Mt. Everest, one of the most coveted climbing mountains on earth, also contains the highest altitude chemical contamination on land. For the first time, meltwater and snow samples from Mt. Everest's ...Khumbu Glacier were analyzed for “forever chemicals” per- and polyfluoroalkyl substances (PFAS). Our research team utilized solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify pollutants sampled from Everest Base Camp, Camp 1, Camp 2, and Everest Balcony. From the 14 PFAS compounds tested for, we found perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexanoic acid (PFHxA) in Mt. Everest snow and meltwater. The highest concentrations found were 26.14 ng/L and 10.34 ng/L PFOS at Base Camp and Camp 2, respectively. However, PFAS species were seen within 1–2 orders of magnitude in all sampling sites with detection, potentially suggesting a widespread presence on the mountain. Our samples are the highest altitude PFAS samples ever retrieved and indicate the need for further sampling both on Mt. Everest and in the below-glacier watershed.
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•For the first time, PFAS were found in snow and meltwater on Mt. Everest from below the Base Camp to the Balcony.•Samples from the Base Camp to the Summit are the first to characterize chemical deposition on the mountain.•Combined atmospheric and local direct deposition elevate concentrations above other alpine regions.•Human pollution impacts on Mt. Everest are both visible and chemical.
Mt. Everest (Qomolangma or Sagarmatha), the highest mount on Earth and located in the central Himalayas between China and Nepal, is characterized by highly concentrated glaciers and diverse ...landscapes, and is considered to be one of the most sensitive area to climate change. In this paper, we comprehensively synthesized the climate and environmental changes in the Mt. Everest region, including changes in air temperature, precipitation, glaciers and glacial lakes, atmospheric environment, river and lake water quality, and vegetation phenology. Historical temperature reconstruction from ice cores and tree rings revealed the distinct features of 20th century warming in the Mt. Everest region. Meteorological observations further proved that the Mt. Everest region has been experiencing significant warming (approximately 0.33 °C/decade) but relatively stable precipitation during 1961−2018 AD. Projected results (during 2006−2099 AD) under different representative concentration pathway scenarios showed a general warming trend in the region, with larger warming occurring in winter than in summer. Meanwhile, the precipitation projections varied spatially with no significant trends over the region. Intensive glacier shrinkage was characterized by decreasing glacier areas, while glacier-fed river runoff increased. Glacial lakes expanded with increasing glacial lake areas and numbers. These findings indicated a clear regional hydrological response to climate warming. Owing to the remote location of Mt. Everest, the present atmospheric environment remained relatively clean; however, long-range transport of atmospheric pollutants from South Asia and West Asia may have substantially influenced the Mt. Everest region, resulting in increasing concentrations of pollutants since the Industrial Revolution. Anthropogenic activities have been shown to influence river and lake water quality in this remote region, especially in the downstream. The end of the vegetation growing season advanced in the northern slope and did not change in southern slope region of the Mt. Everest, and there was no significant change in start date of the growing season in the region. This review will enhance our understanding of climate and environmental changes in the Mt. Everest region under global warming.
•Climate and environmental changes were synthesized in the Mt. Everest region.•Glaciers have retreated significantly, posing impacts to river runoff and glacial lakes.•Transboundary transport of atmospheric pollutants influenced the region.•TThere was no significant change in start date of the growing season.
This case study provides a framework for future monitoring and evidence for human source pollution in the Khumbu region, Nepal. We analyzed the chemical composition (major ions, major/trace elements, ...black carbon, and stable water isotopes) of pre-monsoon stream water (4300–5250 m) and snow (5200–6665 m) samples collected from Mt. Everest, Mt. Lobuche, and the Imja Valley during the 2019 pre-monsoon season, in addition to a shallow ice core recovered from the Khumbu Glacier (5300 m). In agreement with previous work, pre-monsoon aerosol deposition is dominated by dust originating from western sources and less frequently by transport from southerly air mass sources as demonstrated by evidence of one of the strongest recorded pre-monsoon events emanating from the Bay of Bengal, Cyclone Fani. Elevated concentrations of human-sourced metals (e.g., Pb, Bi, As) are found in surface snow and stream chemistry collected in the Khumbu region. As the most comprehensive case study of environmental chemistry in the Khumbu region, this research offers sufficient evidence for increased monitoring in this watershed and surrounding areas.
