Travertine, a secondary calcite deposit formed in tectonically and geothermally active regions of the Tibetan Plateau, preserves diverse environmental signals, including evidence of past human activity. The Quesang site contains prehistoric human hand- and footprint impressions whose ages have long been debated. Here, we applied isothermal thermoluminescence dating to travertine samples, evaluating the reliability of the equivalent dose measurements and the influence of erosion on dose rate estimates. Electron spin resonance and U-Th dating were also used for cross-validation. Our results show that isothermal thermoluminescence dating provides robust and reliable ages, confirming the prehistoric origin of the hand- and footprints and resolving previous chronological controversies. Beyond Quesang, isothermal thermoluminescence dating offers a promising approach for dating human traces in travertine and other carbonate deposits, providing new insights into the timing and distribution of early human presence on the Tibetan Plateau.

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.

Carbon dioxide removal is critical to net-zero pathways achieving the Paris Agreement 1.5 °C target, yet its effectiveness in reducing humid heat stress risks remains uncertain. Here, we examine the hysteresis and reversibility of humid heat stress in China under carbon dioxide removal scenarios. Humid heat responds asymmetrically during warming and removal especially in eastern and southern China, producing a hysteretic and partially reversible trajectory. This results from unequal adjustments of temperature and relative humidity, which constrain heat-stress recovery even as global temperatures decline. Moist static energy analysis indicates suppressed vertical energy export over eastern China and enhanced transport of warm moisture from tropical oceans, sustaining humid heat during the removal. Consequently, severe humid heat stress persists, with over 0.2 billion people affected, more than 66% of which is due to hysteresis. These findings highlight enduring heat-related risks and the urgent need for adaptation alongside mitigation. Severe humid heat stress threatens over 0.2 billion people in China during carbon dioxide removal, driven by unequal temperature/humidity adjustments, as sustained warm moisture transport prevents rapid recovery, according to moist static energy analysis.

Reconstructing past sea-level changes is critical in Quaternary science. On remote oceanic reefs, aragonite-to-calcite alteration occurs during subaerial exposure, directly recording the timing of sea-level fall. U-Th dating of coral calcite is challenging due to open-system issues. However, following calcite formation, the accumulated thermoluminescence (TL) signal can date the initial subaerial exposure event. This study pioneers the application of isothermal thermoluminescence (ITL) dating of reef calcite from the Xisha Islands, South China Sea. ITL single-aliquot regenerative-dose protocol improved the precision of equivalent dose measurement. By integrating dose rate simulation within a Bayesian framework constrained by U-Th ages, we obtained ITL ages of 127.0 +/- 8.0 and 138.5 +/- 1.5 ka for two reef core samples, dating sea-level lowstands to late Marine Isotope Stage 6. Our results demonstrate that ITL dating of reef calcite enables the high-resolution chronostratigraphic reconstruction of sea-level sequences back to at least 1.5 million years ago.

