Scientists drilled only 200 meters into Antarctica and uncovered Earth's oldest ice with 6-million-year-old air trapped inside

Imagine prying open a time capsule sealed since the days of saber-toothed cats. That’s more or less what a team of American scientists did when they extracted ice cores from a remote corner of Antarctica. Ice that has been frozen in place for roughly 6 million years, making it the oldest directly dated ice ever recovered from anywhere on Earth.

The discovery was published in October 2025 in the journal Proceedings of the National Academy of Sciences (PNAS), and it’s a really big deal; not just as a scientific record, but for what it means for understanding our planet’s future.

This ice is from a completely different Earth
The ice dates back to the Miocene epoch, when the Earth looked almost nothing like it does today. The planet was far warmer, sea levels far higher, and the world was teeming with animals we would hardly recognize, saber-toothed cats, early mammoths and ancient rhinos roaming around the Arctic.


The ice was found in the blue ice region of Allan Hills in East Antarctica between 2019 and 2023 by a team led by Sarah Shackleton, an assistant scientist at the Woods Hole Oceanographic Institution in Massachusetts. They drilled 330 to 660 feet into the ice sheet, not very deep by Antarctic standards, and what they pulled out was extraordinary.

“Ice cores are like time machines that let scientists take a look at what our planet was like in the past,” Shackleton said. “The Allan Hills cores help us travel much further back than we imagined possible.”

The real prize is the air bubbles inside
Here comes the exciting part. Trapped in the ice are tiny air bubbles that have not been disturbed in 6 million years. That means scientists now have direct access to samples of the ancient atmosphere of Earth, the actual air from a completely different geological era.

Ice cores offer a means of reconstructing past levels of greenhouse gases and ocean heat content, allowing scientists to gain a deeper understanding of the natural drivers of climate change over millions of years, according to Shackleton et al. The previous oldest continuous ice core record went back 800,000 years. This finding extends the direct record more than seven times further back in time.

The researchers also traced oxygen isotopes in the ice to estimate temperature changes over time. But over the last 6 million years, the Allan Hills region cooled about 22 degrees Fahrenheit (12 degrees Celsius), which the study describes as the first direct measurement of long-term Antarctic cooling ever recorded.

Why it matters for Americans right now
This is not some ancient history lesson. With the U.S. experiencing increasingly intense hurricane seasons, record-setting heat waves across the South and Southwest, and wildfires tearing through communities from California to Texas, it’s more important than ever to know precisely how Earth’s climate has changed and why.

For this kind of deep-time detective work, scientists have long relied on ice cores. As the study by Brook & Buizert, published in Nature, documented, Antarctic ice cores reveal tight linkages among greenhouse gases, aerosols, and global climate over hundreds of thousands of years, and how radically different our present atmosphere is from its natural range of variability. Now, the 6-million-year-old Allan Hills ice pushes that window back dramatically into an era scientists have never before been able to study directly.

By studying a warmer ancient Earth, when sea levels were much higher than they are today, climate scientists gain critical data to model what could happen if current warming trends continue unabated.

How the ice survived for 6 million years
It’s a fair question: how does anything survive that long in such an extreme environment? The Allan Hills area, about 6,500 feet above sea level, is a rare combination of near-motionless ice flow and rugged mountain terrain that effectively held the ancient ice in place. The newer snow is always getting blown away by the strong winds, and the bitter cold keeps the ice almost perfectly still.

“That makes Allan Hills one of the best places in the world to find shallow old ice, and one of the toughest places to spend a field season,” Shackleton noted.

Funded by NSF’s Center for Oldest Ice Exploration (COLDEX), the research team already has plans to return. A new long-term study of the Allan Hills region is planned between 2026 and 2031, with the hope of possibly finding even older ice.

6 million years of frozen history, and scientists are just getting started.