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•Document chemical composition of snow, stream, and ice from Khumbu region, Nepal•Provide a framework for future monitoring of environmental chemistry•Characterize chemical signatures in snow and stream chemistry•Provide evidence for elevated levels of human-sourced metals in snow and streams•Increased tourism in the Khumbu are likely contributors to high metal concentrations
Inorganic particulate nitrate (p-NO3−), gaseous nitric acid (HNO3(g)) and nitrogen oxides (NOx = NO + NO2), as main atmospheric pollutants, have detrimental effects on human health and ...aquatic/terrestrial ecosystems. Referred to as the ‘Third Pole’ and the ‘Water Tower of Asia’, the Tibetan Plateau (TP) has attracted wide attention on its environmental changes. Here, we evaluated the oxidation processes of atmospheric nitrate as well as traced its potential sources by analyzing the isotopic compositions of nitrate (δ15N, δ18O, and Δ17O) in the aerosols collected from the Mt. Everest region during April to September 2018. Over the entire sampling campaigns, the average of δ15N(NO3−), δ18O(NO3−), and Δ17O(NO3−) was −5.1 ± 2.3‰, 66.7 ± 10.2‰, and 24.1 ± 3.9‰, respectively. The seasonal variation in Δ17O(NO3−) indicates the relative importance of O3 and HO2/RO2/OH in NOx oxidation processes among different seasons. A significant correlation between NO3− and Ca2+ and frequent dust storms in the Mt. Everest region indicate that initially, the atmospheric nitrate in this region might have undergone a process of settling; subsequently, it got re-suspended in the dust. Compared with the Δ17O(NO3−) values in the northern TP, our observed significantly higher values suggest that spatial variations in atmospheric Δ17O(NO3−) exist within the TP, and this might result from the spatial variations of the atmospheric O3 levels, especially the stratospheric O3, over the TP. The observed δ15N(NO3−) values predicted remarkably low δ15N values in the NOx of the sources and the N isotopic fractionation plays a crucial role in the seasonal changes of δ15N(NO3−). Combined with the results from the backward trajectory analysis of air mass, we suggest that the vehicle exhausts and agricultural activities in South Asia play a dominant role in determining the nitrate levels in the Mt. Everest region.
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•Isotopic compositions of atmospheric nitrate in Mt. Everest region were reported.•Importance of O3 and HO2/RO2/OH in NOx oxidation processes changed among seasons.•Spatial variations in atmospheric Δ17O(NO3–) exist within TP.•N isotopic fractionation plays a crucial role in seasonal changes of δ15N(NO3–).•Vehicle exhaust and agricultural activities in South Asia are main NOx sources.
Main findings: Importance of O3 and HO2/RO2/OH in NOx oxidation processes changed among different seasons; vehicle exhausts and agricultural activities in South Asia are the main NOx sources.
Alpine treelines act as bio-indicators and bio-monitors of environmental change impacts in high elevation forests. This dendro-ecological study carried out in treeline ecotones in the Sagarmatha (Mt. ...Everest) National Park (SNP), eastern Nepal Himalaya, aimed to assess treeline dynamics and to understand the response of treeline forming Abies spectabilis (D. Don, Mirb) and Betula utilis (D. Don) to environmental change. At three treeline sites we placed two to four belt transects (size: 20m wide, variable length) which bisected the treeline as well as the tree species limit. The results revealed spatio-temporally heterogeneous regeneration with a higher regeneration of A. spectabilis compared to B. utilis. Warm temperatures during summer (JJA) growing seasons combined with sufficient moisture favored the growth of A. spectabilis while moisture stress during spring seasons (MAM) mainly limited the growth of B. utilis. The regeneration of A. spectabilis was favored by high temperatures throughout the year with sufficient moisture. The climatic response of the regeneration of B. utilis was spatiotemporally different and variable. Results predict a changing community structure in the treeline in response to future environmental change. During the past 200 years, A. spectabilis shifted upward by about 0.93m/yr and B. utilis by 0.42m/yr, with stabilization during the second half of the 20th century at the majority of the sites. The recent stability in treeline position of both species at most sites indicated that in addition to favorable climate, species-specific competitive abilities during the recruitment phase, recruitment suppression in the Krummholz and dwarf scrub belts, and grazing determine regeneration success and treeline position in the region.
