The history of Holocene fire evolution and its influencing factors are hot scientific issues. The middle (Xinjiang) and eastern (Xi'an-Dunhuang) parts of the Silk Road were affected by different climatic systems, and there are obvious differences in the mode and intensity of human activities in the middle and late Holocene. Research on the history of paleo-fires in this region and their relationship with climate change and human activities has received extensive attention. Based on the analysis of black carbon in the sediments of two alpine lakes, and combining the available paleo-climatic results, archaeological and historical literature, we reconstructed the paleo-fire history of the middle and late Holocene in the  area. We revealed the relationship between paleo-fires and the changes in climate, vegetation, and human activities in different regions, and explored the differences in the patterns of paleo-fires in the study area in terms of temporal and spatial variations, and their possible driving mechanisms. The above work will help to understand the pattern and mechanism of ancient fires in the mid-eastern Silk Road on a centennial and millennial scale, which is of great theoretical value and practical significance for future fire prevention and control measures in the context of climate change, and also provides a valuable case study for understanding the impact of human activities on the environment.

How to cite: Zhang, S. and Dong, G.: Fires history and the human impact during the mid-late Holocene in the mid-eastern Silk Roads, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7343, https://doi.org/10.5194/egusphere-egu24-7343, 2024.

Tibetan antelope is the only genus of large mammal endemic to the Tibetan Plateau. In the past decades, the antelope population has been significantly affected by human activities, including massive illegal hunting, followed by strict protection policies and establishments of natural reserves. Various techniques and many efforts have been devoted to monitoring changes in antelope population as well as migration recently. However, it remains unclear how the antelope population changed in the past, and how it varied with climate and environment. Here, we present sedimentary records at Lake Zonag, one of the major calving grounds for the Tibetan antelope, to study past changes in antelope population and response to environment changes. The sedimentary fecal sterols, produced by antelopes, captured the sudden decrease in antelope due to illegal hunting in past decades, as well as the recent recovery. The antelope population varied significantly during the past 9000 years, generally following environment changes revealed by geochemical elements in the same sediment core. Large antelope population likely lived in environment with relatively warm, humid and dense vegetation cover, while small antelope population occurred in adverse environment with relatively cold, dry and sparge vegetation cover. Two periods with notably low antelope population were observed at 5100-4500 and 4100-3700 cal yr before present. The increase in antelope population in the past 400 years likely result from protection from early Tibetans. This study provides a perspective method to reconstruct past changes in antelope population, to study its response to environment changes, and to provide historical comparison for wildlife protection.

How to cite: Hou, J.: Responses of Tibetan antelope population to environment changes during the Holocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11012, https://doi.org/10.5194/egusphere-egu24-11012, 2024.

The Qilian Mountains (QLMs) serve as an 'eco-security barrier' in western China, substantially impacting downstream ecosystems and water resource utilization. However, the hydrological evolution characteristics of the QLMs during the last millennium remain controversial, and the ecological response to climate change remains poorly understood. Here, we present a pH record based on the brGDGTs (branched glycerol dialkyl glycerol tetraethers) of ¹⁴C-dated sediments from Lake Maozangtianchi and compare it with X-ray fluorescence elemental data and grain size to reconstruct the history of summer monsoon precipitation variability during the last 900 years. The history of eco-environment changes was also reconstructed from the total n-alkane contents. Our results show that, on a centennial timescale, precipitation in the watershed was high during the periods 1100‒1300 CE, and 1750‒2000 CE, while precipitation was low during the period 1400‒1750 CE; there was an abrupt decrease during the MWP (Medieval Warm Period) to LIA (Little Ice Age) transition (1300‒1400 CE). This result, coherent with hydroclimate records from the monsoonal margin of northern China, is likely forced by a combination of El Niño‒Southern Oscillation related to tropical Pacific sea-surface temperature and the meridional shift of the Intertropical Convergence Zone. In addition, there was a coupled relationship between plant biomass in the watershed and monsoon precipitation variation, with higher plant biomass during 1100‒1200 CE, 1750‒1900 CE, and 1950‒2000 CE, and lower values during 1200‒1400 CE and 1900‒1950 CE. In contrast, plant biomass was decoupled with monsoon precipitation during 1400‒1750 CE and exhibited a slightly increase trend. Precipitation is a key climatic factor controlling plant biomass in the QLMs; however, during LIA, nutrients carried by dust and decreased evapotranspiration played important roles in increasing plant biomass. Our research emphasizes the significant moderating effects of exogenic dust on vegetation changes in alpine ecosystems under a context of climatic deterioration.

