Sedimentary Pediastrum record of middle–late Holocene temperature change and its impacts on early human culture in the desert-oasis area of northwestern China

Although the pattern of Holocene temperature variations in central Asia is complex, it is clear that temperature played a fundamental role in influencing humidity conditions and regional human activity. We reconstructed temperature changes using Pediastrum species data, verified by clumped isotopes (Δ47), in the carbonates of sediment cores recovered from Bosten Lake in Xinjiang Province, northwestern China. Combined with archaeological data, the results indicate an unusually warm climatic interval that peaked at ∼4.7–4.3 kyr and promoted human occupation of the Altai Mountains. The climate cooled during 4.2–4.1 kyr and 3.6–3.5 kyr, as indicated by the decrease or absence of Pediastrum simplex. These cold events may have triggered the southward human migration out of the Altai region, resulting in the widespread distribution of archaeological sites at lower latitudes, in the Tienshan Mountains, and in the desert-oasis areas of the Tarim Basin in southern Xinjiang. Our data support the notion that a series of cultural transitions across the monsoonal Loess Plateau and Tibetan Plateau of China may have been linked to temperature changes during the middle to late Holocene.