Glaciers cover ~10% of Earth’s land surface, and their meltwater rivers are home to diverse biological communities that play central roles maintaining water quality, supporting fisheries, and subsidising the diet of terrestrial birds and mammals1,2. However, current unprecedented rates of glacier shrinkage3 are expected to cause major changes to algae and invertebrate biodiversity in rivers worldwide with largely unknown consequences4,5. Whilst knowledge of co-dependencies among biological groups is critical for predicting biodiversity change and driving conservation actions6, the intricate species-interactions shaping glacial-river food webs remain poorly understood4. Here we use >3500 newly observed feeding interactions among diatoms and invertebrates from rivers in the European Alps to demonstrate how decreasing glacier influence leads to increases in food web size as habitats become warmer, more stable, and less turbid. These responses are consistent with mountain-river biomonitoring observations from a new global meta-analysis of >190 studies. With decreasing glacier influence, diatoms became more species-rich and abundant both in real terms and relative to invertebrate consumers, and mean trophic level declined implying more efficient primary production transfer to consumers. We show this reorganisation is predictable from constituent species’ body mass and abundance, allowing projections to be made for rivers where species interactions remain unstudied. By demonstrating predictable links between species composition, traits, food web structure, and shrinking glaciers, this study significantly advances our ability to forecast ecological responses in rapidly changing mountain environments.

The water, food and energy security of millions of people is at risk in several regions of the tropical Andes because climate change is altering water storage in high Andean wetlands (bofedales), lakes and glacier ice. These features play a crucial role in delaying water release, particularly in many semiarid regions with pronounced seasonal precipitation, sustaining baseflows and water quality. Changing water availability impacts both high Andean pastoralist systems and other productive systems downstream, including bigger cities in the inter-Andean valleys. Here we outline the hydrological and geomorphological relationships between glaciers, lakes and bofedal wetlands, and the way in which catchment features such as moraines, talus slopes and sandar interact with catchment hydrology in the tropical Andes of Peru. We present a geomorphological map of catchment features in the Cordillera Vilcanota, Southern Peru, and explore how these features can impact hydrogeological processes. We suggest the ways in which well mapped and dated catchment features can provide a damming or groundwater/surface water exchange mechanism for bofedal development and sustenance. We find that glacial lakes will grow modestly as glaciers retreat, but will not provide an equivalent water storage to compensate for the loss of glacier ice. We find that bofedales are well developed within glacial limits, with glacial processes such as erosion and formation of moraines providing the poorly drained conditions suitable for their development. However, we find that the majority of the bofedales are largely hydrologically independent of contemporary glaciers, and could perhaps buffer water supply as glaciers dwindle and disappear. Such analysis enables an improved understanding of the timeframe for the formation of bofedal wetlands and for them to provide their key ecosystem services of water retention and remediation capacity, buffering drought, providing forage for high-Andean livestock herding, carbon storing and sequestration.

Tropical glaciers are important indicators of climate change, provide freshwater resources for downstream communities, and form an important component of the hydrological cycle. Understanding the dynamics and patterns of behaviour of tropical palaeoglaciers is important for interpreting their sensitivities and vulnerabilities. Glacier advances in the high tropical Peruvian Andes occurred multiple times during the last glacial cycle and Holocene, leaving complex geomorphological evidence on the landscape. The substantial topographic, geological and climatic variability in this region leads to high geomorphic diversity. However, few detailed geomorphological studies have been conducted to date, leading to considerable uncertainty in the behaviours and drivers of tropical palaeoglaciers. Here, we provide a detailed geomorphological analysis of the Cordillera Vilcanota, Cusco region, southern Peru (71 degrees W, 13.7 degrees S), and use morphostratigraphic principles to reconstruct the former maximum icefield extent and palaeoglacier advances. Across this domain, we mapped similar to 23,000 features encompassing five key environments: glacier, subglacial, ice-marginal, fluvial and lacustrine. The mapped features show evidence of both modern-day polythermal and temperate ice margins, with low meltwater volumes leading to small-scale glaciofluvial landform formation. However, larger moraines, beyond those well-dated to the Younger Dryas and Antarctic Cold Reversal, assumed to represent Last Glacial Maximum and earlier advances, suggest that conditions were temperate and drained by more substantial rivers, with coupled flow of ice and till, and evidence of subglacial scouring, drumlin formation and the deposition of substantial moraines and large palaeosandar. Our reconstructed maximum icefield covers 2,660 km(2) and was drained by multiple topographically constrained ice lobes across the region. In the north, these ice lobes reached an elevation of 3,500 m asl, but were limited to above 4,500 m asl in the south, likely reflecting the dominant moisture sources. Our geomorphological mapping reveals seven clear ice margins, morphostratigraphically correlated across the study region, reflecting at least seven palaeoglacier advances during the last glacial cycle, including the Late Glacial period and the Holocene.

