The Ice Age That Never Came
The next ice age may have begun 2,000 years ago, only to be halted by human-driven climate change, according to a study published in Science. Researchers at Columbia University’s Lamont-Doherty Earth Observatory tracked the retreat and regrowth of the Laurentide Ice Sheet, the largest ice mass of the Pleistocene, which once covered much of North America. By analyzing rocks and vegetation beneath the Barnes Ice Cap, they found that the ice sheet started expanding again around 2,000 years ago, potentially marking the onset of a new glacial period. “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 first author.
Reconstructing the Past
Scientists used two methods to map the ice sheet’s history: cosmogenic beryllium-10 dating and carbon-14 analysis. Beryllium-10 accumulates in rocks exposed to cosmic radiation, while carbon-14 decays in plant material buried by ice. These techniques revealed that the Laurentide Ice Sheet shrank to its smallest size 3,600 years ago, then began regrowing. By 2,000 years ago, the Barnes Ice Cap—its last remnant—had started expanding, suggesting a new ice age was underway. “It was the beginning of a new glacial period, more conversationally known as the next ice age,” said Young.
The Role of Human Activity
The Barnes Ice Cap reached its maximum size around 1960, but rising summer temperatures reversed its growth. By the 1960s, anthropogenic warming had already begun to melt the ice cap, a trend linked to industrial emissions since the 18th century. “The first renewed growth of an ice sheet may mark the beginning of a glacial period, even thousands of years before continental ice sheets develop,” the study noted. The researchers also note that the Little Ice Age, which ended in the late 19th century, was a period of cooling. “Global warming ended a period of glaciation that had already begun,” Young said.
What Lies Ahead
Models predict the Barnes Ice Cap will vanish entirely under current climate conditions, marking the end of the Laurentide Ice Sheet’s legacy. “That will be the true very last remains of the Laurentide, disappearing for good,” Young concluded. The study highlights a stark shift: what was once a natural, predictable cycle is now disrupted by human activity. “It’s a very powerful example of how we have jolted the system,” he added. Other Arctic ice caps, including those in the Canadian Arctic and North Atlantic, are also shrinking rapidly, with summer temperatures playing a central role.
Barnes Ice Cap's Glacial History Revealed
The Barnes Ice Cap, now the last vestige of the Laurentide Ice Sheet, is roughly the size of Delaware. It was once part of an ice mass that stretched from the Arctic Circle to Illinois, with ice up to 3 kilometers thick. Its retreat has revealed ancient bedrock, offering a rare glimpse into Earth’s glacial history.
FAQ
When did the next ice age begin?
The next ice age may have begun 2,000 years ago, as the Laurentide Ice Sheet started regrowing, according to the study. However, human-driven climate change halted this process.
How did scientists track the ice sheet’s history?
Researchers used cosmogenic beryllium-10 and carbon-14 dating to analyze rocks and vegetation beneath the Barnes Ice Cap. These methods revealed when the ice sheet expanded and retreated.
What caused the Barnes Ice Cap to shrink?
Rising summer temperatures since the 1960s, linked to greenhouse gas emissions from the Industrial Revolution, have caused the Barnes Ice Cap to lose mass faster than it can recover. “Almost all of its losses can be explained by rising summer temperatures,” the study noted.
Pro Tips
Stay informed about climate trends by following updates from the Lamont-Doherty Earth Observatory or reading the full Science study. Understanding glacial cycles helps contextualize current climate change, as natural and human factors interact in complex ways.
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