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We investigate the role of glacier structures in controlling ice‐front morphology and dynamics of four Himalayan lake‐terminating glaciers over a 20‐year period. At Imja, Trakarding, Lumdin and Dang Pu glaciers, lake area was mapped between 2000 and 2020 using Landsat 5/7/8 and Sentinel‐2 imagery. Discrete glacier flow units were identified, with glacier structures (e.g., open crevasses, transverse structures, longitudinal structures) digitised using the finest resolution panchromatic bands in each year (30, 15, or 10 m). Mapping revealed a distinct pattern of transverse structures towards the terminus of each glacier that influence ice‐front position and morphology and are then exploited via iceberg calving events. Our structural analysis also illustrates the role of subsurface conduits in calving events. During subsurface conduit collapse, glacier recession is enhanced, leading to calving along adjacent transverse structures. Furthermore, our analysis shows that ice‐front morphology influences the pattern of glacier recession. Ice fronts with distinct ice aprons undergo slower periods of recession than ice fronts with ice cliffs. We conclude that glacier structures are important in determining ice‐front morphologies at lake‐terminating Himalayan glaciers, and therefore, structural analysis is vital when assessing future ice‐front positions and behaviour, as well as rates of glacier recession. [ABSTRACT FROM AUTHOR]

The presence of a developed boundary layer decouples a glacier's response from ambient conditions, suggesting that sensitivity to climate change is increased by glacier retreat. To test this hypothesis, we explore six years of distributed meteorological data on a small Swiss glacier in the period 2001–2022. Large glacier fragmentation has occurred since 2001 (−35% area change up to 2022) coinciding with notable frontal retreat, an observed switch from down‐glacier katabatic to up‐glacier valley winds and an increased sensitivity (ratio) of on‐glacier to off‐glacier temperature. As the glacier ceases to develop density‐driven katabatic winds, sensible heat fluxes on the glacier are increasingly determined by the conditions occurring outside the boundary layer of the glacier, sealing the glacier's demise as the climate continues to warm and experience an increased frequency of extreme summers. Plain Language Summary: Down‐glacier winds promote a unique micro‐climate, maintaining relatively lower temperatures over the surface of mountain glaciers. Using six years of meteorological data in the period 2001–2022, we observe increases in the relative changes of above‐ice air temperatures compared to temperatures outside the glacier. As the glacier ceases to develop its own micro‐climate, warmer winds generated by heated valley slopes increasingly control the amount of heat transfer to melt glacier ice. This work offers new observational evidence that suggests that, as glaciers continue to shrink and fragment, they becoming increasingly sensitive to future climate warming. Key Points: On‐glacier air temperatures have become more sensitive to ambient temperatures in a warming climateUp‐valley winds have increased >20% between 2001 and 2021, making sensible heat fluxes more dependent on conditions outside the glacierThe decay of the katabatic system due to glacier retreat indicates a nonlinear sensitivity of the glacier to continued warming [ABSTRACT FROM AUTHOR]

Landsystem relationships between glaciers and rock debris supply in a mountain landscape domain, (), are described. Decimal latitude-longitude [dLL] geolocations are used to identify features and transects in an information landscape. Geo-located features are coded, enabling transects between a 1976 expedition and 2019 Google Earth imagery to be compared. Rock debris is progressively added to 1-3 km long glaciers which become debris-covered. Cirque glaciers eventually assume rock glacier (RG) forms when supraglacial debris loads are high. Some rock glacier snouts reach main valley floors and still advance over meadows. This behaviour is attributed to high geomorphic activity producing rock detritus and transport to glaciers in the early Little Ice Age. The advances of rock glacier snouts are a consequence of thinning; low-angle glaciers still moving beneath debris-covered glaciers (GLd) covers. Persistent melt pools continue to develop within the surface debris cover of glaciers and rock glaciers and expose glacier ice. All the rock glaciers are below the regional snowline and permafrost can be discounted for rock glacier formation. Scree slope (SS) development may ultimately be sufficient to cover bare glacier ice moving from a glacier (GL) to debris-covered glacier (GLd) to rock glacier (RG). Reverse slopes in the debris at the foot of screes mark the mass continuum of glacier flow below the debris cover, not the 'rooting zone' of a permafrost-derived RG. Scree slopes themselves show no evidence of rock glacier-like flow. A simple glacier ice-debris transport continuum model is sufficient and necessary for rock glacier formation and flow. [ABSTRACT FROM AUTHOR]

Climate and environmental changes in the Arctic Ocean due to global warming have been linked to extreme climate change in mid-latitude regions, including the Korean Peninsula, requiring a better understanding of the Arctic climate system based on the paleo-analog. This review introduces three paleoenvironmental research cases using neodymium isotopes (143Nd/144Nd, εNd) measured on two different fractions of marine sediments: silicate-bound ‘detrital’ and Fe-Mn oxide-dominated ‘authigenic’ fractions. In the first case, detrital εNd in core HH17-1085-GC on the continental shelf off northern Svalbard was used for tracing changes in sediment provenance and associated glacier behavior over the last 16.3 ka. The second case showed the potential use of authigenic εNd as a quasi-conservative water mass tracer. Three prominent εNd peaks and troughs observed in core PS72/410-1 from the Mendeleev Ridge in the western Arctic Ocean over the past 76 ka suggested episodic meltwater discharge events during 51~46, 39~35 and 21~13 ka BP. The last case proposed the use of the difference between authigenic and detrital εNd as a proxy for reconstructing glacier fluctuation. The idea is based on the assumption that enhanced glacial erosion during glacier advances can supply sufficient freshly-exposed rock substrate for incongruent weathering, potentially leading to greater isotopic decoupling between bedrock and dissolved weathering products as recorded in detrital and authigenic εNd, respectively. Thus, it would be worthwhile to take advantage of sedimentary εNd to improve our understanding of past environmental changes in polar regions. [ABSTRACT FROM AUTHOR]

Glacier phototroph blooms on the surfaces of ice sheets and glaciers cause albedo reduction, leading to increased melting rates. We observed seasonal changes in the abundance of phototrophs on the Qaanaaq Ice Cap in northwestern Greenland from June to August 2014, and reproduced these changes using numerical and empirical models. The phototroph community on the ice surface mainly consisted of the glacier alga Ancylonema nordenskioldii and the cyanobacterium Phormidesmis priestleyi. The glacier alga appeared on the ice surface in late June, after which its abundance increased exponentially throughout the melting period. A logistic growth model designed for snow algal growth reproduced the measured exponential increases, suggesting that growth could be explained using the model as a function of the ice melting duration. Cyanobacteria appeared and their abundance increased in late July but did not change exponentially thereafter. The abundance of cyanobacteria was explained with an empirical model expressed as a function of the amount of mineral dust on the bare ice surface. Our numerical and empirical models for reproducing glacier algae and cyanobacteria could be useful for quantifying the albedo reduction caused by their growth and the melt rates of the Greenland ice sheet and glaciers in the future. [ABSTRACT FROM AUTHOR]