An accurate global reconstruction of glacier mass change since the Little Ice Age (LIA) is of importance for, e.g., glacier mass change attribution studies and constraining the past sea-level budget. However, there are significant inconsistencies between reconstructions of the global LIA volume derived from (i) glacier length change records and (ii) glacier models that include the build-up to the LIA. The inconsistencies are present in both the magnitude and timing of the LIA maximum. Model reconstructions have shown a smaller peak of glacier volume, occurring many decades later than glacier length records indicate. Furthermore, as the maximum LIA volume did not occur synchronously between glaciers, the sampling choice of glaciers from the global population will have an impact on the total reconstructed LIA volume. Here, we tested the effect of different sampling strategies on reconstructed LIA volume, using a model based reconstruction from the Open Global Glacier Model, forced with the Last Millennium Reanalysis, as a surrogate world. Our analysis shows that glaciers for which length change observations prior to 1945 are available (the “real-world sample”) are not representative of the global signal. This shortcoming has the potential to explain large inconsistencies between the model-based reconstructions of glacier mass and reconstructions from observations. While the real-world sample is skewed, it is still a better representation of the global signal than would be expected from a random sample of the same size.

Understanding of Southern Hemisphere glacier response to climatic changes is limited by a paucity of direct observations. However, glacier Equilibrium Line Altitudes (ELAs), which are determined by air temperature and precipitation and represent glacier mass balance, can be approximated using remote sensing of end of summer snowline altitudes (SLAEOS). This study shows that SLAEOS increased on the majority of 6364 glaciers and by up to 7.18 m yr−1 between 2000 and 2023 across five Southern Hemisphere mountain regions. Over this period anomalies from the multi-decadal mean SLAEOS became predominantly positive for all regions. In the most extreme cases, the rate of SLAEOS rise accelerated by up to x 4.0 in the western Southern Alps of New Zealand when comparing pre- and post-2010 rates of change. Contrastingly, the western Antarctic Peninsula and the western Southern Andes experienced declining SLAEOS and slowing rates of change at -1.0 and − 8.1 m yr−1, respectively. These spatio-temporal patterns reveal the interplay of temperature and precipitation, and the effects of them on a wide variety of mountain glaciers and ice cap outlet glaciers, with implications for understanding glacier response times, committed ice losses and overall meltwater production in the coming decades.

The food and water security of 90 million people depends on the Andean Mountain water tower, which is at risk in several regions because climate change is altering water storage in high altitude wetlands (bofedales), lakes, snow and glacier ice. These features play a crucial role in delaying water release, particularly in many semiarid regions with pronounced seasonal drought, sustaining baseflows and water quality. Changing water availability impacts both high Andean pastoralist systems and other productive systems downstream, including bigger cities in the inter-Andean valleys. Here we outline the hydrological and geomorphological relationships between glaciers, lakes and wetlands, and the way in which catchment features such as moraines, talus slopes and sandar interact with catchment hydrology in the tropical Andes of Peru. We present a geomorphological map of catchment features in the Cordillera Vilcanota, Cusco region, Peru, and explore how these features can impact hydrogeological processes. We explore the ways in which well mapped and dated catchment features can give a damming or groundwater/surface water exchange mechanism for bofedal development. Such analysis enables an improved understanding of the timeframe for the formation of wetlands and for them to provide their key ecosystem services of water retention capacity, buffering drought, providing forage for alpaca and herding, and carbon storing and sequestration.

