Land-to-lake glacier terminus transition can alter glacier dynamics and enhance mass loss. However, the magnitude and timing of dynamic changes during this transition remain poorly constrained, especially in hyperhumid regions such as western Patagonia. We analyze this process at four glaciers by acquired bathymetry data combined with multi-temporal remote-sensing observations to track lake development and glacier retreat. Although each glacier shows distinct patterns, three glaciers underwent marked periods of rapid retreat associated with the onset of buoyant conditions at the termini, while the fourth glacier appears to be entering this stage. Results indicate that during rapid retreat, subaqueous ice loss contributed to 8-40% of total mass loss, underscoring its relevance for glacier mass balance. Based on land-lake contact and dynamics behavior, we propose reclassifying Exploradores Glacier from land- to lake-terminating. The analysis is constrained by the limited spatial coverage of bathymetric surveys, particularly at Grosse and Exploradores Glaciers. Nevertheless, the findings underline the importance of improving bed models and buoyant condition analysis to anticipate glacier changes. Many Patagonian glaciers are expected to evolve into lake-terminating systems, making updated inventories and inclusion of subaqueous mass loss critical for hazard assessment and projections of future ice loss.

Abstract. Sea‑level rise, driven by anthropogenic greenhouse‑gas forcing, is one of the best indicators of climate change. Satellite altimetry, the global Argo profiling network, and space‑borne gravimetry (GRACE/GRACE‑FO) have enabled quantitative monitoring of the sea‑level budget, yet recent analyses reveal a persistent non‑closure after 2015. We present an updated assessment of the global and regional sea‑level budget for the satellite era (1993–2022), extending the previous ESA‑CCI evaluation with refined uncertainty characterisation and an objective inverse closure framework. Global-mean sea-level (GMSL) trend and associated uncertainties at 90 % confidence level are accelerating from 3.39 ± 0.20 mm yr-1 for 1993–2022 to 3.86 ± 0.18 mm yr-1 for 2004–2022. GMSL is driven primarily by land‑ice mass loss of 1.44 ± 0.09 mm yr-1 and 1.74 ± 0.09 mm yr-1, respectively, alongside the thermosteric contribution of 1.24 ± 0.14 mm yr-1 and 1.32 ± 0.15 mm yr-1, for the same periods. The budget closes robustly until 2015 with residuals under 0.3 mm yr-1 (less than 10 % of the trend). Thereafter a statistically significant residual trend emerges, independent of the barystatic sea-level either from gravimetry or via the global water budget, indicating either a systematic inconsistency or multiple single‑dataset artifact. Regional analysis identifies persistent non‑closure in the North Atlantic, around Australia, and to a lesser extent in the North Pacific—patterns that resemble the largest steric signals and suggest underestimation of deep‑ocean steric contributions or overestimation of altimetric sea-level. An objective weighted‑least‑squares inversion (applicable from 2004 onward) demonstrates that a closed solution exists within combined uncertainties for 2004–2016, but closure fails at the 1σ level from 2017 onward, with less than 32 % probability of consistency. The inversion requires modest adjustments to satellite altimetry but substantial corrections to the gravimetric mass term, suggesting the GRACE‑FO transition as a likely source of the budget breakdown. These findings highlight the need for improved deep‑ocean observations, refined gravimetric processing, and spatial error‑correlation estimates to achieve reliable sea‑level budget closure at regional scales in the continued satellite era.

Abstract. Groundwater is one of the most important freshwater resources for ecosystems and mankind. Because of its fundamental role in the Earth's water and energy cycles, groundwater has been declared an essential climate variable by GCOS, the Global Climate Observing System. Similar to other subsurface states and fluxes, groundwater is difficult to monitor at the global scale, with sufficient spatial coverage and over climate-relevant time scales. The Global Gravity-based Groundwater Product (G3P) is a global observation-based data set of large-scale groundwater storage variations. G3P capitalizes on the unique capability of GRACE and GRACE-FO satellite gravimetry as the only remote sensing technology to monitor subsurface mass variations. In a mass balance approach, satellite-based, in situ observation-based and model-based water storage variations of snow water equivalent, root-zone soil moisture, glacier mass, and surface water storage are subtracted from GRACE/-FO terrestrial water storage anomalies to result in monthly variations of groundwater storage. For this combination, the individual compartmental storage data are spatially filtered to be consistent with the spatial resolution of terrestrial water storage from satellite gravimetry. The G3P data set presented here covers the period 2002 to 2023 with monthly resolution on a 0.5° global grid and includes propagated uncertainty information. We describe the details of the G3P data processing chain and of each contributing data stream, provide examples of spatial and temporal groundwater storage variations represented by the G3P data set, and present exemplary evaluation results against in situ groundwater observations for three large aquifer systems. G3P is a prototype for an operational global groundwater service, under development as a cross-cutting extension of the existing portfolio of the Copernicus Climate Change Service C3S. The G3P data set is available via GFZ Data Services at https://doi.org/10.5880/G3P.2024.001 (Güntner et al., 2024).