We used Sentinel-2 satellite imagery at 10 m resolution to map the extent of Norway's glaciers and ice-marginal lakes over 2018–19. We applied a standardized semi-automated band ratio method to derive glacier outlines and ice-marginal lakes. To optimise the results, we manually edited the ice-lake interfaces, debris, snow and parts of the glaciers situated under shadow. We compared our Sentinel-2 derived outlines with very high-resolution aerial orthophotos and Pléiades satellite orthoimages. Glaciers larger than 0.3 km2 have area differences within 7%, whereas values are larger for smaller glaciers. The orthophotos and orthoimages provide more details and a higher mapping accuracy for individual glaciers, but require manual digitisation, have smaller spatial and temporal coverage and can have adverse snow conditions. We found a total glacier area of 2328 ± 70 km2 of which the ten largest glaciers accounted for 52%. The glacier area decreased 15% since the previous inventory (Landsat data from 1999 to 2006), the reduction being largest in northern Norway (22%) compared to southern Norway (10%). We detected more than 2000 previously undetected smaller glaciers and ice patches (covering 37 km2) and 360 new ice-marginal lakes.

Himalayan mountain ranges separate the Tibetan plateau from the Indian subcontinent, where challenging topography, ongoing orogeny, and weather conditions are significant factors behind mass movements. The detachment of a composite rock-ice mass occurred on 7-Feb-2021 over the north-eastern slope of the Trisul mountain resulting in devastation along the Rishiganga-Dhauliganga valley, Uttarakhand. In this study, an attempt is made to understand the failure mechanism of the overhang wedge, where prolonged glacial mobility is seen as a possible factor behind the formation of such a structure. The temporal movement (2020–2021; annual & seasonal) of metamorphosed ice is assessed using sub-pixel offset tracking of Sentinel-1A-GRD data. Kinematic analysis checks failure susceptibility due to joint sets within the rockmass. Slope stability analysis is performed using probabilistic back analysis for three values of coefficient of variation (CoV), i.e., 10%, 15%, and 20% considering cohesion (c) and angle of internal friction (ϕ) as random variables. The detachment impact is quantified using rockfall simulation and parameters such as maximum bounce height, total kinetic energy, and translational velocity. Finally, probabilistic analysis of parameters is performed that may be useful in developing a mitigation system.

A first-order question in the studies of the Solar System is how its outer zone known as the Kuiper belt was created and evolved. Two end-member models, involving coagulation vs. streaming instability, make different predictions—testable by the cratering history of Kuiper Belt Objects (KBOs)—about the cumulative size-frequency distribution (SFD) of the KBOs. Among all of the imaged KBOs, Pluto’s largest icy moon, Charon, appears to preserve the largest size range of seemingly undisturbed craters, their diameters (D) on Charon ranging from < 1 km to > 220 km. Current work shows that Charon’s craters with D < 10−20 km are fewer than those expected by the coagulation mechanism, but whether this is an artifact of post-cratering modification of smaller craters is unknown. We address this issue by conducting systematic photogeological mapping and performing detailed landform analysis using the highest resolution images obtained by the New Horizons spacecraft, which reveal a range of differentiable terrains on Charon. The most important findings of our work include (1) truncation and obliteration of large craters (diameters > 30−40 km) and their crater rim ridges along the eastern edges of several north-trending, eastward-convex, arcuate ranges in Oz Terra of the northern encountered hemisphere, (2) lobate ridges, lobate knob trains, and lobate aprons resembling glacial moraine landforms on Earth, (3) dendritic channel systems containing hanging valleys, and (4) locally striated surfaces defined by parallel ridges, knob trains, and grooves that are > 40−50 km in length. The above observations and the topographic dichotomy of Charon’s encountered hemisphere can be explained by a landscape-evolution model that involves (i) a giant impact that created the Vulcan Planitia basin and the extensional fault zone along its northern rim, (ii) a transient atmosphere capable of driving N2-ice glacial erosion of the water-ice bedrock and transporting water-ice debris to sedimentary basins, (iii) regional glacial erosion and transport of earlier emplaced impact ejecta deposits from the highlands of Oz Terra into the lowland basin of Vulcan Planitia, (iv) syn-glaciation north-trending thrusting, interpreted to have been induced by Charon’s despinning, and (v) the development of a water-ice debris cover layer over subsurface N2 ice below Vulcan Planitia during global deglaciation. The infilling of the Vulcan Planitia could have been accompanied by cryovolcanism. The extensive modification of impact craters means that the size-frequency distributions of Charon’s craters should serve only as a lower bound when used to test formation mechanisms proposed for Kuiper belt objects.

Abstract The Pasterze is Austria's largest glacier, and it is experiencing rapid downwasting and retreat. A mosaic of complex sedimentary deposits has been produced in recent years which have not hitherto been studied, yet provide excellent lessons into the facies distribution expected from a dying valley glacier. In this paper, a new glaciological–geomorphological–geological map is presented for the glacier in July 2021. Freshly exposed (since 2018) tills and flutes constitute a subglacial sediment–landform assemblage. An ice‐marginal sediment–landform assemblage comprises meltwater streams, a delta system and proglacial lake terrace deposits. The supraglacial assemblage, meanwhile, includes fossil englacial channel deposits revealed by ablation, together with debris bands, rockfall deposits and supraglacial channel deposits. Collectively, these sediment–landform assemblages constitute the building blocks of a dying glacier landsystem.

Glaciers and ice caps (GICs) are important contributors of meltwater runoff and to global sea level rise. However, knowledge of GIC mass changes is largely restricted to the last few decades. Here we show the extent of 5327 Greenland GICs during Little Ice Age (LIA) termination (1900) and reveal that they have fragmented into 5467 glaciers in 2001, losing at least 587 km3 from their ablation areas, equating to 499 Gt at a rate of 4.34 Gt yr−1. We estimate that the long‐term mean mass balance in glacier ablation areas has been at least −0.18 to −0.22 m w.e. yr−1 and note the rate between 2000 and 2019 has been three times that. Glaciers with ice‐marginal lakes formed since the LIA termination have had the fastest changing mass balance. Considerable spatial variability in glacier changes suggest compounding regional and local factors present challenges for understanding glacier evolution. Plain Language Summary: Glaciers and ice caps of Greenland peripheral to the ice sheet are important contributors of meltwater to the oceans and to global sea‐level rise. In this study we map the extent of 5467 glaciers during the Little Ice Age (LIA) termination c. 1900 and calculate that they have lost at least 587 km3. The rate of mass change of these glaciers between 2000 and 2019 was three times more negative than the long‐term average (of 4.34 Gt yr−1) since the LIA. Lake‐terminating glaciers now lose mass the fastest compared with land‐ or marine‐terminating glaciers. Considerable spatial variability in glacier responses suggests local factors are important and makes glacier evolution complex. Key Points: Total volume loss of at least 587 km3 since the Little Ice Age (LIA) termination, equating to 499 Gt and to 1.38 mm sea level equivalentGlacier mass balance from 2000 to 2019 is three times more negative than since the LIA but five times more negative in the North regionLake‐terminating glaciers have experienced the greatest change in rate of mass loss [ABSTRACT FROM AUTHOR]

