Ice core analysis reveals cooling period 6 M years ago

Ice core analysis reveals cooling period 6 M years ago. Scientists have extracted ice cores from Antarctica dating back 6 million years, which represents the oldest ice cores directly dated, according to a study in the Proceedings of the National Academy of Sciences. Analysis of water and air from the ice reveals a significant cooling period during the Pliocene era, with temperatures dropping by about 12 degrees Celsius.

Ancient Ice from Antarctica Reveals 6 Million Years of Atmospheric Secrets

By Stefanie Waldek

Space.com Contributor

November 3, 2025

The study, published in the Proceedings of the National Academy of Sciences (PNAS), was led by Dr. Sarah Shackleton, a paleoclimatologist at the Woods Hole Oceanographic Institution.

Two UMaine collaborators on the project are from the University of Maine: Douglas Introne, an expert in stable water isotopes, and Andrei Kurbatov, a volcanologist specializing in Antarctic ice cores.

This discovery traces its roots to a pioneering collaboration between UMaine and Princeton University, kickstarted over a decade ago in Allen Hills Blue Ice area, Antarctica. That initiative, detailed at https://www.ancientice.org/2MBIA/, has since evolved into a global effort to hunt for the world’s oldest ice (COLDEX), pushing the boundaries of what we thought possible in ice core science.