Search

We present climate-dependent changes in the high-mountain forest ecotone, old-growth forests, alpine phytocenoses, and deglaciated forelands in the Aktru glacial basin (Altai Republic, Russia). A number of independent sources (variations in upper treeline altitude, dendrochronological data, analysis of lacustrine sediments and botanical and geographical studies linked with the dynamics of glacial-dammed lakes in the Chuya and Kurai intermountain depressions) suggest Holocene temperatures reached about 4 °C higher than today. Unlike the European Alps, glaciers in the continental Altai Mountains disappeared before forming again. Also, the upper altitudinal limit of mountain forests during the Holocene was greater than in the European Alps. The high variability of mountain ecosystems in southern Siberia suggests their potential instability in a currently changing climate. However, periglacial successions associated with the strong continental climate and glacier retreat represent an area of increasing biodiversity and plant cover. The historical and current sensitivity of the continental mountains to climate variations which exceeds that of the European Alps requires greater understanding, environmental protection, and increased social responsibility for the consequences of anthropogenic contributions to climate change: the isolated Altai areas contribute little to climate changes, but are greatly affected by them., (© 2021. Royal Swedish Academy of Sciences.)

The Asian westerly jet streams in the upper troposphere play a pivotal role in shaping precipitation patterns, sustaining the diverse but fragile ecosystems in arid Central Asia. Despite their significance, the evolution history of these jet streams and their synergistic effects with the monsoon systems on regional climate change in Asia during the Holocene remain poorly understood. To address this gap, we present a continuous pollen record since 8.6 cal ka BP from Lake Shuang in the Altai Mountains. The first two principal components of the pollen data are employed to track regional changes in vegetation, summer moisture, and winter temperature. Meanwhile, the pollen data and the TraCE‐21ka simulation results were compared to reveal the dynamic mechanism of regional climate change. Results indicate a humid phase spanning the interval ∼8 to 5 cal ka BP in this region, which broadly coincides with the intensification of the Indian Summer Monsoon. This temporal correlation is potentially linked to the poleward shift of the Asian jet, as suggested by simulation results. Furthermore, our data show a consistent winter warming trend throughout the Holocene, indicated by changes in the dominant tree pollen taxa and a reduction of cold‐resistant‐taxa. This trend is associated with the weakening of the East Asian Winter Monsoon, influenced by increasing winter solar insolation and atmospheric CO2 concentration. Overall, our research provides strong paleoclimatological evidence highlighting the interconnected meteorological roles of the Asian jet and monsoon systems in shaping regional climates. Plain Language Summary: The Asian westerly jet streams in the upper troposphere have strong links with the precipitation that maintains the fragile ecosystems of arid Central Asia. Understanding the evolution of the Asian jet streams and their relationship with the winter and summer monsoon system is important for understanding climatic changes in this hydrologically‐constrained region. Pollen data help us to look into the past changes in vegetation and climate. Based on our study from the Altai Mountains, the abundance of birch forest was promoted under a humid climate, while pine forest grew with warmer winter conditions. The humid period in this region lasted from ∼8 to 5 cal ka BP and was linked to increasing summer precipitation. The increase of tree species well‐suited for warmer winter indicates a sustained winter warming trend since the early Holocene. We suggest that this warming trend was caused by the combination of the combined increases in winter insolation and atmospheric CO2 concentration. This persistent Holocene winter warming trend occurred in the regions controlled by the Asian jet and winter monsoon, providing strong evidence for a relationship between them. Key Points: A Holocene pollen record from Lake Shuang in the Altai Mountains shows a humid period during ∼8–5 cal ka BP with persistent winter warmingThis humid period maybe due to a poleward shift of the Asian jet center linked with a strong Indian Summer MonsoonHolocene winter warming was caused by the increasing of CO2 concentration and solar insolation [ABSTRACT FROM AUTHOR]

With a warming climate, temperature extremes have been a main global issue in recent decades due to their potential influence on the sustainable development of human life and natural ecosystems. In this study, 12 indicators of extreme temperature events are used to evaluate the spatiotemporal distribution, periodic structure and teleconnections with large-scale atmospheric circulation in Xinjiang, Northwest China by combining wavelet coherence (WTC) analysis based on continuous wavelet transform (CWT) analysis with the sequential Mann-Kendall test. We find that over the past six decades, the climate in Xinjiang has become warmer and has suffered from increases in the frequency of warm extremes and decreases in the frequency of cold extremes. Warm extremes have mainly occurred in the southern Tianshan Mountains surrounding the Tarim Basin and western part of the Taklamakan Desert, and cold extremes have primarily occurred in the southwestern Altai Mountains and northern foot of the Tianshan Mountains. Extreme temperature events, including warm extremes, cold extremes, and other temperature indices, have significant interannual variability, with the main oscillation periods at smaller (2–4-year band), intermediate (4–7-year band), and greater time scales in recent decades. Furthermore, cold-extreme indices, including frost days, cool days, and cool nights all show a clear changepoint during 1990–1997 at the 95% confidence level, and both ice days and cold spell duration indicator have a potential changepoint during 1981–1986. However, the changing points for warmextreme indices are detected during 1992–1998. The temperature variables are significantly correlated with the EI Niño-Southern Oscillation (ENSO) and Arctic Oscillation (AO), but less well correlated with the Pacific Decadal Oscillation (PDO). The phase difference in the WTC spectra is not uniform between temperature extremes and climatic oscillations. Our findings will have important implications for local governments in taking effective measures to mitigate the potential effects of regional climate warming due to human activities in Xinjiang. [ABSTRACT FROM AUTHOR]

The evolution of a glacial lake is a true reflection of glacial and climatic change. Currently, the study of glacial lakes in the Altai Mountains is mainly concerned with the application of high-resolution remote sensing images to monitor and evaluate the potential hazards of glacial lakes. At present, there is no rapid and large-scale method to monitor the dynamical variation in glacial lakes in the Altai Mountains, and there is little research on predicting its future tendency. Based on the supervised classification results obtained by Google Earth Engine (GEE), combined with an analysis of meteorological data, we analyzed the spatial and temporal variations in glacial lakes in the Altai Mountains between 2000 and 2020, and used the MCE-CA-Markov model to predict their changes in the future. According to the results, as of 2020, there are 3824 glacial lakes in the Altai Mountains, with an area of 682.38 km2. Over the entire period, the glacial lake quantity growth rates and area were 47.82% and 17.07%, respectively. The distribution of glacial lakes in this region showed a larger concentration in the north than in the south. Most glacial lakes had areas smaller than 0.1 km2, and there was minimal change observed in glacial lakes larger than 0.2 km2. Analyzing the regional elevation in 100 m intervals, the study found that glacial lakes were predominantly distributed at elevations from 2000 m to 3000 m. Interannual rainfall and temperature fluctuations in the Altai Mountains have slowed since 2014, and the trends for the area and number of glacial lakes have stabilized. The growth of glacial lakes in both number and surface area is expected to continue through 2025 and 2030, although the pace of change will slow. In the context of small increases in precipitation and large increases in temperature, in the future, glacial lakes with faster surface area growth rates will be located primarily in the southern Altai Mountains. [ABSTRACT FROM AUTHOR]

Mt. Munkhkhairkhan is the most crucial region for understanding climate and glaciation changes in Mongolia. This study investigated the relationship between glacial area changes and the climate elements of Mt. Munkhkhairkhan in the Mongolian-Altai Mountains using a remote sensing approach, in-situ observations, the Mann–Kendall (MK) test, Innovative Trend Analysis Method (ITAM), Sen's slope estimator test, and statistical analysis. The study results showed that for the last 30 years, the annual average air temperature of Mt. Munkhkhairkhan has been slightly increasing. Total annual precipitation (mainly snow) in the mountain area decreased from 1990 to 2000, but since 2000, a significant increase in precipitation levels has appeared. For the last 30 years, the glacial area has decreased by 32% to 11.7 km2. Multiple regression results showed a strong correlation between Temperature, Precipitation, and Glaciers (Multiple R = 0.69, R2 = 0.48). Ruther indicated that Temperature (t = −2.332, p = 0.036) and Precipitation (t = −3.212, p = 0.007) were significant predictors in the model. Air temperature and precipitation explained 48 percent of the change in the glacier area, and R = 0.69 is a strong correlation. The glaciers and snow area in the study area have changed due to climate warming and precipitation changes and are located in arid and semi-arid regions of Central Asia. This study of Mt. Munkhairkhan shows that climate change significantly impacts glaciers and snow. [ABSTRACT FROM AUTHOR]