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Microbial communities and nutrient dynamics in glaciers and ice sheets continuously change as the hydrological conditions within and on the ice change. Glaciers and ice sheets can be considered bioreactors as microbiomes transform nutrients that enter these icy systems and alter the meltwater chemistry. Global warming is increasing meltwater discharge, affecting nutrient and cell export, and altering proglacial systems. In this review, we integrate the current understanding of glacial hydrology, microbial activity, and nutrient and carbon dynamics to highlight their interdependence and variability on daily and seasonal time scales, as well as their impact on proglacial environments. [ABSTRACT FROM AUTHOR]

The accessibility and simplicity of monitoring instruments and processing methods are crucial for environmental monitoring worldwide. There is growing evidence that proglacial discharge may be observed by listening to the glacier terminus using sophisticated tools, such as the micro‐barometer arrays that are used for nuclear‐test monitoring and the fiber‐optic technologies that are becoming increasingly used in geophysics. However, the prohibitive cost, instrumental complexity, overwhelming data volumes, and computational demands of these approaches mean that only the wealthiest countries can afford such technologies. We employ an intentionally inexpensive approach to monitor proglacial discharge by recording the audible sound that is generated near the glacier terminus, and we show that a simple microphone can tell us how much water is discharged by a glacier. This study demonstrates that sound can provide essential information on runoff and therefore contribute to environmental assessments of glaciers and disaster risk reduction of glacial flood events. Plain Language Summary: Glacier monitoring is essential for sea‐level‐rise forecasting, water management, and providing an early warning of potential glacial flooding; however, the necessary monitoring data are currently scarce and often difficult to collect. Recent studies on turbulent streams and melting glaciers have suggested that the acoustic signals that are generated from these systems can serve as a proxy for high‐resolution discharge monitoring. We collected acoustic and runoff records from the terminus of Qaanaaq Glacier, Greenland, to examine this sound–glacier discharge relationship. We demonstrate that the proglacial discharge can be estimated from the audible sound that is generated near the terminus, without the need for expensive monitoring equipment and sophisticated machine‐learning analysis. We identify that the 50–375 Hz frequency band may serve as the most efficient proxy and associate the recorded sound (and previously reported persistent infrasound) with the turbulent proglacial stream. Our non‐invasive approach is ∼100 times cheaper than current fiber‐optic technology, can easily be deployed at any safe location near the terminus, and requires only basic processing of the recorded signal, thereby making it a safe, affordable, and effective approach to monitoring discharge. It may also be a viable tool for long‐term glacier monitoring, particularly where glacial flooding events pose a risk. Key Points: Sound propagating in the atmosphere can be used to estimate proglacial dischargeAudible frequencies between 50 and 375 Hz are most informative at a short rangeA simple microphone is a promising and economical tool for glacial hydrology [ABSTRACT FROM AUTHOR]

The glacier recession of the North-Chuya ridge, Altai, after the maximum of the Little Ice Age (LIA) is estimated based on remote sensing and in situ studies of the Bolshoi Maashei glacier. The glacier area decreased from 304.9 ± 23.49 km2 at the LIA maximum to 140.24 ± 16.19 km2 in 2000 and 120.02 ± 16.19 km2 in 2021. The average equilibrium-line altitude (ELA) rise after the LIA was 207 m. The reduction of glaciers was caused by the warming trend, most rapid in the 1990s, and by the decrease in precipitation after the mid-1980s. The volume of glaciers decreased from approximately 16.5 km3 in the LIA maximum to 5.6–5.8 km3 by 2021. From the LIA maximum to 2022, the Bolshoi Maashei glacier decreased from 17.49 km2 to 6.25 km2, and the lower point rose from 2160 m to 2225 m. After the LIA, the glacial snout retreat was about 1 km. The fastest retreat of the glacier terminus was estimated in 2010–2022 as 14.0 m a−1 on average. The glacier mass balance index was calculated, with the results showing a strong negative trend from the mid-1980s until now. Strong melt rates caused the increase in the area of the Maashei lake, which could lead to the weakening of its dam, and prepared for its failure in 2012. The current climatic tendencies are unfavorable for the glaciers. [ABSTRACT FROM AUTHOR]

In this study monthly Temperature Lapse Rates and basic downscaling technique of subtracting means are used to construct temperature (T) series over East Rathong glacier by using multiple data sets from Automatic Weather Stations (AWS) at Himalayan Mountaineering Institute (HMI), Gangtok Indian Meteorological Department (IMD), Yuksum and ERA5reanalysis data. Precipitation (P) over glacier is estimated using Gangtok IMD data and downscaled ERA5 data. The P data is downscaled using local scaling factor method. Change in volume of 0.180 km3 (from 1962 to 2020) estimated using satellite data are used to construct Mass Balance (MB) series for the glacier. It is observed that the glacier is losing its mass with increasing T, Aerosol Optical Depth (AOD) (from 0.1 in 1980 to 0.2 in 2020), and increasing Pmainly during June-July-August months when temperatures are already high. This study is important as it used multiple data sets along with field data extracted from the literature to study climatic impacts on East Rathong glacier. Data generated from this study may be used in mass balance projection of the glaciers in the absence of field data. [ABSTRACT FROM AUTHOR]

As the highest peak on the earth, Mt. Qomolangma provides an unparalleled platform to study glacier‐atmosphere interaction. Although glacier surface energy balance (SEB) on Mt. Qomolangma was examined during warm season, relevant knowledge during cold season is still unknown, which prevents a complete understanding of all‐season glacier SEB on it. Based on an in‐situ observation from October 2007 to January 2008, this study presents a cold‐season glacier SEB result at 6,523 m above sea level on Mt. Qomolangma and identifies its atmospheric control. Our results show that the observational period experienced strong winds and deficient clouds. Near‐surface wind speeds usually exceeded 10 m s−1, resulting in a substantial sensible heat transport toward glacier and thus enhancing outgoing longwave radiation, which, under the combined effect of deficient clouds, eventually caused an increase in longwave radiative loss. The large solar zenith angle and relatively high albedo of the glacier surface led to a small absorption of solar irradiance, which, in combination with the strong longwave radiation loss, resulted in a semi‐permanent surface radiative loss. Uncommon over the highly reflective glacier surface, clouds decreased the incident solar radiation more than increased the longwave radiation, demonstrating that the clouds' shading effect surpassed its greenhouse effect. As a vital heat sink, the turbulent latent heat induced an average sublimation rate of 0.8 mm water equivalent per day. This study provides valuable insights into the atmospheric control on the cold‐season glacier‐atmosphere interaction at high altitudes on Mt. Qomolangma when meteorological variables are subject to the westerlies. Plain Language Summary: Mt. Qomolangma is the highest mountain on the earth. Qomolangma's glacier retreat is a warning sign for rapid climate warming. Understanding the atmospheric control on Qomolangma's glacier mass loss is critical. This paper thoroughly examines how the energy associated with Qomolangma's glacier mass loss at 6523 m above sea level was governed in the cold season. We find that wind speed is an important factor. On one hand, its increase enhanced the energy input toward glacier, increasing surface temperature and thus letting more energy escape from glacier surface under the combined influence of small cloud cover; on the other hand, the increase in wind speed enhanced the mass loss of sublimation, lowering surface temperature. Cloud cover is another factor. The clouds' shading effect of decreasing incoming sunlight surpassed its greenhouse effect of increasing energy toward glacier, making less energy arriving at the glacier surface and thus decreasing mass loss. Additionally, at the highly reflective glacier surface, glacier received weak sunlight in cold season because a significant portion of the relatively modest incoming sunlight was reflected to the sky. These results provide valuable insights into the atmospheric control on Qomolangma's glacier mass loss in the cold season. Key Points: We present 3.5 months of autumn and wintertime glacier surface energy balance at 6,523 m above sea level on Mt. QomolangmaThere was a semi‐permanent surface radiative loss due to deficient clouds, large solar zenith angle, and high albedo of glacier surfaceClouds reduced solar irradiance more than increased longwave radiation, implying that their shading effect surpassed the greenhouse effect [ABSTRACT FROM AUTHOR]

