Human Activity Has Halted Earth’s Million-Year Cycle

Jakarta — Nature had already begun preparing. Around 2,000 years ago, polar ice sheets began to grow again, a sign that Earth was heading towards its next ice age. But scientists now say that this did not happen—not because of a celestial object or a volcano, but because of humans themselves.

Technically, Earth is still in an ice age that began 34 million years ago, because the ice in Antarctica and Greenland has never melted completely. During that period, the planet has repeatedly shifted between cold phases that freeze the land and warmer phases that melt it.

Humans are now living through a warm phase that began around 11,700 years ago.

But signs have begun to change. Recent research indicates that ancient ice sheets in North America had shrunk to their smallest extent around 3,000 years ago, before beginning to grow again 2,000 years ago. The process was following a pattern that had repeated for millions of years—until it suddenly stopped.

“The process had just begun; everything was normal, the next ice age was on its way, and then it suddenly stopped,” said Nicolás Young, a researcher at Columbia University who led the study, as quoted by IFL Science on Thursday (29 October 2026).

Evidence from the remains of ice sheets in Canada shows that the ice continued to grow until around 60 years ago. Then temperatures rose and its growth came to an abrupt halt. Human-driven warming was sufficient to counter the cooling that would otherwise have taken place.

The impact is not merely a delay. Professor Shaun Marcott estimates that human-caused climate change could postpone the next ice age by hundreds of thousands of years.

“Humans have now become a geological force capable of disrupting a natural cycle that has lasted millions of years and changing Earth’s climate far into the future,” the research team wrote in the journal Science.

This change does not simply mean that ice will not expand. The loss of the ice-age cycle would affect Earth’s biological and physical systems, which have evolved alongside it over the past two million years. Could Earth return to its cycle if carbon emissions were reduced? Scientists say that remains possible, but the outcome is uncertain.