Under the global warming, it is particularly important to explore the response of extreme climate to global climate change over the arid regions. Based on daily temperature (maximum, minimum, and average) and precipitation data from meteorological stations in Xinjiang, China, we analyzed the spatiotemporal characteristics of extreme temperature and extreme precipitation events via combining thin plate smoothing spline function interpolation, Sen's slope, and Mann–Kendall test. Our results showed that during 1960–2019, the extreme low temperature index of frost days (FD), icing days (ID), cold days (TX10p), cold nights (TN10p), and cold speel duration index (CSDI) all showed the downward trend to varying degrees, and the extreme high temperature index of summer days (SD25), warm days (TX90p), warm night (TN90p), and warm speel duration index (WSDI) all showed an upward trend to varying degrees, and the extreme low temperature index of high altitude mountains decreases more than that of the basin and plains. In addition, all the extreme temperature indices are closely related to the annual average temperature in Xinjiang (R > 0.6). Among the extreme precipitation indices, except for the consecutive dry days (CDD), the other extreme precipitation indices showed increasing trends to different degrees, but the changes in extreme precipitation in Xinjiang were mainly manifested by the increase of heavy precipitation in a short period (the increase of heavy precipitation and extreme heavy precipitation was the largest, 44.8 mm/10a and 17.6 mm/10a, respectively) and spatially concentrated in the Ili River and Altai Mountains in northern Xinjiang. Meanwhile, annual precipitation was positively correlated with the extreme precipitation index (R > 0.4), except for the CDD. This study provides theoretical support for the prevention and control of natural disasters in the dry zone. [ABSTRACT FROM AUTHOR]

Understanding the impacts of human activities on landscapes necessitates a comprehensive analysis of historical changes in climate, vegetation, fire and land utilization. The human-environment interactions were investigated through the analysis of new charcoal data from Kelashazi Peat in the Altai Mountains, compared with the detailed paleoenvironmental records and historical human activities (e.g., agriculture and pastoralism) at other three distinct sites. The findings suggest that the late-Holocene (prior to ∼2000 years ago) fire activities were mainly influenced by temperature at higher elevations and were primarily driven by vegetation cover at lower elevations. Over the past two millennia, human activities have increasingly impacted fire dynamics. Elevated fire frequencies during the Medieval Warm Period at higher elevations were linked to warmer climates and intensified pastoral activities. Lower fire incidences at lower elevations may be attributed to population outflows during the Medieval Warm Period, while heightened fire occurrences at lower elevations might result from increasing agricultural activities during the Little Ice Age. This study underscores the intricate interplay between natural climate-vegetation-fire dynamics and anthropogenic burning trends in the late Holocene across different elevations of the Altai Mountains within the Arid Central Asia. • Fire activities before ∼2000 years were modulated by temperature at higher elevations and by vegetable cover at lower elevations • Warm climate and intensified pasture led to increased fires activities at higher elevations at the MWP. • Increasing agriculture activities in the cold-dry LIA led to higher fire occurrence at lower elevations. [ABSTRACT FROM AUTHOR]

Investigating the spatial and temporal changes in snow cover over mountain areas is significant for understanding the impact of regional climate variability. In this study, using cloud‐removed snow cover data, which are generated based on Moderate Resolution Imaging Spectroradiometer (MODIS) daily snow cover products, the spatiotemporal changes of snow cover fraction (SCF) and its relationship with temperature and precipitation changes from 2002 to 2020 were examined over Altai Mountains, China. The results demonstrate that the distribution and changes of SCF are highly spatiotemporally heterogeneous. Within a year, the maximum SCF occurs in January at 98.6%, and the minimum appears in July at 8.7%. The annual‐mean SCF shows an increasing trend at 0.09%·annum−1, owing to the significantly increasing SCF in the snow accumulation period at 0.5%·annum−1 and the decreasing SCF in the snow melting period at −0.2%·annum−1. The SCF distribution, as well as its interannual change, is greatly influenced by elevation. During the snow cover period, a positive linear correlation between SCF and elevation is found at 0.02%·m−1 (p <.01). The annual‐mean SCF decreases in the area below 1,200 m, whereas it increases in the area above 1,200 m. Accordingly, the elevation‐dependent SCF results in various SCF distributions on different slopes and watersheds. The SCF shows an apparent pattern in different aspects, with similar SCFs between the north and east aspects and between the west and south aspects but a difference between the northeast aspects and the westsouth aspects. The SCF is negatively correlated with air temperature (r = −0.74, p < 0.01) and positively correlated with precipitation (r = 0.74, p < 0.01). In addition, temperature shows a significant and larger correlation with SCF in both the snow accumulation and melting periods, indicating the major factor of temperature for the changes in SCF. [ABSTRACT FROM AUTHOR]

It is important to study the relationships between tree growth and phenology and climate factors in Central Asia for the sustainable development of forest ecology and the exploration of carbon sink potential in the region in a context of global change. Herein, the process-based Vaganov-Shashkin model was used to simulate tree-ring growth rates, to assess a cambial phenology (start and end of growing season) of larch trees (Larix sibirica) based on three sites located on three different latitudes in the Altai-Sayan Mountains in Central Asia over 1960–2018. It was shown that the principal factor limiting growth rates was temperature in RU (located in southern central Siberia), cambial dynamic was unimodal. In RU site, although the length of growing season did not change significantly over the past 59 years, it was correlated with tree radial growth. Moisture was the principal factor limiting the growth rates of AL and FY (located in Chinese Altai Mountains), and cambium dynamics were bimodal and unimodal, respectively. Temperature and precipitation before the start of the growing season lengthen the growing season, but this did not promote the tree radial growth. In conclusion, we determined that the climate-influenced intra-seasonal growth rate regulated tree growth rather than length of growing season in this area. In this study, the VS-simulation showed high potential develop a long-term reconstruction of cambial phenology in the Altai Mountains, which was conducive to a more comprehensive understanding of the exogenous-endogenous factors effects on tree-ring growth.

The evolution of a glacial lake is a true reflection of glacial and climatic change. Currently, the study of glacial lakes in the Altai Mountains is mainly concerned with the application of high-resolution remote sensing images to monitor and evaluate the potential hazards of glacial lakes. At present, there is no rapid and large-scale method to monitor the dynamical variation in glacial lakes in the Altai Mountains, and there is little research on predicting its future tendency. Based on the supervised classification results obtained by Google Earth Engine (GEE), combined with an analysis of meteorological data, we analyzed the spatial and temporal variations in glacial lakes in the Altai Mountains between 2000 and 2020, and used the MCE-CA-Markov model to predict their changes in the future. According to the results, as of 2020, there are 3824 glacial lakes in the Altai Mountains, with an area of 682.38 km2. Over the entire period, the glacial lake quantity growth rates and area were 47.82% and 17.07%, respectively. The distribution of glacial lakes in this region showed a larger concentration in the north than in the south. Most glacial lakes had areas smaller than 0.1 km2, and there was minimal change observed in glacial lakes larger than 0.2 km2. Analyzing the regional elevation in 100 m intervals, the study found that glacial lakes were predominantly distributed at elevations from 2000 m to 3000 m. Interannual rainfall and temperature fluctuations in the Altai Mountains have slowed since 2014, and the trends for the area and number of glacial lakes have stabilized. The growth of glacial lakes in both number and surface area is expected to continue through 2025 and 2030, although the pace of change will slow. In the context of small increases in precipitation and large increases in temperature, in the future, glacial lakes with faster surface area growth rates will be located primarily in the southern Altai Mountains.

