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Central Asia represents a key region for our understanding of early human dispersal patterns, because it served as a migration corridor that linked the Levant and southern Caucasus with Northeast Asia. However, no Early Palaeolithic sites in Central Asia are anchored with reliable age constraints, including the thick loess-palaeosol sections in Tajikistan that recorded early human activities and environmental changes over multiple glacial-interglacial cycles. This lack of absolute age constraints is presently a key factor limiting our understanding of the early human occupation history of this region. Here, we provide a comprehensive description and an absolute chronological framework for the Early Palaeolithic Karatau Culture; defined by the rich lithic assemblages found in palaeosols in the Khovaling Loess Plateau, Tajikistan. Age constraints are provided through multi-method analysis of three loess-palaeosol sections in the Khovaling Loess Plateau, combining luminescence ages, cosmogenic ²⁶Al-¹⁰Be concentrations, and magnetostratigraphic boundaries into a probabilistic inverse age-depth model. This model shows that the Karatau Culture flourished with the onset of Marine Isotope Stage 15, thrived during Marine Isotope Stage 13 and 11, but disappeared around onset of Marine Isotope Stage 10. We frame the archaeological occupations within local and regional ecological settings to better understand the drivers of Pleistocene human migrations in Central Asia.

Loess-paleosol sequences across Asia provide a critical archive of past dust deposition and climate dynamics shaped by westerlies and Asian monsoons. We compile luminescence ages and climatic proxies from 107 loess sections to reconstruct dust mass accumulation rates (MARs) and hydroclimate variability over the past 130 thousand years (ka). The results reveal a consistent pattern: high MARs and low moisture during Marine Isotope Stages (MIS) 4 to 2 (71 to 12 ka) and low MARs with high moisture during MIS 5 (130 to 71 ka) and MIS 1 (12 ka to present). These shifts are driven by cooling-induced changes in atmospheric humidity linked to fluctuations in ice volume across glacial-interglacial cycles. Within MIS 5, MIS 4 to 2, and MIS 1, pronounced spatial and temporal contrasts in MARs and moisture emerge between westerlies-dominated northern Iran and central Asia and monsoon-dominated East Asia. Notably, westerly and monsoonal precipitation vary out of phase, driven by insolation-controlled shifts in moisture transport.

The last 1.2 million years have witnessed fundamental changes in global climate, including substantial intensification of global glaciations and a shift from obliquity-to eccentricity-paced glacial-interglacial cycles. However, the effect of these changes on prevailing wind direction and mineral dust transport pathways remains enigmatic. Here, we utilize anisotropy of magnetic susceptibility (AMS) of Tajik loess over the last 1.2 Ma to constrain past wind regimes in the Afghan-Tajik Basin of southern Central Asia. The area is located at the intersection of the Siberian High pressure system, the Mid-Latitude Westerlies, and the Indian Summer Monsoon, and acts as one of the largest dust-emitting regions globally. AMS measures the magnetic fabric of loess, a function of dust transporting wind directions and post-depositional processes, and here we apply the technique to three different loess-palaeosol sections on the Khovaling Loess Plateau, Tajikistan. In addition to constraining post depositional reworking, we show through comparison to modern modelled and observed wind regimes that AMS does indeed reflect the directions of dust-transporting winds that, while partly affected by meso-scale and local topography, are ultimately driven by regional wind systems. Our results demonstrate that the directions of these dust-transporting winds have remained stable for the last 1.2 million years. This remarkable resilience of the dust transporting wind regime suggests a stability of the wider synoptic wind field despite major global climate transitions and regional orogenic uplift.

Greenland ice cores demonstrate that transient last glacial cold climate events (stadials) were associated with greatly enhanced atmospheric dust loading. Detailed radiocarbon dating of loess in central Europe reveals concurrent increases in dust activity in dust-emitting regions. However, the causes of these changes in dust emission and the role of dust in rapid climate change remain unclear. We address this uncertainty through multi-proxy analysis of loess sources in Hungary. Our results demonstrate that loess particles were dominantly produced by subglacial grinding processes in the eastern Alps. These particles were released along with stadial Alpine Ice Sheet-driven meltwater pulses, turning major river systems into efficient dust sources for loess deposition in Europe. Concurrent strengthened anticyclonic circulation over northern Europe would have caused wider dispersal of Alpine Ice Sheet-derived dust as far as Greenland. Resultant continental-hemispheric scale changes in atmospheric dust loading likely amplified concomitant North Atlantic climate cooling and ice sheet decay during Greenland stadials.