Gypsum veins in loess deposits are valuable paleoclimate archives in arid and semi-arid regions. Although previous thermoluminescence (TL) studies on gypsum have demonstrated its potential for luminescence dating, the blue-light stimulated luminescence (BLSL) characteristics of gypsum in such settings remain unexplored. We applied a low-temperature BLSL dating approach to investigate gypsum veins from the Jiuzhoutai loess section on the Chinese Loess Plateau. Determination of the equivalent dose (D-e) was performed using the single-aliquot regenerative (SAR) protocol. A series of experimental conditions, including tests of preheat temperature, stimulation temperature, OSL bleaching temperature, and dose recovery, were used to evaluate the feasibility of the SAR-BLSL protocol for D-e determination of the gypsum in the loess deposits. Pulse-annealing and anomalous fading tests were used to assess signal stability. Pulse annealing experiments yielded parameters of E approximate to 1.87 eV and the frequency factor (s) of 1.16 & times; 10(17) sec(-1), corresponding to an electron lifetime of similar to 6.05 & times; 10(8) y, at an ambient temperature of 10 degrees C for first-order kinetics assumption. This indicates potential thermal stability at least on million-year timescales. Nevertheless, measurable anomalous fading was observed (g(2d) = 9.35 +/- 1.20%) that warrants further evaluation for age correction. TL signal loss tests confirmed the efficient removal of traps associated with the similar to 280 degrees C TL peak, while also inducing an unstable, photo-transferred TL peak at similar to 300 degrees C that is most pronounced during early stimulation. Consistently, D-e(t) analysis shows a plateau at similar to 18-22 s (309 +/- 5 Gy) that agrees with the ITL-derived D-e (316 +/- 4 Gy) within uncertainty, supporting use of the late-decay interval to better isolate the slow component. Dose-response curves are well fitted by a single-exponential function. Regenerative doses up to 4000 Gy constrain D-0 similar to 600-700 Gy, and the average D-e results yielded a value of 144 +/- 6 Gy. After applying an experimental g value-based fading correction, the BLSL age of gypsum was calculated as 256 +/- 80 ka. We conclude that BLSL dating is applicable to the dating of gypsum within loess deposits, but routine tests of signal stability and cautious interpretation of BLSL ages are required because of potential fading.

Outbreaks of epidemics are human ecological disasters and have caused huge losses of human life and social disturbances in human history. But their impact on human culture has never been systematically and quantitatively studied. This study hypothesizes that such gigantic human ecological pressure would have created a great need for cultural innovations. By quantitatively examining and modeling the process using the time-series of cultural innovations and human ecological-socioeconomic proxies in European history (1000-1900 CE) based on the basic principles of causal inference, the paper demonstrates that infectious disease epidemics and socioeconomic stress stimulated the flourishment of thinkers and philosophical thoughts across different philosophies in truth, knowledge, and ethics, and promoted scientific discovery/technological innovations in a macro scale. Based on the results of Poisson regression and analysis of marginal effects, when the epidemics increased by 1, the average number of philosophical thinkers increased by 0.85, and their average impact score increased by 4.04. When the Consumer Price Index (CPI) increased by 0.1, the average number of philosophical thinkers increased by 8.9, and the average impact score increased by 29.79. The results of linear regression further show that when the epidemics increased by 1, the average scientific discoveries and technological innovations (SDTI) increased by 0.128 units; when CPI increased by 10%, the average SDTI increased by 0.15 units. Infectious disease epidemics have generally played an important role in generating cultural dynamics during the study period. The results imply that the recurrent outbreaks of the COVID-19 pandemic would likely lead to another thriving phase of cultural innovations.