Background: Medicinal plants have always played an important role in the history of human health. However, the populations and sustainable use of medicinal plants have been severely affected by human activities and climate change. Little is known about the current conservation status and distribution pattern of medicinal plants. In this study, based on accurate geographical distribution information of 9756 medicinal plants, we identified diversity hotspots and conservation gaps, evaluated conservation effectiveness of nature reserves, and predicted suitable habitat areas for medicinal plants in China to provide scientific guidance for their long-term conservation and sustainable use. Results: A total of 150 diversity hotspot grid cells, mainly concentrated in central and southern China, were identified. These only accounted for 5% of the total distribution area but contained 96% of the medicinal plants of the country. The hotspot grid cells included all traditional hotspot areas, but we also detected three new hotspots, namely Mufu-Lushan Mountains, Tianshan-Altai Mountains, and Changbai Mountains. The current national and provincial nature reserves protect 125 hotspot grid cells, which harbor 94% of all medicinal plants. However, 25 hotspot grid cells, distributed in the Tianshan-Altai Mountains and Hengduan Mountains, are located outside the national and provincial nature reserves. An analysis of the predicted effects of climate change indicated that the suitable habitat areas will shift from southern to northern China, and that southern China will face a considerable loss of suitable habitat areas, while the east and west parts of China will encompass remarkably more suitable habitat areas in the future. Conclusions: The current conservation networks have achieved high conservation effectiveness with regard to medicinal plants; however, the conservation gaps we identified should not be neglected, and conservation planning needs to take into account the predicted shifts of some hotspots of medicinal plants due to climate change. [ABSTRACT FROM AUTHOR]

The climate in the Altai Mountains is determined by two major climate systems whose dominance has varied over time, leading to significant spatio-temporal changes in temperature and precipitation during the Holocene. This study aimed at the reconstruction of the local to regional moisture and temperature conditions in an alpine belt of the southern Mongolian Altai during the Late Holocene. It thereby contributes to a more comprehensive understanding of the region's palaeoclimate in the Holocene. Our reconstruction is based on palynological and sediment analyses as well as radiometric age determinations of samples from a 130 cm exposed soil/sediment profile within the alpine belt. Largely supported by sedimentological and geochemical observations, the pollen assemblages indicate a warm and dry period between about 2600 and 2250 cal a BP, a subsequent cold and humid phase extending to about 130 cal a BP, and a return to warm and dry conditions lasting to present. Our data support the results of recent studies on the regional climate variability and the observation of significant differences in the mode of climate changes and its temporal sequence within the Altai Mountains. Although the pollen assemblages in the profile reflected a continuous anthropo-zoogenic influence on the study site's vegetation climatic signals were clearly detectable, underlining the indicator value of the pollen data from the Alpine sediments for regional palaeoclimatic reconstruction. [ABSTRACT FROM AUTHOR]

The paper considers changes in the annual and seasonal runoff, as well as the ice regime of the Mayma River in response to changing climatic conditions in the catchment area during the period of 1940–2016. Significant positive trends, especially occurring during the winter months, have been identified in the long-term course of annual and seasonal air temperatures. A significant decrease in precipitation rate is observed in the cold period of the year. According to the analysis of the hydrological characteristics for the periods of 1940–1975 (the background period) and of 1976–2016 (the period of contemporary climate change), the annual runoff for the Mayma River basin shows a downward trend against the background of the observed climatic changes. The decrease in annual flow is the result of a decrease in the flood flow. Thus, with the observed winter warming and a decrease in the amount of solid precipitation, the average maximum discharge for the wettest month (April) decreased by 35 % in the period of 1976–2016 with respect to the background level of the 1940–1976 period. Winter warming contributes to less soil freezing and replenishment of groundwater during periods of winter thaw and intensive snowmelt, which lead to an increase in runoff in the last winter months and the first months of summer-autumn low-flow periods. Winter warming manifested itself in the ice mode of the river Mayma. Since the beginning of the period of the current climate change (1976) there has been an observed decrease in the duration of ice freeze-up and a shift towards later freezing dates and earlier break-up dates.

Climate over Asian montane rangelands is changing faster than the global average, posing serious threats to the future of the region's livestock‐based economies and cultures. Effects of climate change on rangeland vegetation likely depend on grazing by herbivores but the potential responses of vegetation to such changes in climate and grazing regimes remain unclear.We examined vegetation responses to experimentally simulated climate change (warming, drought and increased rainfall) and grazing (clipping vegetation) between 2015 and 2018 at two mountain rangeland sites: Spiti valley, in the Indian Trans‐Himalaya and Tost, in the Gobi‐Altai Mountains in Mongolia.Clipping and climate change manipulations interactively reduced vegetation cover and biomass but did not affect species richness. Treatment effects and their interactions varied between sites. In ungrazed plots, vegetation cover and biomass declined sharply in response to warming (18%–35%) and drought (20%–50%) at the two sites, and, surprisingly also declined slightly in response to increased rainfall (20%) at Tost. While the effects of climate treatments were largely similar in the grazed and ungrazed plots in Tost, they were larger in the ungrazed plots in Spiti. The decline in vegetation cover was driven by a decline in the cover of both forbs and grasses.In combination, grazing and warming (Tost) or drought (Spiti) had sub‐additive effects, that is, the decrease in vegetation cover in response to grazing and warming/drought was less than the sum of their independent effects but greater than the effect of either manipulation alone. Of the two, warming had a greater effect than drought at the more arid site (Tost), whereas drought had a larger effect at the more mesic site (Spiti).Synthesis and applications. Our findings show that future changes in climate, including just over 1°C of warming, could undermine the sustainability of pastoral economies and the persistence of wildlife across Asian montane rangelands. Furthermore, grazing by herbivores will play an important role in mediating rangeland responses to climate change; thus, pasture management in concert with local pastoralists will be crucial in mitigating the adverse effects of climate change on rangelands, pastoral livelihoods and wildlife populations. [ABSTRACT FROM AUTHOR]

Located in the intermediate zone between the taiga forests in Siberian Plain and the deserts in Central Asia, the Altai Mountains are of scientific concern about Holocene climate change in the past decades. However, researches about modern climate changes are relatively scarce in the Altai Mountains. In this study, temporal- spatial changes of air temperature and precipitation were investigated systematically in the Altai Mountains based on fifteen meteorological records over the period of 1970–2015. The Altai Mountains experienced a rapid warming trend with a rate of 0.41°C/decade and an insignificantly wetting trend at a rate of 4.82 mm/decade during 1970–2015. The magnitude of temperature trend was negatively correlated with elevation in cold season (spring and winter), whereas that was positively correlated with elevation in warm season (summer and autumn). The cyclonic anomalies to the northwest and an anticyclonic anomalies to the southeast blocked the southward cold air and then provided the favorable condition for an increasing precipitation via the southwesternly wind in the Altai Mountains. [ABSTRACT FROM AUTHOR]

In the semiarid climate of northwestern Mongolia, glaciers are critical contributors to water resources, particularly during the dry summer months. Nevertheless, our knowledge of the contribution of glacier runoff in the Upper Khovd River Basin (UKRB) is limited. This study investigates the impact of glacier recession on the UKRB's hydrology in western Mongolia's Altai Mountains. The analysis included glaciological method measurements, satellite-derived glacier extent records, and a simple ice ablation model. Our modeling used a mass balance gradient of 0.50 meters water equivalent 100 m–1 for the years 2000, 2010, and 2016 and included a sensitivity analysis that applied lower and upper mass balance gradient values and ±200 m around the equilibrium line altitude (ELA). The glacier contribution to the UKRB's water resources decreased from almost 8% in 2000 to 6.7% in 2016. Hypsometries revealed that glacier areas decreased at all elevations, indicating that only small accumulation zones exist. Therefore, applying a modeled increased ELA better represents glacier contribution to total runoff, at 18.7% in 2000 and 15.4% in 2016. The decreasing glacier runoff contribution indicates that the UKRB glaciers have passed the tipping point of an increased contribution that first follows enhanced melting. The continued glacier recession and uncertain water availability represent challenges for water resource management and future human–water relations in the Mongolian Altai.

