Researchers examining ice cores from the Guliya Plateau in northwestern Tibet have identified frozen material that may extend more than 128,000 years into the past, significantly extending the previously understood glacial history of the region. The discovery represents the oldest ice ever recovered from this part of Tibet and offers a rare opportunity to study how mountain glaciers responded to major shifts in Earth’s climate over an extended timespan.
The research team collected ice samples from the Guliya Plateau during two separate expeditions 23 years apart. Analysis of oxygen isotopes in both samples revealed consistent patterns, suggesting the ice has maintained a reliable record of past environmental conditions. Lead researcher Lonnie Thompson emphasized the importance of this reproducibility, noting that identical results separated by decades provide valuable information about how ice behaves over extended periods.
Establishing the age of ice that has remained frozen for tens of thousands of years required sophisticated techniques. The international team utilized advanced dating methods involving radioactive isotopes of beryllium and chlorine, which decay at predictable rates and can be used to identify significant events in Earth’s history. The researchers detected evidence of the Leschamp Geomagnetic Excursion, a disturbance in Earth’s magnetic field occurring more than 41,000 years ago that left distinctive chemical signatures in the ice. Comparisons with oxygen isotope records from nearby Tibetan cave deposits supported the extended timeline.
Previous research had suggested the Guliya ice record reached back only to the middle of the Holocene epoch, which began nearly 12,000 years ago following the last ice age. The new evidence demonstrates that portions of the ice are considerably older, indicating that large ice masses in Tibet persisted as Earth emerged from the last glacial period. Thompson noted this finding contradicts assumptions that such ice sheets would have disappeared during early Holocene warming.
The research team plans to conduct additional analyses of the Guliya cores to investigate how other climate indicators fit into this extended history. The more precise timeline could help answer fundamental questions about when glaciation began, how long ice ages lasted, and when retreat occurred. The findings were published in Science Advances and received support from the U.S. National Science Foundation.
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