Exploration of human ichnology began in the 20th century and significant advancements have been made in the 21st century. These imprints, including footprints and handprints, are invaluable resources for elucidating the evolutionary trajectories and living contexts of ancient human populations. Unlike traditional archaeological remains, such as human fossils, cultural layers, and faunal and floral remains, exceptionally well-preserved imprints can offer unique insights into aspects like muscle morphology, mobility patterns, gender distinctions, height, and ancient population demographics. On a global scale, noteworthy ichnological research includes analyses of hominin tracks found in volcanic ash in Tanzania, Africa (dated to 3.66 Ma), footprints at White Sands National Park in New Mexico, USA (dated to 23-20 ka), and handprints discovered in Indonesian caves (dated to 51.8 ka). These imprints have significantly contributed to research on the evolution, migration, and behavioral cognition of ancient human societies. However, relatively little attention has been paid to the study of ancient human ichnology within China, and international investigations of imprints within travertine deposits are scarce. Since the 1980s, over 100 archaic human handprints and footprints have been discovered at different elevations within the multilayered sediments of the Quesang hot spring travertine, in the central Tibetan Plateau. This travertine is composed of calcium carbonate formed from the precipitation of CaCO3-supersatuated thermogenic water from the deep, underlying carbonate rocks and deposited at different elevations from 4043 m a.s.l. to 4270 m a.s.l. since 500000 a BP. The archaic hominins intentionally and unintentionally pressed their hands and feet on the surface of the soft travertine that was recently deposited when the water emerged on the surface, after which the travertine was rapidly dehydrated to form trace fossils within the travertine beds. Evidence of 3D modeling and anatomic analysis indicates that they were made by the impression of hominin hands and feet when the travertine was in a soft state, and not by carving or the use of tools. Four groups of hand and foot traces are imprinted in laminated travertine layers at two locations from the top to downslope. The older traces were exposed by weathering/sliding of the overlying layer and were preserved under the arid climate and alkaline precipitation of Tibet. U-Th dating is currently the most dependable chronometric technique for dating the thermogenic travertine, after several dating methods were tested. Pure and dense travertine samples from different depths were selected for U-Th dating, and age modeling samples eliminated the possibility of 'open system' behavior by using stratigraphic and geochemical methods. The traces in Group 4 were dated to 187.7 +/- 9.6 and 207.3 +/- 9.3 ka BP, and those in Group 1, 2 and 3 were dated to between 9.2 +/- 2 and 6.6 +/- 1 ka BP. This remarkable discovery of hominin traces further demonstrates that ancient humans, possibly Denisovans, inhabited this Alpine hypoxic environment since the middle Pleistocene, and they represent the earliest artistic behavior within the archaic hominins.

IntroductionUnder global warming, urban dwellers have been at significant health risk due to urban heat islands and frequent extreme heat events in recent years. Most previous assessments of heat health risk focused on the regional scale. Therefore, we aim to evaluate the fine level heat health risk of Shijiazhuang, China.MethodsResidential community was as choose as basic evaluation unit. The heat health risks of 1,086 residential communities in the main urban area of Shijiazhuang were assessed by the risk framework of the IPCC, in which the risk was multiplicatively aggregated by hazard, exposure, and vulnerability.ResultsIn 2023, the hazard followed a center-periphery pattern with decreasing value from the city center to the periphery, whereas vulnerability presented the opposite trend. This pattern aligned with the finding that hazard-dominant risk residential communities were generally distributed close to the center and the vulnerability-dominant risk appeared primarily near the periphery. Five villages some distance from the city center were evaluated to present very high risk, with vulnerability as the dominant risk factor. Two of the five villages were identified as priority control communities, and increasing the percentage of water bodies and vegetation was the most practical way to lower the heat health risk.DiscussionThe differences in population exposure indicator may greatly affects the stability of heat risk mapping output. The results can assist urban managers in gathering comprehensive information about the heat health risk and developing effective mitigation strategies.

In the summer of 2022, the Tibetan Plateau experienced a record-breaking compound hot and dry event (CHDE). This study quantifies the contribution of anthropogenic influence to this compound event using a set of high-resolution statistical downscaling results from six CMIP6 models. The Copula function was used to calculate the joint probability of the compound event. The results show that in the summer of 2022, hot conditions in the Tibetan Plateau broke records since 1961, with a return period of 408 years. The dry conditions were also uncommon, with a return period of 47 years. The hot and dry compound event is particularly rare, with a return period of more than 20,000 years. Based on the results from statistical downscaling models, it was found that anthropogenic influence has increased the risks of dry and hot conditions similar to those in the Tibetan Plateau in 2022 by factors of 3.3 [1.5, 5.2] and 14 [8.6, 21.2], respectively. Additionally, the risk of compound events has been increased by a factor of 46.7 [26.7, 77.6]. In the future, with the intensification of warm-wet situations on the Tibetan Plateau, the hot conditions similar to 2022 are expected to increase remarkably, with the risk of occurrence rising by factors of 56 [34, 108] and 75 [44, 162] during the periods 2021-2040 and 2051-2070, respectively. Conversely, dry conditions are projected to decrease, with reductions of 0.21 [0.075, 0.46] and 0.51 [0.3, 1.2] times in the two future periods. However, the risk of compound events is expected to increase, with increases of 3.3 [1.5, 5.2] times and 11 [6, 25] times during the two periods. This study is the first to use downscaled simulation to conduct event attribution analysis for the Tibetan Plateau, which can deepen the understanding of the influence of human activities on compound events.