We here preset a result of high-resolution pollen data of a lacustrine-peat sediment core from Yushenkule (YSKL) Peat, southern Altai Mountains, northwestern China. We aim to reconstruct the palaeovegetation and palaeoclimate variations in the southern Altai Mountains and further evaluate the role of autogenic process of the raised bog itself in driving the local vegetation dynamics. The pollen data of YSKL core-2 show two major vegetation stages in YSKL Peat area and the surrounding areas during the data-covering period. During the stage lasting from ~4870 to ~2550 cal. yr BP, regional vegetation was dominated by desert steppe and local vegetation in YSKL Peat was characterized by Artemisia -dominated mountain steppe. During the stage lasting from ~2550 to ~700 cal. yr BP, regional vegetation was characterized by Artemisia -dominated steppe and local vegetation in YSKL Peat was characterized by Cyperaceae-dominated wetland herbs. The Ar/Am (Artemisia /Amaranthaceae) ratio-indicated moisture increasing trend of southern Altai Mountains can attribute to the combined effects of decreased temperature and increased precipitation. The lithologic transition from lake to peat of YSKL core-2 can be explained by invoking the variations in the areal extent of ice covers in the Altai Mountains. [ABSTRACT FROM AUTHOR]

Based on pollen data of 274 samples from a 550-cm core at Kelashazi Peat in the southern Altai Mountains within China, we reconstructed the Holocene vegetation dynamics and climatic change. The pollen assemblages and the associated biome scores indicate that the vegetation in Kelashazi valley was dominated by alpine meadows during the early Holocene (before ~8.2 cal. kyr BP) and by taiga forests in the middle Holocene (~8.2-~5.6 cal. kyr BP) that was followed by an expansion of alpine meadows (~5.6-~3.2 cal. kyr BP). The pollen-based temperature index-indicated thermal maximum lasting from ~8.0 to ~5.6 cal. kyr BP was consistent with temperature stack for 60–30°N and the later onset warming at Kelashazi Peat was associated with the cooling influence of remnant ice sheets in the early Holocene. The pollen-based increasing moisture index curve from Kelashazi Peat is in a good agreement with the synthesized decreasing aridity index curve in low-elevation regions of the Altai Mountains and the surrounding areas during the data-overlapping period between ~12.0 and ~3.2 cal. kyr BP. The Holocene wetting trend at Kelashazi Peat might have resulted not only from the increasing trend of NAO-related winter precipitation but also from the increasing trend of AMO-modulated summer precipitation. • Holocene vegetation and climate changes was reconstructed in the southern Altai Mountains. • Thermal maximum was consistent with temperature stack for 60–30°N. • Moisture reconstruction is consistent with synthesized Holocene aridity index in low-elevation regions. • Holocene wetting trend have resulted from the increasing trends of NAO-related winter precipitation and AMO-related summer precipitation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A moisture record over the past ~2200 years in the southern Altai Mountains. • The moisture variations in the Altai Mountains have been paced by precipitation variations. • The precipitation variations in the Altai Mountains were primarily related to the NAO variations. Abstract A ∼2200-year moisture history of the southern Altai Mountains (i.e., Chinese Altai) was established based on peat δ13C celluose data obtained at Yushenkule (YSKL) Peat. Generally speaking, the moisture record from YSKL Peat exhibits a "cool-wet" DACP (Dark Age Cold Period from ∼500 to ∼800 CE), a "warm-dry" MWP (Medieval Warm Period from ∼800 to ∼1200 CE), a "cool-wet" LIA (Little Ice Age from ∼1200 to ∼1900 CE), and a "warm-dry" CWP (Current Warm Period since ∼1900 CE). But, RWP (Roman Warm Period from prior to ∼100 CE to ∼500 CE) is an exception (i.e., "warm-wet"). If the heat-water combinations within those major temperature-change events are further examined, the "warm-dry/cool-wet" generalization collapses. The comparisons between the variations in the peat δ13C celluose -based moisture obtained from YSKL Peat and the variations of reconstructed climatic variables in the referenced sequences suggest that the moisture variations in the Altai Mountains have been basically controlled by the precipitation that was primarily modulated by the NAO variations. [ABSTRACT FROM AUTHOR]

In the semiarid climate of northwestern Mongolia, glaciers are critical contributors to water resources, particularly during the dry summer months. Nevertheless, our knowledge of the contribution of glacier runoff in the Upper Khovd River Basin (UKRB) is limited. This study investigates the impact of glacier recession on the UKRB's hydrology in western Mongolia's Altai Mountains. The analysis included glaciological method measurements, satellite-derived glacier extent records, and a simple ice ablation model. Our modeling used a mass balance gradient of 0.50 meters water equivalent 100 m–1 for the years 2000, 2010, and 2016 and included a sensitivity analysis that applied lower and upper mass balance gradient values and ±200 m around the equilibrium line altitude (ELA). The glacier contribution to the UKRB's water resources decreased from almost 8% in 2000 to 6.7% in 2016. Hypsometries revealed that glacier areas decreased at all elevations, indicating that only small accumulation zones exist. Therefore, applying a modeled increased ELA better represents glacier contribution to total runoff, at 18.7% in 2000 and 15.4% in 2016. The decreasing glacier runoff contribution indicates that the UKRB glaciers have passed the tipping point of an increased contribution that first follows enhanced melting. The continued glacier recession and uncertain water availability represent challenges for water resource management and future human–water relations in the Mongolian Altai. [ABSTRACT FROM AUTHOR]

Abstract The effective humidity, resulting from the balance between evapotranspiration and precipitation, largely controls the environmental conditions under the highly continental, semi-humid to arid climate of Mongolia. Minor variations of temperature and precipitation have resulted in considerable environmental changes over the Holocene, affecting vegetation composition and density, soil formation, geomorphological activity, desertification processes, lake level and glacier distribution. Thus, various paleoclimatic archives have been investigated in several studies over the last decades. Here, we present an overview of the existing reconstructions of climatic changes over the Late Glacial and Holocene. The aim of this work is to obtain a spatially differentiated synthesis of the currently available paleoenvironmental information, and to point to existing contradictions and knowledge gaps. Our results suggest that during the Late Glacial, dry and cold conditions dominated, whereas the early Holocene was warm, and characterized by increasing humidity. 6000 years ago, the temperature began to decrease. Enhanced aridity occurred in the rain shadow east of the Altai and Khangai Mountains, pointing to increasing influence of the westerlies. In the Valley of Great Lakes, east of the Altai Mountains, the Late Glacial was characterized by high lake levels that steadily decreased over the Holocene. In the Valley of Gobi Lakes, south of the Khangai Mountains, high lake levels persisted from the early Holocene until the beginning of the mid-Holocene. In contrast, the lake level of Telmen Nuur, north of the Khangai Mountains, remained low until the end of the mid-Holocene. Periods of enhanced eolian transport and deposition occurred from the Late Glacial until the early Holocene, and again during the late Holocene. In between, during the mid-Holocene, no soil erosion by eolian and fluvial processes took place over large areas. The present state of research shows that the limited number of investigated archives and the unbalanced spatial distribution of the studied sites hamper an integrative reconstruction with appropriate spatial and temporal resolution. Paleoclimate interpretations by different authors, which were derived from the same archives or from neighboring archives in the same region diverge in paleotemperature and -humidity. Thus, paleoclimate at a regional scale of up to 100 km, as well as the timing of climate changes at a temporal scale of several centuries is still ambiguous in Mongolia. Further challenges include the multiple possible causes of lake level changes and the difficulty to distinguish (i) between climatic and anthropogenic impacts on vegetation and landscape, and (ii) between local, regional and global signals in the proxy data. In addition, there are ambiguities with respect to the ages of various materials that are obtained by radiocarbon and luminescence dating. Highlights • The proxy data for paleoclimatic reconstructions in Mongolia derived from different archives is partly inconsistent. • Unbalanced spatial distribution of the studied siteshampers an integrative reconstruction with appropriate resolution. • There are difficulties to distinguish between climatic and anthropogenic impacts on vegetation and landscape. • Local, regional and global signals superimpose in the proxy data. • Multiple causes control lake level changes in Mongolia. [ABSTRACT FROM AUTHOR]

Understanding peat carbon dynamics in the past is of significance, given the uncertainties as to whether there will be an increase or a reduction in carbon as a result of future climate change. Studies of peat carbon dynamics have primarily been conducted in monsoon-influenced China. However, data relating to carbon dynamics in peat deposits has not yet been investigated in Westerlies-influenced Northwest China (NWC). In this study, the Holocene carbon accumulation rate (CAR) is explored at the Tuolehaite peat core, with a mean rate of growth of 2.4 yr mm ^−1 , 0.4 mm yr ^−1 , in the high-elevation Altai Mountains within NWC. Its CAR shows a decreasing trend, ranging from 4.8 to 68.8 g C m ^−2 yr ^−1 , with a mean of 28.0 g C m ^−2 yr ^−1 since the Holocene epoch. Comparisons of the CAR in the Westerlies-influenced NWC with that in the monsoon-influenced Qinghai-Tibetan Plateau, Northeast China, and South China, reveal that the Holocene CAR trend in relatively high-elevation peat deposits (e.g. Tuolehaite Peat and Hongyuan Peat) is opposite to that found in relatively low-elevation peat deposits (e.g. Hani Peat and Dahu Peat). Different driving factors (temperature and precipitation) of CAR could be responsible for these opposing trends. To be specific, temperature is the main driving factor influencing the CAR in relatively high-elevation peat deposits, whereas precipitation is the key driving factor controlling the CAR in relatively low-elevation peat deposits. Our work indicates that comprehensive investigations into peat CARs in both Westerlies-influenced and monsoon-influenced regions contribute to an understanding of the peat CAR pattern in China as a whole.

