A team of scientists has successfully extracted ice samples that are 6 million years old from the frozen Allan Hills, in eastern Antarctica, marking a milestone in the history of climate research.
This discovery, the oldest ever directly dated, was led by Sarah Shackleton of the Woods Hole Oceanographic Institution and John Higgins of Princeton University, and was published in the journal PNAS on October 28.
The air bubbles trapped in the ice, which come from a time when the Earth was significantly warmer, have served as a time capsule, providing a unique insight into the Earth’s climate during the Miocene.
A research that opens many possibilities
The researchers determined the age of the ice using argon isotope dating in these bubbles, a method that allows for direct dating without the need to analyze surrounding soil or rocks.
Analyses have revealed that the Allan Hills region has cooled by approximately 12 °C over the last 6 million years, thus providing the first quantified evidence of cooling in Antarctica since that ancient warm period.
Ed Brook, director of COLDEX and paleoclimatologist at Oregon State University, highlighted the importance of these ice cores, as they will act as ‘climate snapshots’, doubling the age of previous records.
This finding comes at a critical time, as global warming, driven by human emissions of greenhouse gases, is rapidly altering the Earth’s climate.
Scientists hope that the study of these ancient air bubbles will help them reconstruct past greenhouse gas concentrations and identify the natural factors behind climate change throughout the history of the planet.
With the successful discovery, the COLDEX team plans to return to Allan Hills between 2026 and 2031 to conduct more drilling and recover even older samples, thus expanding our understanding of Earth’s climate in ancient times.