Glaciers lost 408 ± 132 Gt of mass during the hydrological year 2025, equivalent to 1.1 ± 0.4 mm sea-level rise. Since 1975, glacier mass loss has totalled 9,583 ± 1,211 Gt, equivalent to 26.4 ± 3.3 mm of sea-level rise, with six of the highest mass-loss years on record occurring in the past seven years.

The rapid retreat of mountain glaciers due to climate change has led to the expansion of glacial lakes, which can produce sudden glacial lake outburst floods (GLOFs) due to the failure of unstable moraine or glacier dams, in some cases triggering a cascade of consequences. This study investigates the evolution of glacial lakes and the occurrence of GLOFs in the Cordillera Darwin and Cloue Icefields of Tierra del Fuego, southernmost South America, from 1945 to 2024 — a region that has not been analysed in detail before. Using historical aerial imagery, satellite data, UAV photogrammetry and field surveys, we document a 461% increase in the number of lakes (from 33 to 185) and a 124% increase in lake area (from 28.2 ± 5.6 to 63.3 ± 1.9 km2) as a result of glacier retreat. A pronounced shift from ice-dammed (71.6%–14.8% of the total area) to moraine-dammed lakes (80.5% by 2024) reflects the destabilisation of the ice margins and the exposure of overdeepened basins. We identified the first recorded southernmost GLOFs in this region, including a moraine collapse in 1997/98 that released ∼8.3 ± 1.2 × 106 m3 of water and a larger, adjacent cascading event in 2018 that released 28.3 × 106 m3 of water through successive moraine dam breaches. The cyclic outflows of the ice-dammed Lago Mateo Martinic (1985–2024) underline the dynamic interactions between ice and water. The results are consistent with global patterns of accelerated lake formation and growth over the last century, and with the diverse and complex processes at GLOFs that make Tierra del Fuego an important natural laboratory for studying the deglacierising environment. This study improves the understanding of glacial lake dynamics in the little-studied southern latitudes and emphasises the accelerated transformation of Andean cryospheric landscapes as warming progresses.

Glacier changes are a sign of climate change and have an impact on the local hazard situation, region runoff, and global sea level. In previous reports of the Intergovernmental Panel on Climate Change (IPCC), the assessment of glacier mass changes was hampered by spatial and temporal limitations as well as by the restricted comparability of different observing methods. The Glacier Mass Balance Intercomparison Exercise (GlaMBIE; https://glambie.org) aims to overcome these challenges in a community effort to reconcile in-situ and remotely sensed observations of glacier mass changes at regional to global scales.In this contribution, we will present the approach and results of the new data-driven consensus estimation of regional and global mass changes from glaciological, DEM-differencing, altimetric, and gravimetric methods. Our reconciled estimate suggests a global glacier mass loss of about 5,500 Gt from 2000 to 2022, with an acceleration of about 25% when comparing the second with the first half period. Since 2000, glaciers regionally have lost between 1 and 30% of their total ice volume, and about 4.5% globally. We will discuss these results in view of differences between observation methods and in comparison to previous IPCC reports, the implications for regional glacier mass loss and global sea-level rise, and remaining opportunities for further research.