Abstract Based on pollen data from 30 sequences reviewed here, we reconstruct the spatial and temporal variations in temperature and in aridity that occurred during the Holocene in the Altai Mountains and the surrounding areas (i.e., the examined area). The synthesized regionally-averaged temperature-index curves from low-elevation regions show that the climate was consistently warming from ~12,000 to ~9000 cal. yr BP and has experienced a gradual cooling trend since ~9000 cal. yr BP. It means that the Holocene temperature trend in low-elevation regions of the examined area has sensitively responded to variations in the total solar irradiance. The synthesized regionally-averaged aridity-index curve exhibits a persistent wetting trend during the Holocene in low-elevation regions. The deduced Holocene precipitation-index variations suggest that the Holocene wetting trend resulted from a combined effect of temperature decreasing and precipitation increasing. The Holocene precipitation increase seems to be associated with the Holocene AMO-like (i.e., Atlantic centennial oscillations) events in the North Atlantic Ocean. However, the early-Holocene variations of temperature and aridity in high-elevation regions were significantly deviated from the variations in low-elevation regions and this deviation was probably a result of permafrost thawing at higher elevations. Highlights • Temperature index in low-elevation regions has sensitively responded to variations in total solar irradiance; • Aridity index exhibits a wetting trend in low-elevation regions; • Wetting trend resulted from a combined effect of temperature decreasing and precipitation increasing; • Early-Holocene temperature and aridity in high-elevation region were affected by permafrost thawing. [ABSTRACT FROM AUTHOR]

Understanding the temporal variations of extreme floods that occur in response to climate change is essential to anticipate the trends in flood magnitude and frequency in the context of global warming. However, long-term records of paleofloods in arid regions are scarce, thus preventing a thorough understanding of such events. In this study, a reconstruction of paleofloods over the past 300 years was conducted through an analysis of grain sizes from the sediments of Kanas Lake in the Altay Mountains of northwestern China. Results showed that grain parameters and frequency distributions can be used to infer possible abrupt environmental events within the lake sedimentary sequence, and two extreme flood events corresponding to ca. 1736-1765 AD and ca. 1890 AD were further identified based on canonical discriminant analysis (CDA) and coarse percentile versus median grain size (C-M) pattern analysis, both of which occurred during warmer and wetter climate conditions by referring to tree-ring records. These two flood events are also evidenced by lake sedimentary records in the Altay and Tianshan mountains. Furthermore, through a comparison with other records, the flood event from ca. 1736-1765 AD in the study region seems to have occurred in both the arid central Asia and the Alps in Europe, and thus may have been associated with changes in the North Atlantic Oscillation (NAO) index. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we report and discuss the results obtained from a survey of plants, microorganisms (bacteria and fungi), and soil elements along a chronosequence in the first 600 m of the Maliy Aktru glacier's forefront (Altai Mountains, Russia). Many glaciers of the world show effects of climate change. Nonetheless, except for some local reports, the ecological effects of deglaciation have been poorly studied and have not been quantitatively assessed in the Altai Mountains. Here, we studied the ecological changes of plants, fungi, bacteria, and soil elements that take the form of a primary ecological succession and that took place over the deglaciated soil of the Maliy Aktru glacier during the last 50 year. According to our measurements, the glacier lost about 12 m per year during the last 50 years. Plant succession shows clear signs of changes along the incremental distance from the glacier forefront. The analysis of the plant α‐ and β‐diversity confirmed an expected increase of them with increasing distance from the glacier forefront. Moreover, the analysis of β‐diversity confirmed the hypothesis of the presence of three main stages of the plant succession: (a) initial (pioneer species) from 30 to 100 m; (b) intermediate (r‐selected species) from 110 to 120–150 m; and (c) final (K‐selected species) from 150 to 550. Our study also shows that saprotrophic communities of fungi are widely distributed in the glacier retreating area with higher relative abundances of saprotroph ascomycetes at early successional stages. The evolution of a primary succession is also evident for bacteria, soil elements, and CO2 emission and respiration. The development of biological communities and the variation in geochemical parameters represent an irrefutable proof that climate change is altering soils that have been long covered by ice. [ABSTRACT FROM AUTHOR]

Abstract: A comprehensive understanding of the regional vegetation responses to long‐term climate change will help to forecast Earth system dynamics. Based on a new well‐dated pollen data set from Kanas Lake and a review on the published pollen records in and around the Altai Mountains, the regional vegetation dynamics and forcing mechanisms are discussed. In the Altai Mountains, the forest optimum occurred during 10–7 ka for the upper forest zone and the tree line decline and/or ecological shifts were caused by climatic cooling from around 7 ka. In the lower forest zone, the forest reached an optimum in the middle Holocene, and then increased openness of the forest, possibly caused by both climate cooling and human activities, took place in the late Holocene. In the lower basins or plains around the Altai Mountains, the development of protograssland or forest benefited from increasing humidity in the middle to late Holocene. [ABSTRACT FROM AUTHOR]

Human settlement within the landscapes of the Altai Mountains, especially in ancient times depended on natural factors. Change in natural conditions led to the mobility of people. This paper analyzes the identification of the relationship between landscapes and placement of cultures in the territory of the Altai Mountains in the Holocene. Additionally , the rhythms of Holocene climate change in the mountains are taken into account. To reach the aim of the study the landscape-archaeological GIS was created. The database of archaeological sites was created with the help of literature sources, archive materials and own field studies. The landscape maps were used to characterize the environmental conditions. The distribution of archaeological sites by types of landscapes proves that the reclaiming of landscapes was irregular in both space and time. There were periods of relative regression because of climatic, political and military factors. Comparison of climatic periods and stages of human exploration of the natural landscape shows that the most active development was during the periods of moist climate. [ABSTRACT FROM AUTHOR]

Dryland biodiversity plays important roles in the fight against desertification and poverty, but is highly vulnerable to the impacts of environmental change. However, little research has been conducted on dual pressure from climate and land cover changes on biodiversity in arid and semi-arid environments. Concequntly, it is crutial to understand the potential impacts of future climate and land cover changes on dryland biodiversity. Here, using the Chinese Altai Mountains as a case study area, we predicted the future spatial distributions and local assemblages of nine threatened mammal species under projected climate and land cover change scenarios for the period 2010–2050. The results show that remarkable declines in mammal species richness as well as high rates of species turnover are seen to occur across large areas in the Chinese Altai Mountains, highlighting an urgent need for developing protection strategies for areas outside of current nature reserve network. The selected mammals are predicted to lose more than 50% of their current ranges on average, which is much higher than species' range gains (around 15%) under future climate and land cover changes. Most of the species are predicted to contract their ranges while moving eastwards and to higher altitudes, raising the need for establishing cross-border migration pathways for species. Furthermore, the inclusion of land cover changes had notable effects on projected range shifts of individual species under climate changes, demonstrating that land cover changes should be incorporated into the assessment of future climate impacts to facilitate biodiversity conservation in arid and semi-arid environments. [ABSTRACT FROM AUTHOR]

