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The postglacial recolonization of Fennoscandian flora and fauna was initiated when the land became accessible as the last ice sheet retreated. In northern Sweden, plants are represented in pollen and macrofossil records, but there is no genetic evidence from the first plants, animals or humans in the region, mainly owing to an absence of osteological finds. The questions of who the first postglacial peoples, or pioneers, were and where they came from therefore remain unanswered. Previous palaeogenomic analyses from remains from adjacent regions have suggested that two main routes into Sweden could have been taken by the pioneers, one from the SW through modern‐day Denmark and Norway, and one from the east via Finland. However, no direct genetic evidence from the pioneers of northern Sweden exists. Modern technology has provided the ancient DNA field with an updated toolbox that could allow for novel approaches for revealing the origin and genetic profiles of the first Scandinavians, of which sedimentary ancient DNA (sedaDNA) is well placed. Lake sediments are now a routine source of sedaDNA that have been used to record environmental changes and detect species that lived in the surrounding lake catchment. This review will provide context and background, a summary of the ground‐breaking studies within the field of lacustrine sedaDNA, and relevant methodology to address the scientific questions at hand. We conclude that the field is mature enough to provide insight into the origins and arrival times of the first postglacial humans that migrated into northern Sweden. [ABSTRACT FROM AUTHOR]

This study uses a multiproxy approach including the first use of 187Os/188Os, %C37:4 biomarkers, carbonate content, sedimentological grain size, geochemical X‐ray fluorescence and microfossil benthic foraminifera species combined with radiocarbon dating, measured on six cores from across the Skagerrak, in order to study the Lateglacial to Middle Holocene history of the area. A new chronostratigraphic framework is developed based on the appearance of specific benthic foraminifera species along with changes in carbonate/X‐ray fluorescence and grain size data. This allowed the correlation of cores based on a series of radiocarbon dated tie points. Analysing the cores together reveals several events recorded in the Skagerrak including: (i) an increased freshwater input (bracketed between 13.3 and 11.3 cal. ka BP) signified by radiogenic 187Os/188Os values, high %C37:4 values and an increase in sand content; (ii) the Glomma drainage event, signified by a sudden appearance of Valvulineria as well as higher %C37:4; and (iii) the opening of the Danish Straits and English Channel leading to the development of modern‐day conditions and circulation patterns in the Skagerrak, signified by the appearance of Hyalinea balthica and a fall in %C37:4. [ABSTRACT FROM AUTHOR]

We present a new model called Bayesian Estimated Glacial Lake Volume (BE‐GLAV) to estimate the volume of proglacial lakes. Presuming the lake cross‐section as trapezoidal, BE‐GLAV uses a Bayesian calibration approach to adjust the cross‐sectional geometry to match modeled and observed lake surface widths. We validated our model using bathymetric measurements from lakes spread across High Mountain Asia (specifically, the Himalaya and Tien‐Shan), with aerial extents ranging from 0.01 to 5.5 km2. The modeled lake volumes agreed with the measured lake volume with a root‐mean‐square absolute uncertainty of ∼14%. With minimum and maximum errors of ∼0.3% and ∼61.2%, BE‐GLAV performed well compared to 10 other models in a model inter‐comparison experiment. Using the measured set of volumes, our model can constrain both the root mean square (RMS) error and the maximum percentage error in modeled lake volume, unlike other models, some of which can compute just the RMS uncertainty. Plain Language Summary: To estimate proglacial lake volume, we suggest a novel numerical model called BE‐GLAV, which is based on Bayesian calibration. The model minimizes the discrepancy between the measured and modeled lake surface width by assuming that the proglacial cross‐section is trapezoidal in shape. The model was applied to 66 lakes located in the Himalaya and Tien‐Shan. Modeled and measured volumes were in good agreement with each other (∼14% mean absolute uncertainty). We also compared our volume estimates to those predicted by 10 other models. These 10 models were scaling relationships between the area and volume of proglacial lakes. The comparison showed that, our model was among the top five performers, reducing the maximum error in lake volume by more than five times. BE‐GLAV is a good alternative to scaling models in areas where bathymetric surveys are scarce. When compared to scaling models, it is easy to implement and requires little calibration. Key Points: Bayesian calibration based estimation of proglacial lake volumeModel was validated over 66 lakes and the maximum error in modelled volume got reduced by >5 times as compared to scaling modelsRequires minimal calibration with observations as compared to scaling models [ABSTRACT FROM AUTHOR]

Addressing impacts of flash droughts (FDs) on the water‐food nexus requires a understanding of FD mechanisms and drivers at the watershed level. Examining climatic drivers, dry and wet spell lengths from 1980 to 2019, we analyzed FD spatial and temporal characteristics, emphasizing areal extent, onset time, and duration. Our findings reveal substantial variations in FDs among different watersheds. Notably, watersheds in the Southern Hemisphere are witnessing expanding, faster‐developing, and longer‐lasting FDs, aligning with climate variations in precipitation and temperature. Additionally, at the watershed scale, the onset and duration of FDs are more influenced by the intensity (magnitude and variability) of climatic drivers than the average length of wet and dry periods. FD‐extents, however, correlate with both climatic conditions and wet and dry periods, underscoring watershed connectivity. Ultimately, our results underscore the necessity for research to comprehend the interplay between FDs and watershed characteristics and how it manifests in overall water resource management. Plain Language Summary: Flash droughts (FDs), which are sudden and severe dry periods, are causing problems for our water and food systems and making it harder to prepare for disasters. To address these challenges effectively, it is crucial to gain a thorough understanding of the underlying mechanisms and factors driving FDs at the watershed level. In this study, we looked at climatic patterns alongside the lengths of dry and wet periods spanning from 1980 to 2019. Our primary focus was on three key aspects: the extent of FDs, when they begin, and how long they persist. Our research findings demonstrate considerable variations in FDs occurrences across different regions. Notably, in the Southern Hemisphere, FDs are expanding rapidly, developing more swiftly, and enduring for extended periods, closely mirroring shifts in precipitation and temperature patterns. Interestingly, the onset and duration of FDs seem to depend more on the intensity of climatic factors than on how long it's been dry or wet. The expansion of FDs in a region is linked to both the climatic and dry/wet periods, emphasizing the geophysical connectivity within a watershed. Key Points: Watersheds in tropical, temperate climates, and with savanna and grassland land cover are more susceptible to flash droughts (FDs)FDs extents are affected by intraannual precipitation variability, but not by intraannual air temperature variabilityThe onset and duration of FD at the watershed scale are influenced more by climate variables, than average wet/dry spell periods [ABSTRACT FROM AUTHOR]

Long‐term records of the flow patterns and dynamics of surge‐type glaciers improve our understanding of their underlying dynamic processes, and are critical to better resolve their contribution to a changing cryosphere. We adapt a modeling approach designed to emulate glacier surging and fold kinematics using the full Stokes ice‐flow model Elmer/Ice to simulate surging of the Dusty Glacier, located in the St. Elias Mountains, Canada. We combine distributed mass‐balance and numerical ice‐flow models to reconstruct the fold kinematics of the 2001–2003 surge of the Dusty Glacier by comparing model results to Landsat‐7 and Sentinel‐2 imagery, and assess the sensitivity of centennial‐scale modeled glacier structure to different mass balance and sliding parameterizations. This study demonstrates the feasibility of using the approach to reconstruct the surface structure kinematics of a surge‐type glacier in nature, highlighting its potential application to other surge‐type glaciers and regions. Plain Language Summary: Glaciers can exhibit irregular flow patterns that complicate predictions of their evolution over the coming decades and centuries. We present a method for reproducing iconic surface structures known as folded medial moraines using glaciological modeling. These moraines are wavy flow patterns found on surge‐type glaciers, highlighted by sediment deposited onto the ice that traces their path. By reconstructing these patterns, the underlying climate and sliding conditions that contributed to the glacier's past flow can be identified. Improving our knowledge of these conditions can help improve glacier flow models. We demonstrate that our methodology successfully reconstructs the flow patterns present on a large surge‐type glacier in Yukon, Canada, and explore its past flow history, and possible future, based on these results. Key Points: We use a distributed mass‐balance model and Elmer/Ice to reconstruct the 2001–2003 surge kinematics of the Dusty Glacier, Yukon, CanadaWe explore the centennial‐scale sensitivity of glacier surface fold geometry to mass balance and sliding parameterizationsThis study is a proof‐of‐concept for further model reconstructions of the past dynamics of surge‐type glaciers [ABSTRACT FROM AUTHOR]

Estimating the frequency and magnitude of natural hazards largely hinges on stationary models, which do not account for changes in the climatological, hydrological, and geophysical baseline conditions. Using five diverse case studies encompassing various natural hazard types, we present advanced statistical and machine learning methods to analyze and model transient states from long‐term inventory data. A novel storminess metric reveals increasing European winter windstorm severity from 1950 to 2010. Non‐stationary extreme value models quantify trends, seasonal shifts, and regional differences in extreme precipitation for Germany between 1941 and 2021. Utilizing quantile sampling and empirical mode decomposition on 148 years of daily weather and discharge data in the European Alps, we assess the impacts of changing snow cover, precipitation, and anthropogenic river network modifications on river runoff. Moreover, a probabilistic framework estimates return periods of glacier lake outburst floods in the Himalayas, demonstrating large differences in 100‐year flood levels. Utilizing a Bayesian change point algorithm, we track the onset of increased seismicity in the southern central United States and find correlation with wastewater injections into deep wells. In conclusion, data science reveals transient states for very different natural hazard types, characterized by diverse forms of change, ranging from gradual trends to sudden change points and from altered seasonality to overall intensity variations. In synergy with the physical understanding of Earth science, we gain important new insights into the dynamics of the studied hazards and their possible mechanisms. Plain Language Summary: According to global databases on natural hazard events and associated risks, there has been a noteworthy escalation in the extent of economic losses during past decades. It is important but difficult to distinguish and disentangle trends due to changing hazard occurrence or damage potential. Accurately quantifying altered hazards requires high‐quality data sets and robust statistical methodologies. Here, we present recent progress in earth and data science toward a quantitative assessment of natural hazards in a changing world. We show that winter storms have become more frequent and more severe in Europe; that extreme precipitation in Germany shows seasonal shifts and changing intensities with regional variation; that river runoff in Central Europe is changing due to modifications of the river network, declining snowpacks, and changes in precipitation; that frequency of glacier lake outburst floods in the Himalayas have remained unchanged over the past 30 years despite rapid glacier melt and lake growth; and that earthquake activity in Oklahoma (USA) has increased with the onset of wastewater injection wells. We infer that recent advances in data science can efficiently provide new knowledge from big data sets, but interpreting these results needs a solid understanding and rather detailed analysis of the underlying processes. Key Points: Time‐dependent approaches are key to capture changing hazards, with diverse altered frequencies, intensities, timing or spatial occurrencesAdvances in data‐driven methods and increasing availability of geodata foster new ways to detect changes in natural hazardsOver‐simplification or averaging over large scales in time or space cause severe information loss and may hide the mechanisms for change [ABSTRACT FROM AUTHOR]