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•Nine data sets of surface elevation difference (Dh) were generated for MB studies.•Dh change between altitude (DDh) was an indicator to locate sharp surface change.•Glacier MB was ...not in a twice negative trend based on the earlier common.•Glacier contribution to Rongbuk runoff was around 30 %–70 % in the 1970 s and 2010 s.•The D_Ts and D_MD well explained Dh change at RG tongue, the TPALT, and the ELA.
Glacier melting in the Himalayas provides indispensable water resources for downstream inhabitants. Glacier mass balance (MB) studies have important implications for hazard management of glacial lake outburst floods (GLOFs). However, Himalayan glacier MB results vary considerably among different studies with large uncertainties in satellite-based geodetic measurements, highlighting the necessity for further independent investigations and validation from multiple satellite platforms. Based on InSAR, photogrammetry, and laser altimetry techniques, we generate nine data sets of surface elevation differences (Dh) to study glacier geodetic MB in Rongbuk Catchment at the northern slope of Mt. Qomolangma. The data sets include five consecutive time periods over the last 48 years, i.e., 1974–2000, 2000–2006, 2006–2012, 2012–2015, and 2015–2021, and four overlapping periods of 1974–2012, 1974–2015, 2000–2015, and 1974–2021. The main results are summarized as follows. 1) Based on common reference DEM, geodetic MB was −0.21 ± 0.11 m w.e.a–1 in 1974–2000, −0.22 ± 0.05 m w.e. a–1 in 1974–2015, and −0.20 ± 0.03 m w.e. a–1 in 1974–2021. Geodetic MB presented negative twice since 2000 as measured by ordinary, consecutive short-term analysis, which was −0.41 ± 0.11 m w.e.a–1 in 2000–2006, −0.50 ± 0.54 m w.e.a–1 in 2006–2012, and −0.45 ± 0.11 m w.e.a–1 in 2015–2021. 2) Data validation by in-situ stake-observations at 5350, 5450, and 5500 m a.s.l in 1959–1960 and the 2000s, our results demonstrated convincing altitude effects on glacier change. Between 5150 m a.s.l. and 5800 m a.s.l., Dh presented a more downwasting rate with increasing altitude. While above 5800 m a.s.l., Dh became less negative with increasing altitude, and glaciers presented thickening trend above 6200 m a.s.l. 3) With the difference of Dh by 10 m altitude intervals (DDh), we located a sharp surface lowering zone on the debris-covered glacier tongue at 5240 ± 20 m in the 1970s. We postulated that it could be the glacier terminus under debris cover, which moved upward by 190 ± 20 m in the past five decades. With DDh, we also defined the turning point altitude at 5800 m ± 20 m, where Dh began to increase to be less negative with altitude. Moreover, summer temperature change and the number of melting days clearly explained the Dh change with altitude. 4) Glacier contribution to runoff was estimated by 30 ± 16 % from 1974 to 2021, however, our data also showed that approximately 70 % of runoff was from melting glaciers in 2015–2021, implying an amplifying effect of recent global warming on glacier contributions. In summary, our findings proved that DDh was an effective indicator for exploring mountain glacier change. The varying results revealed here indicates that more studies would be helpful to define and predict glacier, climatic and hydrological changes in the Himalayas with multiple techniques and observations based on a common reference over long term.
