Ancient Tibetan Ice Cores Extend Mountain Climate Record to 128,000 Years

Two drilling campaigns separated by 23 years

Scientists extracted ice cores from the Guliya Plateau in northwestern Tibet during two separate expeditions conducted in 1992 and 2015, applying geochemical innovation to examine atmospheric history. Despite the quarter-century gap between drillings, laboratory measurements showed identical patterns of oxygen isotopes throughout the ice layers, according to findings published in the journal Science Advances.

Lead author Lonnie Thompson, professor of earth sciences and senior research scientist at the Byrd Polar Research Center at Ohio State University, noted that such reproducibility proves the ice cap preserved an undisturbed sequence of atmospheric history. Prior to this work, researchers believed the Guliya ice dated only to the middle of the Holocene, the geological epoch that began roughly 12,000 years ago.

“If you get an identical record a quarter of a century later, it can tell you a lot about the behavior of the ice over time.”

— Lonnie Thompson, professor of earth sciences at The Ohio State University

Radioactive isotopes track a geomagnetic disturbance

Dating ancient mountain ice required measuring radioactive isotopes of beryllium and chlorine, which decay at known rates. The international team used these chemical tracers to detect the Leschamp Geomagnetic Excursion, a temporary collapse of Earth's magnetic field that increased cosmic ray influx from space more than 41,000 years ago, as reported by ScienceDaily.

By cross-referencing these isotopic signatures with oxygen records from nearby Tibetan cave mineral deposits, the team established that the deepest core sections stretch back past 128,000 years. Outside of Greenland and Antarctica, previous mountaintop ice records such as those from Huascarán in Peru reached back just over 30,000 years.

Glacial survival through planetary warming cycles

The revised age confirms that large ice masses on the Tibetan Plateau did not vanish during past transitions between glacial and interglacial stages. Understanding the physical mechanisms that allowed the Guliya ice cap to endure extreme thermal variations provides empirical baseline data for modern sustainability and glacial models.

The research team plans further isotopic tests on archived core sections to track when past periods of glaciation started and how rapidly natural retreat occurred across Central Asia.

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