What drove late Holocene dust activity in central Asia, natural processes or human activity?

Abstract

Dust from interior Asia can be transported to a vast down-wind area by the Westerlies, exerting great influence on global climate and human health. However, the relative roles of natural climatic and anthropogenic processes on dust activity in interior Asia remain ambiguous. Here, we present new climatic records from an accurately dated aeolian sequence in the southern Tarim Basin (TB), an important location along the ancient Silk Road, and a source region for dust emission. In combination with analyses of historical documents within the TB and modern-day metrological data, we found that dust activity in the TB is controlled by climatically-related environmental change in this region after at least 4 ka, expressed by high correlation between dust activity records and newly obtained humidity and temperature proxy records from the same section. This high correlation is further supported by our analysis of modern meteorological data in central Asia. Human activities in this region, modulated by both natural climate-environment change and socio-political reasons, accelerated the process of environment deterioration and increased dust activity, especially after ~2 ka. We subsequently suggest that dust activity in central Asia during the last 4 ka is governed primarily by variations of the intensity and relative position of the Northern Hemisphere Westerly jet, based on records comparison and analysis on modern-day dust storm events. These observations provide important boundary conditions for the accurate prediction and numerical simulation of dust activity.