Increased late Holocene dust activity revealed by loess accumulation rates in Central Asia

Abstract

Dust from the vast arid and semi-arid regions of arid Central Asia (ACA) makes a large contribution to global-scale dust cycles. However, systematic and regional-scale reconstructions of dust activity in ACA are lacking, thus hindering the exploration of its relationship with climate change. Aeolian loess deposits provide valuable records of past dust activity and its linkages to climate. We constructed a stacked, normalized dust mass accumulation rate (MAR) record from 17 loess sections with high-resolution dating, together with a probability density record based on 189 absolute ages from 39 Holocene loess sections. These records were used to reconstruct the temporal pattern of Holocene dust activity in ACA, which shows a pronounced increase during the late Holocene. After evaluating the temporal variation of moisture conditions at different altitudes in ACA, we conclude that while dust activity during the early and middle Holocene was driven predominantly by climate change, this was not the case in the late Holocene. Taking the mountain-basin system of the Yili Basin in Xinjiang as an example, we propose that dust activity on a large spatial scale was not completely controlled by changes in moisture conditions, and that regional factors, such as fluvial geomorphic processes, played an important role in increasing the materials supply to the areas of dust accumulation. We speculate that dust activity may intensify in ACA under future global warming scenarios.