Norway is at the forefront of monitoring ice patches and glaciers for archaeological remains, and thousands of artifacts have been recovered over the past two decades due to accelerating melting. The majority of finds stem from the lower latitudes of the country and relatively little is known about the glacial archaeology of Norway's far north. We use historical maps and high-resolution LiDAR derived elevation models to monitor ice flow and melt. We employ a terrain ruggedness index to map areas of non-moving ice which possibly contain well-preserved archaeological finds, and model least cost paths to understand the accessibility for humans and animals of an archaeologically unexplored landscape. We then conduct a sailboat supported exploratory survey on the arctic island of Seiland. While we fail to locate archaeologically productive ice, we identify and date a so far unknown type of archaeological stone structure likely related to sheltering and reindeer hunting/herding activities. [ABSTRACT FROM AUTHOR]

Glacier and ice sheet surfaces host diverse communities of microorganisms whose activity (or inactivity) influences biogeochemical cycles and ice melting. Supraglacial microbes endure various environmental extremes including resource scarcity, frequent temperature fluctuations above and below the freezing point of water, and high UV irradiance during summer followed by months of total darkness during winter. One strategy that enables microbial life to persist through environmental extremes is dormancy, which despite being prevalent among microbial communities in natural settings, has not been directly measured and quantified in glacier surface ecosystems. Here, we use a combination of metabarcoding and metatranscriptomic analyses, as well as cell‐specific activity (BONCAT) incubations to assess the diversity and activity of microbial communities from glacial surfaces in Iceland and Greenland. We also present a new ecological model for glacier microorganisms and simulate physiological state‐changes in the glacial microbial community under idealized (i) freezing, (ii) thawing, and (iii) freeze–thaw conditions. We show that a high proportion (>50%) of bacterial cells are translationally active in‐situ on snow and ice surfaces, with Actinomycetota, Pseudomonadota, and Planctomycetota dominating the total and active community compositions, and that glacier microorganisms, even when frozen, could resume translational activity within 24 h after thawing. Our data suggest that glacial microorganisms respond rapidly to dynamic and changing conditions typical of their natural environment. We deduce that the biology and biogeochemistry of glacier surfaces are shaped by processes occurring over short (i.e., daily) timescales, and thus are susceptible to change following the expected alterations to the melt‐regime of glaciers driven by climate change. A better understanding of the activity of microorganisms on glacier surfaces is critical in addressing the growing concern of climate change in Polar regions, as well as for their use as analogues to life in potentially habitable icy worlds. [ABSTRACT FROM AUTHOR]

The mechanisms underlying the survival of bacteria in low temperature and high radiation are not yet fully understood. Nakamurella sp. PAMC28650 was isolated from a glacier of Rwenzori Mountain, Uganda, which species belonged to Nakamurella genus based on 16S rRNA phylogeny, ANI (average nucleotide identity), and BLAST Ring Image Generator (BRIG) analysis among Frankineae suborder. We conducted the whole genome sequencing and comparative genomics of Nakamurella sp. PAMC28650, to understand the genomic features pertaining to survival in cold environment, along with high UV (ultraviolet) radiation. This study highlights the role of polysaccharide in cold adaptation, mining of the UV protection-related secondary metabolites and other related to cold adaptation mechanism through different bioinformatics tools, and providing a brief overview of the genes present in DNA repair systems. Nakamurella sp. PAMC28650 contained glycogen and cellulose metabolism pathways, mycosporine-like amino acids and isorenieratene-synthesizing gene cluster, and a number of DNA repair systems. Also, the genome analysis showed osmoregulation-related genes and cold shock proteins. We infer these genomic features are linked to bacterial survival in cold and UV radiation. [ABSTRACT FROM AUTHOR]

Droughts can lead to extreme low flow situations in rivers, with resulting severe impacts. Upstream snow and ice melt in many of the world's mountain water towers can alleviate the hydrological consequences of drought, yet global warming threatens the cryosphere. To improve the understanding of melt water contributions during drought in the case of future glacier retreat, we developed stress‐test storyline scenarios to model streamflow and tested them in the European river Rhine basin. Meteorological conditions of past drought and low flow years in Europe, 1976, 2003, and 2018, were repeated at three future moments in time, representing nowadays, near future and far future conditions. The latter two conditions were obtained by climate projections under the RCP8.5 scenario. Results show that the low flow situations caused by the meteorological drought situations aggravate in future conditions, more so for the far future and for the year 2003 because of the relatively large glacier ice melt contribution in the past. Summer (July–September) streamflow may decline by 5%–25% far downstream and 30%–70% upstream and the duration of extreme low flow situations may double compared to the selected past drought events. These results are relevant for the Rhine as a major European river but stand exemplary for many other river basins and highlight the importance of cryospheric changes for downstream low flow situations in a changing climate. The stress‐test scenarios allow a glimpse into future extreme low flow events aiding adaptation planning, and might be adapted to include other important low flow drivers. Plain Language Summary: Extended periods with strongly reduced rainfall, in combination with hot summers, lead to accumulating water shortages. As a result, water levels in rivers drop which causes problems, e.g., for shipping, cooling of power plants and drinking and irrigation water supply. During such drought periods, melt water from snow and ice is important for water supply. However, glaciers are projected to further decline in a warming climate, possibly worsen future low flow situations. To quantify this effect, we modeled the amount of water flowing through the Rhine basin (a) for past low flow events in 1976, 2003, and 2018 and (b) for hypothetical situations where we repeat the weather data of those past low flow years at three moments in the future. The results show that flows upstream and downstream in the river Rhine would get even lower in future conditions and cause low flow situations to lengthen considerably. Especially for the year 2003, which had high ice melt contributions in the past, changes are large. In summer, the flow during already critical low flow situations may decrease by up to 70% upstream, and by up to 30% downstream. The results show a glimpse into future low flow events and may help adaptation planning. Key Points: A model framework for the Rhine basin was developed to simulate streamflow during extreme past drought years in future conditionsExtreme low flows as in 1976, 2003, and 2018 would aggravate in a future with declined glacier cover and snow packRepeating the drought and heatwave of 2003 in the future results in largest reductions in summer streamflow (70% upstream, 30% downstream) [ABSTRACT FROM AUTHOR]

