Ice core evidence for asynchronous glaciation on the Tibetan Plateau

Over the last two decades, ice core records have been systematically recovered from low-latitude, high-elevation ice fields from across the Tibetan Plateau (TP) and each core has provided new information about regional climate and environmental change. When viewed collectively, these ice core histories provide compelling evidence that the growth (glaciation) and decay (deglaciation) of large ice fields in the lower latitudes are often asynchronous with high-latitude glaciation and deglaciation that occur on Milankovitch time scales. Here, we examine the evidence for asynchronous glaciation on the TP as recorded in ice cores from the Guliya ice cap on the northwestern margin, and the Puruogangri ice cap and Dasuopu glacier in central Tibet and along the southern margin of the TP, respectively. We contend that although stable isotopic records from Antarctica, Greenland, Tanzania, Peru, and Bolivia suggest global-scale cooling during the last glacial stage, over much of the TP precipitation is a stronger driver of glaciation. Here, we present evidence suggesting that glacier expansion on the southern and central TP is driven mainly by variations in monsoonal precipitation that is modulated by precession-driven insolation changes. The basal (oldest) ice in the Puruograngri and Dasuopu ice fields was deposited in the early to mid-Holocene, while ice near the base of Guliya is more than 500,000 yr old.