High resolution DEMs obtained from LiDAR topographic data have led to improved landform inventories (e.g. landslides and fault scarps) and understanding of geomorphic event frequency. Here we use airborne LiDAR mapping to investigate meltwater pathways associated with the Tweed Valley palaeo ice-stream (UK). In particular we focus on a gorge downstream of Palaeolake Milfield, previously mapped as a sub-glacial meltwater channel, where the identification of abandoned headcut channels, run-up bars, rock-cut terrace surfaces and eddy flow features attest to formation by a sub-aerial glacial lake outburst flood (GLOF) caused by breaching of a sediment dam, likely an esker ridge. Mapping of these landforms combined with analysis of the gorge rim elevations and cross-section variability revealed a two phase event with another breach site downstream following flow blockage by higher elevation drumlin topography. We estimate the magnitude of peak flow to be 1-3 × 103 m3/s, duration of the event to range from 16-155 days, and a specific sediment yield of 107-109 m3/km2/yr. We identified other outburst pathways in the lower Tweed basin that help delineate an ice margin position of the retreating Tweed Valley ice stream. The results suggest that low magnitude outburst floods are under-represented in Quaternary geomorphological maps. We therefore recommend regional LiDAR mapping of meltwater pathways to identify other GLOFs in order to better quantify the pattern of freshwater and sediment fluxes from melting ice sheets to oceans. Despite the relatively low magnitude of the Till outburst event, it had a significant impact on the landscape development of the lower Tweed Valley through the creation of a new tributary pathway and triggering of rapid knickpoint retreat encouraging new regional models of post-glacial fluvial landscape response. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Holocene glaciers have contributed to an abundance of unstable sediments in mountainous environments. In permafrost environments, these sediments can contain ground ice and are subject to rapid geomorphic activity and evolution under condition of a warming climate. To understand the influence of ground ice distribution on this activity since the Little Ice Age (LIA), we have investigated the Pierre Ronde and Rognes proglacial areas, two cirque glacier systems located in the periglacial belt of the Mont Blanc massif. For the first time, electrical resistivity tomography, temperature data loggers and differential global positioning systems (dGPS) are combined with historical documents and glaciological data analysis to produce a complete study of evolution in time and space of these small landsystems since the LIA. This approach allows to explain spatial heterogeneity of current internal structure and dynamics. The studied sites are a complex assemblage of debris-covered glacier, ice-rich frozen debris and unfrozen debris. Ground ice distribution is related to former glacier thermal regime, isolating effect of debris cover, water supply to specific zones, and topography. In relation with this internal structure, present dynamics are dominated by rapid ice melt in the debris-covered upper slopes, slow creep processes in marginal glacigenic rock glaciers, and weak, superficial reworking in deglaciated moraines. Since the LIA, geomorphic activity is mainly spatially restricted within the proglacial areas. Sediment exportation has occurred in a limited part of the former Rognes Glacier and through water pocket outburst flood and debris flows in Pierre Ronde. Both sites contributed little sediment supply to the downslope geomorphic system, rather by episodic events than by constant supply. In that way, during Holocene and even in a paraglacial context as the recent deglaciation, proglacial areas of cirque glaciers act mostly as sediment sinks, when active geomorphic processes are unable to evacuate sediment downslope, especially because of the slope angle weakness. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Cryospheric responses to climate warming include glacier retreat, altitude‐dependent thermal instability, and abundant meltwater, which increase the frequency of catastrophic glacier hazard chain (CGHC) events. Here we investigated the formation mechanism of a special CGHC event in 2018, in the Sedongpu Glacier, Eastern Himalayas, China. Based on the multi‐source remote sensing, seismic signal analysis, and numerical simulation, we conducted long‐term retrospective analysis and co‐event process reconstruction. The results show that the event could be divided into two phases. First, the hanging glacier with a volume of 8.5 × 106 m3 collapsed onto the downstream trunk glacier. Next, ∼1.17 × 108 m3 eroded materials from the impacted glacier transformed into debris flow and traveled downstream 8 km. During the cascading process, ice‐rock avalanche momentum and glacier velocity are key factors in determining CGHC formation and eventual volume. Our study helps better understand the domino effects of the CGHC disaster. Plain Language Summary: Glacier instability in cryosphere is significantly influenced by global warming. The glacial lake outburst floods are the most widely studied and catastrophic events resulting from this instability, but they are not the only ones. In recent years, increasing catastrophic glacier hazard chain (CGHC) events have reminded us of disasters during climate warming, especially in the Himalayas region. Here, we report a typical CGHC event in the Eastern Himalayas, where the retreated glaciers are widely distributed. Based on our observations and simulations, we completed the retrospective analysis of CGHC through its formation conditions, evolution process, and specific kinematic process. These analyses help us understand the driving mechanism, the volume‐increasing effect, and the super‐fluidity of CGHC. Our findings help improve such hazard chain identification and mitigation in the Eastern Himalayas and glacierized environments elsewhere in the world. Key Points: New insights of Ice‐rock avalanche hazard chain on retreated hanging glacier in Eastern HimalayaErosion process on the trunk glacier led to a volume‐increasing and super‐fluidity of catastrophic glacier hazard chain (CGHC)The pre‐evolution and formation of CGHC were closely related to climate warming [ABSTRACT FROM AUTHOR]

As the world's glaciers recede in response to a warming atmosphere, a change in the magnitude and frequency of related hazards is expected. Among the most destructive hazards are glacier lake outburst floods (GLOFs), and their future evolution is concerning for local populations and sustainable development policy. Central to this is a better understanding of triggers. There is a long‐standing assumption that earthquakes are a major GLOF trigger, and seismic activity is consistently included as a key hazard assessment criterion. Here, we provide the first empirical evidence that this assumption is largely incorrect. Focusing on the Tropical Andes, we show that, of 59 earthquakes (1900–2021) the effects of which intersect with known glacier lakes, only one has triggered GLOFs. We argue that, to help develop climate resilient protocols, the focus for future assessments should be on understanding other key GLOF drivers, such as thawing permafrost and underlying structural geology. Plain Language Summary: Climate change is increasing glacier melt in high mountains and increasing the size and number of glacial lakes. Over time, these lakes may drain catastrophically to generate glacier lake outburst floods (GLOFs), which can devastate downstream communities and destroy valuable infrastructure such as roads, bridges, and hydroelectric power facilities. As a result, many risk assessments have been carried out to understand what the triggers of GLOFs might be, in order to better predict their occurrence. One of the main triggers has been assumed to be earthquakes, but this association has not been properly tested. In this paper, we use earthquake and GLOF data from the Peruvian and Bolivian Andes to test this and find that there is little association between earthquakes and GLOFs. We conclude by arguing that focus needs to be on other GLOF triggers, and earthquake activity should be used as a secondary – not primary – indicator in GLOF susceptibility studies. Key Points: Glacier lake outburst floods (GLOFs) are a major risk concern, with earthquakes being commonly considered effective triggers in hazard assessmentsOf 59 earthquakes (1900–2021), the effects of which intersect lakes in the Tropical Andes, only one triggered GLOFsWe suggest that earthquake activity should be used as a secondary – not primary – susceptibility indicator for GLOFs [ABSTRACT FROM AUTHOR]

Subsurface deposits in recently glaciated marine areas are highly heterogeneous, representing a range of glacial and postglacial environments and processes including glacitectonism, overconsolidation, fluvial and lacustrine deposition, and transgression. These heterogeneities are often linked to variations in engineering properties, with important implications for the design and installation of offshore wind infrastructure. In this study we present an integrated geological characterization of the Sørlige Nordsjø II offshore wind site, located in waters of 50–70 m depth along the southern border of the Norwegian North Sea, focusing on the evolution of the area's depositional setting during the late Quaternary period and its implications for offshore wind development. We integrate interpretations from a marine geological data set acquired in 2022 with legacy 3D seismic data and a review of the current understanding of the southern North Sea's complex glacial history. A preliminary ground model and accompanying risk map for the site is presented with five main geological units: (i) homogeneous and layered marine sands covering most of the site, with patchy distribution and coarser‐grained deposits in the east; (ii) buried, layered channel deposits containing organic material and possible associated shallow gas; (iii) buried, stiff glacilacustrine clay deposits; (iv) a buried, layered, glacitectonized unit incised by tunnel valleys, with a sandy marine infill; and (v) mounded tills and glacitectonized deposits containing boulders, exposed to shallowly buried in the east. Salt diapirism and gas migration were also found to be important potential geohazards at the site. Three‐dimensional seismic attribute maps were found to be a powerful aid to understanding the distribution and genesis of seismic facies identified on 2D high‐resolution sub‐bottom profiles. This type of data integration is an under‐utilized methodology for generating detailed preliminary ground models, which can inform more cost‐effective site survey and early foundation concept planning at geologically complex offshore wind sites. [ABSTRACT FROM AUTHOR]