古人类印迹学的研究始于20世纪,并在21世纪快速发展.作为研究古人类演化过程和生存环境的重要媒介,古人类印迹(如脚印、手印等)具有其他考古遗存(如骨骼化石、动植物遗存、文化层等)所不具备的优势:保存状况完好的印迹可以反映古人类的肌肉形态、运动状态、性别、身高和种群构成等信息.在全球范围内,非洲坦桑尼亚火山灰上的脚印(～3.66 Ma),北美洲白沙国家公园的脚印(23～20 ka)以及印度尼西亚洞穴中的手印(51.8 ka)等,都是代表性的印迹学研究成果,为古人类演化、迁移和行为认知等方面的研究提供了关键线索.自20世纪80年代以来,青藏高原中部邱桑温泉的泉华多期沉积层中有超过100个古人类手印和脚印被陆续发现,时间跨度超过20万年.古人类印迹学研究在国内很少涉及,国际上对泉华沉积上的古人类印迹学研究也比较少,因而本文系统地综述和讨论了青藏高原上泉华形成的地质、地貌及水文条件;古人类手脚印印迹的形成过程、保存条件及其基本鉴定特征;印迹的采样、定年方法;以及印迹形态学反映的古人类行为特征等,并回应了泉华U-Th测年结果存在的一些争议.本文旨在吸纳更多有兴趣的学者加入古人类印迹学研究行列,使古人类印迹学研究成为中国考古和古环境研究中一个新的领域.

The anomalous hydrothermal conditions during growing seasons, i.e. less precipitation and high temperature, could induce an unstable water resource supply and pose great threats to regional agro-pastoral production, particularly in water-scarce drylands. Owing to the biases in the simulations of global climate models, quantifying the anthropogenic influences on such high-impact hot–dry extremes and future risks in the arid and semi-arid areas remains challenging. Based on CN05.1 observations and statistically downscaled simulations from the Coupled Model Intercomparison Project Phase 6, we conducted a comprehensive attribution and projection on the 2022- and 2023-like growing-season hot–dry extremes in Northwest China (NWC). Observations reveal that NWC experienced a fourfold increase in the occurrence of anomalously hot–dry growing seasons during 1991–2023 relative to that in 1961–1990. Attribution indicates that anthropogenic forcings have doubled/tripled the likelihood of 2022/2023-like hot–dry growing seasons in NWC largely due to human-induced warming. NWC is expected to experience increasingly hot growing seasons but with slight precipitation changes in the 21st century under the intermediate greenhouse gas emission (SSP2-4.5) scenario. The likelihood of 2022/2023-like hot–dry growing seasons in NWC will be more than 1–5 times that in the present-day (1991–2020), which is still dominated by rising temperature. To alleviate the stress of hot–dry growing seasons on agro-pastoral systems, we underscore the urgency of developing effective adaptation and mitigation strategies for water resource management in water-limited drylands.

The multi-model ensemble (MME) approaches are highly regarded in climate prediction and risk assessment for their capacity to integrate multiple global climate models (GCMs) and minimize uncertainties associated with individual models. However, the quantitative impacts of spatial scale, weighted ensemble, and bias correction on the spatiotemporal comprehensive performance of MME remain unknown. In this study, we comprehensively assessed the historical simulation capabilities of 41 CMIP6 GCMs at national, basin, and grid scales. Additionally, we investigated the impact of bias correction and weighted ensemble on enhancing climate simulation performance. The results indicate that CMIP6 models exhibit notable differences in simulating regional climate characteristics of China across different scales. Weighted multi-model ensemble schemes incorporating better-performing models consistently outperform equal-weight approaches, achieving an average 20.67% reduction in the DISO (distance between indices of simulation and observation) index, with temporal performance improvements being particularly pronounced. Bias correction played a critical role in the enhancement of MMEs, reducing DISO values by 41.60% on average, particularly in the spatial dimension. Among all MMEs, the grid-scale optimized ensemble (GBQ), combining bias correction, model selection, and performance-based weighting, demonstrated superior comprehensive performance, achieving the lowest DISO values across spatial and temporal dimensions. These findings provide new insights for enhancing regional climate simulation and evaluation, and they provide more reliable scientific information for investigating climate change and formulating adaptation strategies in China.