Abstract The speed‐up of glaciers following ice shelf collapse can accelerate ice mass loss dramatically. Investigating the deformation of landfast sea ice enables studying its resistive (buttressing) stresses and mechanisms driving ice collapse. Here, we apply offset tracking to Sentinel‐1A/B synthetic aperture radar data to obtain a 2014–2022 time‐series of horizontal velocity and strain rate fields of landfast ice filling the embayment formerly covered by the Larsen B Ice Shelf, Antarctic Peninsula until 2002. The landfast ice disintegrated in 2022, and we find that it was precipitated by a few large opening rifts. Grounded glaciers did not accelerate instantaneously after the collapse, which implies little buttressing effect from landfast ice, a conclusion also supported by the near‐zero correlation between glacier velocity and landfast ice area. Our observations suggest that buttressing stresses are unlikely to be recovered by landfast sea ice over sub‐decadal timescales following the collapse of an ice shelf.

There is increasing evidence that fossil-fuel burning, and consequential global heating of 1.1°C to date, has led to the increased occurrence and severity of extreme environmental events. It is well documented how such events have impacted society outside Antarctica through enhanced levels of rainfall and flooding, heatwaves and wildfires, drought and water/food shortages and episodes of intense cooling. Here, we briefly examine evidence for extreme events in Antarctica and the Southern Ocean across a variety of environments and timescales. We show how vulnerable natural Antarctic systems are to extreme events and highlight how governance and environmental protection of the continent must take them into account. Given future additional heating of at least 0.4°C is now unavoidable (to contain heating to the “Paris Agreement 1.5°C” scenario), and may indeed be higher unless drastic action is successfully taken on reducing greenhouse gas emissions to net zero by mid-Century, we explain it is virtually certain that future Antarctic extreme events will be more pronounced than those observed to date.

Abstract Glacier growth affects the local climate, and in turn, can either promote or prohibit its own growth. Such feedback has not been considered in modeling the glaciers of the Tibetan Plateau and its surroundings (TPS) during the Last Glacial Maximum (LGM; ∼28–23 ka). We find that the volume/area of the glaciers simulated by a coupled glacier‐climate model is 20%/10% less than that by a standalone glacier model forced with fixed climate fields; glaciers advance toward their western rims and yet decrease in the interior of TPS. Such changes in spatial patterns improve model‐data comparison. Moreover, the expansion of glaciers warms the winter surface temperature of the eastern TPS and decreases precipitation almost everywhere. These effects are primarily due to the added surface elevation, which blocks the water vapor brought by westerlies and south‐westerlies, reducing precipitation and increasing surface temperatures to the east and northeast of the newly grown glaciers.

Abstract The presence of a developed boundary layer decouples a glacier's response from ambient conditions, suggesting that sensitivity to climate change is increased by glacier retreat. To test this hypothesis, we explore six years of distributed meteorological data on a small Swiss glacier in the period 2001–2022. Large glacier fragmentation has occurred since 2001 (−35% area change up to 2022) coinciding with notable frontal retreat, an observed switch from down‐glacier katabatic to up‐glacier valley winds and an increased sensitivity (ratio) of on‐glacier to off‐glacier temperature. As the glacier ceases to develop density‐driven katabatic winds, sensible heat fluxes on the glacier are increasingly determined by the conditions occurring outside the boundary layer of the glacier, sealing the glacier's demise as the climate continues to warm and experience an increased frequency of extreme summers.

While mountain water faces threats posed by climate change, particularly in snow-dominated and glacierized systems, the role of groundwater (GW) in sustaining streamflow in these systems remains elusive. Changing mountain headwaters, marked by reduced snowpacks, retreating glaciers, shifting precipitation patterns, and rising temperatures, pose a crucial question: what is the resilience of streamflow in these mountains, and what role does GW play in this resilience? This is particularly uncertain in tropical high mountains where the seasonality of precipitation and glacier melt govern streamflow generation. A glacio-hydrological model was created using the Cold Regions Hydrological Modelling platform to investigate cryosphere-surface water–GW interactions in the Quilcayhuanca Basin, in Peru’s Cordillera Blanca. The model was forced by in-situ meteorological observations and parameterized using numerous data sources and process-based studies in the basin. Model results show that during the dry season, 37% of streamflow is generated from GW discharge, increasing to 56% during the lowest flows. Evapotranspiration is the largest mass flux from the basin at the peak of the dry season. Precipitation, temperature, and glacier change scenarios were used to assess the sensitivity of basin hydrology to climate change and glacier retreat. In a warmer, wetter, and nearly deglaciated future, Quilcayhuanca basin streamflow is expected to decrease by 4%–19% annually, with a larger volumetric change in overland and vadose zone flow than in GW flow. The range in values is more closely linked to uncertainty in precipitation change than temperature change. Despite a strong reduction in snow and ice contribution to streamflow with warming and deglaciation, the concomitant increase in precipitation can limit the changes in streamflow and GW flow, showcasing the resilience of the system to shifts in climate and glacier cover.

A 54-year-long series of continuous instrumental measurements of mass balance and its main components has already been accumulated at the Djankuat Glacier, which is representative of the Caucasus and the most studied glacier in Russia. The anomalies of these indicators in 2017/2018–2020/2021 were evaluated against an analysis of meteorological reasons that predetermined them. Each of the four balance years under consideration represents a particular anomaly of varying severity. As for conditions of mass income, three years saw accumulation higher than average, and in one year (2018/2019) it approached the norm. As for summer ablation conditions, similarly, in one season (2019) the melting differed from the average only slightly, but in the other three it was much higher. Consequently, in one year (2020/2021) the state of the glacier was close to normal, in another (2017/2018) the budget situation was much more favorable for Djankuat, and in the other two the final losses significantly exceeded the average annual mass loss rate. At the same time, in 2019/2020, an absolute record of ablation since the beginning of monitoring in 1967/1968 was recorded (4360 mm w.e.). Nevertheless, although negative mass balance values continue to be recorded annually, signs of an inevitable slowdown in the rate of glacier degradation in the Caucasus have appeared in the last 4-year-long period: the continued growth of winter snow accumulation overlaps the ongoing intensification of summer melting. The growth of debris cover in terms of area and thickness also affects this mass loss slowdown to some extent. This inhibits ablation, exerting a heat-insulating effect. Because of this, the congruence of mass balance parameters vs. altitude curves is distorted. Also, a tendency toward increasing annual glacier mass turnover was revealed for the last half-century. This fact gradually increases the energy of glaciation and indirectly indicates a weakening of continentality in the climate of the Caucasian highlands.

