period that had been underway for millennia.
The Barnes Ice Cap Chronology on Baffin Island
The Barnes Ice Cap is the last surviving remnant of the Laurentide Ice Sheet, a gargantuan mass of ice that once covered nearly 30 percent of North America during the last ice age. At its peak, the ice sheet reached up to two miles thick and extended from the Arctic Circle as far south as Illinois.
As the climate warmed following the end of the last glacial period about 11,700 years ago, the Laurentide Ice Sheet shrank dramatically. By roughly 3,600 years ago, the remaining ice cover had receded inside the modern boundaries of the Barnes Ice Cap. Then, around 2,000 years ago, cooler temperatures caused the ice cap to slowly re-expand across the tundra.
Researchers tracked this ancient advance by analyzing vegetation once encased in the ice. Because the Barnes Ice Cap is frozen directly to its underlying bedrock rather than sliding like a typical glacier, it preserved delicate mosses as it crept forward. Radiocarbon dating of these plants established when the ice first entombed them, while beryllium-10 isotope dating on nearby rocks helped reconstruct the broader timeline.
We can actually track the expansion of the ice margin as it’s progressively covering mosses and killing (them).
Nicolás Young, geochemist at Columbia University
How Industrial Warming Reversals Stopped Glaciation
That multi-century growth trend continued undisturbed until the mid-20th century. By the 1960s, however, summer temperatures in the region had spiked so sharply that the ice cap began losing more mass in the summer than it accumulated during the winter. Weather archives record the summer of 1961 as one of the hottest of the 20th century.
The study’s authors argue that this regrowth marked the literal birth of Earth’s next glacial period, but human greenhouse gas emissions cut it short in its infancy. Rather than waiting for continent-spanning ice sheets to lock up global sea levels—a process that takes tens of thousands of years—the researchers point to the initial expansion of an ice sheet as the true marker of glacial inception.
It was just getting started, everything was normal, the next glaciation was about to happen — and yet it stopped. It’s a very powerful example of how we have jolted the system.
Nicolás Young, a study author and a geochemist at the Lamont-Doherty Earth Observatory
Scientific Debate Over Glacial Timelines
While outside experts have praised the dating techniques used in the study, the interpretation has sparked discussion among climatologists regarding long-term climate models. Andrey Ganopolski, a physicist at the Potsdam Institute for Climate Impact Research, noted that other modeling studies suggest the next natural ice age would not be expected for another 50,000 years even without human intervention.
Ganopolski argued that the localized expansion of the Barnes Ice Cap is insufficient to support the conclusion that a new glacial cycle had already begun and was subsequently aborted. In a perspective piece accompanying the research, Shaun Marcott, a glaciologist and professor at the University of Wisconsin-Madison, stated that future greenhouse gas emissions could forestall future ice ages for hundreds of thousands of years.
Climate models indicate that the Barnes Ice Cap itself is likely to vanish entirely within the next 300 years under current warming trajectories. Without this anchor point for ice growth, the dynamics of future glaciations remain fundamentally altered as Earth enters an industrial climatic era.