How to cite: Guo, S., Wu, D., Wang, T., Chen, L., Li, Y., Wang, T., Shao, S., and Zhou, A.: Hydrological evolution and differential response of the eco-environment recorded in Lake Maozangtianchi, eastern Qilian Mountains, over the past 900 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14850, https://doi.org/10.5194/egusphere-egu24-14850, 2024.

Arid central Asia, the largest non-zonal arid zone globally, serves as a crucial region for the westerlies-dominated climate regime (WDCR). Despite observing a warm-wet trend in recent years, the response of surface landscape elements such as lakes and vegetation to this climate change remains uncertain. In this study, we conduct an analysis of long-term trends (1992-2020) in lake area and NDVI across arid central Asia while comparing them with key climate factors including precipitation, drought index, and soil moisture. Our findings reveal that lakes are expanding and vegetation is greening in most regions situated at elevations exceeding 100 meters. Conversely, lakes are shrinking and vegetation is browning solely in low-altitude areas (<100m). The changes observed in water body area and NDVI exhibit robust spatiotemporal consistency that aligns with the ongoing warm-wet trend represented by the WDCR. Climate factors, particularly precipitation, exert a pivotal influence on the variations observed in surface water and vegetation within arid central Asia. 

How to cite: Chen, S., Su, Y., and Chen, F.: Synchronized responses of lake and vegetation dynamics to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15973, https://doi.org/10.5194/egusphere-egu24-15973, 2024.

The Himalayan region is a key area for climate and environmental change and has experienced rapid and pronounced changes over the past decades. Paleoenvironmental studies from this region are crucial to understand natural climate variability. Here we investigate a ~150 cm long sediment core, spanning over the last ~7 cal. ka BP, from a small high-altitude Lake Gosainkunda (surface area ~2.3 km², 4300 m elevation) in the central Himalayas using a multiproxy approach. Several maxima in allochthonous elements such as Ti and K, sand, as well as white layers indicate increased erosion, possibly related to flood events. Low input of allochthonous elements and sand from ~7 to 6 cal. ka BP, and from ~5 to 1.8 cal. ka BP implies reduced erosion interpreted to be associated with low precipitation. Contemporaneously, high values of log(Si/Ti), log(Ca/Ti), BSi, and inc/coh indicate high aquatic productivity, mainly controlled by higher growing season temperature and shorter duration of ice cover. High allochthonous and sand input from ~6 to 5 cal. ka BP and from ~1.8 to 1 cal. ka BP indicate increased erosion related to high precipitation. Concurrently, low aquatic productivity and authigenic carbonate production as well as positive excursion in bulk δ¹³C and δ¹⁵N values suggest reduced growing season temperatures and longer ice-cover. In the last ~1 ka, increased allochthonous input is related to increased anthropogenic activity in the catchment. We are now aiming to apply a suite of lipid biomarkers including the compound-specific hydrogen isotopic composition of n-alkanes for paleohydrological reconstruction as well as polycyclic aromatic hydrocarbons and faecal biomarkers to investigate paleo-fires and human impacts.

How to cite: Acharya, S., Rana, D., Prochnow, M., Dulias, K., Dawadi, B., Schwalb, A., and Zech, R.: A Paleoenvironmental record from Lake Gosainkunda, Nepal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18320, https://doi.org/10.5194/egusphere-egu24-18320, 2024.

The Earth's climate is currently undergoing significant transformations, marked by increasing temperatures, more frequent extreme events, and shifts in precipitation patterns. To comprehend these changes on decadal to centennial time scales and contextualize current climate change, it is essential to leverage paleoclimatic data spanning centuries to millennia. This analytical approach enhances our insight into natural climate variability, trends, and extremes, facilitating projections, planning, and preparation for the future.

Paleoclimate reconstructions, utilizing physical, chemical, biological, or detailed documentary records, offer valuable insights into climate conditions and variability across different historical periods. In contrast, climate models provide comprehensive information and data describing the entire climate system. Paleoclimate models specifically simulate the climate of past centuries to millennia by reconstructing the forcings influencing Earth's energy and, consequently, its climate. However, global circulation models with low horizontal resolution fall short in fully elucidating atmospheric pattern interactions and linking potential climate impacts contributing to significant societal events in history.

Recognizing these limitations, regional climate models emerge as promising tools for a more realistic representation of topography and regional climate information pertinent to paleoclimate studies. In our investigation, we employ the fully paleoclimate-adjusted regional climate model COSMO-CLM over China on a 0.22° resolution. This model incorporates external forcings such as solar, orbital, volcanic, greenhouse gas, and land-use changes, aiming to reduce reliance on input from coarse-resolution General Circulation Models (GCMs). The goal is to produce simulations that better capture climate changes over the past 2000 years at the regional scale.

