Scientists drilling deep into the Guliya Plateau in northwestern Tibet have recovered ice cores dating back more than 128,000 years, extending the region’s known glacial record by more than 100,000 years and providing a rare, non-polar archive of Earth’s ancient climate history.
Ice Cores from the Guliya Plateau Reveal a 128,000-Year Record
The discovery shatters previous assumptions that mountaintop ice in Tibet could only trace back to the middle of the Holocene epoch, which began nearly 12,000 years ago. The samples recovered from drilling operations conducted in 1992 and 2015 share strikingly similar oxygen isotope patterns. This high degree of reproducibility across cores pulled 23 years apart gives researchers high confidence in the physical integrity of the trapped environmental data.
Reproducibility of the records within a given ice cap is extremely important. Lonnie Thompson, lead author of the study, a professor of earth sciences and senior research scientist at the Byrd Polar Research Center at The Ohio State University, explained the significance of the timeline matching. Securing a matching profile 25 years later offers valuable insights regarding how glaciers evolve and behave over time.
Dating Ancient Ice Using Beryllium and Chlorine Isotopes
Dating ice compressed over tens of thousands of years requires precise analytical methods. The international research team used advanced dating methods involving radioactive isotopes of beryllium and chlorine. These elements decay at predictable rates, acting as a reliable chronological clock.
The team successfully detected the chemical signature of the Leschamp Geomagnetic Excursion, a major disruption in Earth’s magnetic field that occurred more than 41,000 years ago. Cross-referencing this anomaly with oxygen isotope records found in nearby Tibetan cave deposits allowed scientists to suggest the Guliya ice record may extend well beyond 128,000 years into the past.
Thompson pointed out that outside of polar areas, this represents our sole high-altitude ice archive reaching such an age, drawing a comparison between Guliya and records from locations like Huascarán that span over 30,000 years.
Understanding How Mountain Glaciers Survived Past Climate Shifts
The persistence of the Guliya ice cap through the end of the last ice age answers a fundamental question about glacial survival. If the ice sheet had melted completely during the early Holocene, scientists would have lost the older layers entirely. Instead, the high elevation and specific local terrain of the plateau preserved the ancient accumulation.
Researchers plan to subject the expanded sample set to further laboratory analysis. By pairing the updated timescale with additional environmental indicators, the team aims to model natural climate cycles, reconstruct historical periods of glaciation, and map out the exact mechanisms of ice loss on the planet.
The big picture is that our results tell a very consistent story, Thompson said. If you get the science right, it’s consistent. It’s our understanding of what it’s trying to tell us that has to catch up.