Pore‐fluid pressure (PP) plays an important role in bed erosion, but the mechanisms that control PP evolution and the resulting feedbacks on flow dynamics are unclear. Here, we develop a general formulation, allowing quantification of the propensity for PP evolution of saturated and unsaturated bed sediments. We conduct erosion experiments by systematically varying grain composition and water content of beds, for investigating effects of PP evolution on flow erosion. With increasing water content, PP shows a slight rise in deforming beds with drained behavior but significant larger rise in undrained beds. Regardless of bed composition, the erosion rate of beds presents a synchronous change tendency with PP evolution due to the loss in basal friction. PP instigates positive feedback that induces a remarkable gain of flow velocity and momentum on wet beds with undrained behavior. Our results help explain observations of volume growth and long run out of debris flows. Plain Language Summary: Debris flows are common geophysical flows consisting of debris grains and muddy water. Debris flows can grow significantly in volume and mobility as they pick up loose sediment from gully bed and banks. The destructive potential of debris flows increases with increasing flow volume and run out. This brings about great challenges for effective early warning of debris flows, design of prevention measures and mapping of hazard zones related to human settlements. It is commonly believed that flow momentum is consumed by carrying static bed sediments. However, flows can gain momentum by overriding wet bed sediments. This can be explained by pore‐pressure generation as debris flows move across wet beds. The increase of measured pore‐fluid pressure is limited for beds with a low water content, but substantial for beds with a higher water content, which strongly affects the erosion rates of bed sediments. Flow velocity and momentum on wet beds are observed to increase significantly but slightly for dryer beds as a result of the pore‐pressure feedback. These findings indicate that the debris composition of the catchment, the water content of bed sediment and the pore‐pressure development should be evaluated when making predictions on debris‐flow hazard. Key Points: Propensity for pore pressure evolution of bed sediments during debris‐flow erosion is evaluated by a Deborah numberSignificant pore pressure and accompanying intense erosion occur for wet bed sediments with undrained behaviorEnhanced pore pressure of wet bed sediments reduces flow basal friction, increasing flow mobility and runout [ABSTRACT FROM AUTHOR]

High‐resolution present‐day earth surface deformation maps from satellites provide important data constraints, which help us better understand tectonic processes and analyze seismic hazards. Here, we use Sentinel‐1 Radar images (2014–2020) and accurate positioning measurements (2009–2019) to get a high‐resolution three‐dimensional earth surface velocity map for the northeastern Tibetan Plateau, and we invert the slip rate and coupling ratio of major regional faults. We find ∼4 mm/yr uplift along an arc from the Qilianshan to Lajishan, relative to the neighboring low‐elevation area to the east, which indicates ongoing rapid orogeny. We find transient deformation along the Laohushan and 1920 M8.5 Haiyuan rupture segments of the Haiyuan fault, whereas the western Haiyuan, southern Liupanshan, central Lajishan and central‐western West Qinling faults are essentially locked above 15–20 km, suggesting a potentially high seismic hazard. Plain Language Summary: The northeast Tibetan Plateau, which is impeded by the tectonically stable Ordos block, continues to grow in response to the far‐field India‐Eurasia collision. This region has several large‐scale active faults that hosted some destructive earthquakes in the last 100 years. Although intensively studied, the fault kinematics of those seismogenic faults are still not clear, mainly because of poor observational constraints. Hence, high‐resolution present‐day deformation maps are essential to answering this question, either of scientific or societal concern. We provide satellite‐based ground deformation rate maps with mm‐accuracy for this region. They show shallow fault creep along some segments of the Haiyuan fault which is better constrained than previous results, active tectonic uplift in the Lajishan. Our work gives new constraints for the seismic hazard for the Northeastern Tibetan Plateau case. Key Points: We derive a new high‐resolution three‐dimensional present‐day deformation map for the Northeastern Tibetan PlateauGeodetic data reveals ongoing rapid uplift along an accurate orogenic belt from the eastern Qilianshan and LajishanNew constraints for the seismic hazard analysis for the Northeastern Tibetan Plateau [ABSTRACT FROM AUTHOR]

Glacial lake outburst floods (GLOF) often have a significant impact on downstream users. Including their effects in hydrological models, identifying past occurrences and assessing their potential impacts are challenges for hydrologists working in mountainous catchments. The regularly outbursting Merzbacher Lake is located in the headwaters of the Aksu River, the most important source of water discharge to the Tarim River, northwest China. Modelling its water resources and the evaluation of potential climate change impacts on river discharge are indispensable for projecting future water availability for the intensively cultivated river oases downstream of the Merzbacher Lake and along the Tarim River. The semi-distributed hydrological model SWIM was calibrated to the outlet station Xiehela on the Kumarik River, by discharge the largest tributary to the Aksu River. The glacial lake outburst floods add to the difficulties of modelling this high-mountain, heavily glaciated catchment with poor data coverage and quality. The aims of the study are to investigate the glacier lake outburst floods using a modelling tool. Results include a two-step model calibration of the Kumarik catchment, an approach for the identification of the outburst floods using the measured gauge data and the modelling results and estimations of the outburst flood volumes. Results show that a catchment model can inform GLOF investigations by providing 'normal' (i.e. without the outburst floods) catchment discharge. The comparison of the simulated and observed discharge proves the occurrence of GLOFs and highlights the influences of the GLOFs on the downstream water balance. © 2013 The Authors. Hydrological Processes Published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT: Recession of high‐mountain glaciers in response to climatic change frequently results in the development of moraine‐dammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km2) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an ice‐contact moraine‐dammed lake to develop. The lake had a maximum volume of 5.5 × 105 m3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 105 m3 of material was removed from the terminal moraine during breach development. Numerical dam‐breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine‐dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146–2200 m3 s‐1. Results from two‐dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s‐1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine‐dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine‐dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact. © 2014 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY A robust Godunov-type numerical scheme solver is proposed for solving 2D SWEs and is applied to simulate flow over complex topography with wetting and drying. In reality, the topography is usually complex and irregular; therefore, to avoid the numerical errors generated by such features, a Homogenous Flux Method is used to handle the bed slope term in the SWEs. The method treats the bed slope term as a flux to be incorporated into the flux gradient and so maintains the balance between the two in a Godunov-type shock-capturing scheme. The main advantages of the method are: first, it is simple and easy to implement; second, numerical experiments demonstrate that it can handle discontinuous or vertical bed topography without any special treatment and third, it is applicable to both steady and unsteady flows. It is demonstrated how the approach set out here can be applied to the nonlinear hyperbolic system of the SWEs. The two-dimensional hyperbolic system is then solved by use of a second-order total-variation-diminishing version of the weighted average flux method in conjunction with a Harten-Lax-van Leer-Contract approximate Riemann solver incorporating the new flux gradient term. Several benchmark tests are presented to validate the model and the approach is verified against experimental measurements from the European Union Concerted Action on Dam Break Modelling project. These show very good agreement. Finally, the method is applied to a volcano-induced outburst flood over an initially dry channel with complex irregular topography to demonstrate the technique's capability in simulating a real flood. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The rheology of debris flows is difficult to characterize owing to the varied composition and to the uneven distribution of the components that may range from clay to large boulders, in addition to water. Few studies have addressed debris flow rheology from observational, experimental, and theoretical viewpoints in conjunction. We present a coupled rheological-numerical model to characterize the debris flows in which cohesive and frictional materials are both present. As a first step, we consider small-scale artificial debris flows in a flume with variable percentages of clay versus sand, and measure separately the rheological properties of sand-clay mixtures. A comparison with the predictions of a modified version of the numerical model BING shows a reasonable agreement between measurements and simulations. As application to a field case, we analyse a recent debris flow that occurred in Fjærland (Western Norway) for which much information is now available. The event was caused by a glacial lake outburst flood (GLOF) originating from the failure of a moraine ridge. In a previous contribution (Breien et al., Landslides, , 5: 271-280) we focused on the hydrological and geomorphological aspects. In particular we documented the marked erosion and reported the change in sediment transport during the event. In contrast to the laboratory debris flows, the presence of large boulders and the higher normal pressure inside the natural debris flow requires the introduction of a novel rheological model that distinguishes between mud-to-clast supported material. We present simulations with a modified BING model with the new cohesive-frictional rheology. To account for the severe erosion operated by the debris flow on the colluvial deposits of Fjærland, we also suggest a simple model for erosion and bulking along the slope path. Numerical simulations suggest that a self-sustaining mechanism could partly explain the extreme growth of debris flows running on a soft terrain. [ABSTRACT FROM AUTHOR]

The 1918 eruption of the glacially capped Katla volcano, southern Iceland, generated a violent jökulhlaup, or glacial outburst flood, inundating a large area of Mýrdalssandur, the proglacial outwash plain, where it deposited ca 1 km3 of volcaniclastic sediment. The character of the 1918 jökulhlaup is contentious, having been variously categorized as a turbulent water flow, a hyperconcentrated flow or as a debris flow, based on localized outcrop analysis. In this study, outcrop-based architectural analyses of the 1918 deposits reveal the presence of lenticular and tabular bedsets associated with deposition from quasi-stationary antidunes and down-current migrating antidunes, and from regular based bedsets, associated with transient chute-and-pool bedforms, all of which are associated with turbulent, transcritical to supercritical water flow conditions. Antidune wavelengths range from 24 to 96 m, corresponding to flow velocities of 6 to 12 m sec−1 and average flow depths of 5 to 19 m. This range of calculated flow velocities is in good agreement with estimates made from eyewitness accounts. Architectural analysis of the 1918 jökulhlaup deposits has led to an improved estimation of flow parameters and flow hydraulics associated with the 1918 jökulhlaup that could not have been achieved through localized outcrop analysis. The observations presented here provide additional sedimentological and architectural criteria for the recognition of deposits associated with transcritical and supercritical water flow conditions. The physical scale of sedimentary architectures associated with the migration of bedforms is largely dependent on the magnitude of the formative flow events or processes; sedimentary analyses must therefore be undertaken at the appropriate physical scale if reliable interpretations, regarding modes of deposition and formative flow hydraulics, are to be made. [ABSTRACT FROM AUTHOR]

An unpredicted sudden outburst flood from Sólheimajökull, Southern Iceland, in July 1999 may herald a major subglacial volcanic eruption beneath Mýrdalsjökull ice cap.. [ABSTRACT FROM AUTHOR]