Exposure to record-breaking heatwaves represents a significant and growing challenge for human health and societal well-being in a changing climate. Comprehending the risks of future exposure to record-breaking heatwaves is vital for devising effective mitigation strategies. However, population data, a key determinant in projecting future exposure risks, has rarely been scrutinized for the uncertainty it introduces into these projections. This study investigates population exposure risks to record-breaking heatwaves from 2020 to 2 100 using four population datasets (ECNU, Lund, NASA SEDAC, and Tsinghua) under various IPCC AR6 shared socioeconomic pathways (SSPs: 1–2.6, 2–4.5, 3–7.0, and 5–8.5). Results indicate that by the 2090s, approximately 0.9 billion, 2 billion, 4.8 billion, and 4 billion people per year will be exposed to record-breaking heatwaves under SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5, accounting for about 10 %, 21 %, 42 %, and 50 % of the total population, respectively. Key risk areas include East Asia, South Asia, Western and Central Europe, the Mediterranean coast, West and East Africa, and the Northeastern United States. Our results also demonstrate good consistency in global population estimates across the datasets under different SSPs, except for Lund, which tends to predict a higher global population than the other datasets by about 8 % in SSP2 and SSP3. The Kappa test results reveal that, in the context of global population distribution, while the datasets of ECNU and Tsinghua, as well as Lund and Tsinghua, display a strong degree of spatial consistency, other dataset combinations show only a moderate level of agreement. Notably, at the subcontinental level, significant disparities emerge in the projected population sizes and distributions across different population projections, and over time, this gap is widening. This will have a significant impact on the estimation of future population exposure. For example, in the Northern Hemisphere mid-to-high latitudes and the Australian region, the ECNU dataset forecasts a higher population growth rate than the other datasets. Subsequently, a similar trend is observed in the projections of population exposure to record-breaking heatwaves. These findings highlight the variability in regional risk projections across different population datasets, providing valuable insights for future population-related risk assessments and informing targeted mitigation efforts.

Accurate simulation of the onset of spring is crucial for predicting the photosynthetic productivity of forest ecosystems. Nonetheless, the potential of phenology simulations on predictions of forest gross primary productivity (GPP) remains poorly understood, with previous studies generally focused on predicting phenology dates themselves or on limited scales. Here, we constructed a framework through the critical process of leaf growth to couple a terrestrial biosphere model—FORCCHN2 with five widely used phenology models, including one-phase (involving heat forcing), two-phase (considering chilling demand), and multi-phase models (integrating photoperiod effects) through the critical process of leaf growth. We evaluated the GPP performance from the multiple forest biomes in 74 eddy covariance (EC) sites and compared the total trends to satellite observations across the northern hemisphere forests. The predictions of the five models could reproduce 62.41–67.24 % variations of the GPP observations in all EC sites. In the deciduous broadleaf forest sites, we found the two-phase and multi-phase coupled models performed better than the one-phase coupled model. Chilling may play an essential role in controlling photosynthetic activity in deciduous broadleaf forests. Moreover, the multi-phase coupled model integrated photoperiod effects performed best at capturing GPP changes of the whole northern hemisphere forests. The predictions also showed the GPP in the northern hemisphere ranged from 21.68 to 26.06 Pg C year−1, and the total GPP showed an increasing trend. This study provides local and regional available evidence for the impact of phenology on photosynthesis with climate warming. The results highlight the necessity for enhancing understanding of the phenology factors on GPP and integrating the appropriate phenology representation to improve predictions of photosynthetic productivity for forests, especially in prediction to large scales and long-term trends.

