Two Thousand Years Ago, a New Ice Age Began—but Human-Caused Climate Change Recently Reversed It, According to New Research

All that’s left of a gargantuan ice sheet that once covered nearly 30 percent of North America is a Delaware-size ice cap in Canada. Scientists have found that the ice cap began to expand around 2,000 years ago—a sign of a new ice age—but it started shrinking in the 1960s

Margherita Bassi | Daily Correspondent

October 27, 2026 10:00 a.m.

Humanity’s greenhouse gas emissions may have warmed the planet enough to reverse the next ice age.

In a study published October 22 in the journal Science, researchers reconstructed the growth and retreat of Canada’s Barnes Ice Cap, which was once a massive stretch of ice called the Laurentide Ice Sheet. The timeline they put together suggests that the ice cap started to expand around 2,000 years ago—a sign a new ice age was beginning—but it was cut short by planet-warming industrialization in the 1960s.

The Laurentide Ice Sheet dominated the landscape of modern-day Canada and the northern United States tens of thousands of years ago. At its peak around 20,000 years ago, it covered almost 30 percent of the continent, extending from above the Arctic Circle to what is now Illinois. The ice was more than two miles thick in some spots.

All that’s left of this formidable feature today is the Barnes Ice Cap. It’s a Delaware-size ice cap on central Baffin Island in Nunavut, Canada.

Over the past 2.6 million years, Earth has been cycling between times with large ice sheets, called glacial periods or colloquially, ice ages, and times without them, or interglacial periods. The last glacial period ended around 11,700 years ago, and we are now in an interglacial period named the Holocene.

In the new study, researchers took advantage of the vegetation once encased in the Barnes Ice Cap. After a period of retreat, “mosses eventually colonized this newly exposed land” on the edge of the ice, lead author Nicolás Young, a paleoclimatologist at Columbia University, tells Wired’s Molly Taft. “These mosses are living there, and things are normal—then, eventually, the ice cap starts to re-expand. The ice covers the moss and kills it.”

Unlike other glaciers that slide around, the Barnes Ice Cap is frozen onto its bedrock. While a sliding glacier would have crushed older vegetation, during periods of expansion, this ice cap encased the greens that had grown around it.

So, Young and colleagues looked at the buildup of a form of beryllium in newly exposed bedrock and in surrounding boulders. The element can tell researchers when rock was exposed to the atmosphere and cosmic rays. They also carbon-dated the recently exposed dead vegetation to figure out when it first died, corresponding to when the ice cap last expanded across that area.

Analyses revealed that the Barnes Ice Cap reached its smallest size around 3,600 years ago. It then started growing again around 2,000 years ago.

“Our approach helped us see the first steps of ice-sheet growth preserved in the landscape. It gave us a rare opportunity to understand how re-glaciation begins and how the Laurentide Ice Sheet re-forms,” study co-author Joerg Schaefer, a geochemist at Columbia University, says in a statement.

Barnes Ice Cap kept growing until the late 1950s. However, its expansion stopped cold, and it began retreating in the next decade, when increased summer temperatures caused the feature to lose more ice than it could gain in the winter. That period of regrowth may have been the beginning of a new ice age, which was brought to an early end by human-driven climate change. The findings support previous research highlighting the same conclusion.

This isn’t the first time researchers have speculated about the start of a modern ice age. Some climate scientists suggested in the 1970s that the world was on the verge of a new ice age. Climate deniers used the claim to argue human-caused global warming wasn’t real, according to Wired.

The new findings, however, point to the devastating effects of climate change, which is drastically altering natural, predictable climate patterns.

“Will another ice age ever transpire? The next glacial inception is generally considered unlikely to occur in the next predicted cycle, but ultimately how many skipped glacial cycles occur is left to choices made by humanity and tied to the future carbon emissions,” Shaun Marcott, an Earth scientist at the University of Wisconsin-Madison who did not participate in the study, writes in a perspective article accompanying the new work.

“Humans are now geologic agents capable of thwarting millions of years of natural glacial cycles and offsetting Earth’s climate for hundreds of thousands of years to come.”