Antarctic Ice Core Unlocks 1.2 Million Years of Unbroken Climate History, Setting New Record

Humans have been recording the weather for thousands of years. Antarctic ice, however, has been at it for over a million.

An international team of scientists has extracted a 1.74-mile-long (2.8 kilometers) ice core in Antarctica, hitting the frozen continent’s bedrock. The core represents a chronological register of Earth’s climate and atmosphere, with the oldest ice dating back as far as 1.2 million years ago, if not more. The achievement, announced in a statement by the “Beyond EPICA – Oldest Ice” project, is expected to provide insight on one of climate science’s most enduring questions.

It’s worth clarifying that this record doesn’t make it the oldest ice core ever extracted—that recognition goes to a 2.7-million-year-old ice core recovered in 2017. What makes the Beyond EPICA core special is its continuous, high-resolution climate record spanning 1.2 million years, offering crucial insights into ancient atmospheric conditions and glacial cycles.

The ice core from the Beyond EPICA project. © Beyond EPICA project. “We have marked a historic moment for climate and environmental science,” said Carlo Barbante of Ca’ Foscari University of Venice, coordinator of Beyond EPICA. The core was retrieved during the project’s fourth Antarctic campaign. “This is the longest continuous record of our past climate from an ice core, and it can reveal the interlink between the carbon cycle and temperature of our planet.”

Between 900,000 and 1.2 million years ago, glacial cycles shifted from lasting 41,000 years to 100,000 years—a shift known as the Mid-Pleistocene Transition. The Beyond EPICA project aims to better understand this ancient climate phenomenon.

Led by The Institute of Polar Sciences of the National Research Council of Italy (ISP-CNR), the scientists worked for more than 200 days, drilling into the ice and processing the ice core at a remote site in East Antarctica called Little Dome C, with a balmy average summer temperature of -31 degrees Fahrenheit (-35 degrees Celsius).

“From preliminary analyses recorded at Little Dome C, we have a strong indication that the uppermost 2,480 meters [1.54 miles] contain a climate record that goes back to 1.2 million years in a high-resolution record where up to 13,000 years are compressed into one meter of ice,” said said Julien Westhoff, a postdoc at the University of Copenhagen and chief scientist in the field for the EPICA project.

The deepest and oldest parts of the core, which were closest to the bedrock, are made of ancient ice “that is heavily deformed, possibly mixed or refrozen and of unknown origin,” as well as rocks from the bedrock itself. This section could further scientists’ understanding of refrozen ice under the Antarctic ice sheet, the glaciation history of this Antarctic region, and the last time the continent was ice-free.

The project still faces significant hurdles, particularly the logistical challenge of transporting the segmented ice cores to a lab without risking melting.

“The precious ice cores extracted during this campaign will be transported back to Europe on board the icebreaker Laura Bassi, maintaining the -50°C [-58 degrees F] cold chain,” said Gianluca Bianchi Fasani, head of the Italian National Agency for New Technologies, Energy, and Sustainable Economic Development’s (ENEA) logistics for Beyond EPICA. “To reach this goal, a strategy was developed involving the design of specialized cold containers and precise scheduling of the National Antarctic Research Program (PNRA) air and naval assets.”

Once the segmented ice core has found its way to a (very cold) lab, it remains to be seen what secrets researchers will unlock within the ancient climate record.