Glaciers, distinct from the Greenland and Antarctic ice sheets, play a crucial role in Earth's climate system by affecting global sea levels, regional freshwater availability, nutrient and energy budgets, and local geohazards. Past assessments of regional to global glacier mass changes were limited in spatial coverage, temporal resolution, and/or temporal coverage. Here, we present a new observation-based dataset of glacier mass changes with global coverage and annual resolution from 1976 to 2024. We use geostatistical modeling for the temporal downscaling of decadal glacier-wide elevation change estimates derived from satellite and airborne geodetic data, with glaciological annual in situ observations. In more detail, we spatially interpolate the annual mass balance anomalies from sparse in situ observations and calibrate them to glacier-wide long-term trends from elevation change observations available for individual glaciers for varying time periods and with global glacier coverage from 2000 to 2019. We then extrapolate the results to yearly time series starting between 1915 and 1976, depending on the regional data availability, and extending to 2024. The time series are calculated separately for each of the world's glaciers and then aggregated to gridded (0.5° latitude and longitude), regional, and global estimates of annual glacier mass changes. Since 1976, Earth's glaciers have lost 9179 ± 621 Gt (187 ± 20 Gt per year) of water, contributing 25.3 ± 1.7 mm (0.5 ± 0.2 mm per year) to the global mean sea level rise. About 41 % (∼ 10 mm) of this loss occurred in the last decade, with 6 % (∼ 1.5 mm) occurring in 2023 alone, the record-breaking year of glacier mass loss. We review the strengths and limitations of our new dataset, validate and discuss related uncertainty estimates in a leave-one-out/block-out cross-validation exercise, and compare our results to earlier assessments. The annual mass change time series for individual glaciers and the derived global gridded annual mass change product are available from the World Glacier Monitoring Service (WGMS) at https://doi.org/10.5904/wgms-amce-2025-02 (Dussaillant et al., 2025).

The first-ever field measurements conducted at the outlet glaciers Gualas and Reichert at the Northern Patagonian Ice Sheet, Chile, provide the basis for this work. Both glaciers currently terminate in large (2 km resp. 9 km length) proglacial lakes. The glaciers have retreated rapidly over the past four decades, whereby Reichert glacier retreated by over 100 m per year. Our bathymetry measurements of these lakes make it possible to estimate the mass loss and make assumptions about floatation of these glaciers during retreat. The lakes have depths of up to 250 resp. 350 m and therefore the volume previously occupied by the glaciers is significant. Recent UAV surveys of the final 3 km of the tongue of both glaciers and satellite data provide high-resolution elevation models and are employed to estimate mass loss since the 2000s. With this preliminary study we aim to investigate whether mass loss of these glaciers has been underestimated due to neglected subaqueous ice mass loss. Knowledge from this study will contribute to improving past, present and future mass change estimates of similar glaciers, with relevance for, e.g., sea level rise contribution from ice sheets and their outlet glaciers.

Glaciers play a fundamental role in the Earth’s water cycles. They are one of the most important freshwater resources for societies and ecosystems and the recent increase in ice melt contributes directly to the rise of ocean levels. For this reasons, they have been declared as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). Within the Copernicus Climate Change Services (C3S), the global gridded annual glacier mass change dataset provides information on changing glacier resources for the last five decades by combining the glacier outlines from the globally complete Randolph Glacier Inventory with the mass balance and elevation change observations from the Fluctuation of Glaciers database of the World Glacier Monitoring Service (WGMS).The glacier change product provides a global assessment of annual glacier mass change and related uncertainties (in m w.e. and Gt) and gridded area changes (km2) since the hydrological year 1975/76 to present, provided in a 0.5°x0.5° (latitude-longitude) global regular grid and in netcdf file format. The new product bridges the gap on spatio-temporal coverage of glacier change observations, providing for the first time in the CDS an annually resolved glacier mass change product using the glacier elevation change sample as calibration. This goal has become feasible at the global scale only recently and thanks to a new globally near-complete (96% of the world’s glaciers) dataset of glacier elevation changes between 2000 and 2020.The global gridded annual glacier mass change product integrates nicely into the family of the gridded ECV products provided by the C3S CDS. It provides new insights into regional to global glacier mass changes and, hence, has a great potential for contributing to the various state of the climate reports as well as to assessments of the global sea-level budget, the global energy cycle or the global water cycle. Continuation and expansion of the glaciological in-situ observation network is essential for providing the temporal variability of the glacier mass change product. Ensuring the continuation of open source spaceborne datasets with extensive acquisitions tasking planned over glaciated regions is crucial for ensuring the good quality of future glacier products, and one of the greatest gaps in the quality and continuation of the glacier services delivered to C3S.