Focusing on specific periods during the Little Ice Age and major tropical volcanic eruptions, we compare our model results with climate reconstructions from various regions in China. The COSMO-CLM successfully reproduces the impact of volcanic eruptions on China's climate, particularly regarding temperature changes. However, the intricate topography introduces complexities that affect the regional model's performance, leading to notable differences compared to other reconstructions, along with inherent uncertainties in the results.

How to cite: Xoplaki, E., Zhang, L., Zhang, M., Hartmann, E., Wagner, S., and Luterbacher, J.: High-resolution palaeoclimate simulation over China in the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18450, https://doi.org/10.5194/egusphere-egu24-18450, 2024.

 Due to the unique environmental conditions of the Tibetan Plateau, understanding when and how the Palaeolithic ancestors migrated and adapted in the region is a key issue in the course of human evolution. In recent years, along with the increased findings of archaeological evidence and a series of high-level studies, our knowledge regarding the prehistorical human activities on the plateau has been dramatically changed. Evidence from the Baishiya Cave in northeastern plateau have shown that Denisovans occupied the cave since at least 200 ka years ago and stayed in the cave for a relatively longer time. The site of Piluo which is located in southeastern side of the plateau indicates that humans possessing handaxe technology dispersed to the plateau at a time older than 130 ka year ago. In addition, a new lithic technological type called Quina technology has also been identified in the southern part of the Hengduanshan Mountains in Yunnan Province, which is probably related to the emergence of a new human group. Altogether, these findings indicate that different types of archaic humans have ever lived on the plateau. The earliest evidence for the arrival of modern humans is from the Nwya Devu site (~4600 m), given the diagnostic blade products excavated from the site. The site has been dated to ca. 40 ka years ago. Based on current evidence, we propose some possible routes for the migration of humans into the plateau. Denisovans may disperse to the plateau from the northeast direction, handaxe population and Quina population may disperse from the southeastern side, while early modern humans may come from the western side, with two possible sources of Central Asia and Southwest Asia. Overall, it is clear that the Palaeolithic Tibetan Plateau consists of an important region for the exchanges of early humans in different areas.

Keywords: Tibetan Plateau, Palaeolithic, Denisovans, Early modern human, Human migration and adaptation

How to cite: Chen, F., Li, H., Zhang, D., Xia, H., and Jia, Z.: Early humans migration and adaptation in the Palaeolithic Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19201, https://doi.org/10.5194/egusphere-egu24-19201, 2024.

Hydroclimate in arid central Asia (ACA) exhibited unique variability due to the dominance of mid-latitude westerlies over the Holocene, yet ACA climate variations during the last interglacial (Marine Isotope Stage (MIS) 5) remain elusive. Here, we present stable isotopes and trace elemental ratios of two coeval stalagmites in Xinjiang (northwest China), to address the orbital and millennial-scale climate shifts of ACA during MIS 5. The isotopic records of Baluk Cave (42°26' N, 84°44' E), spanning from 101.9 ka to 78.3 ka BP (before 1950 CE), show distinctly negative δ¹⁸O and δ¹³C values in the interstadials (i.e., MIS 5a and 5c), relative to the values in the stadial (MIS 5b). Such variations well correspond to the element data (X/Ca, X=Mg, Sr, and Ba), which exhibit values relatively higher in 5c and 5a compared with the 5b. These jointly suggest a key role of precession in orbital-scale climate evolution in ACA, closely following the insolation changes in warm-season (May to September) at 50°N.

Specifically, the X/Ca ratios suggested relatively dry climate in 5c and 5a while wetter climate in 5b, supporting a ‘warm/dry and cold/wet’ pattern in ACA during the last interglacial. This pattern is further supported by the simulated precipitation variation using the CESM general circulation model. Moreover, the millennial-scale climate shift across the MIS 5b/5a transition is evidenced by depleted isotopic values in Baluk Cave (i.e., ~2.5‰ in δ¹⁸O and ~1.9‰ in δ¹³C), initiating at 87.2±0.5 ka BP and terminating at 84.1±0.4 ka BP. The onset and termination of this millennial event in ACA are comparable with those recorded by speleothems in eastern China and northern India, and with changes in northern hemispheric temperature, atmospheric methane and CO₂ concentrations as inferred by the bi-polar ice cores. Our multi-proxy study suggests a close coupling between the large-scale westerly jet circulation, as suggested by δ¹⁸O, and local effective moisture in ACA, as documented by X/Ca, on orbital and millennial- scales.

How to cite: Liu, X., Wang, X., Shen, C.-C., Li, H., Ruan, J., Liu, G., Yang, Y., and Chen, F.: Replicated stalagmite records revealed orbital and millennial-scale hydroclimate changes in arid central Asia across the MIS 5 stadial-interstadial transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21523, https://doi.org/10.5194/egusphere-egu24-21523, 2024.