To predict future spatio-temporal patterns of climate change, we should fully understand the spatio-temporal patterns of climate change during the past millennium. But, we are not yet able to delineate the patterns because the qualities of the retrieved proxy records and the spatial coverage of those records are not adequate. Northern Xinjiang of China is one of such areas where the records are not adequate. Here, we present a 500-yr land-surface moisture sequence from Heiyangpo Peat (48.34°N, 87.18°E, 1353 m a.s.l) in the southern Altai Mountains within northern Xinjiang. Specifically, peat carbon isotope value of cellulose (δC) was used to estimate the warm-season moisture variations and the degree of humification was used to constrain the δC-based hydrological interpretation. The climatic attributions of the interpreted hydrological variations were based on the warm-season temperature reconstructed from Belukha ice core and the warm-season precipitation inferred from the reconstructed Atlantic Multidecadal Oscillations (AMO). The results show that humification decreased and the δC-suggested moisture decreased from ~1510 to ~1775 AD, implying that a constant drying condition may have inhibited peat decay. Our comparison with reconstructed climatic parameters suggests that the moisture-level decline was most likely resulted from a constant decline of precipitation. The results also show that humification kept a stable level and the δC-suggested moisture also decreased from ~1775 to ~2013 AD, implying that peat decay in the acrotelm primarily did not depend on the water availability or an aerobic environment. Again, our comparison with reconstructed climatic parameters suggests that the land-surface moisturelevel decline was most likely resulted from a steady warming of growing-season temperature. [ABSTRACT FROM AUTHOR]

With changing climatic conditions and snow cover regime, regional hydrological cycle for a snowy basin will change and further available surface water resources will be redistributed. Assessing snow meltwater effect on runoff is the key to water safety, under climate warming and fast social-economic developing status. In this study, stable isotopic technology was utilized to analyze the snow meltwater effect on regional hydrological processes, and to declare the response of snow hydrology to climate change and snow cover regime, together with longterm meteorological and hydrological observations, in the headwater of Irtysh River, Chinese Altai Mountains during 1961-2015. The average δ18O values of rainfall, snowfall, meltwater, groundwater and river water for 2014-2015 hydrological year were -10.9‰, -22.3‰, -21.7‰, -15.7‰ and -16.0‰, respectively. The results from stable isotopes, snow melting observation and remote sensing indicated that the meltwater effect on hydrological processes in Kayiertesi River Basin mainly occurred during snowmelt supplying period from April to June. The contribution of meltwater to runoff reached 58.1% during this period, but rainfall, meltwater and groundwater supplied 49.1%, 36.9% and 14.0% of water resource to annual runoff, respectively. With rising air temperature and increasing snowfall in cold season, the snow water equivalent (SWE) had an increasing trend but the snow cover duration declined by about one month including 13-day delay of the first day and 17-day advancement of the end day during 1961-2016. Increase in SWE provided more available water resource. However, variations in snow cover timing had resulted in redistribution of surface water resource, represented by an increase of discharge percentage in April and May, and a decline in June and July. This trend of snow hydrology will render a deficit of water resource in June and July when the water resource demand is high for agricultural irrigation and industrial manufacture. [ABSTRACT FROM AUTHOR]

The Altai Mountains contain 1281 glaciers covering an area of 1191 km 2 . These glaciers have undergone significant changes in glacial length and area over the past decade. However, mass changes of these glaciers and their impacts remain poorly understood. Here we present surface mass balances of all glaciers in the region for the period 1990–2011, using a glacier mass-balance model forced by the outputs of a regional climate model. Our results indicate that the mean specific mass balance for the whole region is about −0.69 m w.e. yr −1 over the entire period, and about 81.3% of these glaciers experience negative net mass balance. We detect an accelerated wastage of these glaciers in recent years, and marked differences in mass change and its sensitivity to climate change for different regions and size classes. In particular, higher mass loss and temperature sensitivity are observed for glaciers smaller than 0.5 km 2 . In addition to temperature rise, a decrease in precipitation in the western part of the region and an increase in precipitation in the eastern part likely contribute to significant sub-region differences in mass loss. With significant glacier wastage, the contribution of all glaciers to regional water resources and sea-level change becomes larger than before, but may not be a potential threat to human populations through impacts on water availability. [ABSTRACT FROM AUTHOR]

Compilation of spore-pollen, diatom and biochemical analyses of samples from the top 80-cm sediments of Manzherok Lake, located on the western foothills of the Altai Mountains (51°49′15.5″N, 85°48′35.7″E, 400 m a.s.l.), revealed influence of regional climate changes during the past 1350 years on the hydrological budget of the lake and the dynamics of the surrounding vegetation. Based on indicator species of diatom complexes in the lake sediments, the reconstructed lake level and pH can be deciphered as (1) shallow pond with relatively high pH prior to the Medieval Warm Period (MWP), (2) dramatic flooding with freshwater in the MWP, (3) lowering of the lake level during the Little Ice Age (LIA), and (4) contemporary rise of the lake level after the LIA. Increased concentrations of the detrital elements and severe degradation of diatom assemblages in the lake sediments took place during the dramatic flooding stage. The reconstructed lake level based on the diatom assemblages is in good agreement with the palynological data which indicate changes from birch forest-steppe to pine and cedar forests in the beginning of MWP, and then to birch-pine anthropogenically transformed forest-steppe in the LIA. Sharp maxima of non pollen palynomorphs Anabaena and Bryales/Algae at the 43–46 cm depth (∼900 a BP) possibly mark ecological crises in lake's biotope. Cold and dry conditions during the LIA were clearly expressed in pollen diagram of Manzherok Lake by decline of maxima of Siberian pine pollen and increase of Artemisia pollen. This study provides evidence to support a dry episode in the 9th century, wet climatic conditions in the MWP and a dry LIA in the Russian Altai Mountains in contrast to the opposite pattern revealed for arid regions of Central Asia and NW China during the same periods (Chen et al., 2010; Eichler et al., 2011; Chen et al., 2015). Our study indicates that, as a small and shallow lake located in the forest-steppe western foothills of the Altai Mountains, Manzherok Lake is more sensitive to high-resolution (less than centennial scale) climatic and environmental variations, in comparison with the large and deep Teletskoye Lake located in the mountain taiga zone of the northern Altai. [ABSTRACT FROM AUTHOR]

The location of the Altai Mountains at the limits of both the Pacific and Atlantic influences implies that this mountain range is an important climatic boundary. Based on pollen data of 188 samples of a 390-cm core from Narenxia Peat in the southern Altai with a chronologic support of 11 accelerator mass spectrometry (AMS) dates, we reconstructed the Holocene climatic change at Narenxia Peat. The reconstruction revealed five stages of climatic change: a cold and dry latest deglacial (prior to ~11,500 cal. yr BP), a warm and wet early-Holocene (~11,500 to ~7000 cal. yr BP), a considerably cooled and dried middle Holocene (~7000 to ~4000 cal. yr BP), a resumed warm and wet late-Holocene (~4000 to ~1200 cal. yr BP), and a relatively cool and dry latest Holocene (past ~1200 years). The reconstructions of mean annual temperature (MAT) and mean annual precipitation (MAP) from Narenxia Peat well resemble the reconstructions of North Atlantic Oscillations (NAO) and El Niño–Southern Oscillations (ENSO). The resemblance implies that the Holocene millennial-scale changes in MAT and MAP in the Altai might have been causally associated with the variations in NAO and ENSO. [ABSTRACT FROM AUTHOR]

A continuous peat sequence collected in the Altai Mountains, Xinjiang Province, northwestern China, provides a new opportunity to reconstruct the Holocene climate history in the arid central mountain region of Asia. Based on AMS 14 C dating, high resolution records of the humification degree and n -alkane distributions reveal that the region experienced a relatively warm and dry early Holocene (10.0–8.0 ka) and a cold and wet early mid-Holocene (8.0–6.3 ka), followed by a warm and dry mid-Holocene (6.3–5.5 ka). A shift to cold and wet conditions occurred between 5.5 and 4.0 ka, and then the climate entered into a warmer period from 4.0 to 2.5 ka. In the late Holocene (2.5–1.0 ka), the region experienced a colder and wetter climate. A gradual shift to warm and dry conditions occurred during the last 1.0 ky in this region. The regional climate patterns have been generally dominated by alternations of warm-dry and cold-wet episodes during the Holocene that were quite different from the warm-wet and cool-dry episodes in the Asian summer monsoon region. Regional comparisons indicate that the climate changes in arid central Asia have been mainly influenced by the North Atlantic Ocean sea surface temperatures (SSTs) via the westerlies. However, owing to the mountainous character of the study areas, glacial meltwater, and other local factors, the climate changes in the Altai Mountains region have not always been concordant with variations of North Atlantic Ocean SSTs. We postulate that the history of moisture balance between regional precipitation, glacier and snow meltwater, and evaporation has been modulated by air temperatures that were mainly influenced by changes in the summer insolation of the Northern Hemisphere. [ABSTRACT FROM AUTHOR]

