The Next Ice Age Began 2,000 Years Ago and Humans Stopped It, Study Says

The next ice age may have already started, and then been stopped by humans, according to a study published Oct. 22, 2026, in the journal Science. Researchers led by Nicolás Young of Columbia University’s Lamont-Doherty Earth Observatory found that Canada’s Barnes Ice Cap, the last surviving piece of the Laurentide Ice Sheet, began growing again about 2,000 years ago before warming reversed that growth around 1960.

Image: Mountains and low cloud in Auyuittuq National Park on Baffin Island, Nunavut, the island that holds the Barnes Ice Cap. Photo: Mike Beauregard, via Wikimedia Commons (CC BY 2.0).

What the Barnes Ice Cap study found

The Laurentide Ice Sheet was the largest of the ice sheets of the Pleistocene, the geologic epoch of repeated ice ages. According to Lamont-Doherty, it covered much of Canada and the northern United States from about 95,000 to 20,000 years ago, stretched from above the Arctic Circle to Illinois and was more than two miles thick in places. In a companion Perspective in Science, glaciologist Shaun Marcott wrote that it covered nearly 30% of North America at its peak.

What remains today is the Barnes Ice Cap, a Delaware-sized body of ice on central Baffin Island in the Canadian Arctic. The team reports that the ice cap shrank to its smallest size of the current warm period sometime after about 3,600 years ago. Then it reversed. Roughly 2,000 years ago, the ice began to expand again, and it kept growing until it reached its largest late-Holocene extent around 1960.

After that, the study says, “anthropogenic summer warming resulted in a negative mass balance, ice margin recession, and the termination of the next glaciation.” In plain terms, the ice cap has been losing more ice each summer than it gains each winter. Lamont-Doherty reports that models of the glacier’s future show it melting completely within the next few centuries.

How scientists dated the ice

The researchers worked at the retreating edge of the ice cap, where bedrock and plants buried for centuries are only now being exposed. By radiocarbon dating vegetation preserved beneath the ice, they reconstructed when the ice sheet shrank, when it advanced back over the land and when it began retreating again, Lamont-Doherty said.

They also measured rare isotopes, beryllium-10 and aluminum-26, in rock samples collected in August 2022 along the southeastern margin of the ice cap. Those isotopes build up when rock is exposed to cosmic rays, so they act as a clock for how long a surface has been ice-free. A public dataset from the project shows that the Laurentide approached and then retreated inside the 2022 ice margin about 3,500 years ago.

Why the next ice age question matters

Ice ages follow slow, predictable changes in Earth’s orbit that alter how much summer sunlight reaches the far north. Marcott compared the pattern to a metronome that has kept time for about 2 million years. Under that theory, declining Northern Hemisphere summer sunlight over the past several thousand years should eventually tip the planet toward a new glaciation.

The new paper argues that tipping point already arrived. Earlier model-based studies suggested the next glaciation would not begin for thousands or even tens of thousands of years, according to Lamont-Doherty. Young and his colleagues argue the first renewed growth of an ice sheet should count as the start of a glacial period, rather than waiting for huge continental sheets to form. The study notes that the low, flat Baffin Island plateau is especially sensitive: a small drop in the snowline quickly spreads permanent snow across the landscape, and the brighter surface reflects more sunlight, cooling the region further.

The authors write that the demise of this renewed growth, “despite the ongoing decline in summer insolation, illustrates the influence of anomalous greenhouse gas forcing on climate.” Science’s editors summarized the finding as evidence that humans caused the end of the next glaciation.

The Boston connection

New Englanders live on the Laurentide’s leftovers. The National Park Service says the Boston area is dotted with drumlins, oblong hills of glacial till shaped by moving ice, and that Boston Harbor is the only partially drowned drumlin field in North America and one of only three in the world. Many of the Boston Harbor Islands are those drumlins. For a closer look at the region’s weather today, see our Massachusetts winter outlook for 2026-27.

The finding also fits a busy stretch for polar and physics research. Earlier this month we covered how the Antarctic IceCube detector helped earn the 2026 Nobel Prize in Physics for Francis Halzen.

The Barnes Ice Cap will not vanish this decade. But if the study holds up, its slow retreat marks the end of a glacial advance that began two millennia ago, and the last remnant of the ice that shaped Boston Harbor.

Sources

• Science: Late Holocene reexpansion of the Laurentide Ice Sheet (Young et al., 2026)
• Science Perspective: Has the next ice age already come and gone? (Marcott)
• Lamont-Doherty Earth Observatory (Columbia University): Climate Change Stopped the Next Ice Age
• Arctic Data Center: In situ cosmogenic isotope measurements from Barnes Ice Cap, Baffin Island 2022
• National Park Service: Geologic Formations, Boston Harbor Islands
• Wikimedia Commons: Auyuittuq National Park, Baffin Island, photo by Mike Beauregard (CC BY 2.0)