An international team of scientists announced Thursday they’ve successfully drilled one of the oldest ice cores yet, penetrating nearly 2 miles (2.8 kilometers) to Antarctic bedrock to reach ice they say is at least 1.2 million years old.

Analysis of the ancient ice is expected to show how Earth’s atmosphere and climate have evolved. That should provide insight into how Ice Age cycles have changed, and may help in understanding how atmospheric carbon changed climate, they said.

“Thanks to the ice core we will understand what has changed in terms of greenhouse gases, chemicals and dusts in the atmosphere,” said Carlo Barbante, an Italian glaciologist and coordinator of Beyond EPICA, the project to obtain the core. Barbante also directs the Polar Science Institute at Italy’s National Research Council.

The same team previously drilled a core about 800,000 years old. The latest drilling went 2.8 kilometers (about 1.7 miles) deep, with a team of 16 scientists and support personnel drilling each summer over four years in average temperatures of about minus-35 Celsius (minus-25.6 Fahrenheit).

Italian researcher Federico Scoto was among the glaciologists and technicians who completed the drilling at the beginning of January at a location called Little Dome C, near Concordia Research Station.

“It was a great a moment for us when we reached the bedrock,” Scoto said. Isotope analysis gave the ice’s age as at least 1.2 million years old.