ORONO — Three University of Maine Climate Change Institute scientists are part of a Princeton University-led team that analyzed 2 million-year-old ice cores from Antarctica to provide the first direct observations of Earth’s climate when furred early ancestors of modern humans still roamed.

CCI associate professor Andrei Kurbatov, CCI director Paul Mayewski, and doctoral student Heather Clifford participated in the research. 

The ice core data provides insights about how the current glacial cycle emerged. Researchers believe that up until about 1.2 million years ago, Earth’s ice ages consisted of thinner, smaller glaciers that came and went every 40,000 years on average, according to the Institute, in a news release.

Then, after what is known as the Mid-Pleistocene Transition, the current world characterized by colder and longer glacial cycles of 100,000 years emerged.

“It is great to see the immense research potential of the Antarctica blue ice areas – that we have recognized for decades at UMaine – are beginning to unveil the hidden secrets of Earth's past climate,” said Kurbatov, in the release.

The ice cores are from Allan Hills, where high winds help create environmental conditions that draw ancient ice toward the surface. 

Gas bubbles trapped in the ice cores – which are the oldest yet recovered – contain pristine samples of carbon dioxide, methane and other gases that serve as “snapshots” of prehistoric atmospheric conditions and temperatures, the researchers recently reported in the journal Nature. 

Because ice flows and compresses over time, the cores the researchers retrieved are like scenes collected from a very long movie that do not show the whole film, but convey the overall plot. The researchers found that although a long-term decline in atmospheric carbon dioxide did not directly lead to today’s colder glacial cycle, temperature and global ice volume nonetheless tracked carbon dioxide closely.

The full Princeton Environmental Institute release can be read here.