Mountain glaciers are a major source of sea-level rise and also represent an important freshwater resource in many mountainous regions. Thus, accurate estimations of their thickness and, therefore, the total ice volume are important both in predicting and mitigating the global and local effects of climate change. However, to date, only 2% of the world’s glaciers outside the ice sheets have any thickness observations, due to the logistical difficulties of obtaining such measurements, creating a large and policy-relevant scientific gap. The recent development of a global-scale ice-velocity dataset, however, provides an ideal opportunity to fill this gap and determine ice thickness across the 98% of glaciers for which no thickness data is available. This can be done by inverting an ice-dynamics model to solve for ice thickness. For accurate thickness results, this needs to be a higher-order model, but such a model is far too computationally cumbersome to apply on a global scale, and simpler, quicker methods usually based on the shallow ice approximation (SIA) are unsuitable, particularly where sliding dominates glacier motion. The only attempt that has been made to leverage the global velocity dataset to retrieve ice thickness has, though, used the SIA, simply because higher-order approaches are not computationally realistic at this scale. Consequently, most of the widely-used global glacier models have made no systematic attempt to invert global ice thickness, owing to these limitations. Allied to this is that, once an inversion is done, subsequent forward modelling is rarely physically consistent with the physics used in the inversion, leading to model inconsistencies that affect the accuracy of simulations. As a solution to these problems, we extend our recent work on the European Alps using a deep-learning-driven inversion model, the Instructed Glacier Model (IGM), that emulates the performance of state-of-the-art higher-order models at a thousandth of the computational cost. This model, by solving a multi-variable optimisation problem, can fully use and assimilate all available input datasets (surface velocity and topography, ice thickness, etc.) as components of its cost function to invert ice thickness. This approach also gives us the possibility of using consistent ice-flow physics for inversion and forward modelling, reducing the magnitude of the shock inherent in traditional modelling approaches. We present here the first results of glacier-ice-thickness inference at a global scale obtained by the inversion of a higher-order three-dimensional ice-flow model.

Patagonia and Tierra del Fuego (Austral Andes) are the most glacierised regions in the Southern Hemisphere, where glaciers have experienced significant mass changes in recent decades. Understanding glacier–climate–water interactions is crucial for addressing future climate challenges. Open-access data play a key role in advancing geoscience research, improving models, and assessing the impacts of hazards and sea-level rise impacts. Here, we present QFuego-Patagonia, a free glacier-related GIS dataset and web portal covering Patagonia and Tierra del Fuego, which provides essential geospatial information across four scientific topics: Glaciology, Atmosphere, Terrain Models, and Glacial Geology and Geomorphology. This initiative aims to foster interdisciplinary research and collaboration, synthesise current knowledge, and establish an advanced glacier data repository that will be continuously updated as new data and insights become available.

The Global Gravity-based Groundwater Product (G3P) has evolved with a new version (V1.12), bringing substantial enhancements to our satellite-based groundwater storage anomaly dataset—a prototype for a future product within the EU Copernicus Climate Change Service. Groundwater as the world's largest distributed freshwater storage, is a vital resource for human, industrial, and agricultural needs. Despite its significance, Copernicus lacks a service delivering operational, observation-based, and globally comprehensive data on changing groundwater resources. G3P could serve as a pivotal extension to the Copernicus portfolio. Leveraging the unique capabilities of GRACE and GRACE-FO satellite gravimetry, G3P monitors subsurface mass variations employing a mass balance approach. This involves subtracting the satellite-based and partly model-based water storage compartments (WSCs) snow water equivalent, root-zone soil moisture, glacier mass and surface water storage from GRACE/GRACE-FO monthly terrestrial water storage anomalies (TWSA). Ensuring a consistent subtraction of individual WSCs from GRACE-TWSA involves filtering them similarly to GRACE-TWSA, using filters whose type and parametrization had to be derived by spatial correlation analyses. The G3P dataset spans more than two decades (from 2002 to 2023) with a monthly resolution and global coverage at 0.5-degree spatial resolution. Notable updates in V1.12 compared to previous versions include an extended data time period until September 2023, modifications of the methodology of several WSCs, and the incorporation of new evaluation results. This study has received funding from the European Union’s Horizon 2020 research and innovation programme for G3P (Global Gravity-based Groundwater Product) under grant agreement nº 870353.

