In the current study, cryoconite samples were collected from six glaciers on the Tibetan Plateau to analyze n-alkanes and n-alkenes. The findings revealed that the concentrations of n-alkanes and n-alkenes varied from 40.1 to 496.1 μg g−1 and from 4.6 to 13.8 μg g−1, respectively. The carbon preference index of the long-chain n-alkanes ranged from 3.3 to 8.4, and the average chain length ranged from 28.7 to 29.3. Moreover, the δ13C of the n-alkanes in cryoconites were within the range of C3 plants, demonstrating that the n-alkanes in cryoconites were only derived from vascular plants. However, the δDmean were more negative than that of C3 plants, which could be caused by dry and humid conditions of glaciers. Unlike n-alkanes, n-alkenes ranged from C17:1 to C30:1 and showed a weak even-over-odd carbon number preference in the Dongkemadi, Yuzhufeng, Laohugou and Tianshan glacier, but a weak odd carbon preference in the Qiyi glacier. The n-alkenes in the YL Snow Mountains showed an obvious odd-over-even carbon number predominance from C17:1 to C22:1 with Cmax at C19:1, and the even-over-odd carbon number preference from C23:1 to C30:1 with Cmax at C28:1. This demonstrated that the n-alkenes of cryoconites may be mainly derived from in situ production in glaciers.

The chemical composition of meltwater-draining Himalayan glacierized basins reflects the dominance of carbonic acid in weathering of silicate and carbonate minerals, yet the role of sulfuric acid-mediated reactions in the mineral weathering and ionic release is still unclear. Here, we present a long-term study (1992–2018) of chemical weathering characteristics of a precipitation-dominated glacierized basin (Dokriani glacier) of central Himalaya. By using new and reprocessed datasets of major ions from the glacial/subglacial zones of the glacier, we suggest that two-thirds of the dissolved load of the meltwater derives from sulfuric acid-mediated weathering of minerals and rocks. We observed a clear control of carbonic acid-mediated reactions in the early ablation periods, while sulfuric acid-mediated reactions dominate in peak and late ablation periods. The slopes and intercepts in best-fit regressions of [*Ca2+ + *Mg2+ vs *SO42− and HCO3−] and [HCO3− vs *SO42−] in meltwater were following the stoichiometric parameters of sulfide oxidation coupled to carbonate dissolution reactions. The glaciers of the central and western Himalaya are in good agreement with the present estimates. We contend that the bedrock lithology has limited or second-order effects over the ionic release from Himalayan glaciers and surmise that these patterns are broadly applicable to the other orogenic systems of the world.

Ice records provide a qualitative rather than a quantitative indication of the trend of climate change. Using the bulk aerodynamic method and degree day model, this study quantified ice mass loss attributable to sublimation/evaporation (S/E) and meltwater on the basis of integrated observations (1960–2006) of glacier-related and atmospheric variables in the northeastern Tibetan Plateau. During 1961–2005, the average annual mass loss in the ice core was 95.33 ± 20.56 mm w.e. (minimum: 78.97 mm w.e. in 1967, maximum: 146.67 mm w.e. in 2001), while the average ratio of the revised annual ice accumulation was 21.2 ± 7.7% (minimum: 11.0% in 1992, maximum 44.8% in 2000). A quantitative formula expressing the relationship between S/E and air temperature at the monthly scale was established, which could be extended to estimation of S/E changes of other glaciers in other regions. The elevation effect on alpine precipitation determined using revised ice accumulation and instrumental data was found remarkable. This work established a method for quantitative assessment of the temporal variation in ice core mass loss, and advanced the reconstruction of long-term precipitation at high elevations. Importantly, the formula established for reconstruction of S/E from temperature time series data could be used in other regions.

In recent years, researchers have focused on the applications of uncrewed aerial vehicles (UAVs) in environmental remote sensing tasks. However, studies on glacier monitoring using UAV technology are relatively scarce, especially for high mountain glacier monitoring. To explore the feasibility of UAV technology for high mountain glaciers, four UAV surveys were deployed on two glaciers of the central Tibetan Plateau. Based on the images retrieved by UAV in 2017 and 2019, orthomosaics and digital elevation models were produced to quantify the length, area and elevation changes in the ablation zone of these two glaciers at different times. Additionally, we utilized several Landsat scenes to derive glacier changes over the last 30 years and combined these with the UAV data to assess the advantages and disadvantages of UAV technology in mountain glacier monitoring.