Abstract Nascent peatlands represent an emerging, nature‐based carbon sink in the global climate system. A warming climate and changing precipitation regime could drive peat initiation beyond the current latitudinal and altitudinal boundaries of the peatland bioclimatic envelope, through increases in plant productivity and moisture availability, with potential implications for global radiative forcing. However, contemporaneous observations of new peat formation remain scarce. We investigate peat initiation within the deglaciating Rob Roy valley in the Southern Alps, Aotearoa/New Zealand. We find that montane peats have developed across the head of the valley since ∼1949 C.E., coinciding with regional climate warming and glacial retreat. Further, we identify a common ecological succession, characterized by a rise in brown mosses (mainly Bryum) beginning around ∼1963 C.E. Our findings indicate the potential for wider peat expansion in increasingly warm and wet montane landscapes. However, further bioclimatic modeling is required to elucidate where future peatland developments may occur.

Ice-marginal lakes influence the dynamic behaviour of glaciers and ice sheets, impacting the rate at which they lose mass. In Greenland, accelerated ice loss over recent decades had led to an increase in the number of lakes bordering the ice sheet margin. This landscape evolution has sparked a growing field of research focused on quantitatively understanding the interactions between lakes and glaciers, so that ice-marginal lakes can be accounted for in models of ice sheet change. Ice loss from the Greenland Ice Sheet directly contributes to global sea level rise; understanding the drivers of this mass loss is important for accurately predicting future sea level. This article outlines recent advances in our understanding of lake-glacier interactions across Greenland during the past, present and future, and discusses key priorities for further research. We conclude by suggesting a series of activities that introduce Post-16 students to relevant datasets and techniques.

Remote sensing is a key tool to derive glacier surface velocities but existing mapping methods, such as cross-correlation techniques, can fail where surface properties change temporally or where large velocity variations occur spatially. High-resolution datasets, such as UAV imagery, offer a promising solution to tackle these issues and to study small-scale glacier dynamics, but new workflows are required to handle such data. Therefore, we tested the potential of new deep learning-based image-matching algorithms for deriving glacier surface velocities across the ablation area of a glacier with strong spatial variability in surface velocities (<5 m/yr to >100 m/yr) and substantial changes in surface properties between image acquisitions. For a thorough comparison of state-of-the-art methods and sensors, we applied three different techniques (cross-correlation using geoCosiCorr3D, feature tracking with ORB using SeaIceDrift and the new deep learning-based method using ICEpy4D) and three different platforms (Sentinel-2, PlanetScope, UAVs) to estimate glacier surface velocities. Results showed lowest errors for velocities derived with the deep learning-based approach applied to UAV imagery (RMSE = 2.17 m/yr, R2 = 0.99), followed by cross-correlation using Sentinel-2 images (RMSE = 21.0 m/yr, R2 = 0.59) and the deep learning-based approach with PlanetScope data (RMSE = 21.28 m/yr, R2 = 0.36). Cross-correlation with geoCosiCorr3D resulted in comparably high errors with the UAV dataset (RMSE = 36.22 m/yr, R2 = 0.24), whereas ORB-based feature tacking showed lowest performance with all sensors. Spatial patterns of computed velocities indicate that applying existing cross-correlation methods for areas with regular displacements or low glacier velocities yields suitable results on UAV data, but innovative deep learning-based approaches are required for resolving rapid changes in velocities or in surface properties. This novel method benefits from improved keypoint detection and matching through training using neural networks and data characterized by challenging geometries, outlier minimization and more robust descriptors by applying cross-attention layers. We conclude that continued development of deep learning-based feature tracking approaches for glacier velocity computations may substantially improve UAV-based velocity derivations applied to challenging situations. This method is able to deliver reliable displacement data in situations where traditional methods fail, which implies a new level of detail in understanding and interpreting glacier dynamics.

The proglacial landscapes of Antarctica offer critical insights into past and ongoing deglaciation processes and the impacts of climate change. This study presents the first geomorphological map of the proglacial part of Stansbury Peninsula (Rip Point) and Cariz Cabo Cape in the northern part of Nelson Island. We identify and characterise a variety of glacial, proglacial, paraglacial, and periglacial landforms using high-resolution drone imagery, fieldwork, and geological data. The defined landforms presented reflect a complex interplay of erosional and depositional processes shaped by multiple glacial advance-retreat cycles since the Last Glacial Maximum, with evidence for significant glacial activity during the Holocene. The presence of hyaloclastite and crystalline erratic boulders further contributes to the reconstruction of glacial dynamics in the region. Our findings provide a crucial dataset and baseline for studies on future Antarctic deglaciation, periglacial processes, and the expansion of proglacial landscapes driven by ongoing climate change.

