Antarctic Ice Cores Extend Earth's Ancient Atmosphere Back to 1.2 Million Years

Bubbles trapped in Antarctic ice at Dome C preserve a continuous record of Earth's atmosphere for about 800,000 years, with the EPICA project drilling a 3,270‑metre core to chart past CO2 and gas compositions; a 2025 follow-up near Little Dome C extends the archive to around 1.2 million years, though the deepest sections show extreme compression that reduces resolution, revealing that CO2 ranged from ~180 ppm in ice ages to ~280 ppm in warmer periods, while today’s levels exceed the natural variation seen in the record.