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.

As a vital component of the "Asian water tower", lakes on the Tibetan Plateau (TP) significantly influence the regional ecosystems and economies and they are also an effective sentinel of climate change. However, the temporal and spatial patterns of lakes and the related hydroclimatic evolution on the northwestern TP (NWTP) remain unclear. We reconstructed the lake level variations of a non-glacier-fed lake, Longjue Co, on the NWTP, using optical dating of paleo-shorelines. The optically stimulated luminescence signals of quartz grains were unsuitable for dating due to high contributions of the medium component, and thus the post-infrared infrared stimulated luminescence signals (pIR 50 IR 170 , pIR 50 IR 225 ) of K-feldspar single grains were used. Internal checks including dose recovery tests, residual dose tests, and anomalous fading tests showed that the pIR 50 IR 170 signal was suitable for paleo-shoreline dating in Longjue Co. However, some of the samples were affected by the incomplete bleaching of pIRIR signals before deposition, and in this case the Minimum Age Model was used to constrain the ages. We also examined the dependence of the K-feldspar equivalent dose (D e ) on grain brightness and explored the possible mechanisms, and the brightest grains were then used for D e calculations. The results show that Longjue Co reached its maximum Holocene level ( +34 m) during the early Holocene (10.06 +/- 1.39 ka), and then after -5 ka it commenced a shrinking trend, punctuated by two rapid lake level decreases. Reference to independent paleoclimate records suggests that the Holocene lake level variations of Longjue Co and the regional hydroclimate were mainly controlled by the Indian summer monsoon.

Lakes on the Tibetan Plateau (TP) play a major role in the regional hydrological cycle and underpin vital ecosystem services. However, the long-term lake evolution and underlying mechanisms, especially on the exorheic southern TP, remain unclear. Here, we reconstructed the lake level variations of Mabu Co and Gala Co on the southern TP through detailed paleo-shoreline dating using post-infrared infrared stimulated luminescence (pIRIR) signals of K-feldspar single grains, and explored the driving forcings based on a comparison of paleoclimate records and geomorphological analysis. The results show that a unified paleolake at Mabu Co and Gala Co at a level -20 m above the modern level (a.m.l.) of Mabu Co developed during the late MIS 3 (35.9 +/- 1.9-29.1 +/- 1.4 ka) in response to increased glacial meltwater and Indian summer monsoon (ISM) rainfall. Under intensive glacier melting, the paleolake reached its maximum level (-29 m a.m.l.) and area (190 km2, -22 times larger than the modern areas of Mabu Co and Gala Co) during the last deglacial (16.8 +/- 1.0-13.6 +/- 0.7 ka) and began to outflow, which triggered incision and lowering of the spill-point. The lake level showed an overall decreasing trend since the last deglacial largely influenced by the lowering of the spill-point. During the last deglacial-early Holocene (12.7 +/- 0.6-9.8 +/- 0.6 ka), a high-stand lower than that in the previous stage (-24 m a. m.l.) was maintained by the strengthened ISM and glacial meltwater. In the mid-Holocene (8.7 +/- 0.9-4.1 +/- 0.3 ka), the paleolake experienced two rapid lake level drops in response to the weakening events of the ISM. The exposed shoreline terrace between the two lakes following the lake level drop after -6 ka provided an ideal living surface for the inhabitants at the Mabu Co site during 4.5-4.0 ka. We found that glacial meltwater and lake spillover processes, apart from the ISM, have exerted great impacts on the hydrological history of Mabu Co and Gala Co. The paleolakes have provided critical resources for humans at the Mabu Co site living in the alpine anoxic environment. Additionally, we suggest that lakes with low spill-points adjacent to exorheic basins on the southern TP should be given more attention regarding flooding hazard risks against increasing precipitation and glacial meltwater in the future.