In glaciology, snow–firn temperature at 10 m is considered a representation of the mean annual air temperature at the surface (MAAT) of the studied site. Although MAAT is an important parameter in ice-sheet investigations, it has not been widely measured in Antarctica. To measure the 10 m snow–firn temperature in Antarctica, a shallow hot-point drill system is designed. In this simple and lightweight system, a hot-point drill can melt boreholes with a diameter of 34 mm in the snow–firn to a depth of 30 m and a temperature sensors string can measure the borehole temperature precisely. In the 2018/19 field season, 16 boreholes along the Zhongshan–Dome A traverse were drilled, and the borehole temperature was measured. Although certain problems existed pertaining to the hot-point drill, a total depth of ~244 m was successfully drilled at an average penetration rate of ~10 m h−1. After borehole drilling, ~12–15 h were generally required for the borehole to achieve thermal equilibrium with the surroundings. Preliminary results demonstrated that the 10 m snow–firn temperature along the traverse route was affected by the increasing altitude and latitude, and it decreased gradually with an increase in the distance from Zhongshan station.

Glacier mass loss in Alaska has implications for global sea level rise, fresh water input into the Gulf of Alaska and terrestrial fresh water resources. We map all glaciers (>4000 km2) on the Kenai Peninsula, south central Alaska, for the years 1986, 1995, 2005 and 2016, using satellite images. Changes in surface elevation and volume are determined by differencing a digital elevation model (DEM) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer stereo images in 2005 from the Interferometric Synthetic Aperture Radar DEM of 2014. The glacier area shrunk by 543 ± 123 km2 (12 ± 3%) between 1986 and 2016. The region-wide mass-balance rate between 2005 and 2014 was −0.94 ± 0.12 m w.e. a−1 (−3.84 ± 0.50 Gt a−1), which is almost twice as negative than found for earlier periods in previous studies indicating an acceleration in glacier mass loss in this region. Area-averaged mass changes were most negative for lake-terminating glaciers (−1.37 ± 0.13 m w.e. a−1), followed by land-terminating glaciers (−1.02 ± 0.13 m w.e. a−1) and tidewater glaciers (−0.45 ± 0.14 m w.e. a−1). Unambiguous attribution of the observed acceleration in mass loss over the last decades is hampered by the scarcity of observational data, especially at high elevation, and by large interannual variability.

Sources and implications of black carbon (BC) and mineral dust (MD) on two glaciers on the central Tibetan Plateau were estimated based on in situ measurements and modeling. The results indicated that BC and MD accounted for ~11 ± 1% and 4 ± 0% of the albedo reduction relative to clean snow, while the radiative forcing varied between 11 and 196 and 1–89 W m−2, respectively. Assessment of BC and MD contributions to the glacier melt can reach up 88 to 434 and 35 to 187 mm w.e., respectively, contributing ~9–23 and 4–10% of the total glacier melt. A footprint analysis indicated that BC and MD deposited on the glaciers originated mainly from the Middle East, Central Asia, North China and South Asia during the study period. Moreover, a potentially large fraction of BC may have originated from local and regional fossil fuel combustion. This study suggests that BC and MD will enhance glacier melt and provides a scientific basis for regional mitigation efforts.

Light-absorbing impurities (LAIs, e.g. black carbon (BC), organic carbon (OC), mineral dust (MD)) deposited on snow cover reduce albedo and accelerate its melting. Northern Xinjiang (NX) is an arid and semi-arid inland region, where snowmelt leads to frequent floods that have been a serious threat to local ecological security. There is still a lack of quantitative assessments of the effects of LAIs on snowmelt in the region. This study investigates spatial variations of LAIs in snow and its effect on snow albedo, radiative forcing (RF) and snowmelt across NX. Results showed that concentrations of BC, OC (only water-insoluble OC), MD ranged from 32 to 8841 ng g−1, 77 to 8568 ng g−1 and 0.46 to 236 µg g−1, respectively. Weather Research and Forecasting Chemistry model suggested that residential emission was the largest source of BC. Snow, Ice, and Aerosol Radiative modelling showed that the average contribution of BC and MD to snow albedo reduction was 17 and 3%, respectively. RF caused by BC significantly exceeded RF caused by MD. In different scenarios, changes in snow cover duration (SCD) caused by BC and MD decreased by 1.36 ± 0.61 to 6.12 ± 3.38 d. Compared with MD, BC was the main dominant factor in reducing snow albedo and SCD across NX.

