Glacial fluctuations in the southern Tibetan Plateau during the past 1000 years

Understanding the pattern and timing of glacial fluctuations in the latest Holocene (<1000 years), along with their cause, is necessary for deconvolving natural drivers of climate variability from anthropogenic impacts. Yet, debates remain on the importance of a global or more regional forcing mechanism. Here, we use Be-10 surface exposure dating, in conjunction with geomorphological mapping, to develop a moraine chronology with decades-to-century-scale resolution in the Xianza Range, southern Tibetan Plateau (TP). Five moraine records east of Mt. Jiare are dated to similar to 991 Common Era (CE), similar to 1415 CE, similar to 1567 CE, similar to 1711 CE, and similar to 1875 CE. The well-established moraine chronologies demonstrate that glaciers achieved the latest Holocene glacial maximum during the Medieval Warm Period (MWP). The less extensive Little Ice Age (LIA) glacial events release an unprecedented finding, which disproves the traditional viewpoint presuming that the LIA in the TP was represented by 2-3 glacial advances. Our results, paired with other climate records, point to, at least, a regional climate cooling signal during the LIA. In the MWP, glacial advance likely reflects the positive North Atlantic Oscillation-related cooling signal as recorded in the Northwestern Atlantic and Mediterranean regions. The strengthened northern mid-latitude westerlies at that time may play a key role in transferring cooling signal to the southern TP.