Using satellite altimetry data, this work quantifies the inter-annual trends and intra-annual fluctuations in water levels of glacial lakes in High Mountain Asia during 2019-2023.

Land cover information is essential for understanding Earth surface processes and ecosystems. Here, we use K-means clustering to classify Landsat 8 Operational Land Imager (OLI) images covering six proglacial sites of sub-Antarctic islands, the Antarctic Peninsula, and the McMurdo Dry Valleys at 30-m resolution. We quantify spatial patterns of water, bedrock, vegetation, and sediments to an accuracy of 77 percent. Vegetation is most abundant on South Georgia (7 percent of the proglacial area) and the South Shetland Islands (1 to 2 percent). Furthermore, we use change vector analysis (CVA) to discriminate landcover change in the twenty-first century. A latitudinal pattern is evident in ice loss and proglacial landscape change; for example, loss of ice on South Georgia and proglacial landcover change is two orders of magnitude greater than in the McMurdo Dry Valleys. Four of the studied sites had similar landscape stability (64 to 68 percent unchanged), with Alexander Island an exception (50 percent change) due to recent enhanced glacier melt. Overall, we show how landcover of proglacial regions of the climaticallysensitive sub-Antarctic and Antarctica has changed since 2000, with a CVA accuracy of 80 percent. These findings inform understanding of geomorphological activity and sediment and nutrient fluxes and hence terrestrial and marine ecosystems.

The Arctic is one of the fastest-warming places on Earth. The High Arctic Archipelago of Svalbard contains over 1500 glaciers that have, overall, experienced widespread thinning and recession since the Little Ice Age (LIA; similar to 1900 CE), and this recession has accelerated since 1990. Here, we showcase the terminal decline since the end of the LIA of Elsabreen and Ferdinandbreen, two small land-terminating glaciers in Petuniabukta, Dickson Land. We map glacier areal extents using previously published data, aerial photographs and satellite imagery (LIA to 2024) and derive ice volume changes by differencing digital elevation models (1938 to 2023). Both glaciers have lost over 93% of their glacier area since the LIA and over 96% of their ice volume since 1938. By 2024, Elsabreen had reduced to a small glacier remnant with little evidence of ice flow, and Ferdinandbreen had fragmented into several separate ice units and completely detached from its original accumulation areas. Both of these vanishing glaciers merit inclusion on the Global Glacier Casualty List.

On 3 October 2023, a multihazard cascade in the Sikkim Himalaya, India, was triggered by 14.7 million m3 of frozen lateral moraine collapsing into South Lhonak Lake, generating an ~20 m tsunami-like impact wave, breaching the moraine, and draining ~50 million m3 of water. The ensuing Glacial Lake Outburst Flood (GLOF) eroded ~270 million m3 of sediment, which overwhelmed infrastructure, including hydropower installations along the Teesta River. The physical scale and human and economic impact of this event prompts urgent reflection on the role of climate change and human activities in exacerbating such disasters. Insights into multihazard evolution are pivotal for informing policy development, enhancing Early Warning Systems (EWS), and spurring paradigm shifts in GLOF risk management strategies in the Himalaya and other mountain environments.

Releasing experimental floods as part of environmental flow programs aims to restore river beds by moving and restoring sediments to improve hydromorphological conditions of the river. However, it remains a challenge to understand how flood release characteristics affect channel morphology, sediment transport, and hydrodynamics. In this study, field surveys and a 2D hydro-morphodynamic and sediment transport numerical model were used to determine how differences in flood magnitude and falling limb alter hydrogeomorphic conditions within a 4 km reach of the lower Spol River. The model was constrained by drone flight-derived high-resolution digital elevation models and two field-measured flood releases. The highest flood magnitude of 40 m3/s resulted in 2,700 m3 of total sediment transport, 2,000 m3 of net total volumetric change and 16 900 m2 more wetted area after the flood. The same flood, simulated with an increase in falling limb slope, resulted in a decrease in the duration of full sediment mobility and a corresponding reduction of 8% in net total volumetric change and 5.3% in the total wetted area. Contrastingly, the lowest flood magnitude of 25 m3/s produced 130% lower total sediment transport, 105% lower net total volumetric changes and 10% less wetted area after the flood. Overall, we show that hydro-morphodynamic modelling of river erosion and deposition combined with spatially rich topographic datasets are extremely useful in forming designed environmental flood scenarios to optimise sediment transport and thus hydrogeomorphic changes to set environmental flows. We contend that scenario modelling is necessary to help water managers optimise the amount of water allocated to environmental flows and to simultaneously restore and maintain riverine dynamics in heavily modified rivers. This research applied a 2D numerical modelling to execute the hydro-morphodynamic simulations of flood scenarios using a wealth of pre- and post-experimental flood data available at the Lower Spol River. Overall, we show that hydro-morphodynamic modelling of river erosion and deposition combined with spatially rich topographic datasets are extremely useful in forming designed environmental flood scenarios to optimise sediment transport and thus hydrogeomorphic changes to set environmental flows.image

