Holocene hydroclimatic change in the Altai Mountains and its impact on human migration

Abstract

An historical perspective on Holocene hydroclimatic change and its driving mechanisms in arid central Asia (ACA) can provide insights into both the sustainable development of the natural ecosystems of the region and ancient human-environment interactions. Here, we characterize changes in the Holocene (11.3–0 cal ka BP) aquatic ecosystem and hydrologic environment of a glacier-fed lake (i.e., Kanas Lake) in the Altai Mountains, based mainly on sedimentary records of cladocerans and Pediastrum. The low total abundances of cladocerans and Pediastrum during the middle to late Holocene (6–0 cal ka BP) suggest that an oligotrophic environment like that of today had developed mainly due to the increased river runoff. The higher runoff during this period resulted mainly from the increased precipitation that is indicated by climatic records from the sediments of Kanas Lake and other environmental archives in ACA. We conclude that the changes in the Holocene hydrological environment of glacier-fed lakes in ACA on the sub-orbital timescale were mainly modulated by the regional precipitation, and that the increased precipitation and hence availability of water resources greatly intensified the trans-Eurasian dispersal of crops and livestock along the grassland routeway.