We project glacier surface mass balances of the Altai Mountains over the period 2006-2100 for the representative concentration pathway (RCP) 4.5 and RCP8.5 scenarios using daily near-surface air temperature and precipitation from 12 global climate models in combination with a surface mass balance model. The results indicate that the Altai glaciers will undergo sustained mass loss throughout the 21st for both RCPs and reveal the future fate of glaciers of different sizes. By 2100, glacier area in the region will shrink by 26 ± 10 % for RCP4.5, while it will shrink by 60 ± 15 % for RCP8.5. According to our simulations, most disappearing glaciers are located in the western part of the Altai Mountains. For RCP4.5, all glaciers disappearing in the twenty-first century have a present-day size smaller than 5.0 km, while for RCP8.5, an additional ~7 % of glaciers in the initial size class of 5.0-10.0 km also vanish. We project different trends in the total meltwater discharge of the region for the two RCPs, which does not peak before 2100, with important consequences for regional water availability, particular for the semi-arid and arid regions. This further highlights the potential implications of change in the Altai glaciers on regional hydrology and environment. [ABSTRACT FROM AUTHOR]

The spatial and temporal dynamics of fir stands damage caused by a large-scale outbreak of the Siberian silk moth ( Dendrolimus sibiricus Tschetv.) in the Altai Mountains has been studied using remote sensing and GIS methods. It is ascertained that forest damages are dissimilar relative to the surface features. The pest outbreak initially occurred on the southwest slopes with mean values of 10° and elevation of 400 m asl. The damages further extended both upward and downward, involving slopes of high steepness and the eastern exposure. The total area of the dead stands comprised 6000 ha, 45% of which were lost due to secondary pest (xylophagous insects) attacks. It is indicated that the use of remote sensing made it possible to determine the beginning of a pest outbreak with one-decade precision. The Siberian silk moth large-scale outbreak occurred against an increase in air temperatures, a decrease in precipitation, and a reduction in late frosts. The tree plants weakened by the Siberian silk moth and water stress were affected by xylophagous insect attacks. The observed and predicted warming and climate aridity increase will facilitate Siberian silk moth outbreaks both within its range and northward of the current margins of the range. [ABSTRACT FROM AUTHOR]

• The principal growth limiting factor shifts from temperature to soil moisture from RU to FY. • Cambial dynamic was bimodal pattern in AL, right-skewed unimodal in FY and unimodal in RU. • The length of growing seasons had a significant positive trends in two sites from Northwest China – Chinese Altai Mountains for the last six decades. • The intra-seasonal growth rate regulated tree growth rather than length of growing season. It is important to study the relationships between tree growth and phenology and climate factors in Central Asia for the sustainable development of forest ecology and the exploration of carbon sink potential in the region in a context of global change. Herein, the process-based Vaganov-Shashkin model was used to simulate tree-ring growth rates, to assess a cambial phenology (start and end of growing season) of larch trees (Larix sibirica) based on three sites located on three different latitudes in the Altai-Sayan Mountains in Central Asia over 1960–2018. It was shown that the principal factor limiting growth rates was temperature in RU (located in southern central Siberia), cambial dynamic was unimodal. In RU site, although the length of growing season did not change significantly over the past 59 years, it was correlated with tree radial growth. Moisture was the principal factor limiting the growth rates of AL and FY (located in Chinese Altai Mountains), and cambium dynamics were bimodal and unimodal, respectively. Temperature and precipitation before the start of the growing season lengthen the growing season, but this did not promote the tree radial growth. In conclusion, we determined that the climate-influenced intra-seasonal growth rate regulated tree growth rather than length of growing season in this area. In this study, the VS-simulation showed high potential develop a long-term reconstruction of cambial phenology in the Altai Mountains, which was conducive to a more comprehensive understanding of the exogenous-endogenous factors effects on tree-ring growth. [ABSTRACT FROM AUTHOR]

Recent botanical and zoological studies have suggested that the Altai Mountains in southern Siberia are an important refugium of the last glacial biota that used to be widespread across northern Eurasia before the Pleistocene–Holocene transition. To obtain insights into the history of this relict biota, we modelled the spatial distribution of habitats during the Last Glacial Maximum (LGM) in the Russian Altai. We prepared a map of the current vegetation of this area based on the ground-truthed remote sensing data, and modelled the distribution of the current vegetation types using the Random Forest technique with climatic predictors. The models were projected onto the CCSM3 model of the LGM climate for the Russian Altai and interpreted for 72% of its area because the remaining part is supposed to have been glaciated during the LGM. The models projected LGM predominance of desert-steppe across most of the non-glaciated area of the Russian Altai, probably associated with areas of typical steppe, tundra grasslands and some other habitat types, including forest patches in stream valleys. It is likely that during the LGM, these habitats supported the cold-adapted open-landscape biota. In the Holocene, most of the previous grassland area changed into forest or forest-steppe and the Pleistocene biota retreated, with the exception of the Chuya Basin and the Ukok Plateau in the southeast, where the habitat change was very small and desert-steppe and associated vegetation types remained preserved. This refugial area is currently rich in the relict Pleistocene species. A different history was suggested for the precipitation-rich area in the northernmost Altai (north of Lake Teletskoye), where the LGM models suggested occurrence of patches of open forest of Larix sibirica and Pinus sibirica in forest-tundra and forest-steppe landscapes. These forests may have provided the LGM refugium for the temperate forest species that currently occur in this precipitation-rich area. [ABSTRACT FROM AUTHOR]

Mountain glaciers are indicators of climate change and of current water resources. They are important ecological systems and can be used to support sustainable development of industry and agriculture. However, due to climate warming, most glaciers are in a state of rapid retreat. Using topographic maps in 1959, ASTER remote sensing data in 2008 and ASTER digital elevation models (DEMs), area, ice surface elevation, and volume changes of glaciers on the Friendship Peak in the Chinese Altai Mountains were analyzed. Results showed that the collective area of all 201 glaciers investigated was reduced by 30.4% from 1959 to 2008. Fifty-five glaciers disappeared entirely. The average rates of reduction in area of glaciers with sizes < 0.5, 0.5–1, 1–4, 4–10, and > 10 km 2 were 25.9%, 30.8%, 30.9%, 35.9%, and 27.4%, respectively. From 1959 to 2008, the elevation of the glacier surface decreased by 20 m at an average rate of 0.4 m a − 1 . For the Kanas Glacier, the changes in ice surface elevation ranged from − 101 to + 38 m. Results showed that glaciers at lower altitudes and smaller sizes experienced more extensive changes in elevation. The intensive glacier ablation over the Friendship Peak in the Altai Mountains was found to be caused by increases in the regional temperature, which occurred at an average rate of 0.52 °C per decade. [ABSTRACT FROM AUTHOR]

June–July mean temperature was reconstructed back to 1698 for the southern Altai Mountains in eastern Central Asia using four temperature series based on tree-ring widths. The reconstruction explains 48% of the variation in the observed temperature from 1962 to 2003. Warm periods occurred during 1714–1732, 1753–1776, 1800–1840, 1866–1886, 1893–1911, and 1943–1969, while the periods of 1708–1713, 1733–1752, 1777–1799, 1841–1865, 1887–1892, 1912–1942, and 1970–1993 were relatively cold. Power spectral and wavelet analyses demonstrated the existence of significant 50-, 14-, 2.8-, and 2.5-year cycles of variability. The results of a spatial correlation analysis suggested that this temperature reconstruction contains climatic signals for a large area of Central Asia. After employing a 21-year low-pass filter, the coherence of the newly reconstructed series with a regional temperature reconstruction for Central Asia and also with a local temperature reconstruction for the Zajsan Lake area of East Kazakhstan indicates that our temperature reconstruction captures broad-scale regional climatic variations in the low-frequency domain. [ABSTRACT FROM AUTHOR]