Abstract Andean glaciers are losing mass rapidly but a centennial‐scale context to those rates is lacking. Here we show the extent of >5,500 glaciers during the Little Ice Age chronozone (LIA; c. 1,400 to c. 1,850) and compute an overall area change of −25% from then to year 2000 at an average rate of −36.5 km2 yr−1 or −0.11% yr−1. Glaciers in the Tropical Andes (Peru, Bolivia) have depleted the most; median −56% of LIA area, and the fastest; median −0.16% yr−1. Up to 10 × acceleration in glacier area loss has occurred in Tropical mountain sub‐regions comparing LIA to 2,000 rates to post‐2000 rates. Regional climate controls inter‐regional variability, whereas local factors affect intra‐region glacier response time. Analyzing glacier area change by river basins and by protected areas leads us to suggest that conservation and environmental management strategies should be re‐visited as proglacial areas expand.

Land cover responses to climate change must be quantified for understanding Arctic climate, managing Arctic water resources, maintaining the health and livelihoods of Arctic societies and for sustainable economic development. This need is especially pressing in Greenland, where climate changes are amongst the most pronounced of anywhere in the Arctic. Ice loss from the Greenland Ice Sheet and from glaciers and ice caps has increased since the 1980s and consequently the proglacial parts of Greenland have expanded rapidly. Here we determine proglacial land cover changes at 30 m spatial resolution across Greenland during the last three decades. Besides the vastly decreased ice cover (− 28,707 km2 ± 9767 km2), we find a doubling in total areal coverage of vegetation (111% ± 13%), a quadrupling in wetlands coverage (380% ± 29%), increased meltwater (15% ± 15%), decreased bare bedrock (− 16% ± 4%) and increased coverage of fine unconsolidated sediment (4% ± 13%). We identify that land cover change is strongly associated with the difference in the number of positive degree days, especially above 6 °C between the 1980s and the present day. Contrastingly, absolute temperature increase has a negligible association with land cover change. We explain that these land cover changes represent local rapid and intense geomorphological activity that has profound consequences for land surface albedo, greenhouse gas emissions, landscape stability and sediment delivery, and biogeochemical processes.

Ice-contact lakes modify glacier geometry and dynamics by shifting the majority of mass loss from the ice surface to the terminus. Lake-terminating glaciers are known to experience greater thinning rates and higher velocities than land-terminating glaciers, but the controls on variability in surface elevation change and ice flow between lake-terminating glaciers in different regions remain poorly explored. We combined existing datasets of glacier velocity, surface elevation change and glacial lake area to characterise the evolution of 352 lake-terminating and land-terminating glaciers within three Himalayan sub-regions between 2000 and 2019. These analyses show that the influence of ice-contact lakes propagates up-glacier across only the lowermost 30% of the hypsometric distribution, even where lakes are well established. We find that ice-contact lakes only affect glacier behaviour when the lakes reach an advanced evolutionary stage; most clearly manifested in the Eastern Himalaya by statistically robust differences in glacier-wide surface elevation change between lake-terminating (-0.68 +/- 0.05 m a-1) and land-terminating (-0.54 +/- 0.04 m a-1) glaciers. These differences are driven by the presence of a greater number of well-developed ice-contact lakes in the Eastern Himalaya compared to in the Western and Central Himalaya, resulting from greater mass loss rates to date.