Using repeat-pass satellite synthetic aperture radar interferometry, we develop a methodology to measure flood-induced erosion and deposition and apply it to a record 1996 glacier outburst flood (jökulhlaup) on Skeiðarársandur, Iceland. The procedures include (1) coregistration of backscatter intensity images to observe morphological differences; (2) mapping of interferometric phase correlation to identify preserved and modified surfaces; and (3) construction, correction, and differencing of pre-jökulhlaup and post-jökulhlaup topography. Procedures 1 and 2 are robust and should be widely applicable to other fluvial environments, while procedure 3 is complicated by uncertainties in phase measurement, baseline estimate, and atmospheric effects. After a correction procedure involving interpolation of digital elevation model elevation differences across low-correlation areas, we find ∼4 m of elevation change are required to calculate volumes of erosion or deposition. This condition was satisfied for the 40 km2 proglacial zone of Skeiðarársandur, where we estimate +38×106 m3 of net sediment deposition along the ice margin, −2 ×106 m3 of net erosion in channels downstream, and a total net balance of +13 × 106. These estimates are supported by field observations and survey data collected in 1997. [ABSTRACT FROM AUTHOR]

Infrequent, large‐magnitude discharge (>106 m3/s) outburst floods—megafloods—can play a major role in landscape evolution. Prehistoric glacial lake outburst megafloods transported and deposited large boulders (≥4 m), yet few studies consider their potential lasting impact on river processes and form. We use a numerical model, constrained by observed boulder size distributions, to investigate the fluvial response to boulder deposition by megaflooding in the Yarlung‐Siang River, eastern Himalaya. Results show that boulder deposition changes local channel steepness (ksn) up to ∼180% compared to simulations without boulder bars, introducing >100 meter‐scale knickpoints to the channel that can be sustained for >20 kyr. Simulations demonstrate that deposition of boulders in a single megaflood can have a greater influence on ksn than another common source of fluvial boulders: incision‐rate‐dependent delivery of boulders from hillslopes. Through widespread boulder deposition, megafloods leave a lasting legacy of channel disequilibrium that compounds over multiple floods and persists for millennia. Plain Language Summary: Megafloods (discharge equivalent to ≥400 instantaneously draining Olympic‐sized swimming pools per second) can transport a lot of material, including car‐ to house‐sized boulders. Because these boulders are so big, they remain in the channel until the next megaflood or until they weather into smaller pieces. We use a computer model to understand the impact of these megaflood deposited boulders on mountain river processes. We find that megaflood boulders can protect the river from being eroded, causing other processes, like tectonic uplift, to outcompete erosion. Megaflood boulders cause small steps to form within the river. Our modeling shows that these effects can be felt for >20,000 yrs after a single flood. We suggest that megaflood deposition (in addition to erosion) can cause a significant, unique change in mountain river processes. Key Points: We studied channel response to megaflood boulder deposition in the eastern Himalaya using a numerical modelMegaflood boulder deposition locally changes channel steepness up to 180%, creating >100 knickpointsThe compounding effect from multiple megaflood boulder deposits in rapid succession perturbs channel form for many thousands of years [ABSTRACT FROM AUTHOR]

The presence of a late Quaternary ice sheet/ice shelf over the East Siberian Sea has been proposed in several papers. Here, we further document its duration/resilience based on the sedimentary, bulk mineralogical, and geochemical (organic matter content and its stable isotopic composition, U‐Th series) properties of a core raised from the southernmost Mendeleev Ridge. The chronostratigraphy of the studied core was mainly built from the 230Th excess (230Thxs) distribution and decay downcore. At the core‐top, peaking 230Thxs values during the early MIS 3 and mid‐MIS 1 encompassing an MIS 2 hiatus were observed. As documented in several papers, these peaks suggest seasonally open ice conditions over proximal continental shelves. Below, the interval spanning MIS 4 and possibly MIS 5d records major ice‐rafting events illustrated by overall high coarse‐fraction contents. Underlying MIS 5e, down to MIS 11, the sediment depicts relatively low sand (1.7±2.5 dw%), high clay (33.5±4.7 dw%), and very low organic carbon (0.10±0.06 dw%) contents, and low δ13Corg values (−24.3±0.9‰). This section is interpreted as recording fine sediment transport by deep currents and/or meltwater plumes below a resilient ice cover, only interrupted by a few short‐duration events. These events include (i) detrital carbonate pulses assigned to deglacial events along the NW Laurentide Ice Sheet margin (Termination (T) III), and (ii) intervals with some planktonic foraminifer occurrences, likely relating to their advection from open areas of the Arctic Ocean (MIS 5e, 9 and 11). All Terminations, but TII and the early MIS 3, show peaking Mn/Al values linked to the submergence of Arctic shelves under a rising sea level. We conclude that the resilient ice cover, likely an ice shelf, has been present over the southern Mendeleev Ridge during most of the interval after the Mid‐Pleistocene Transition and was favoured by the low summer insolation of the MIS 14 to 10 interval. [ABSTRACT FROM AUTHOR]

High‐Alpine regions are prone to a large variety of geohazards, among which earthquakes have the strongest impact on landscape and local population. Historic records indicate a moderate to high seismic activity in the northern, south‐western and central parts of Switzerland. In contrast, south‐eastern Switzerland has less historic earthquake chronicles due to the low population density, resulting in a poorly constrained seismic event catalogue. The aim of this study is to evaluate the palaeoseismic activity for south‐eastern Switzerland by using the sedimentary record of Lake Silvaplana in the Engadine Valley. A dense grid of high‐resolution two‐dimensional seismic profiles, high‐resolution bathymetry and a 10 m long sediment core from the deepest basin were used to investigate the stratigraphy of the lake sediments. The bathymetry reveals a flat basin, flanked by steep slopes to the north‐west and south‐east. The acoustic basement consists of four ridges, and gently‐dipping fans to the south‐west and north‐east. Expressions of slope failure can be identified in all domains of the lake floor and the subsurface data. Multiple coevally‐triggered chaotic mass‐flow deposits, overlain by megaturbidites with a coarse‐sand base, have been detected along ten horizons in the seismic data. The four most recent of these deposits are cored and radiocarbon dated to approximately 230, 310, 960 and 1330 cal yr bp, indicating four over‐regional seismic events that triggered large slope failures in Lake Silvaplana in the last 1400 years. Correlation with sediments of Lake Sils, Lake Como, Lake Iseo and Lake Ledro indicate within radiocarbon uncertainties a large earthquake around 1330 cal yr bp. Within their age ranges, the postulated earthquake at 310 cal yr bp (1640 ce) further correlates with a moment magnitude Mw ca 5.4 event in Ftan in 1622 ce, and the 960 cal yr bp (990 ce) earthquake correlates with a Mw ca 5.2 earthquake in Brescia in 1065 ce. Six mass‐movement deposits, also suggested to be caused by earthquakes, were not reached by the sediment core and have suggested ages between 7800 and 11 300 cal yr bp. Thus, Lake Silvaplana sediments provide the first reliable record of seismic activity for the mid and Late Holocene in this region, likely related to the neotectonic activity of the Engadine Line, a major fault zone running along the main valley. [ABSTRACT FROM AUTHOR]

Deglaciation has led to the transformation of glaciers into rock glaciers in various mountainous regions worldwide. However, the science of permafrost and rock glaciers remains under‐researched in the Himalayan region. This study presents a detailed inventory, dynamics, and permafrost distribution map for the Jhelum basin in the Kashmir Himalaya. The Permafrost Zonation Map (PZM) is created using a Logistic Regression Model based on topographic and climatic variables. High‐resolution satellite images are used to identify rock glaciers as visual indicators. Active and relic rock glaciers are classified based on surface topography and geomorphology. Results reveal 207 rock glaciers in the Jhelum basin, covering ∼50 km2, with over 100 falling into the active category. The PZM aligns well with the global permafrost zonation index map. Slope, aspect, and elevation of rock glaciers are computed using the ASTER Digital Elevation Model. The average elevations range from 3,700 m to 4,550 m, and the average surface slope ranges from 12° to 26°, with maximum slopes from 25° to 65°. Most rock glaciers are oriented toward the south or southeast. Field investigations confirm that these rock glaciers occur in highly elevated regions with steep slopes. This study provides valuable information on the high areal abundance of permafrost in the Himalayan region and suggests increased risks of thawing permafrost due to climate warming in the future. The findings contribute to the understanding of permafrost and rock glaciers, filling knowledge gaps in the Himalayan context. Plain Language Summary: In this study, we focused on understanding how glaciers turn into rock glaciers and how permafrost is distributed in the Jhelum basin of the Kashmir Himalaya. We found that many glaciers in mountainous regions around the world have transformed into rock glaciers due to deglaciation. However, there is limited research on permafrost and rock glaciers in the Himalayan region. Using satellite images and on‐the‐ground investigations, we created a detailed inventory and map of rock glaciers in the Jhelum basin. We also developed a permafrost distribution map by considering factors like temperature, solar radiation, and slope aspect. This map helps us understand where permafrost is located in the area. Our findings revealed that there are 207 rock glaciers in the Jhelum basin, covering an area of approximately 50 square kilometers. More than 100 of these rock glaciers are active. The map we created aligns well with existing global permafrost maps, showing the accuracy of our approach. This study enhances our knowledge of permafrost and rock glaciers in the Himalayan region, providing important information about their presence and the potential risks associated with thawing permafrost due to climate change. Key Points: Study investigates glacier‐to‐rock glacier transformation in Jhelum basin, Kashmir Himalaya due to deglaciationPresents detailed rock glacier inventory, dynamics, and permafrost distribution map using satellite images and field investigationsHighlights high permafrost abundance in Himalayan region, indicating increased thawing risks with climate warming [ABSTRACT FROM AUTHOR]