Radiocarbon and OSL dating are the two main approaches used to date aeolian deposits in arid central Asia (ACA). Previous results showed that, compared with OSL dating, the C-14 ages of loess deposits in ACA are underestimated when the loess age is beyond similar to 25 ka. However, the cause of this radiocarbon age underestimation has not been adequately addressed. In this study, we measured the C-14 ages of different dating materials, including pyrolysis volatile (Py-V), pyrolysis residue (Py-R), humin, and total organic carbon fractions from two loess sections in ACA (the Hoalin section in the western Pamir Mountains, and the TLD16 section in the northern Tianshan Mountains). The results show that different dating material yielded different C-14 ages for all the loess samples, and all the radiocarbon ages obtained are younger than their corresponding OSL ages. Based on these results, together with a regional comparison of 78 C-14 ages from ACA with their corresponding OSL ages, we propose that the C-14 age underestimation is mainly due to the contamination by the deep penetration of the extended root systems of the plants that grow in arid areas, whereas this effect is less significant in the summer monsoon-dominated Chinese Loess Plateau.

Gypsum deposits within loess deposits are an important indicator of weathering processes and climate change. We conducted a thermoluminescence (TL) dating study of the gypsum from loess deposits of the Jiuzhoutai section in the western Chinese Loess Plateau. Determination of the equivalent doses (D-e) of gypsum samples was conducted using several protocols, including single-aliquot regenerative-dose (SAR-TL), multiple-aliquot additive dose (MAAD-TL), and Isothermal TL of SAR (SAR-ITL). The TL glow peak at 280 degrees C was targeted because of its reported stable signals. The test dose check, estimation of sensitivity changes, and the dose recovery test were applied to assess the applicability of the different protocols, and the characteristics of the thermoluminescence signals for gypsum were evaluated. The D-e results for the SAR-TL, MAAD-TL, and SAR-ITL protocols were within the error ranges. Among the three protocols, SAR-ITL did not involve high-temperature heating and it provided a more accurate D-e value, and thus it was used for D-e determinations for gypsum dating. With a dose rate of 1.74 +/- 0.07 Gy/ka, the minimum TL age of the gypsum veins was similar to 182 +/- 7 ka. U-series dating was also applied to the same samples for comparison. However, the extremely low ratio of Th-230/Th-232 (<= 4 x 10(-6)) of the gypsum veins deposited within the loess resulted in a large error of the U-series dates. We conclude that TL dating is more appropriate for the dating of gypsum in loess deposits.

Abstract At first glance, assessing future landslide‐exposed population appears to be a straightforward task if landslide hazard estimates, climate change, and population projections are available. However, the intersection of landslide hazard with socioeconomic elements may result in significant variation of estimated landslide exposure due to considerable variations in population projections. This study aims to investigate the effects of different sources of population data on the evaluation of landslide‐exposed population in China under four Shared Socioeconomic Pathways (SSPs) scenarios. We utilize multiple global climate models (GCMs) from Coupled Model Intercomparison Project Phase 6 and six high‐resolution spatially explicit static and dynamic population data sets to drive available landslide models. The results indicate an overall rise in landslide hazard projections, with an increase in the potential impact area of 0.4%–2.7% and an increase in the landslide frequency of 4.7%–20.1%, depending on the SSPs scenarios and future periods. However, the likely changes in future landslide exposed population, as modeled by incorporating population data from different sources with landslide hazard, yield divergent outcomes depending on the population data source. Thus, some of the projections depict an increase in future landslide exposure, while others show a clear decrease. The nationwide divergence ranged from −64% to +48%. These divergent findings were mainly attributed to differences in population data and a lesser extent to variations in GCMs. The present findings highlight the need to pay closer attention to the dynamic evolution of the elements at risk and the associated data uncertainties.