The airborne glacier and ice surface topography interferometer (GLISTIN-A) is a single-pass radar interferometer developed for accurate high-resolution swath mapping of dynamic ice surfaces. We present the first validation results of the operational sensor, collected in 2013 over glaciers in Alaska and followed by more exhaustive collections from Greenland in 2016 and 2017. In Alaska, overlapping flight-tracks were mosaicked to mitigate potential residual trends across-track and the resultant maps are validated with lidar. Furthermore, repeat acquisitions of Columbia Glacier collected with a three day separation indicate excellent stability and repeatability. Commencing 2016, GLISTIN-A has circumnavigated Greenland for 4 consecutive years. Due to flight hour limitations, overlapping swaths were not flown. In 2016, comparison with airborne lidar data finds that residual systematic errors exhibit evenly distributed small slopes (all less than 10 millidegrees) and nadir biases were typically less than 1 m. Similarly 2017 data exhibited up to meter-scale nadir biases and evenly distributed residual slopes with a standard deviation of ~10 millidegrees). All satisfied the science accuracy requirements of the Greenland campaigns (3 m accuracy across an 8 km swath).

Temporal variations in ice sheet flow directly impact the internal structure within ice sheets through englacial deformation. Large-scale changes in the vertical stratigraphy within ice sheets have been previously conducted on centennial to millennial timescales; however, intra-annual changes in the morphology of internal layers have yet to be explored. Over a period of 2 years, we use autonomous phase-sensitive radio-echo sounding to track the daily displacement of internal layers on Store Glacier, West Greenland, to millimeter accuracy. At a site located ∼30 km from the calving terminus, where the ice is ∼600 m thick and flows at ∼700 m/a, we measure distinct seasonal variations in vertical velocities and vertical strain rates over a 2-year period. Prior to the melt season (March-June), we observe increasingly nonlinear englacial deformation with negative vertical strain rates (i.e., strain thinning) in the upper half of the ice column of approximately -0.03 a-1, whereas the ice below thickens under vertical strain reaching up to +0.16 a-1. Early in the melt season (June-July), vertical thinning gradually ceases as the glacier increasingly thickens. During late summer to midwinter (August-February), vertical thickening occurs linearly throughout the entire ice column, with strain rates averaging 0.016 a-1. We show that these complex variations are unrelated to topographic setting and localized basal slip and hypothesize that this seasonality is driven by far-field perturbations in the glaciers force balance, in this case generated by variations in basal hydrology near the glaciers terminus and propagated tens of kilometers upstream through transient basal lubrication longitudinal coupling.

Abstract This study appraised and compared the performance of process-based hydrological SWAT (soil and water assessment tool) with a machine learning-based multi-layer perceptron (MLP) models for simulating streamflow in the Upper Indus Basin. The study period ranges from 1998 to 2013, where SWAT and MLP models were calibrated/trained and validated/tested for multiple sites during 1998–2005 and 2006–2013, respectively. The performance of both models was evaluated using nash–sutcliffe efficiency (NSE), coefficient of determination (R 2), Percent BIAS (PBIAS), and mean absolute percentage error (MAPE). Results illustrated the relatively poor performance of the SWAT model as compared with the MLP model. NSE, PBIAS, R 2, and MAPE for SWAT (MLP) models during calibration ranged from the minimum of 0.81 (0.90), 3.49 (0.02), 0.80 (0.25) and 7.61 (0.01) to the maximum of 0.86 (0.99), 9.84 (0.12), 0.87 (0.99), and 15.71 (0.267), respectively. The poor performance of SWAT compared with MLP might be influenced by several factors, including the selection of sensitive parameters, selection of snow specific sensitive parameters that might not represent actual snow conditions, potential limitations of the SCS-CN method used to simulate streamflow, and lack of SWAT ability to capture the hydropeaking in Indus River sub-basins (at Shatial bridge and Bisham Qila). Based on the robust performance of the MLP model, the current study recommends to develop and assess machine learning models and merging the SWAT model with machine learning models.

BackgroundGlaciers cover ~ 10% of land but are among the least explored environments on Earth. The basal portion of glaciers often harbors unique aquatic microbial ecosystems in the absence of sunlight, and knowledge on the microbial community structures and their metabolic potential is very limited. Here, we provide insights into the microbial lifestyle present at the base of the Matanuska Glacier, Alaska.ResultsDNA and RNA were extracted from samples of the Matanuska Glacier basal ice. Using Illumina MiSeq and HiSeq sequencing, we investigated the microbial diversity with the metagenomic shotgun reads and 16S ribosomal RNA data. We further assembled 9 partial and draft bacterial genomes from the metagenomic assembly, and identified key metabolic pathways such as sulfur oxidation and nitrification. Collectively, our analyses suggest a prevalence of lithotrophic and heterotrophic metabolisms in the subglacial microbiome.ConclusionOur results present the first metagenomic assembly and bacterial draft genomes for a subglacial environment. These results extend our understanding of the chemical and biological processes in subglacial environments critically influenced by global climate change.

Abstract Glaciers and ice caps (GICs) are important contributors of meltwater runoff and to global sea level rise. However, knowledge of GIC mass changes is largely restricted to the last few decades. Here we show the extent of 5327 Greenland GICs during Little Ice Age (LIA) termination (1900) and reveal that they have fragmented into 5467 glaciers in 2001, losing at least 587 km3 from their ablation areas, equating to 499 Gt at a rate of 4.34 Gt yr−1. We estimate that the long‐term mean mass balance in glacier ablation areas has been at least −0.18 to −0.22 m w.e. yr−1 and note the rate between 2000 and 2019 has been three times that. Glaciers with ice‐marginal lakes formed since the LIA termination have had the fastest changing mass balance. Considerable spatial variability in glacier changes suggest compounding regional and local factors present challenges for understanding glacier evolution.

Abstract The accessibility and simplicity of monitoring instruments and processing methods are crucial for environmental monitoring worldwide. There is growing evidence that proglacial discharge may be observed by listening to the glacier terminus using sophisticated tools, such as the micro‐barometer arrays that are used for nuclear‐test monitoring and the fiber‐optic technologies that are becoming increasingly used in geophysics. However, the prohibitive cost, instrumental complexity, overwhelming data volumes, and computational demands of these approaches mean that only the wealthiest countries can afford such technologies. We employ an intentionally inexpensive approach to monitor proglacial discharge by recording the audible sound that is generated near the glacier terminus, and we show that a simple microphone can tell us how much water is discharged by a glacier. This study demonstrates that sound can provide essential information on runoff and therefore contribute to environmental assessments of glaciers and disaster risk reduction of glacial flood events.

