An Ice Age Was Coming. Our Emissions Reversed It

Humans may have warmed the planet to the point of hitting pause on the next big deep-freeze. A new study in Science concludes that Earth was edging into a fresh glacial period about 2,000 years ago, only for human-driven greenhouse gas emissions to reverse course by the 1960s. "It was just getting started… and yet it stopped," says lead author Nicolás Young of Columbia University, calling it a stark example of how much we've "jolted the system." Though it may not feel like it, we are currently living through an ice age that began 34 million years ago, with its last glacial period, marked by colder temperatures and glacial advance, ending about 11,700 years ago, Gizmodo reports.

This ushered in an interglacial period marked by warmer temperatures and glacial retreat—the Holocene we're experiencing now, per Smithsonian. By looking at plant remains newly uncovered by the retreat of Canada's Barnes Ice Cap, the last fragment of a vast ice sheet now in its dying days, researchers found the ice cap reached its smallest size 3,600 years ago and began growing again 1,600 years later—a sign of glaciation—before modern warming forced it back. In an analysis accompanying the study, glaciologist Shaun Marcott notes that our current interglacial period could potentially last hundreds of thousands more years as a result of greenhouse gas emissions, disrupting a system that has governed Earth's climate for billions of years.