Scientists have long known that Earth’s climate goes through cycles of ice ages and warmer periods.

Around 2.5 million years ago, the planet entered a phase marked by repeated ice ages, with the most recent one ending about 11,700 years ago.

Now, new research suggests the next ice age might begin in about 10,000 years—if human activities weren’t affecting the climate.

An international team, including researchers from UC Santa Barbara, studied how small changes in Earth’s orbit around the sun influence global climate.

Their findings, published in Science, provide a clearer understanding of Earth’s ice age cycles.

The team analyzed climate data from the past million years, examining how ice sheets in the Northern Hemisphere changed along with deep ocean temperatures. They found that shifts in Earth’s orbit—such as its shape, tilt, and wobble—played a key role in starting and ending ice ages.

Professor Lorraine Lisiecki from UCSB explained, “We found a clear pattern linking Earth’s orbit to shifts between ice ages and warm interglacial periods, like the one we are in now.” Different types of orbital changes either triggered or ended ice ages.

Professor Stephen Barker from Cardiff University was surprised by how clear the pattern was. “It’s amazing that this connection wasn’t fully recognized before,” he said. While scientists have suspected a link between Earth’s orbit and climate for over a century, it wasn’t confirmed with real data until the 1970s. Even then, it was difficult to pinpoint exactly which orbital shifts were most important for glacial cycles.

By studying long-term climate records, the researchers identified a predictable pattern over the past 900,000 years. This pattern suggests that, without human influence, Earth would remain in a stable interglacial period for thousands of years before slowly transitioning into another ice age.

Co-author Chronis Tzedakis from University College London emphasized, “According to natural cycles, the next ice age should begin in about 10,000 years.” However, human activities—especially the release of greenhouse gases like carbon dioxide—are disrupting this natural cycle.

Gregor Knorr from the Alfred Wegener Institute added, “Because of human emissions, it is very unlikely that an ice age will occur as expected. Our climate has already been pushed off its natural path.”

The team hopes to use past climate data to create a model predicting Earth’s natural climate for the next 10,000–20,000 years. By combining this data with modern climate simulations, scientists can better understand how human-made climate change will shape the planet’s future.

“Now that we know Earth’s long-term climate is largely predictable, we can use past trends to make more accurate future predictions,” Barker said. “This information is crucial for making smart decisions about greenhouse gas emissions today, as they will have lasting effects for thousands of years.”