Abstract Droughts can lead to extreme low flow situations in rivers, with resulting severe impacts. Upstream snow and ice melt in many of the world's mountain water towers can alleviate the hydrological consequences of drought, yet global warming threatens the cryosphere. To improve the understanding of melt water contributions during drought in the case of future glacier retreat, we developed stress‐test storyline scenarios to model streamflow and tested them in the European river Rhine basin. Meteorological conditions of past drought and low flow years in Europe, 1976, 2003, and 2018, were repeated at three future moments in time, representing nowadays, near future and far future conditions. The latter two conditions were obtained by climate projections under the RCP8.5 scenario. Results show that the low flow situations caused by the meteorological drought situations aggravate in future conditions, more so for the far future and for the year 2003 because of the relatively large glacier ice melt contribution in the past. Summer (July–September) streamflow may decline by 5%–25% far downstream and 30%–70% upstream and the duration of extreme low flow situations may double compared to the selected past drought events. These results are relevant for the Rhine as a major European river but stand exemplary for many other river basins and highlight the importance of cryospheric changes for downstream low flow situations in a changing climate. The stress‐test scenarios allow a glimpse into future extreme low flow events aiding adaptation planning, and might be adapted to include other important low flow drivers.

Glacier mass balance and its sensitivity to climate change depend to a large degree on the albedo and albedo feedback. Although recent increasing studies reconstruct the annual surface mass balance (SMB) based on the relationships between satellite-derived minimum albedo and annual glaciological mass balance (so-called albedo method), a relationship remains conjectural for Tien Shan glaciers. Accumulation and ablation occur simultaneously in summer, causing different surface processes. We examine this relationship using glaciological mass-balance data and the equilibrium-line altitude (ELA) made on the eastern branch of Urumqi Glacier No. 1 (UG1-E), Tuyuksu, Golubin and Glacier No. 354, and ablation-season (May–September) albedo retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) images from 2000 to 2021. Compared with minimum ablation-season albedo, we find higher coefficients of determination between mean ablation-season albedo and glaciological mass balance at UG1-E and Tuyuksu. In contrast, for Golubin and Glacier No. 354, glaciological mass balance is higher correlated to minimum ablation-season albedo than mean ablation-season albedo. This difference is related to the glaciological mass-balance time period. The relationship between albedo and glaciological mass balance is obtained over a shorter time for Golubin (8 years) and Glacier No. 354 (9 years) than for UG1-E (20 years) and Tuyuksu (20 years). Non-etheless, based on the correlativity between MODIS-derived mean ablation-season albedo and minimum ablation-season albedo and glaciological mass balance of Golubin and Glacier No. 354 over the 2011–2019 period, the annual SMB for these glaciers can be reconstructed using the albedo method over the period 2000–2010. Comparison with previously reconstructed results indicated that the mass balance derived from albedo is robust for Glacier No. 354, while for Golubin, the results derived from the albedo method only captured the relative changes in mass balance. The current study suggested that ablation-season albedo can be regarded as a proxy for annual mass balance, and mean ablation-season albedo may be more reliable than minimum ablation-season albedo for some Tien Shan glaciers.

The concentration of heavy metals (Cr, Ni, Mo, Mn, Pb, Zn, Ag, Cu, Cd, Co, Al, Fe, V) in one of the most powerful glaciation sites in the Caucasus (Mount Elbrus) since the mid-20th century is investigated. To compare the concentrations of heavy metals in the sources of the Baksan River with those in the Garabashi glacier, a stationary point at a level of 4000 m was chosen, where observations of the glacier mass balance are carried out. The number of pit samples depended on the snow accumulation and varied from 7–8 to 18–20 in accordance with the depth of the seasonal snow layer. The concentrations of heavy metals in the ice, snow, and river water samples were determined during the period from 1978 to 2010 at High-mountain Geophysical Institute by the emission spectral analysis. The analysis of samples from 2018–2021 was performed by the atomic absorption method on an MGA-915 spectrometer. Among all categories of the samples taken on the Elbrus slope, the least impurities were found in pure ice on the tongue of the glacier: it contains three times less impurities of Ag, Ni, Mo, Pb: 0.014, 1.15, 0.18, 0.83 g/L, respectively. In some samples, the metal content is below the detection limit. The concentrations of heavy metals in the seasonal snow pack and river water in the Elbrus region are one–two orders of magnitude lower than maximum permissible concentrations for sanitary water bodies. For the Baksan River basin and the Elbrus glaciation region, there is a slight decrease in the concentrations of heavy metals from the end of the 20th century until the present, with intensive degradation of glaciers. [ABSTRACT FROM AUTHOR]

In the last decade, unmanned aerial vehicles (UAVs) have been used for scientific research specially for glaciological applications in Antarctica. In the study an UAV was used to detect changes in Znosko glacier surface, map the glacier contour, snow line and estimate the geodetic mass balance. Znosko glacier (ZG) located in King George Island (KGI), Antarctic Peninsula has an estimated total area of 1.77 km2 (January 2020), a length of 1.9 km and maximum elevation of 300 metres above sea level (m a.s.l.). The aerial photogrammetric survey was carried out in two field campaigns (austral summer 2019 and 2020) during the XXVI and XXVII Peruvian Antarctic Operation using a Quadcopter for image acquisition. Our findings reveal a negative geodetic mass balance for the periods 2019–2012, 2020–2019 and 2020–2012 with −15.25, −2.76 and −17.97 metre water equivalent (m w.e.) respectively. Analysis of these datasets confirm a mass loss with a heterogeneous pattern between accumulation and ablation zone. Furthermore, glacier outlines reveal that ZG front has lost approximately 3% of its area between 2012 and 2020 by calving effect. [ABSTRACT FROM AUTHOR]

Polar marine environments host a complex assemblage of cold-adapted auto- and heterotrophic microorganisms that affect water biogeochemistry and ecosystem functions. However, due to logistical difficulties, remote regions like those in close proximity to glaciers have received little attention, resulting in a paucity of microbiological data. To fill these gaps and obtain novel insights into microbial structure and function in Arctic regions, a survey of microbial communities in an area close to the Blomstrandbreen glacier in Kongsfjorden (Svalbard Archipelago; Arctic Ocean) was carried out during an early summer period. An Unmanned Autonomous Vehicle designed to safely obtain seawater samples from offshore-glacier transects (PROTEUS, Portable RObotic Technology for Unmanned Surveys) was equipped with an automatic remotely-controlled water multi-sampler so that it could sample just beneath the glacier, where access from the sea is difficult and dangerous. The samples were analysed by image analysis for the abundance of total prokaryotes, viable and respiring cells, their morphological traits and biomass; by flow cytometry for autotrophic and prokaryotic cells (with high and low nucleic acid contents) as well as virus-like particle counts; by BIOLOG ECOPLATES for potential community metabolism; and by fluorimetry for potential enzymatic activity rates on organic polymers. Contextually, the main physical and chemical (temperature, salinity, pH, dissolved oxygen and nutrients) parameters were detected. Altogether, besides the PROTEUS vehicle's suitability for collecting samples from otherwise inaccessible sites, the multivariate analysis of the overall dataset allowed the identification of three main sub-regions differently affected by the haline gradient (close to the glacier) or terrigenous inputs coming from the coast. A complex microbiological scenario was depicted by different patterns of microbial abundance and metabolism among the transects, suggesting that ice melting and Atlantic water inflow differently supported microbial growth. [ABSTRACT FROM AUTHOR]