The accurate quantification of current and past Himalayan glacier mass budgets is vital if we are to understand the evolution of the Asian water tower, which provides water to the planet’s most ...populous region. In this work, we generated a geodetic time series spanning six decades over 79 glaciers surrounding Mt. Everest and found consistent acceleration of glacier mass loss between the 1960s (−0.23 ± 0.12 mwe a−1) and the modern era (−0.38 ± 0.11 mwe a−1 from 2009 to 2018). Glacier mass loss has varied depending on glacier terminus type and surface characteristics, and glacier thinning is now occurring at extreme altitudes (>6,000 masl). Our time series also captures the first documented surge of a glacier in the Mt. Everest region. These multi-decadal observations of glacier mass loss form a baseline dataset against which physically based glacier evolution models could be calibrated before they are used for predicting future meltwater yield.
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•Glaciers around Mt. Everest have thinned by more than 100 m since the 1960s•The rate of ice mass loss has consistently accelerated over the past six decades•Glacier thinning has occurred at above 6,000 masl•Surge-type glacier behavior has been identified for the first time in the region
Meltwater from Himalayan glaciers sustains the flow of rivers that are heavily depended on by downstream communities across the densely populated region of Southeast Asia. Himalayan glaciers are shrinking in response to a changing climate, and measurements of glacier mass loss are vital for the calibration of models used for predicting the future variability of meltwater runoff. Here, we produced the longest possible time series of glacier mass-change measurements from satellite archives and found that the rate of ice loss from glaciers close to Mt. Everest has consistently increased since the early 1960s. We show how glacial lakes in the region have amplified ice loss and illustrate how ice loss has begun to occur at extreme altitudes, where large volumes of ice that were formerly less susceptible to melt are stored. The rate of ice loss across the Himalaya is likely to increase in the coming decades in response to further warming, which could be amplified at high altitude.
We generated the longest possible time series of glacier elevation-change measurements from satellite image archives to show how glaciers around Mt. Everest have reacted to climatic change since the 1960s. The rate of ice loss in the region has consistently increased over the last six decades, and ice loss is now occurring at extreme altitudes. Accurate, long-term measurements of ice-loss rates are vital if we are to understand the impact of glacier recession on local and regional hydrology.
In 2019, the National Geographic and Rolex Perpetual Planet Everest expedition successfully retrieved the greatest diversity of scientific data ever from the mountain. The confluence of geologic, ...hydrologic, chemical and microbial hazards emergent as climate change increases glacier melt is significant. We review the findings of increased opportunity for landslides, water pollution, human waste contamination and earthquake events. Further monitoring and policy are needed to ensure the safety of residents, future climbers, and trekkers in the Mt. Everest watershed.
The majority of research dealing with the impacts of the Himalayan climate on human physiology focuses on low air temperature, high wind speed, and low air pressure and oxygen content, potentially ...leading to hypothermia and hypoxia. Only a few studies describe the influence of the weather conditions in the Himalayas on the body’s ability to maintain thermal balance. The aim of the present research is to trace the heat exchange between humans and their surroundings during a typical, 6-day summit attempt of Mount Everest in the spring and winter seasons. Additionally, an emergency night outdoors without tent protection is considered. Daily variation of the heat balance components were calculated by the MENEX_HA model using meteorological data collected at automatic weather stations installed during a National Geographic expedition in 2019–2020. The data represent the hourly values of the measured meteorological parameters. The research shows that in spite of extreme environmental conditions in the sub-summit zone of Mount Everest during the spring weather window, it is possible to keep heat equilibrium of the climbers’ body. This can be achieved by the use of appropriate clothing and by regulating activity level. In winter, extreme environmental conditions in the sub-summit zone make it impossible to maintain heat equilibrium and lead to hypothermia. The emergency night in the sub-peak zone leads to gradual cooling of the body which in winter can cause severe hypothermia of the climber’s body. At altitudes < 7000 m, climbers should consider using clothing that allows variation of insulation and active regulation of their fit around the body.
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