Discovery of 6-Million-Year-Old Ice Sample in Antarctica

Scientists specializing in glaciology and climate history have discovered a 6-million-year-old ice sample in the Allan Hills of Antarctica. This discovery, published in the Proceedings of the National Academy of Sciences, offers a unique and direct glimpse into Earth’s ancient atmosphere, providing an unparalleled record of the planet’s past climate.

A Glimpse into a Warmer Ancient World

The oldest sample collected from the Allan Hills dates back 6 million years, a period when geological records indicate that Earth was significantly warmer, with sea levels much higher than today. This research effort was led by Sarah Shackleton from the Woods Hole Oceanographic Institution and John Higgins from Princeton University, both part of the Center for Oldest Ice Exploration (COLDEX), funded by the National Science Foundation.

Shackleton described the ice as “time machines” that allow scientists to see what Earth was like in the past. She emphasized that “the ice core in the Allan Hills helps us travel further back in time than we ever imagined.”

A Global Race to Probe the Depths of Time

COLDEX is one of several international teams striving to extend the ice record beyond the previous limit of 800,000 years. A European project recently announced a deep core reaching 1.2 million years in East Antarctica, but the Allan Hills samples push the timeline back several million more years, albeit in separate parts rather than a single continuous core.

COLDEX researchers work in a remote field site in the Allan Hills, spending months drilling through hundreds of meters of ice near the edge of the Antarctic ice sheet. In this region, rugged terrain and ice flow patterns work together to preserve very old ice near the surface.

Reconstructing 6 Million Years of Cooling

Analyses of oxygen isotopes in the ice revealed that the region has cooled by about 12 degrees Celsius over the past 6 million years. This is the first direct evidence quantifying the cooling of Antarctica’s climate since that ancient warm period.

Future research will focus on reconstructing greenhouse gas concentrations and ocean temperatures preserved within the ice bubbles—key indicators for understanding the natural forces driving long-term climate change.

Conclusion

The discovery of ancient ice in the Allan Hills marks a significant scientific achievement that enhances our understanding of Earth’s climate over millions of years. Thanks to the collaborative efforts of the COLDEX team and their international partners, we are closer to reconstructing detailed accounts of Earth’s climate evolution over time. With plans for further missions to the Allan Hills, scientists are eager to uncover deeper secrets of Earth’s ancient atmosphere and climate history.