Windblown mineral dust is a nutrient source to the ocean, influencing global ocean productivity, ocean carbon uptake and climate. In this Review, we examine how dust emission fluxes, sources and compositions have changed over the past 7 Myr and consider the implications for ocean productivity. Since the Late Cenozoic, global cooling and orogenic uplift have enhanced dust emissions from major source regions and fluxes to downwind ocean basins, with the associated nutrient supply varying with dust origin. Glacially derived Asian dust contains higher concentrations of ferrous iron (typically exceeding 30% of the total iron) and phosphorus than the aged, highly oxidized mineral dust from North Africa, which has negligible ferrous iron content. Indeed, Asian dust has a notable influence on Pacific Ocean productivity and, potentially, climate. For example, Middle Pleistocene increases in the content of Asian dust Fe2+ (~45%) and P (~55%) coincided with a threefold to fivefold rise in glacial productivity in the South China Sea and a concurrent shift in phytoplankton ecology in the lower-latitude North Pacific. Therefore, decreasing glaciogenic dust–nutrient supply under continued global warming could notably impact ocean productivity, especially in the Pacific Ocean. Future research should focus on constraining the composition and bioavailability of dust-derived nutrients across a wide range of globally important dust sources so that dust composition and related feedbacks can be better parameterized in Earth system models.

Environmental magnetism, including the use of magnetic susceptibility (MS), has formed the backbone of analyzing past terrestrial climate dynamics recorded in loess deposits world-wide. However, the nature of MS signal response and frequency dependence (χ_FD) varies between loess sequences, which can limit the applicability of the approach. Here, we explore how measuring MS using multiple alternating-current field frequencies can transform our understanding of the past climate record in loess. We compare loess MS data measured at 15 different frequencies from diverse environments across the Northern Hemisphere, and provide high-resolution data for a late Quaternary loess-paleosol section in Tajikistan. Additionally, we study the magnetic mineral composition in selected Tajik loess samples using rock magnetic methods and Raman spectroscopy and assess the usefulness of calculating superparamagnetic nanoparticle (SP) size distributions from multi-frequency magnetic susceptibility. Our results demonstrate that using this approach to determine χ_FD has several advantages over widely used dual-frequency approaches: (a) Inclusion of a wider grain size range of magnetism-bearing SP particles in measuring χ_FD, allowing for a more complete analysis of the environmental drivers behind the MS signal; (b) Higher sensitivity of the χ_FD palaeoclimate proxy to climatic changes; and (c) Increased statistical meaningfulness of the χ_FD proxy by allowing quantification of uncertainty. Our approach is particularly beneficial for understanding sites characterized by low-susceptibility samples and potentially diverse processes of magnetic enhancement. However, we advocate its routine use even in more typical loess sequences due to its greater sensitivity to climatic changes and better understanding of inherent proxy uncertainties.

Loess-paleosol sequences have been used in Asia to study climate and environmental changes during the Quaternary. The scarcity of age control datasets and proxy indices analysis data for Asian loess has limited our understanding of loess depositional processes and the reconstruction of paleoclimatic changes from loess-paleosol records. In this study, we present a dataset that includes 1785 quartz optically stimulated luminescence ages and 1038 K-feldspar post-infrared infrared stimulated luminescence ages from 128 loess-paleosol sequences located in different regions of Asia. We generate 38 high-resolution age-depth models of loess records based on the provided datasets. We provide data on 12,365 grain size records, 14,964 magnetic susceptibility records, 2204 CaCO₃ content records, and 3326 color reflection records. This dataset contains the most detailed and accurate chronologies and proxy index data for loess records in Asia yet published. It provides fundamental data for understanding the spatial-temporal variations in loess depositional processes and climatic changes across the continent during the mid-late Quaternary.

