Overview
- Researchers recovered the oldest directly dated ice and air on Earth from the Allan Hills region of East Antarctica, placing the material at about 6 million years old.
- The team dated the samples by measuring an isotope of argon in trapped air bubbles, yielding a set of discontinuous climate snapshots rather than a continuous record.
- Oxygen-isotope data indicate the Allan Hills area cooled by roughly 12 degrees Celsius over the last 6 million years, providing the first direct estimate of long-term Antarctic cooling for that interval.
- Shallow drilling to depths of 100–200 meters was possible because winds, extreme cold, and local topography preserve very old ice near the surface, in contrast to >2,000-meter deep drilling at interior sites.
- One basal sample lacked gas and could not be dated, suggesting potentially older ice, and COLDEX plans additional drilling soon along with a 2026–2031 study to extend records and extract greenhouse-gas and ocean-heat information.