The 8.2 ka event is the most significant global climate anomaly of the Holocene epoch, but a lack of records from Mainland Southeast Asia (MSEA) currently limits our understanding of the spatial and temporal extent of the climate response. A newly developed speleothem record from Tham Doun Mai Cave, Northern Laos provides the first high‐resolution record of this event in MSEA. Our multiproxy record (δ18O, δ13C, Mg/Ca, Sr/Ca, and petrographic data), anchored in time by 9 U‐Th ages, reveals a significant reduction in local rainfall amount and weakening of the monsoon at the event onset at ∼8.29 ± 0.03 ka BP. This response lasts for a minimum of ∼170 years, similar to event length estimates from other speleothem δ18O monsoon records. Interestingly, however, our δ13C and Mg/Ca data, proxies for local hydrology, show that abrupt changes to local rainfall amounts began decades earlier (∼70 years) than registered in the δ18O. Moreover, the δ13C and Mg/Ca also show that reductions in rainfall continued for at least ∼200 years longer than the weakening of the monsoon inferred from the δ18O. Our interpretations suggest that drier conditions brought on by the 8.2 ka event in MSEA were felt beyond the temporal boundaries defined by δ18O‐inferred monsoon intensity, and an initial wet period (or precursor event) may have preceded the local drying. Most existing Asian Monsoon proxy records of the 8.2 ka event may lack the resolution and/or multiproxy information necessary to establish local and regional hydrological sensitivity to abrupt climate change. Plain Language Summary: The most significant global climate event in the last ∼11,000 years occurred ∼8,200 years ago (the "8.2 ka event"). Many globally distributed records of past climate (paleoclimate) document significant changes during the event, but there are few from Mainland Southeast Asia available to reconstruct the climate impacts in this region. We present a new speleothem (cave sample) record from Tham Doun Mai Cave, Northern Laos that uses multiple geochemical and physical signals (proxies) to document local and regional climate effects of the 8.2 ka event at a high resolution. Using oxygen isotopes, we find that the 8.2 ka event weakened regional monsoon intensity for at least ∼170 years, which resembles findings from other studies. However, other proxies suggest local rainfall changed abruptly decades before the signal of monsoon weakening. Additionally, local drying may have lasted much longer than current estimates of 8.2 ka event responses. Most proxy records of the 8.2 ka event in monsoon regions lack similar multiproxy information and/or do not have high enough resolution to fully capture the climatic response. Additional records like ours from monsoon regions may assist in establishing how sensitive local and regional rainfall is to abrupt climate change. Key Points: High‐resolution speleothem record of the 8.2 ka event in northern Laos shows weakened monsoon intensity and reduced local rainfall amountsMultiproxy data suggest the disruption to local rainfall amounts started decades before the weakened monsoon intensity inferred from δ18OPrevious monsoon records of the event lack the resolution and/or multiproxy dimensions needed to reconstruct local hydrologic changes [ABSTRACT FROM AUTHOR]

The Arctic has experienced rapid change associated with warming since the 1970s. The rapid retreat of the terrestrial cryosphere can release a large amount greenhouse gas from the permafrost regions into the air, and the sea ice decline will affect the CO2 and CH4 balance in the ocean. Changes in the Arctic provide feedback mechanisms that can also impinge on the global ocean's thermohaline circulation. During the past years, the overall natural processes in the Arctic have been studied although the magnitude and timing of carbon release from the cryosphere changes require further investigation. However, few studies have been conducted to link the natural and social systems in the Arctic. Scientists and policymakers must consider the coupled Arctic land, ocean, and social systems in their decisions for coping with climate change. Plain Language Summary: The Arctic is warming more than twice the global average. The Arctic is connected to the rest of the world through the climate system, it appears to be the first domino to fall, with the other dominoes pointing south. The Arctic science community and the people who live in the Arctic have known the rapid Arctic changes for a long time. It has been recognized that the cryosphere components are declining, and the carbon cycle in both the land and ocean will be affected by the cryosphere shrinkage. Despite some scientific breakthroughs, there are still major knowledge gaps in the Arctic carbon cycle. The policymakers at this stage are not only asking for more data about the Arctic changes, they also need scientific suggestions to cope with Arctic changes. The science community should work together to draw a full picture of the Arctic changes that include both natural and social systems. Key Points: The changing Arctic carbon cycle can affect global climateMore field observation should be carried out in the Arctic land and oceanThe Arctic land, ocean, and social domain should be considered as a system [ABSTRACT FROM AUTHOR]

A warming environment is promoting the thawing process in ice‐rich moraine soils in cold alpine regions, thereby accelerating the formation/development of geohazards in these regions. The mechanism of these geohazards is closely related to the thermal‐hydraulic (TH) coupling behavior of moraine soils, which has rarely been investigated. Here, we conducted a series of bench‐scale TH coupling simulations of moraine soils with ice inclusions in a warming environment. The numerical model was conceptualized from a field survey on the Qinghai‐Tibet Plateau, which consists of a porous medium embedded with multilayer ice cubes with warmer water continuously flowing through it. A TH coupling framework considering ice‐water phase change was established to implement this coupled simulation with different initial ice contents and hydraulic gradients. The simulated results showed phased and nonlinear evolutionary features of temperature, ice content, and permeability for the moraine soil system. Further analyses showed that these complex evolutionary features can be reproduced by empirical formulas, with concise expressions following dimensional consistency and some coefficients having potential physical meanings. The discriminant models of two equilibrium states were finally developed to predict the critical times of structure stabilization and thermal equilibrium of the moraine soil system. This study presents the complex evolution of TH coupling properties of moraine soils, and simultaneously demonstrates that these properties can be predicted and characterized. Plain Language Summary: Due to large‐scale and multistage glacier evolution, substantial moraine soils have accumulated in cold alpine regions. These moraine soils include abundant buried ice in various configurations formed during glacial evolution, and the thawing of this buried ice is accelerating the development of geohazards in these regions. The initiation and evolution of these geohazards are largely controlled by heat transport and groundwater flow induced by ice‐water phase change in moraine soils, but these coupling processes are poorly understood and poorly characterized. Here, we numerically investigated the thermal‐hydraulic (TH) coupling behaviors of moraine soils with ice inclusions in a warming environment. The simulated results revealed phased and nonlinear evolutionary features of the moraine soil system, with respect to heat transport, pore structure, and hydraulic conductivity. We demonstrated that these complex evolutionary features can be well characterized by empirical formulas, and their equilibrium states can be predicted based on the initial ice content and applied hydraulic gradient. These findings and results deepen our understanding of TH coupling behavior for moraine soils with ice inclusions, and serve as a basis for characterizing evolutionary processes of geohazards related to moraine soils in cold alpine regions under climate warming. Key Points: Fully coupled thermal‐hydraulic simulations considering phase change were conducted for moraine soils with separate ice inclusionsEvolution of heat transport, ice content, and hydraulic conductivity of moraine soil was quantitatively characterizedEquilibrium‐state discrimination models were developed to predict structure stabilization and thermal equilibrium of the moraine soil system [ABSTRACT FROM AUTHOR]

Small glaciers are one of the best indicators of climatic variations and their short‐term effects. Located in the Spanish Pyrenees, the Maladeta is one of these glaciers. Its systematic observation began in the 1980s, being one of the few Pyrenean glaciers with a tongue‐shaped front. This study presents the evolution of the Maladeta glacial tongue over a decade (2010–2020) through multiple geomatic techniques. Surveys have ranged from Total Stations and Global Navigation Satellite System devices to massive data capture techniques such as Terrestrial Laser Scanners or Unmanned Aerial Vehicles photogrammetry. The aim is to analyze in detail the loss of surface area and thickness of the glacier and its transition from being a glacier with a tongue partially determined by climate to a topoclimatically determined cirque glacier. The results reveal a tongue retreat of over 5 m/yr and area losses of over 0.2 ha/yr, along with ice thickness and volume losses of −1.7 m/yr and over −21 × 103 m3/yr, respectively. If this trend continues, the tongue, and possibly the Maladeta glacier, could disappear by the end of the 2030s. [ABSTRACT FROM AUTHOR]

With global warming, changes in glaciers and glacial lakes on the Tibetan Plateau call for a serious inspection. The Southeastern Tibetan Plateau (SETP) is a typical monsoonal marine glacier area that is extremely vulnerable to climate change. It is affected by both humid and warm Indian Ocean currents. Outlines of glaciers and glacial lakes in SETP have been extracted from Landsat satellite images with an automatic extraction method based on image compositing with Google Earth Engine and Random Forest algorithm. Alongside the outlines, meteorological data have been collected from 1990 to 2021. The results show that since 1990 the glacier area of SETP has retreated by about 2165.33 km2 (~25.28%), the glacial lake area has increased by about 36.41 km2 (~21.45%), and their number has increased by 477 (~27.32%). The reliability and scientific validity of this study is proven by comparison with existing glacier inventories. By analyzing the meteorological data, the inverse correlation between the glacier area and temperature has been found. Despite decreases in cumulative precipitation, the glacial lake level rise and consequent area expansion have been observed. A fitting equation for the response pattern of glacier changes to temperature and precipitation change is presented and will provide a basis for future studies. [ABSTRACT FROM AUTHOR]

Populations and infrastructure in high mountain regions are exposed to a wide range of natural hazards, the frequency, magnitude, and location of which are extremely sensitive to climate change. In cases where several hazards can occur simultaneously or where the occurrence of one event will change the disposition of another, assessments need to account for complex process chains. While process chains are widely recognized as a major threat, no systematic analysis has hitherto been undertaken. We therefore establish new understanding on the factors that directly trigger or alter the disposition for subsequent events in the chain and derive a novel classification scheme and parameters to aid natural hazard assessment. Process chains in high mountains are commonly associated with glacier retreat or permafrost degradation. Regional differences exist in the nature and rate of sequencing—some process chains are almost instantaneous, while other linkages are delayed. Process chains involving rapid sequences are difficult to predict, and impacts are often devastating. We demonstrate that process chains are triggered most frequently by progressive failures, being the result of gradual landscape weakening and not due to the occurrence of a distinct process. If fluvial processes are part of the process chain the reach (or mobility) of process chains is increased. Increased mobility can also occur if sediment deposition areas along river channels are activated. As climate changes causes glacial environments to transform into sediment‐rich paraglacial and fluvial landscapes, it is expected that the mobility of process chains will increase in the future. Plain Language Summary: Communities and their infrastructure located in mountain regions of the world are particularly susceptible to natural hazards, such as floods and landslides. While these events on their own can be bad enough, when such events occur at the same time or cause a chain‐reaction of different processes, consequences can be worse and extend far downstream. In view of this, we have undertaken a first comprehensive review of 51 relevant events occurring across different mountain regions globally to better understand how these process chains develop, and to identify which conditions increase the likelihood and or size of these events. A key finding is that process chains most frequently begin as the result of a mountain slope gradually becoming unstable over time, and in these cases, no other trigger such as an earthquake or unusually wet or hot weather are necessary. Far‐reaching process chains occur when rivers are involved and when additional gravel and debris sources are added to the mix. As a consequence of climate warming, icy mountain landscapes are thawing and become more unstable, increasing the risk of such process chains in the future. Key Points: High mountain hazard process chains commonly are associated with glacier retreat or permafrost degradationProcess chains are triggered most frequently by progressive failure, which is a result of long‐lasting landscape weakeningAn important implication of climate change is that we can expect an increase in the reach (horizontal length along the flow path) of process chain events in the future [ABSTRACT FROM AUTHOR]

