Ancient Antarctic ice reveals Earth’s warm past

Until now, the oldest continuous ice cores dated back about 800,000 years. The COLDEX team has now extended that record roughly sixfold, reaching into a deep past when Antarctica’s climate was undergoing dramatic change.

Rather than drilling deep into the continental interior, as recent European projects have done to retrieve a 1.2-million-year-old core, the U.S. scientists pursued a different path. They targeted the edges of the East Antarctic Ice Sheet, where winds, exposed rock ridges, and extreme cold have naturally preserved layers of ancient ice near the surface.

Fieldwork in the Allan Hills demands months of living in one of the harshest environments on Earth. Researchers camp on the ice and drill through frozen layers up to 200 meters thick, piecing together fragments of climate history that have survived for millions of years.

Preliminary analyses show that Antarctica has cooled by about 12°C over the past six million years, the first direct evidence of such long-term temperature decline on the continent. By reconstructing atmospheric carbon levels and ocean heat from that time, scientists hope to better understand how natural climate cycles unfolded before human influence, and how similar processes could influence modern global warming.

The COLDEX team plans to return to the Allan Hills within the next year to search for even older samples. A larger project, running from 2026 to 2031, aims to push the ice record deeper into Earth’s geological history, potentially uncovering the earliest preserved air ever found on the planet.

Earlier, Kazinform News Agency reported that, according to Copernicus data, the Antarctic ozone hole developed ahead of schedule.