Cryoconite is a dark-coloured granular sediment that contains biological and mineralogical components, and it plays a pivotal role in geochemistry, carbon cycling and glacier mass balance. In this work, we collected cryoconite samples from Laohugou Glacier No. 12 (LHG) on the north-eastern Tibetan Plateau during the summer of 2015 and measured the spectral albedo. To explore the impacts of this sediment on surface ablation, the ice melting differences between the cryoconite-free (removed) ice and the intact layers were compared. The results showed that the mean concentrations of black carbon (BC), organic carbon (OC) and total iron (Fe) in the LHG cryoconite were 1.28, 11.18 and 39.94 mg g−1, respectively. BC was found to play a stronger role in solar light adsorption than OC and free Fe. In addition, ice covered by cryoconite exhibited the lowest mean reflectance (i.e., <0.1). Compared with the cryoconite-free ice surface, cryoconite effectively absorbed solar energy and enhanced glacial melting at a rate of 2.27–3.28 cm d−1, and free Fe, BC and OC were estimated to contribute 1.01, 0.99 and 0.76 cm d−1, respectively. This study provides important insights for understanding the role of cryoconite in the glacier mass balance of the northern Tibetan Plateau.

Dissolved organic matter (DOM) in mountain glaciers is an important source of carbon for downstream aquatic systems, and its impact is expected to increase due to the increased melting rate of glaciers. We present a comprehensive study of Laohugou glacier no. 12 (LHG) at the northern edge of the Tibetan Plateau to characterize the DOM composition and sources by analyzing surface fresh snow, granular ice samples, and snow pit samples which covered a whole year cycle of 2014/15. Excitation–emission matrix fluorescence spectroscopy analysis of the DOM with parallel factor analysis (EEM-PARAFAC) identified four components, including a microbially humic-like component (C1), two protein-like components (C2 and C3) and a terrestrial humic-like component (C4). The use of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) showed that DOM from all these samples was dominated by CHO and CHON molecular formulas, mainly corresponding to lipids and aliphatic/proteins compounds, reflecting the presence of significant amounts of microbially derived and/or deposited biogenic DOM. The molecular compositions of DOM showed more CHON compounds in granular ice than in fresh snow, likely suggesting newly formed DOM from microbes during snowmelting.

We analyzed a 2-year time series of meteorological data (January 2011–December 2012) from three automatic weather stations on Laohugou glacier No. 12, western Qilian Mountains, China. Air temperature, humidity and incoming radiation were significantly correlated between the three sites, while wind speed and direction were not. In this work, we focus on the effects of clouds on other meteorological parameters and on glacier melt. On an average, ~18% of top-of-atmosphere shortwave radiation was attenuated by the clear-sky atmosphere, and clouds attenuated a further 12%. Most of the time the monthly average increases in net longwave radiation caused by clouds were larger than decreases in net shortwave radiation but there was a tendency to lose energy during the daytime when melting was most intense. Air temperature and wind speed related to turbulent heat flux were found to suppress glacier melt during cloudy periods, while increased water vapor pressure during cloudy days could enhance glacier melt by reducing energy loss by latent heat. From these results, we have increased the physical understanding of the significance of cloud effects on continental glaciers.

A 40.9 m ice core was recovered from Far East Rongbuk Glacier (FER), Qomolangma (Mount Everest), Himalaya, and an 80.4 m core from neighboring East Rongbuk Glacier (ER). Both are dated by seasonal variations of δ18O and major-ionic profiles, together with references of β-activity peaks. In this paper we compare the chemical records of these two cores to show post-depositional modification processes. The smoothed β18O profiles of the two cores show a similar trend. However, the mean β18O value of the FER core for the period 1954—96 is 3.12%o less than that of the corresponding part of the ER core, and the major-ionic profiles of the two cores differ considerably. We suggest that melting-away of the snow layer deposited during the pre-monsoon season may account for lower β18O values of the FER than of the ER core, and higher terrestrial ion concentrations in the FER core for the period 1957-63 may contribute to changes by chemical reactions in the presence of snowmelting. The significantly decreased NH4 and, to a lesser degree, SO42 concentrations in the FER core could be caused by the ion elution process that moved most chemicals away with runoff.

This work quantifies glacier variations in the Naimona’nyi area of the western Himalaya by integrating glacier spatial data from ASTER and the Landsat series of satellite imagery at four different times: 1976, 1990, 1999 and 2003. Comparison of the results from individual images with those from the integrated method indicates that the integrated approach provides a better result. Glacier variations were mapped and analyzed; discrepancies between images could be detected and removed from the integrated data using remap tables in Arc/Info grid both graphically and numerically. Our results show that glaciers in the region both retreated and advanced during the last 28 years; however, retreat dominates. The variation of glaciers in the western Himalayan region is dramatic compared with other regions in high Asia. From 1976 to 2003, glacier area decreased from 84.41 km2 to 77.29 km2. Sequential images show that glacier areas shrank by 0.17, 0.19 and 0.77 km2 a−1, on average, during the periods 1976–90, 1990–99 and 1999–2003, respectively, suggesting that glacier retreat has accelerated.

