When you drill 364 meters (1194 feet) down into Antarctic ice, taking out a cylindrical section called an ice core, you can find out about the Earth’s temperature and carbon dioxide levels from over 20,000 years ago. Information is held within the oxygen atoms in the ice and the air bubbles that formed within it.

Measuring ice cores is an effective form of time travel for scientists like the British Antarctic Survey team, who are studying how the Earth’s climate is changing. And Antarctica is full of untapped information:

Antarctica is thought to have been covered by ice for over 30 million years. So far, scientists have drilled ice cores stretching back 800,000 years, and they are now working to extend their records back to 1.4 million years ago.

In this video, Ice Core Scientist Nerilie Abram explains the process. You can also read more about the team’s work here.