Permafrost warming and degradation is well documented across the Arctic. However, observation‐ and model‐based studies typically consider thaw to occur at 0°C, neglecting the widespread occurrence of saline permafrost in coastal plain regions. In this study, we document rapid saline permafrost thaw below a shallow arctic lake. Over the 15‐year period, the lakebed subsided by 0.6 m as ice‐rich, saline permafrost thawed. Repeat transient electromagnetic measurements show that near‐surface bulk sediment electrical conductivity increased by 198% between 2016 and 2022. Analysis of wintertime Synthetic Aperture Radar satellite imagery indicates a transition from a bedfast to a floating ice lake with brackish water due to saline permafrost thaw. The regime shift likely contributed to the 65% increase in thermokarst lake lateral expansion rates. Our results indicate that thawing saline permafrost may be contributing to an increase in landscape change rates in the Arctic faster than anticipated. Plain Language Summary: In this study, we combine direct field measurements, near‐surface geophysical studies, and remote sensing change detection to document the rapid thaw of saline permafrost below a shallow thermokarst lake on the Arctic Coastal Plain of northern Alaska. Thaw of ice‐rich saline permafrost resulted in an increase in the lake depth by 0.6 m over a 15‐year period. The transition from a bedfast ice lake to a floating ice lake with brackish water is responsible for the increase near‐surface bulk sediment electrical conductivity and likely contributed to an increase in the lateral expansion rate of the lake. Our findings indicate that active permafrost thaw is likely occurring below shallow arctic lakes at temperatures below 0°C. Key Points: We document the rapid thaw and subsidence of saline permafrost below a shallow thermokarst lake in Arctic AlaskaWe hypothesize that rapid saline permafrost degradation is occurring below shallow arctic lakes at sub‐zero temperaturesThawing saline permafrost may be contributing to an increase in landscape change rates in the Arctic [ABSTRACT FROM AUTHOR]

Six gridded temperature datasets (T‐datasets) were evaluated for the first time over the South American continent, through the case study of Bolivia, by comparing them with temperature records acquired from 82 meteorological stations spanning the 1995–2010 period. The comparisons were carried out at the daily time step considering different seasons (annual scale, austral summer and austral winter) and regions (Amazon, La Plata and Altiplano basins). Overall, the climate hazards group infrared temperature with stations (CHIRTS) and the climate prediction centre (CPC) T‐datasets provided the most reliable mean daily temperature (Tmean) and also described well the temporal variability of minimum and maximum daily temperature estimates (Tn and Tx). Tmean, Tn and Tx trends were analysed over the 1983–2016 period to observe temperature temporal evolution across the three regions. Despite some general agreements between the trends (Tmean, Tx and Tn), large discrepancies are also observed. It was found that CPC overestimates and CHIRTS underestimates mean temperature trends and that CPC (CHIRTS) was better than CHIRTS (CPC) to estimate Tx (Tn) trends, both in magnitude and space. Furthermore, opposing trends (i.e., warming and cooling) are described by CPC and CHIRTS for some specific regions, which call into question their reliability for such analyses. These findings highlight the need to validate gridded temperature products with reliable ground data for the regions under study, particularly if they have a wide elevation range. [ABSTRACT FROM AUTHOR]

River management is founded on predictable self‐organisation between river form and catchment controls in alluvial rivers. However, a substantial proportion of rivers are not fully alluvial. In previously glaciated landscapes, boulder‐rich glacial till influences river channel form and process. Increasing interest in nature‐ and process‐based river restoration requires knowledge of pre‐disturbance natural processes, which does not exist for semi‐ and non‐alluvial rivers in Fennoscandia. We aimed to determine the role of Pleistocene glaciation and subsequent deglaciation versus Holocene fluvial processes in controlling channel form of boulder‐bed rivers in Fennoscandia. We quantified morphological characteristics of northern Swedish boulder‐bed rivers, in which channel morphology was minimally impacted by humans, and used the degree of alluvial signatures to infer fluvial and legacy glacial controls. We conducted surveys of reach‐scale channel geometry, boulder and wood distributions and catchment characteristics for 20 reference reaches (drainage area: 11–114 km2). Reaches ranged in slope from 1% to 8% and were extremely diverse in channel geometry. Rivers showed little self‐organisation at the reach scale; no association exists between channel width and channel slope or bed sediment size. Boulders were rarely clustered into bedforms (e.g., step‐pools) typical of boulder‐bed mountain rivers. Drainage area was positively correlated with channel capacity but not channel width, slope or sediment size. Channel boulder density was best predicted by surveys of terrestrial boulders. Consequently, channel geometry, boulder size and the distribution of boulders were primarily controlled by legacy glacial conditioning rather than current fluvial processes, with some alluvial adjustment of smaller particles within the boulder template. Therefore, restoration of semi‐alluvial rivers should take into account local sediment and geomorphic conditions rather than use management principles built for fully alluvial rivers. [ABSTRACT FROM AUTHOR]

The origin of supraglacial debris covers is often conceptualised as the formation of a surface lag by melt‐out of englacial debris from slow‐moving ice, where complexity arises from feedback between debris thickness and sub‐debris ice melt. Here, we examine the origin of a debris cover from the perspective of debris provenance and changing tributary supply in a high‐elevation compound valley glacier. Geochemical analysis of 11 major elements in 21 debris samples from six tributaries of Khumbu Glacier (Nepal) shows unambiguous statistical differentiation of debris sources reflecting lithological differences between tributary catchments. Twenty‐four samples from transects across the ablation area are partitioned according to their source areas using the FR2000 sediment unmixing model. We estimate the age of ice at each transect using a higher order ice flow model. The results show greater proportions of debris from lateral tributaries in downglacier locations that have experienced longer flowline histories. More recently, ice from the Main Himalayan Divide (Western Cwm) has become relatively more important. This suggests a change in the state of the lower glacier's structure depending on the relative ice discharges of lateral and divide sources. Ice flux from lower elevation tributaries was more important probably prior to a weakening of the Indian Summer Monsoon at around 1420 CE. The lower elevation tributaries lie within the range of late Holocene equilibrium line altitude variation and therefore respond most sensitively to climatic drivers of the glacier's flow structure. Negative glacier mass balance since around 1900 CE caused tributary glaciers to detach and high‐elevation catchments to re‐establish as the dominant ice source to Khumbu Glacier. [ABSTRACT FROM AUTHOR]

Proglacial areas are dynamic landscapes and important indicators of geomorphic changes related to climate warming. Systematic and repeat surveys of landforms presently evolving on glacier forelands facilitate the quantification of rates of change and an improved understanding of the processes generating those changes. We report short‐term (2014–2022) transformations of the proglacial landscape in front of Kvíárjökull, SE Iceland, and place them in a longer‐term context of glacial landsystem evolution using aerial image archives since 1945. Short‐term quantification uses a time series of uncrewed aerial vehicle (UAV) surveys, processed utilizing a structure‐from‐motion (SfM) workflow, to produce digital elevation models (DEMs) and orthophoto mosaics. The land elements surveyed include a kame terrace staircase, an outwash plain, an ice‐cored hummocky moraine complex and ice‐cored hummocky terrain with discontinuous sinuous ridges, for which elevation and volumetric changes are quantified. The kame terraces between 2014 and 2022 and the outwash plain between 2016 and 2022 were mainly stable with, respectively, 87% and 85% of their surfaces showing no change. The ice‐cored hummocky terrain with discontinuous sinuous ridges underwent a volume loss of 64,632 m3 in 2016–2022, with a maximum surface lowering of ≤9 m. The most dynamic land element was the ice‐cored hummocky moraine complex, with transformations recorded for more than 87% of its area in 2014–2022; the surface was lowered by ≤23 m in some places, with a total volume loss of 365,773 m3. Our results confirm the ongoing degradation of ice‐cored moraine and outwash complexes at variable rates related to buried ice volume and age of deglaciation. The evolution of chaotic hummocky terrain from debris‐covered glacier ice, glacitectonic thrust masses, outwash fans/heads and complex englacial esker networks is an important modern analogue for informing palaeoglaciological reconstructions. [ABSTRACT FROM AUTHOR]

The high‐mountain system, a storehouse of major waterways that support important ecosystem services to about 1.5 billion people in the Himalaya, is facing unprecedented challenges due to climate change during the 21st century. Intensified floods, accelerating glacial retreat, rapid permafrost degradation, and prolonged droughts are altering the natural hydrological balances and generating unpredictable spatial and temporal distributions of water availability. Anthropogenic activities are adding further pressure onto Himalayan waterways. The fundamental question of waterway management in this region is therefore how this hydro‐meteorological transformation, caused by climate change and anthropogenic perturbations, can be tackled to find avenues for sustainability. This requires a framework that can diagnose threats at a range of spatial and temporal scales and provide recommendations for strong adaptive measures for sustainable future waterways. This focus paper assesses the current literature base to bring together our understanding of how recent climatic changes have threatened waterways in the Asian Himalayas, how society has been responding to rapidly changing waterway conditions, and what adaptive options are available for the region. The study finds that Himalayan waterways are crucial in protecting nature and society. The implementation of integrated waterways management measures, the rapid advancement of waterway infrastructure technologies, and the improved governance of waterways are more critical than ever. This article is categorized under:Engineering Water > Sustainable Engineering of Water [ABSTRACT FROM AUTHOR]