For a better understanding of snow metamorphosing processes and more precise snow-ice-core interpretations, it is necessary to know the extent of microscale spatial variability of isotopic and chemical distributions in a snowpack. This work presents an investigation on the horizontal heterogeneity of the isotopic and chemical distributions in a firn pack on East Rongbuk Glacier at Qomolangma (Mount Everest), central Himalaya. One pit wall of 1.2 ×1.2m2 at 6520ma.s.l. was sampled at intervals of 10 cm in a matrix pattern with a total of 144 samples collected. All the samples were analyzed for δ18O and ionic concentrations. Small horizontal isotopic and large chemical heterogeneities were found. The averaged coefficient of variation (CV) of the twelve 10 cm thick layers for δ18O is 0.052, and in the whole snow thickness of 120 cm it is 0.016, which is in the range of analytic precision and thus indicates complete homogeneity. However, the ionic distribution shows considerable heterogeneity. The averaged CV values of the 10 cm thick layers for ionic concentrations vary in the range 0.628–1.477 depending on the ions. Based on these CV values, the heterogeneity sequence is: Mg2+> Ca2+> K+> Na+> Cl–> SO42–> PO43–> NO3–> NH4+. The averaged CV values for all the ions, except for NH4+, decrease with increasing snow thickness, although the decreasing rates and extents are different. However, the CV values of different ions are still large and in the range 0.183–1.116 when the snow thickness increases to 120 cm. The heterogeneity sequence becomes: K+> Mg2+> Ca2+> NH4+> Na+> Cl–> PO43–> NO3–> SO42–. The CV average change with thickness is different for NH4+. From 20 to 100 cm it increases slightly with increasing thickness, but all the values are lower than the average of 10cm thick layers.

High-resolution chemical records from an 80.4m ice core from the central Himalaya demonstrate climatic and environmental changes since 1844. the chronological net accumulation series shows a sharp decrease from the mid-1950s, which is coincident with the widely observed glacier retreat. A negative correlation is found between the ice-core δ18O record and the monsoon precipitation for Indian region 7. the temporal variation of the terrestrial ions (Ca2+ and Mg2+) is controlled by both the monsoon precipitation for Indian regions 3,7 and 8, located directly south and west of the Himalaya, and the dust-storm duration and frequency in the northern arid regions, such as the Taklimakan desert, China. the NH4+ profile is fairly flat until the 1940s, then substantially increases until the end of the 1980s, with a slight decrease during the 1990s which may reflect new agricultural practices. the SO42– and NO3– profiles show an apparent increasing trend, especially during the period 1940s–80s. Moreover, SO42– concentrations for the East Rongbuk Glacier core are roughly double that of the nearby Dasuopu core at Xixabangma, Himalaya, due to local human activity including that of climbing teams who use gasoline for cooking, energy and transport.

To investigate the effects of depositional and post-depositional processes on chemical records in the snowpack, seven monthly snow pits were sampled at the same site on the pass of Zhadang (ZD) glacier (30˚28.079' N, 90˚39.032' E; 5800ma.s.l.), Nyainqentanglha mountain, southern Tibetan Plateau, between April and October 2006. Meteorological data from an automatic weather station at the sampling site showed that the annual mean air temperature was –5.6˚C on the pass and that monthly air temperature was above 0˚C from June to August, indicating that snowmelt could occur in this high-elevation region during the summer. An analysis of δ18O and major-ion variability in snow pits suggests that glaciochemical recordswere influenced by both meltwater percolation in mid-summer (July and August) and seasonal deposition. Less negative δ18O values and high concentrations of major ions occurred during the spring. The trends of δ18O variations in the ZD snow pits were consistent with those in precipitation sampled at the nearby Nam Co station for all months except for July and August, suggesting that climate signals are well preserved in the snow-pit δ18O records during the non-summer months. However, these climate signals were destroyed by strong percolation of meltwater during mid-summer.

