In a dome of white canvas perched on the roof of the world, Lonnie Thompson and his team drilled into ice that had not seen sunlight for more than 128,000 years. On the remote Guliya Plateau in northwestern Tibet, where the air is thin and temperatures plunge below freezing even in summer, they pulled up frozen time — ancient ice cores holding secrets from Earth’s last ice age. These samples are now the oldest ever recovered from high mountain glaciers anywhere on the planet.
This discovery matters because mountain ice acts like a climate diary, recording temperature shifts, atmospheric gases, and even magnetic changes over millennia. Until now, scientists thought most tropical and subtropical glaciers melted away during warm periods, erasing their deep past. The oldest non-polar ice core before this — from Huascarán in Peru — only went back about 30,000 years. But Guliya proves some high-altitude glaciers survived, preserving clues to how Earth warmed and cooled long before humans shaped the climate.
To confirm the age, researchers used rare isotopes: beryllium-10 and chlorine-36. These radioactive elements decay at known rates and left clear traces from a major event called the Laschamp geomagnetic excursion, when Earth’s magnetic field briefly flipped around 41,000 years ago. By matching those markers with oxygen isotope patterns in nearby cave deposits, the team showed the ice record extends far beyond that — likely over 128,000 years. Even more convincing? Ice cores taken in 1992 and again in 2015 show nearly identical chemical fingerprints, proving the record is stable and reliable.
The finding rewrites what we know about glacial survival. If all high mountain ice had vanished during the early Holocene — the warm period starting 12,000 years ago — it would mean no remnants of the last ice age remained outside the poles. But Guliya’s enduring ice says otherwise. It means Earth’s cold spells can leave behind survivors, even in unlikely places. Now, scientists plan to dig deeper — literally — using these cores to study ancient dust, microbes, and greenhouse gas levels across hundreds of centuries.
As Lonnie Thompson puts it, 'If you get the science right, it's consistent.' And this ice, silent for over a hundred millennia, is finally telling a story we can trust.