Within the international climate regime, legal aspects surrounding loss and damage (L&D) are contentious topics, implicating liability, compensation and notions of vulnerability. The attribution of responsibility and the pursuit of redress for L&D present intricate legal and governance challenges. The ongoing debates under the United Nations Framework Convention on Climate Change are characterized by a pronounced North–South divide and have done little to provide tangible support to those most affected by L&D. This apparent neglect has prompted exploration of alternative avenues for climate harm redress. The burgeoning field of litigation for liability and compensation of climate harm holds potential significance for L&D discourse, but its efficacy, especially in compensation claims relating to the adverse effects of climate change, is uncertain. There is, as yet, no precedent of plaintiffs succeeding in an L&D case, with numerous legal, evidentiary and practical barriers persisting, particularly for Global South plaintiffs aiming to hold Northern governments and actors accountable. This article scrutinizes recent advances in climate litigation and their potential to facilitate or obstruct L&D litigation. Focusing on seminal L&D cases, namely, Lliuya v RWE and Asmania et al v Holcim, we present a novel legal critique of climate litigation's capacity to assist climate‐vulnerable States, populations and communities in pursuing redress for L&D, based on pertinent case law and an examination of overarching issues of attribution and extraterritorial jurisdiction. [ABSTRACT FROM AUTHOR]

Frequent floods in the Koshi River have left the Nepalese vulnerable to erosion and recurring inundation—especially those living on the floodplains. The situation is worsening because water flow in the river is highly uncertain, affected by rainfall in the mountains and by climate change, and influenced by the Koshi barrage, which is governed by the Koshi River Agreement, a bilateral river agreement with India. This study addresses how Koshi River governance contributes to the vulnerability of riverine communities in Nepal by drawing upon ideas about vulnerability and vulnerability mapping. A household survey and interviews were conducted in 2015 for a comparative study of people living on two river islands located upstream and downstream of the barrage. Findings remain relevant because of persistent governance challenges and growing climate change effects, escalating islanders' vulnerability to recurrent floods. The islanders' vulnerability was produced locally and also shaped by historical, social, economic, political, geographical, and ecological processes occurring at multiple scales. That insight highlights the need to study the broader political economy of hazard production to understand vulnerability in the context of governance. [ABSTRACT FROM AUTHOR]

Climate change affects glaciers all over the world causing glacial recession with the formation of new lakes. Glaciers of Mount Tronador (41° S, Patagonia, Argentina) underwent an increase of more than 200 m in the equilibrium‐line altitude (ELA), from 1994 to 2016. The proglacial Lake Ventisquero Negro showed a continuous increase in lake surface area since 2009, when a glacial outburst flood (GLOF) occurred. The Ventisquero Negro glacier is a debris‐covered glacier located below the timberline; thus, the lake receives meltwater from both clean and debris‐rich ice.This study analyses the proglacial lake after the GLOF event, particularly the nutrient content, dissolved organic matter and bacterial respiration. Our main hypothesis was that the melting of debris‐rich and clean ice would differentially affect nutrient inputs and bacterial respiration in the early ontogeny of the lake.Sampling was conducted in austral spring–summer seasons (2012 to 2016) following the GLOF event. We carried out bacterial respiration experiments with lake water and two treatments enriched with clean or debris‐rich ice from the glacier. Additionally, we carried out an another enrichment experiment with phosphate‐P and glucose‐C alone or in combination.The lake exhibited high turbidity levels due to a high concentration of suspended solids. Vertical light profiles showed that almost the entire water column was aphotic. Phosphorus (P) concentration was high and was positively related to total suspended solids. Accordingly, P concentration was higher in debris‐rich than in clean ice. However, the dissolved organic carbon concentrations in the lake were found to remain relatively constant through time (less than 50 μmol/L).Analysing fluorescent excitation–emission matrices, we determined that the dissolved organic matter is very simple with only two peaks, one corresponding to protein‐like compounds (C1) and the other to humic‐like compounds (C2), coming from clean ice and debris‐rich ice, respectively. C1 was present in all samples, while C2 was comparatively more important during summer, coinciding with higher temperatures and melting.This study supports the hypothesis that melting of clean and debris‐rich ice would affect DOM and P input at early stages of a proglacial lake formed by the recession of a debris‐covered glacier. Bacterial respiration was observed to be positively affected by debris‐rich ice melting and to be P limited. Thus, P is a major controlling factor for carbon dynamics in a newly formed proglacial lake. [ABSTRACT FROM AUTHOR]

Holocene relative shore‐level changes and development of the Ģipka palaeolagoon in the western Gulf of Riga are reconstructed using multiproxy analyses by combining litho‐, biostratigraphical and chronological data with remote sensing and geophysical data. The results show the development of the Ģipka basin from the Ancylus Lake/Initial Litorina Sea coastal zone (before c. 9.1 cal. ka BP) to coastal fen (c. 9.1 to 8.4 cal. ka BP) and gradual development of the Litorina Sea lagoon (c. 8.4 to 4.8 cal. ka BP) and its transition to a freshwater coastal lake (c. 4.8 to 4.6 cal. ka BP), fen (c. 4.6 to 4.2 cal. ka BP), and river floodplain (since c. 4.2 cal. ka BP). The highest shorelines of the Ancylus Lake and Litorina Sea were mapped at an elevation of 12–11 and 9 m a.s.l., respectively. A new relative shore level (RSL) curve for the western Gulf of Riga was constructed based on RSL data from the Ģipka area and from nearby Ruhnu Island studied earlier. The reconstruction shows that the beginning of the last marine transgression in the western Gulf of Riga started at c. 8.4 cal. ka BP, and concurred with the 1.9 m RSL rise event recorded from the North Sea basin. Diatom analysis results indicate the existence of the Ģipka lagoon between c. 7.7 and 4.8 cal. ka BP, with the highest salinity c. 6.1 cal. ka BP. During the existence of the brackish lagoon, settlement sites of the Neolithic hunter–gatherer groups existed on the shores of the lagoon in the period c. 6.0 to 5.0 cal. ka BP. [ABSTRACT FROM AUTHOR]

To reconstruct past environmental changes, a range of indirect or proxy approaches can be applied to Quaternary archives. Here, we review the complementary and novel insights that have been provided by the analysis of chemical fossils (biomarkers). Biomarkers have a biological source that can be highly specific (e.g. produced by a small group of organisms) or more general. We show that biomarkers are able to quantify key climate variables (particularly water and air temperature) and can provide qualitative evidence for changes in hydrology, vegetation, human–environment interactions and biogeochemical cycling. In many settings, biomarker proxies provide the opportunity to simultaneously reconstruct multiple climate or environmental variables, alongside complementary and long‐established approaches to palaeoenvironmental reconstruction. Multi‐proxy studies have provided rich sets of data to explore both the drivers and impacts of palaeoenvironmental change. As new biomarker proxies continue to be developed and refined, there is further potential to answer emerging questions for Quaternary science and environmental change. [ABSTRACT FROM AUTHOR]

The mountains systems of Central Asia are primary targets to study late Pleistocene climate evolution given their location at the crossroads of several atmospheric circulation systems. The timing of glacier extent during this period remains understudied, especially in the Altai Mountains. Here, we have reconstructed glacier extent during three main Late Pleistocene stadials in the upper Kalguty basin (south‐eastern Russian Altai) based on field‐based geomorphic analysis. Additionally, surface exposure dating with 10Be and 26Al at a key site was used to infer a minimum‐limiting age for the outermost well‐preserved Pleistocene frontal moraine system and to date the inception of glacier withdrawal. According to our data, around 20.6 ± 1.8 ka Kalguty Glacier was still 200 m thick at the key site, 10 km upstream of the outermost moraine, and the site was totally deglaciated shortly after 20.4 ± 0.4 ka. These results point to a rapid retreat of this low‐gradient valley glacier after its probably MIS 2 maximum which was prior to 21 ka and probably prior to 22.5 ka. Two other glacier stages have been identified upvalley, characterized by a depression of the equilibrium‐line altitude of 420 and 314 m with respect to the Little Ice Age, thus corresponding to Lateglacial advances. Our glacier reconstruction further provides a geomorphological and geochronological background to put into context archaeological findings in this area. [ABSTRACT FROM AUTHOR]

Two composite sedimentary sequences sampled in the ice‐proximal (12CS) and ice‐distal (02CS) areas of Coronation Fjord (Baffin Island, Nunavut, Canada) were investigated in order to reconstruct the effect of climate variability on 600 years of changes in sediment transfer from the eastern Penny Ice Cap (PIC). Detrital proxies, and physical and sedimentological analyses revealed that glacial meltwater discharges led to frequent rapidly deposited layers (RDLs) in ice‐proximal settings. RDLs in ice‐distal settings involved the sudden release of a large quantity of sediment‐laden water during floods probably originating from adjacent fjords with large sandur deltas. Laminated sediments with ice‐rafted debris throughout the Little Ice Age interval in the ice‐proximal environment suggest that colder conditions promoted glacier growth, leading to successive episodes of turbid hyperpycnal meltwater plumes and iceberg calving in Coronation Fjord. Since 1850 ce, the accelerated Coronation retreat in response to modern warming has led to increased sedimentation rates, abrupt mineralogical and grain size proxy variations and more frequent RDLs. Similar trends between the detrital proxies of the ice‐proximal core and Atlantic Multidecadal Oscillation record and Arctic surface air temperature suggest high connectivity between atmospheric and sea surface temperature variations and PIC dynamics over the last 600 years. [ABSTRACT FROM AUTHOR]

The Laurentide Ice Sheet (LIS) was the largest ice sheet in the Northern Hemisphere during the last glacial cycle. The effects of its demise on global climate and sea‐level changes during the subsequent deglaciation are unequivocal. Understanding the interplay between ice sheets and long‐term or short‐term (e.g. abrupt) climatic events is therefore crucial for predicting future rates of ice sheet melting and their potential contribution to sea‐level changes. Here, we present 37 new 10Be surface exposure ages from easternmost Québec–Labrador that allow us to identify close ties between regional deglaciation history and climate. These results reveal that the LIS was disconnected from the Newfoundland Ice Cap by ~14.1 ka. Samples collected from moraine boulders indicate that this event was followed by five major stillstands and/or readvance stages of the LIS margin. Integrating our new moraine ages with those of earlier studies allows us to depict a temporal framework including events at ~12.9, ~11.5, ~10.4, ~9.3 and ~8.4–8.2 ka. These moraine ages highlight a strong sensitivity of the LIS to temperature changes in the Northern Hemisphere, as the documented continental ice margin stabilizations coincide with abrupt cooling events recorded in Greenland ice cores. These observations support the idea of a negative feedback mechanism induced by meltwater forcings into the North Atlantic Ocean which, in turn, provoked repeated cold reversals during the Younger Dryas and early Holocene. [ABSTRACT FROM AUTHOR]

