As the ice cap forms, it traps air bubbles, which then remain isolated. It has allowed us to reconstruct our past climate of 800,000 years ago. This was the date of the oldest Antarctic ice sampling thanks to a ice core drilled near the base of the Antarctic ice sheet.
www.pnas.org/doi/10.1073/...
Miocene and Pliocene ice and air from the Allan Hills blue ice area, East Antarctica | PNAS
Antarctic ice cores provide a unique archive of Earth’s atmosphere and its largest
extant ice sheet. The oldest continuous ice core extends back 80...
