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Numerous studies have explored paleoenvironmental conditions in China's dune fields around the mid-Holocene (MH), ∼6000 calendar years ago, often based on individual paleosol-aeolian sand depositional sequences and local-scale landscape dynamics. So far, continent-scale modeling studies have only indirectly assessed dune activation and stabilization processes via changes in simulated precipitation, net precipitation (precipitation minus evaporation), and effective moisture (precipitation divided by evaporation). Here we conducted a comprehensive study using gridded data on potential evapotranspiration, precipitation, and surface wind velocity from 13 climate models participating in the Paleoclimate Modeling Intercomparison Project phases 4 (PMIP4) and compared the model results with geological records. Our evaluation of spatial patterns of dune activity in northern China around the MH reveals that the intensity of annual MH dune activity exhibited significant differences between the eastern and western parts of Chinese deserts compared to those of the preindustrial period (PI). Dune activity was significantly weaker in the eastern region, while in the western part, it was considerably stronger. The key drivers of this disparity were the distinct spatial variations in near-surface wind speed and effective moisture between the two regions. Compared with the optically stimulated luminescence ages of the paleosol-aeolian sand sedimentary sequences derived from a compilation of geological records from 88 sites across northern China, the model results suggest that the weakening of dune activity and the process of dune stabilization in eastern China around the MH were mainly attributed to a significant increase in effective moisture and a concurrent decrease in near-surface wind speed due to the intensified East Asian summer monsoon. Additionally, the weakening of westerlies in western China resulted in reduced effective moisture, contributing to increased sand availability for dune development and subsequent desert expansion. • Mid-Holocene dune activity in Chinese deserts varied regionally, differing from preindustrial period. • Varied wind speed and moisture caused different mid-Holocene aeolian activities in northern China's western and eastern desert belt. • Numerical simulations aid in interpreting field-based geological findings comprehensively. [ABSTRACT FROM AUTHOR]

This paper presents the environmental history and its responses to palaeoclimatic changes since the start of the Holocene in the eastern portion of the desert belt (sand seas and sandy lands) in northern China by comparing the aeolian sandpalaeosol sequences and their palaeoclimatic proxies. The optically stimulated luminescence (OSL) ages of the aeolian sandpalaeosol sedimentary sequences and a series of palaeoenvironmental proxies show that: (1) The large-scale dune landscape currently in the Kubuqi Sand Sea was formed during the Holocene in general; and the palaeosol was generally developed during the period of 4–2 ka, indicating conditions favorable for vegetation growth, soil development, and organic carbon accumulation due to increased precipitation or effective moisture and weakened aeolian activities; the large-scale expansion of dunes in the recent 2 ka is closely linked to human activities. The variable discharge of the Yellow River with diversions for irrigation may have resulted in a more consistent supply of aeolian particles for dune field expansion. (2) The dune landscape of the Hunshandake Sandy Land was likely formed around 12 ka, and before this, the western part of the Hunshandake Sandy Land would have been covered by a single large lake; it was obviously wetter than today in the sandy land during the period of 9.6–3 ka and the palaeosols were developed at the same time. But the aeolian activities have not been completely dormant in this long-lasting wetter epoch; because the Holocene wetter period was likely time-transgressive across the region. (3) The palaeosol of the Hulunbuir Sandy Land began to develop as early as 14.5 ka, probably continuing until the last 2 ka. The palaeosol development of various dune fields in the eastern portion of the desert belt (sand seas and sandy lands) in northern China is spatially heterogeneous, and even the palaeosol development time in different locations within each sandy land is inconsistent. During the middle Holocene (especially the 7.5–3.5 ka), all the sandy lands were stabilized in general and the intensity of aeolian activities was significantly weakened. The number of palaeoenvironmental records in the eastern portion of the desert belt (sand seas and sandy lands) in northern China has increased rapidly in the past decade, but the amount of published data still does not match the vast extent of the dune fields. It does require much more in-depth palaeoenvironmental studies for a full understanding of the relationship between aeolian activities and climate change in northern China. [ABSTRACT FROM AUTHOR]

The Kubuqi Desert is the only active sand sea in the semiarid regions of northern China and occurs along the southern margin of the Yellow River. Little is known about the age and origin of this large (17,000 km 2 ) sand sea with a present annual precipitation of 200‐480 mm. Sand drift potentials indicated net capable winds for aeolian transport are from the northwest, though winds are stronger to north beyond the dune field than within the sand sea. Geomorphic and stratigraphic observations indicate that Holocene aeolian sand often drapes over bedrock and river terraces as a palimpsest landscape. Field investigations identified four stratigraphic sections with multiple aeolian sand units and palaeosols, with age control by optically stimulated luminescence (OSL) dating of quartz grains. Palaeosols are weakly developed, mostly accumulative A horizon with organic carbon content < 1% and reflect sand sheet deposition possibly in a steppe environment. Although sediments near river channels or former lakes might give old ages, the initial formation and age of the Kubuqi sand sea should be judged from the occurrence of the sandy palimpsest of the landscape that is OSL dated to the Holocene in general. The latest period of aeolian reactivation may be related to human activity associated with grazing and farming from lost cities in the Kubuqi Desert during the Han (206 B.C. – A.D. 220) and the Tang (A.D. 608 – 907) Dynasties. Also, variable discharge of the Yellow River with local diversions for irrigation and throughout the catchment resulted in possibly an increased supply of aeolian particles for dune field expansion in the past 2 ka. [ABSTRACT FROM AUTHOR]