Amplified dust cycle in Central Asia linked to desert expansion and environmental transformations since 1980

Abstract

Central Asia is experiencing an expansion of desert area. Desert in Central Asia has expanded northward by over 100 km since the 1980s. Shrinking of the Aral Sea and the Caspian Sea has led to the emergence of new and significant dust sources globally. This promotes the increased dust emission with significant climatic impacts. However, spatiotemporal evolutions of the dust cycle over recent decades across this area have rarely been investigated under global warming scenario, therefore resulting in incomplete knowledge regarding the dust transport pathways, spatial structure and deposition processes. Here we combine satellite observations with investigations of the spatial grain-size gradient of loess sediments to reconstruct its dust cycle model. Abundant dust aerosols originating from the western deserts are transported eastward at upper levels and mainly deposited in the piedmont of the Pamir Plateau and Tien Shan. Based on these new knowledge, we examined the dust deposition and loading over Central Asia using multi-source remote sensing data from MERRA-2, MODIS, OMI, and TMOS, and found that its dust cycle has been intensifying since 1980. This increasing trend contrasts with that in NW China, despite both regions being dominated by a broad warming and wetting pattern. We argue that intensively expanding desert area, potentially associated with land surface modifications, may be responsible for intensifying dust activity in Central Asia. These results offer new insights into future trends of dust dynamics in Central Asia and their intricate links with climate change under global warming. Our finding demonstrates the potential of integrating modern satellite observations and paleo-dust records to investigate regional dust dynamics.