The extent of glaciers in the western French Alps foreland during the last glacial maximum (LGM, 26.5-19 ka) has not yet been determined, so understanding glacial paleogeography during the LGM remains an open question. This study focuses on the glacial chronology in the western French Alps piedmont using 10Be surface exposure ages on nine glacial boulders and 12 erratic boulders. Results indicate an LGM glacier advance between ca. 24 and 21 ka. During the late LGM, a smaller glacier readvance or stabilization phase occurred at ca. 19 ka, which was followed by a withdrawal phase between ca. 19 and 16.5 ka. Our outcomes show that the LGM extent in the western French Alps was similar or slightly less extensive than the pre-LGM ice extents during the last glacial. Such paleogeography has also been suggested in the western Italian Alps, which share the same accumulation zone with the western French Alps glaciers. The LGM dynamic of the western French Alps foreland glaciers highlighted by our exposure ages is consistent with the timing of the LGM glacier advances and deglaciation with the western Italian ice lobes. [ABSTRACT FROM AUTHOR]

On 3 July 2022, a section of the Marmolada glacier (Marmolada Group, Fassa Dolomites, Southern Limestone Alps) collapsed, causing an ice avalanche resulting in the death of 11 alpinists. Before the event, there were no clear signs of any potential collapse, and no warning notices were broadcasted; due to the velocity of the avalanche, no escape was possible for the involved persons. In this work, a preliminary analysis of the Marmolada glacier collapse is performed with four optical channels space imaging provided by Planet Labs, with resolution of 3 m per pixel. Pre- and post-event satellite observations are employed to assess the areas involved in the event: multispectral images can be compared to identify the collapse area and the debris conoid. A first estimation suggests a collapse area of about 4800 m2 and a collapse volume of about 96,000 m3. In addition, historical data from the Planet Labs optical pictures database can be employed to compare the status of the detached glacier and the evolution of the crevasses on its surface. [ABSTRACT FROM AUTHOR]

The accelerating flux of glacial meltwater to the oceans due to global warming is a potential trigger for future climate disturbance. Past disruption of Atlantic Ocean circulation, driven by melting of land‐based ice, is linked in models to reduced ocean‐atmosphere heat transfer and abrupt cooling during stadial events. The most recent stadial, the Younger Dryas (YD), is traditionally viewed as a severe cooling centered on the North Atlantic but with hemispheric influence. However, indications of summer warmth question whether YD cooling was truly year‐round or restricted to winter. Here, we present a beryllium‐10‐dated glacier record from the north‐east North Atlantic, coupled with 2‐D glacier‐climate modeling, to reconstruct Lateglacial summer air temperature patterns. Our record reveals that, contrary to the prevailing model, the last glacial advance in Scotland did not occur during the YD but predated the stadial, while the YD itself was characterized by warming‐driven deglaciation. We argue that these apparently paradoxical findings can be reconciled with regional and global climate events by invoking enhanced North Atlantic seasonality—with anomalously cold winters but warming summers—as an intrinsic response to globally increased poleward heat fluxes. Plain Language Summary: The accelerating melting of the Greenland Ice Sheet has key ramifications for North Atlantic Ocean circulation and heat transport. In the paleoclimate record, discrete periods of ocean current weakening are linked to increased meltwater input from collapsing ice sheets and are believed to have driven severe year‐round cooling of adjacent landmasses; these periods are known as stadials. Yet, research on the Younger Dryas (YD) stadial suggests that summers may have remained warm. We present a new glacier record from northwest Scotland to reconstruct patterns of stadial summer air temperature in the North Atlantic. Our data reveal that the last glacial advance did not occur during the YD, as widely assumed, but predated the stadial. The YD itself was a period of deglaciation indicative of summer climate warming. We propose that stadials are anomalous periods of high seasonality in the North Atlantic region, with cold winters but warming summers, and might be a persistent feature of AMOC disruption, both past and future. Key Points: Lateglacial fluctuations of Scottish glaciers are dated with 10Be. Equilibrium line altitudes are resolved via glacier‐climate modelingThe last pulse of glaciation culminated prior to the Younger Dryas (YD), while the stadial was characterized by deglaciation and summer warmingThe YD stadial was defined by anomalous thermal seasonality in the North Atlantic region, rather than by year‐round cooling [ABSTRACT FROM AUTHOR]

Monitoring alpine lakes is important for understanding the regional environmental changes caused by global warming. In this study, we provided a detailed analysis of alpine lake changes in the Tianshan Mountains (TS) and discussed their driving forces based on Landsat TM/ETM+/OLI, WorldView-2, Bing, Google Earth, and ASTER imagery, along with climatic data from 1990 to 2015. The results showed that during the study period, the total number and area of alpine lakes in the eastern TS exhibited an increasing trend, by 64.06% and 47.92%, respectively. Furthermore, the continuous expansion of glacial lakes contributed 95.12% and 94.17% to the total increase in the number and area, respectively, of alpine lakes. Non-glacial lakes exhibited only intermittent expansion. Since the 1990s, the new glacial lakes in the eastern TS have been mainly proglacial and extraglacial lakes. Over the past 25 years, eastern TS has experienced a temperature increase rate of 0.47 °C/10a, which is higher than that in other TS regions. The rapidly warming climate and glacier recession are the primary causes of the accelerated expansion of glacial lakes in the eastern TS. [ABSTRACT FROM AUTHOR]

On the basis of in situ weather observations and a physical-based model, verified by a glaciological method, this article investigates the surface energy balance of the Aldegondabreen glacier during the summer melt season of 2021. Aldegondabreen (5.3 km2) is a low-elevation glacier near the western shore of Spitsbergen Island. On the timescale of the whole melt season, the prevalent positive heat flux is a shortwave radiative balance (84 percent). This result is in accordance with previous studies on similar low-elevation Svalbard glaciers. However, in August and September, when the sun is low, the turbulent fluxes may outweigh the input of the shortwave balance. The study identified six events of significantly increased turbulent fluxes, which contributed to 10 percent of the total heat influx, and attributed them to the particular type of synoptic situation. All of these events are related to cyclonic activity, which drastically increased the wind speed in the study area and, consequently, both sensible and latent heat fluxes. The frequency of the extreme cyclonic events in the Svalbard region is increasing, which may potentially extend the duration of the glacier melt season in the mid- and late autumn or reduce the accumulation of solid precipitation in that time period. [ABSTRACT FROM AUTHOR]