A 43 year oxalate record has been recovered in a 14.08m ice core from Ürümqi glacier No. 1 (43˚06’N, 86˚49’ E), a mid-latitude glacier at Ürümqi river head, Tien Shan, western China. Averaging 3.6±9.2 ng g–1 the oxalate has a background level <2 ng g–1 with sporadic concentration enhancements. Most of the spikes reach beyond 10 ng g–1 and have durations 51 year. the oxalate variation correlates with that in Far East Rongbuk Glacier (27˚59’N, 86˚55’ E), Qomolangma (Mount Everest), which is located 1600 kmawayacross the Qinghai–Tibetan Plateau and Taklimakandesert. Although the concentration enhancement in the latter is much higher, and lasts longer, oxalate reaches its highest concentration in both cores at the same time, during winter. the correlation of oxalate records suggests that the two areas may have had the same kind of local sources, but with a much larger (COO)22– flux in the Qomolangma area, or that they may have had a common source in the Indian subcontinent through the longitudinal atmospheric circulation. the concentration variation in the past 40 years coincides with industrial/economic development in southern Asia, and is mainly due to anthropogenic pollution.

Samples collected from four snow pits at Eclipse Icefield, Yukon, Canada, were analyzed for stable isotopes and major ions to assess seasonal and spatial variability in snow chemistry. Accumulation since the end of the 2001 summer season over the 0.1 km2 area sampled ranges from 0.77 to 1.16mw.e. Snow-pit stratigraphy and chemical records demonstrate that the low accumulation at pit 3 is due to an under-representation of winter snow accumulation at that site. For all major-ion species, chemical concentrations are independent of snow accumulation rate. Seasonal variations are evident in the major-ion records and can be divided between sea-salt species (Na+, Cl−) that peak in late fall to winter, and dust (Ca2+, Mg2+, K+) and other species (NH4+, NO3−, SO42–, C2O22–) that peak in late spring to summer. The signal common to all four snow pits identified by empirical orthogonal function analysis ranges from 49% of the total variance for Na+ and Cl− to as high as 80% of the total variance for SO42–. There is greater spatial variability in species associated with coarse-mode particles (Na+, Cl−, Ca2+, Mg2+) than in species present mainly in accumulation-mode aerosols (SO42–, NH4+) or in the gas phase (NO3−).

We present highly resolved, annually dated, calibrated proxies for atmospheric circulation from several Antarctic ice cores (ITASE (International Trans-Antarctic Scientific Expedition), Siple Dome, Law Dome) that reveal decadal-scale associations with a South Pole ice-core 10Be proxy for solar variability over the last 600 years and annual-scale associations with solar variability since AD 1720. We show that increased (decreased) solar irradiance is associated with increased (decreased) zonal wind strength near the edge of the Antarctic polar vortex. The association is particularly strong in the Indian and Pacific Oceans and as such may contribute to understanding climate forcing that controls drought in Australia and other Southern Hemisphere climate events. We also include evidence suggestive of solar forcing of atmospheric circulation near the edge of the Arctic polar vortex based on ice-core records from Mount Logan, Yukon Territory, Canada, and both central and south Greenland as enticement for future investigations. Our identification of solar forcing of the polar atmosphere and its impact on lower latitudes offers a mechanism for better understanding modern climate variability and potentially the initiation of abrupt climate-change events that operate on decadal and faster scales.

Using US National Centers for Environmental Prediction/US National Center for Atmospheric Research re-analysis data, we investigate the relationships between crustal ion (nssCa2+) concentrations from three West Antarctic ice cores, namely, Siple Dome (SD), ITASE00-1 (IT001) and ITASE01-5 (IT015), and primary components of the climate system, namely, air pressure/geopotential height, zonal (u) and meridional (v) wind strength. Linear correlation analyses between nssCa2+ concentrations and both air-pressure and wind fields for the period of overlap between records indicate that the SD nssCa2+ variation is positively correlated with spring circumpolar zonal wind, while IT001 nssCa2+ has a positive correlation with circumpolar zonal wind throughout the year (r > 0.3, p < 0.01). Intensified Southern Westerlies circulation is conducive to transport of more crustal aerosols to both sites. Further correlation analyses between nssCa2+ concentrations from SD and IT001 and atmospheric circulation suggest that the high inland plateau (represented by core IT001) is largely influenced by transport from the upper troposphere. IT015 nssCa2+ is negatively correlated with westerly wind in October and November, suggesting that stronger westerly circulation may weaken the transport of crustal species to IT015. Correlations of nssCa2+ from the three ice cores with the Antarctic Oscillation index are consistent with results developed from the wind-field investigation. In addition, calibration between nssCa2+ concentration and the multivariate El Niño–Southern Oscillation (ENSO) index shows that crustal species transport to IT001 is enhanced during strong ENSO events.