Pleistocene loess records of the Khovaling Loess Plateau (KLP) in Tajikistan provide rich collections of lithic artifacts demonstrating past human presence in the region. To understand the timing of human activity and environmental conditions prevailing at that time U–Th dating and clumped/stable C/O isotope measurements have been applied to modern and Pleistocene soil carbonates (SCs) collected at several sites on the KLP and surroundings. U–Th ages were corrected by two methods: 1) assuming an initial [²³⁰Th/²³²Th] activity ratio of 0.85 ± 0.25 based on gamma spectrometry of loess/paleosol samples, and 2) the isochron technique using leachates and fully dissolved subsamples. Diagenetic alteration and potential U/Th mobilization and related isotope fractionation due to alpha-recoil was also modelled and found to be minor in the studied soil carbonates. Compared to model ages as references, uncorrected ²³⁰Th ages are only acceptable if measured [²³⁰Th/²³²Th] activity ratios of leachates are high (>30), while ²³⁰Th ages derived using method 1 are mostly overcorrected. It appears that SCs can be reliably dated by the U-series disequilibrium method in this sedimentary setting, but isochron dating cannot be spared. Application of the isochron method is required to derive ²³⁰Th_model ages, which ensures that the non-zero initial ²³⁰Th and possible U–Th gain/loss due to alpha-recoil can be simultaneously corrected and reliable U–Th ages obtained. U–Th ages of Pleistocene SCs clearly demonstrate post-pedogenic ingrowth of multiple, non-contemporaneous populations of SCs within loess/paleosol units, and that SC formation happened in many cases under cold, presumably dry glacial climate conditions. Considering that U–Th ages of SCs provide minimum ages of the sediment in which they form, these ages can be useful in developing loess stratigraphic models and for correlation of paleosols with marine isotope stages. This implies that the age of a given paleosol and any lithic artifacts it may contain, indicating human activity, cannot be younger than the age of SCs formed in that paleosol. This is due to the nature of soil carbonates, which can be the product of both syn- and post-depositional processes.

Clumped isotope thermometry of SCs collected from modern soils at three sites in Tajikistan provide evidence for SCs dominantly recording summer season soil temperatures, while the calculated soil water oxygen isotope signatures reflect annual signals and carbonate precipitation from source waters incorporating rainfall from prior to and during SC formation. In contrast, some Pleistocene SCs record soil temperatures and stable isotope compositions more appropriate to glacial conditions, confirming the findings of U–Th ages, and highlighting the primary role of aridity-driven soil moisture changes in SC precipitation in this setting. Considering the interpretative complexities of SC stable isotope compositions, involving issues such as SC formation depth within a soil/paleosol profile, seasonality of SC growth and violation of the law of superposition, SC stable isotope proxy records of past climates cannot be considered as a set of clearly sequential data through time. This implies that such SC-based stable isotope records must be accompanied by U–Th dating of carbonates to be meaningful.

Sediments of the Lena River represent an important environmental archive for understanding the Quaternary history of North-Eastern Siberia. However, at present, the structure, origin and age of the Lena River terraces are poorly known. This article presents results of lithofacies analysis and absolute dating of the Ust’-Buotama section exposing the fourth (Bestyakh) terrace of the Lena River. We report the first quartz and K-feldspar luminescence ages, the reliability of which was argued by age relations and standard tests. Three stratigraphic units have been recognized in the section (depths from the top): lacustrine-alluvial deposits (85–120 m) of the Mavrinka Formation; aeolian sand deposits of the Dolkuma Formation (23–85 m), and Holocene aeolian dune sediments (0–23 m). The resulting chronology suggests that the sediments of the Mavrinka Formation were deposited no later than 300 ka (MIS 9 or later). Deposition of the Dolkuma Formation occurred from ∼30 ka to ∼15 ka (late MIS 3 - late MIS 2). Holocene aeolian dune formed during initial Neoglacial cooling post climatic optimum (c. 5.5 cal ka BP). More extensive Late Holocene dune sediments which formed ∼400 years ago are coeval with Little Ice Age (11th-19th centuries).

Situated at the southernmost limits of the late Pleistocene Eurasian permafrost zone, the loess–paleosol sequences of the Lower Volga region contain numerous traces of cryogenesis. Cryogenic features are represented by thin vertical wedges in loess and paleosols, and involutions and wedges in alluvial deposits. Here we describe and interpret four stages of cryogenesis during the late Pleistocene, based on analysis of cryogenic structure morphology, morphoscopy of quartz grains, and micromorphology of subaerial sediments, in addition to calculation of the Cryogenic Weathering Index and a new luminescence chronology derived from published ages. These stages differ in type and distribution of cryostructures and formed in different paleogeographic conditions. Stage I, dated 95–90 ka (Marine Isotope Stage [MIS] 5b), is characterized by the existence of continuous permafrost in northern part of the Lower Volga valley. Stage II (75–70 ka, MIS 5a/MIS 4) is characterized by dry and cold conditions and widespread permafrost. During stage III (52–45 ka, MIS 3b/c), the permafrost was thin and of sporadic distribution. Stage IV (37–35 ka, MIS 3a) is characterized by thin and rare sporadic permafrost. The processes of cryogenic transformation of sediments in the region during these stages took place under both permafrost and seasonal frost conditions. The results obtained significantly improve current understanding of the extent of the permafrost in the south of the East European Plain during the late Pleistocene.