Overview
- The COLDEX consortium recovered near-surface ice and trapped air from the Allan Hills in East Antarctica directly dated to about six million years, establishing a new age record.
- Age determination relied on measurements of an argon isotope in the air bubbles, while oxygen‑isotope data indicate roughly 12 degrees Celsius of long‑term regional cooling.
- A unique Allan Hills configuration concentrates ancient ice close to the surface, allowing drilling at roughly 100–200 meters rather than the multi‑kilometer depths used elsewhere.
- The cores provide discontinuous climate snapshots that researchers will use to reconstruct past greenhouse‑gas concentrations and ocean heat.
- Teams plan additional field seasons to expand the snapshot library and test preservation hypotheses, with the find far exceeding previous directly dated ice records of ~800,000 years and a 1.2‑million‑year European core.