Holocene moisture and aeolian activity recorded in loess from the Yarlung Tsangpo, Southern Tibetan Plateau

Abstract

As a part of the third pole of the earth, the southern Tibetan Plateau (southern TP) is sensitive to climate change. Understanding how this region evolved in the past offers valuable insights for understanding future climate trends. Despite many efforts, the evolution of moisture and aeolian activity during the Holocene in the southern TP remains controversial, in part due to the complex topography and regional atmospheric circulation. In addition, constructing a sound chronology for aeolian sediments using radiocarbon is challenging. Here we use the low-temperature organic carbon fraction from a sediment profile from the middle reaches of the Yarlung Tsangpo, southern TP. We reconstructed a Holocene history of humidity and dust using grain size, magnetic susceptibility, and organic matter as climate proxies. The reconstructed history features three distinct stages. During the early Holocene (11.7–8.3 ka B·P), the climate was humid with weak dust activity, under the influence of the Indian Summer Monsoon (ISM). But during 8.3–5.8 ka B·P, moisture was also influenced by the North Atlantic Oscillation (NAO). Diminished solar activity led to a negative NAO phase, intensifying aeolian activity. From 5.8 ka B·P onward, enhanced winter insolation and stronger mid-latitude westerlies (MLW) contributed to a renewed warm and humid climate. This study provided an insight in which to view the interplay of Holocene climatic systems and environmental change in the southern TP.