The evolution and current state of landscapes around Lake Teletskoye have not previously been studied in detail. In the valley of the Malye Chily River, which flows into Lake Teletskoye, the timing of dam failure and draining of two morainedammed lakes has been identified. Botanical analysis, ash content determination, and radiocarbon dating of two peat profiles provide insight into postglacial evolution of wetlands related to this landscape. We found clear evidence of the disappearance from the peat of higher vascular species that, today, grows mostly in the plains of Siberia. Correlation of the data obtained with the accepted chronology of the Holocene events in the Russian Altai suggests the following stages of postglacial environmental change in the Malye Chily River valley: (1) the continuation of the Late Wiirm glaciation degradation (before 7000 cal. yr BP); (2) Holocene Climate Optimum (7000-5000 cal. yr BP); (3) Akkem cooling (5000-4200 cal. yr BP); (4) warm period (4200-3700 cal. yr BP); and (5) Historical cooling (3700-1600 cal. yr BP). [ABSTRACT FROM AUTHOR]

Highlights: [•] Climate change exerts great effects on the dynamics of the forests in semi-arid Altai Mountains. [•] There is a strong coupling between tree growth, forest recruitment and climate variations in semi-arid Altai Mountains. [•] Tree growth and forest recruitment show divergent responses to climate variations in these semi-arid mountain forests. [Copyright &y& Elsevier]

• Introduction: Siberian larch ( Larix sibirica) is a highly climate sensitive species. Presently, the Altay Mountains is covered by widespread forests dominated by Siberian larch and thus has a great potential for dendroclimatological studies. However, tree-ring network of the Altay Mountains has not yet been well developed. The development of the new chronologies and the knowledge about the influence of climatic variables on tree growth is needed. • Method: X-ray densitometric techniques were applied to obtain ring width (RW) and maximum latewood density (MXD) of Siberian larch from two upper tree line sites in the Altay Mountains, China. Climatic responses in ring widths and maximum latewood densities from the Altay Mountains (China, Russia, and Mongolia) were investigated by simple correlation analyses. To assess the common growth forces among the individual sites of the Altay Mountains, simple correlation, principal component analyses, and spatial correlation analysis were applied over the common period of the chronologies. • Results: Ring width and maximum latewood density increases with decreasing precipitation, increasing temperature from late spring to late summer during the growing season. Based on the results of principal component analyses and spatial correlation analysis, summer temperature (June-July) is the most important forces on the Siberian larch growth of the Altay Mountains. The growth of Siberian larch in the Altay Mountains captures the current warming trend. The growth of Siberian larch did not clearly lose its sensitivity under most recent warming in our study areas. • Conclusions: The new MXD chronologies is presently the longest, absolutely dated, tree-ring density record yet developed from China. The climate response analysis shows that the RW and MXD of Siberian larch have strong responses to temperature in the growing season. Thus, MXD and RW of Siberian larch provides the best information for climate reconstruction in the warm season. Tree-rings of Siberian larch allow detecting the recently observed warming trend and putting it into the long-term climatic context in the Altay Mountains, due to the strong growth sensitivity to temperature change. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge about the dynamics of modern glaciers is relevant for evaluating climatic change. However, there is very little and conflicting information about the extent of modern glaciers in northwestern Mongolia. Thus, the aim of this paper is to present detailed data about the extent of modern glaciers in the Turgen–Kharkhiraa Mountains in the northwestern part of the Mongolian Altai and to distinguish three main phases of ice extent: in 1991, in 1948, and back to the Holocene glacial epoch including the so-called Little Ice Age (LIA) — a worldwide cooling period beginning in the 16th century and lasting until the end of the 19th century (). Based on field work, topographic maps and aerial photographs of this region, the investigations have shown glacier retreat in 1991, since 1948, as compared to Holocene glaciations including the so-called Little Ice Age period. Using the toe-to-summit altitude (TSAM) method, the overall modern snowline can be calculated at about 3537–3559masl; the area of present glaciers can be calculated to be 33.8km2 for the Turgen Mountains and 39.5km2 for the Kharkhiraa Mountains. This is more than 25% of the glaciated area of Mongolia. The LIA snowline was about ∼80m lower (3461–3480masl), whereby the glaciated areas during the LIA was 76.8km2 and 80.8km2 in the two mountain systems, respectively. In conclusion, there has been a remarkable glacier retreat from this Holocene and Little Ice Age compared to the glaciation in 1948 and 1991. This glacier retreat coincides with an increase in the snowlines. [Copyright &y& Elsevier]

Results of research into climate and glacier dynamics in the Altai Mountains (Russia) over the period of instrumental observations (1952-2008) are presented in this article. About 1030 glaciers with a total area of 805 km and volume of 42.5 km have been recorded in the Altai Region. The average summer air temperature in different regions of the Altai has increased during the study period from about 0.2°C (Aktru) to 1.1°C (Akkem). The annual atmospheric precipitation rate has also increased, by 8-10%. Since 1952, the glacier area in different regions of the Altai has decreased by 9-27%, and volume by 12-24%. By 2008, as a result of degradation, the total number of glaciers was 953 with an area of 724 km and volume of 38 km. [ABSTRACT FROM AUTHOR]

Abstract: The territory of East Kazakhstan (the Southern Altai Mountains, the Bukhtarma and Zaisan/Black Irtysh Basins), still insufficiently investigated because of its proximity to the Kazakh–Russian–Chinese border zone, shows a complex Quaternary history and the associated environmental transformations reflected by intensive geomorphic processes related to the past global climate evolution in conjunction with the regional neotectonic activity. The marked climatic changes are indicated by the preserved palaeolandscape forms in both the mountain and steppe regions, as well as by the glacial and sedimentary geology, palaeoecology and geoarchaeology proxy records indicating long-term variations in temperature as well as humidity. Following the generally warmer Early Pleistocene climates, witnessed by the distribution of deeply weathered red palaeosols, the increased continentality and relief gradient during the Middle and particularly the Late Pleistocene led to establishment of the present-type forest-steppe/semi-desert during warm stages, and the periglacial arid steppe during cold stages correlated with the glaciations in the southern Altai Mountains, and loess deposition in the foothills. The mapped glacigenic and high-resolution loess-palaeosol sections, and contextual environmental archaeology data from the Pleistocene occupation sites provide new evidence of a rather pronounced natural dynamics. Spectacular glaciofluvial terraces in the principal mountain valleys indicate the presence of deep ice-dammed last glacial lakes documented from other parts of the Altai that were subjected to cataclysmic drainages during deglaciations. The recently discovered localities in the Bukhtarma River valley in diverse settings bear witness of a much earlier (Middle–Upper Palaeolithic) inhabitation of this geographically marginal area and adaptation to local mountain and steppe environments predating the Holocene prehistoric cultures. This paper summarizes some results of the initial multidisciplinary Quaternary field studies in the southern Altai region of East Kazakhstan and the adjacent part of Gorno Altai (2003-2007). [Copyright &y& Elsevier]

The frozen tombs of the Scythian civilization, preserved for over 2000 years in the permafrost of the Russian, Mongolian, Chinese and Kazakh Altai Mountains, are a major archaeological find dating back to the 1920s. Inside the tombs lie bodies which have often been so well preserved in the frozen ground that even the tattoos on their skin remain intact. Grave robbers and fortune hunters have been the tombs' traditional enemies but, today, a new threat hangs over them. Climatic change is causing the permafrost in this part of Siberia to thaw. With the permafrost that preserves the kurgans now gradually thawing, the remaining frozen tombs and the insights they provide into the ancient nomad Scythian culture could be lost for ever, after 2000 years of perfect conservation. The University of Ghent (Belgium) and the UNESCO World Heritage Centre, together with local institutions in Russia and Kazakhstan, have started a project to preserve the remaining frozen tombs. Besides making an inventory of the archaeological heritage in several research areas in Russia and Kazakhstan, they are looking for ways to detect the tombs that are frozen, and are searching for technical solutions to preserve the frozen tombs in situ. [ABSTRACT FROM AUTHOR]