This study analyses the long‐term dynamics in the Chauvet glacial and periglacial system (southern French Alps) over seven decades (1948–2020), where several lake outburst floods have been documented since 1930. To accurately describe and explain the complex dynamics of this site, our multidisciplinary approach combines (1) photogrammetry of historical aerial photographs and modern high‐resolution satellite and UAV images, (2) geophysical surveys and (3) geomorphological mapping. We provide evidence for spatial and functional interactions between glacial and periglacial features, especially in the lower sector where different landforms with variable ice‐ and debris‐content and specific dynamics are interplayed. We found the highest thinning rates on ice‐rich terrain located in the central part of the valley bottom, which, together with bedrock morphology, most probably determine the location of the thermokarst. We also documented an overall acceleration of the creeping of the landforms after the 2000s, with a flow direction largely oriented towards the thermokarst depression. The outburst water flowed through a conduit whose successive opening and closure seem to mainly depend on the rate of lateral convergence of left‐ and right‐hand landforms and on the rate of ice melting (and roof collapse) along the conduit walls. Today, the site of Chauvet still represents a potential hazard for the region due to the large water storage capacity (up to 180 000 ± 450 m3) and the development of a predominantly bucket shape in the thermokarst sector. [ABSTRACT FROM AUTHOR]

The ultimate demise of the Laurentide Ice Sheet (LIS) and the preceding and succeeding oceanographic changes along the western Labrador Sea offer insights critically important to improve climate predictions of expected future climate warming and further melting of the Greenland ice cap. However, while the final disappearance of the LIS during the Holocene is rather well constrained, the response of sea ice during the resulting meltwater events is not fully understood. Here, we present reconstructions of paleoceanographic changes over the past 9.3 Kyr BP on the northwestern Labrador Shelf, with a special focus on the interaction between the final meltwater event around 8.2 Kyr BP and sea ice and phytoplankton productivity (e.g., IP25, HBI III (Z), brassicasterol, dinosterol, biogenic opal, total organic carbon). Our records indicate low sea‐ice cover and high phytoplankton productivity on the Labrador Shelf prior to 8.9 Kyr BP, sea‐ice formation was favored by decreased surface salinities due to the meltwater events from Lake Agassiz‐Ojibway and the Hudson Bay Ice Saddle from 8.55 Kyr BP onwards. For the past ca. 7.5 Kyr BP sea ice is mainly transported to the study area by local ocean currents such as the inner Labrador and Baffin Current. Our findings provide new insights into the response of sea ice to increased meltwater discharge as well as shifts in atmospheric and oceanic circulation. Key Points: Sea ice on the Labrador Shelf mainly follows the solar insolation and meltwater input from the decaying Laurentide Ice SheetSea ice increased following the Lake Agassiz outburst and Hudson Bay Ice Saddle Collapse between 8.5 and 8.2 Kyr BPLow sea ice conditions during the Holocene Thermal Maximum were replaced by an increase following the Neoglacial cooling trend [ABSTRACT FROM AUTHOR]

Himalaya is experiencing frequent catastrophic mass movement events such as avalanches and landslides, causing loss of human lives and infrastructure. Millions of people reside in critical zones potentially exposed to such catastrophes. Despite this, a comprehensive assessment of mass movement exposure is lacking at a regional scale. Here, we developed a novel method of determining mass movement trajectories and applied it to the Himalayan Mountain ranges for the first time to quantify the exposure of infrastructure, waterways, roadways, and population in six mountain ranges, including Hindu Kush, Karakoram, western Himalaya, eastern Himalaya, central Himalaya, and Hengduan Shan. Our results reveal that the exposure of buildings and roadways to mass movements is highest in Karakoram, whereas central Himalaya has the highest exposed waterways. The hotspots of exposed roadways are concentrated in Nepal, the North Indian states of Uttarakhand, Himachal Pradesh, the Union Territory of Ladakh, and China's Sichuan Province. Our analysis shows that the population in the central Himalaya is currently at the highest exposure to mass movement impacts. Projected future populations based on Shared Socio‐economic and Representative Concentration Pathways suggest that changing settlement patterns and emission scenarios will significantly influence the potential impact of these events on the human population. Assessment of anticipated secondary hazards (glacial lake outburst floods) shows an increase in probable headward impacts of mass movements on glacial lakes in the future. Our findings will support researchers, policymakers, stakeholders, and local governments in identifying critical areas that require detailed investigation for risk reduction and mitigation. Plain Language Summary: Avalanches and landslides are common in mountainous terrain like the Himalaya. Failure of the steep slopes can threaten infrastructure and population in the downstream regions. Also, such failures in glaciated terrain can potentially impact high‐altitude lakes, thereby leading to downstream flooding. The assessment carried out in this study covering the mountain ranges in the Hindukush Karakoram Himalaya identifies the exposed elements, including buildings, roadways, waterways, population, and glacial lakes to potential mass movements. Further, downstream impact from glacial lake outburst depends on the location of the lake with respect to the mass movement impact direction, that is, striking direction. Our findings show that the exposure depends on the mass movement magnitude and is concentrated in the eastern and central Himalayas, where population and lake densities are high. Also, exposure of buildings and roadways to mass movements is highest in Karakoram. Future population exposure to slope failures shows significant changes based on the varied socio‐economic conditions. Key Points: First‐order assessment shows that central Himalaya has the highest exposed waterways to potential mass movementsCentral Himalaya is identified as the hotspot with the highest exposed population to mass movements in the present as well as in the futureHeadward impacts on glacial lakes are highest in Eastern Himalaya, which shifts to the Karakoram and Western Himalaya in the future [ABSTRACT FROM AUTHOR]

The rapid climate changes of recent decades are causing rapid glacier recession in the high Arctic and the loss of large patches and blocks of dead ice. Their temporally differentiated melting is very significantly transforming the relief of marginal zones, creating dead‐ice landscapes. The article focuses on dead‐ice degradation processes in the forelands of two glaciers (Erikkabreen and Haakenbreen) on Oscar II Land in Spitsbergen. Detailed in‐field geomorphological mappings have been conducted twice (in 1989 and 2022) in the two glaciers' forelands. These were combined with analysis of available photogrammetry and Digital Elevation Models, allowing the authors to describe the dynamics of dead‐ice melting processes within various landforms and the effect of those processes on the forms' ultimate morphology. This provided a broad view of the trajectory of melt processes depending on local geomorphological and hydrological conditions. Particular attention was paid to the interactions between the evolution of permafrost and the course of melting of dead ice. In light of the highly dynamic thermokarst processes in the forelands of Svalbard glaciers, the term 'dead‐ice‐rich permafrost' is proposed. It was found that global climate changes are increasing the role of dead ice in transforming the relief of glacier forelands, thereby increasing the occurrence of dead‐ice landscapes. The conclusions confirmed those for other contemporary glaciation areas and may significantly help in interpreting the morphogenesis of glacial relief formed during past continental glaciations. [ABSTRACT FROM AUTHOR]

The structural change of the Svalbard landscape from glacially dominated to paraglacial, that has taken place since the termination of the Little Ice Age (ca. 1900) is expressed by the widespread retreat of glaciers and progressive exposure of glacial landforms. This study provides insights into the rate of post‐LIA deglaciation and associated paraglacial transformation in the foreland of Gåsbreen, one of the first ever investigated glacier systems in the Arctic. Glacier is situated in Sørkapp Land (Southern Spitsbergen), a region characterized by one of the fastest deglaciation rates in the entire Svalbard Archipelago. During the investigated period, 1938–2020, the Gåsbreen was in a recession that accelerated after 1990, leading to its foreland increasing from 2.2 to 5.8 km2. The dynamics of landscape change in the glacier foreland, exposed since the end of LIA, manifested in i.e. the formation of ice‐dammed lakes, degradation in the surface of ice‐cored moraines and the landforms that are underlain by dead‐ice. Mass movements and debris flow on ice‐cored moraines and fluvioglacial processes had a great influence on this transformation. Enhanced proglacial runoff intensified denudation, transport and accumulation of sediments, which resulted, in: an increase in the extent of sandurs and proglacial riverbeds, an increase in the area of glacial lakes, extending and changing of the course of rivers in the glacier foreland. At the same time, the major lake system in the area—Goësvatnet underwent several cycles of filling and draining, often through glacial outburst flooding events. [ABSTRACT FROM AUTHOR]

Sandur plains are extensive sedimentary bodies formed in proglacial settings by glaciofluvial processes. Icelandic sandar have been hypothesised to be comprised of thick alluvial successions that provide critical insight into the processes that contributed to their formation and evolution. However, to‐date, most sandar research has focused on the analysis of sedimentary successions associated to topographically‐confined and small‐scale systems. These, however, do not capture the variety or scale of processes that influence sandar architecture. Therefore, detailed subsurface analysis of large‐scale and unconfined sandar is vital to understand how these systems respond to fundamental drivers, such as: (i) glacier oscillations, and (ii) episodic sediment flux from glacier outburst floods (aka. jökulhlaups). We report an extensive, low‐frequency (40 & 100 MHz) ground‐penetrating radar (GPR) survey of the ice‐proximal component of a large‐scale (~1300km2 $\unicode{x0007E}1300\,{\text{km}}^{2}$) active sandur in southeast Iceland. A bright and continuous reflection (PR1) is identified within all radargrams and provides a boundary between pre‐LIA and LIA to present‐day sedimentation. GPR data reveals a ~50 m thick ice‐proximal sediment wedge that is attributed to jökulhlaup and surge‐related glaciofluvial activity during the Little Ice Age (LIA). An approximate rate of deposition of 0.2–0.65 m a−1 ${{\rm{a}}}^{-1}$ has been calculated for the sediment wedge above PR1. Furthermore, we propose an extensive, sandur‐wide, pre‐LIA ice marginal limit of Skeiðarárökull, southeast Iceland, based on observations reported here and in previous work. [ABSTRACT FROM AUTHOR]