Digital elevation models (DEMs) from the spaceborne interferometric radar mission TanDEM-X hold a large potential for glacier elevation change assessments and monitoring. However, a bias is potentially introduced through the penetration of the X-band signal into snow and firn that can be substantial. The magnitude of this bias has been analysed in some glaciarized regions of the world; still, the knowledge about X-band penetration of TanDEM-X in the European Alps is limited.In this study, we investigated the unique situation of almost synchronous acquisition of TanDEM-X and Pléiades DEMs over the Grosser Aletschgletscher, complemented with in-situ observations (ground penetrating radar, snow cores, snow pits), all within a four-day period in late winter 2021. The comparison of the TanDEM-X and Pléiades DEM revealed an elevation bias due to radar penetration of up to 8 m above 3400 m. Further, the concurrent in-situ measurements reveal that the signal is not obstructed by the last summer horizon but reaches into perennial firn.Our study improves our understanding about the magnitude of X-band penetration of TanDEM-X in the Alps and the underlying process with a relevance for glaciology, snow science, remote sensing and the wider geoscience community.

Glacier changes are a sign of climate change and have an impact on the local hazard situation, region runoff, and global sea level. In previous reports of the Intergovernmental Panel on Climate Change (IPCC), the assessment of glacier mass changes was hampered by spatial and temporal limitations as well as by the restricted comparability of different observing methods. The Glacier Mass Balance Intercomparison Exercise (GlaMBIE; https://glambie.org) aims to overcome these challenges in a community effort to reconcile in-situ and remotely sensed observations of glacier mass changes at regional to global scales. In this contribution, we will present the approach and results of the new data-driven consensus estimation of regional and global mass changes from glaciological, DEM-differencing, altimetric, and gravimetric methods. Our reconciled estimate suggests a global glacier mass loss of about 5,500 Gt from 2000 to 2022, with an acceleration of about 25% when comparing the second with the first half period. Since 2000, glaciers regionally have lost between 1 and 30% of their total ice volume, and about 4.5% globally. We will discuss these results in view of differences between observation methods and in comparison to previous IPCC reports, the implications for regional glacier mass loss and global sea-level rise, and remaining opportunities for further research.

Observations of glacier mass changes are key to understanding the response of glaciers to climate change and related impacts, such as regional runoff, ecosystem changes, and global sea level rise. Spaceborne optical and radar sensors make it possible to quantify glacier elevation changes, and thus multi-annual mass changes, on a regional and global scale. However, estimates from a growing number of studies show a wide range of results with differences often beyond uncertainty bounds. Here, we present the outcome of a community-based inter-comparison experiment using spaceborne optical stereo (ASTER) and synthetic aperture radar interferometry (TanDEM-X) data to estimate elevation changes for defined glaciers and target periods that pose different assessment challenges. Using provided or self-processed digital elevation models (DEMs) for five test sites, 12 research groups provided a total of 97 spaceborne elevation-change datasets using various processing approaches. Validation with airborne data showed that using an ensemble estimate is promising to reduce random errors from different instruments and processing methods but still requires a more comprehensive investigation and correction of systematic errors. We found that scene selection, DEM processing, and co-registration have the biggest impact on the results. Other processing steps, such as treating spatial data voids, differences in survey periods, or radar penetration, can still be important for individual cases. Future research should focus on testing different implementations of individual processing steps (e.g. co-registration) and addressing issues related to temporal corrections, radar penetration, glacier area changes, and density conversion. Finally, there is a clear need for our community to develop best practices, use open, reproducible software, and assess overall uncertainty to enhance inter-comparison and empower physical process insights across glacier elevation-change studies.

Abstract. Glaciers, distinct from the Greenland and Antarctic ice sheets, play a crucial role in Earth's climate system by affecting global sea levels, freshwater availability, nutrient and energy budgets and regional climate patterns. Accurate measurements of glacier mass changes are needed to understand and project glacier evolution and its related impacts on the climate system. Two distinct methods allow to measure glacier mass changes at high spatial resolution. Remotely sensed surface elevation data provides volume change estimates over large glacierized regions for multi-annual to decadal time periods. Field glaciological measurements provide annually to seasonally resolved information on glacier mass change for a small sample of the world’s glaciers. By combining the two methods we provide annual time series of individual glacier mass changes and related uncertainties spanning the hydrological years from 1976 to 2023. The per-glacier time series can then be seamlessly integrated into annually resolved global regular grids of glacier mass changes at user-specified spatial resolution. Our results undergo a leave-one-out cross-validation confirming uncertainty estimates at the glacier level to be in the conservative side. Our dataset provides a new baseline for future glacier change modelling assessments and their impact on the world's energy, water, and sea-level budget. The present annual mass change time-series for the individual glaciers and the derived global gridded annual mass change product at a spatial resolution of 0.5° latitude and longitude will be made available from the WGMS webpage. During the review process, the dataset is temporarily available from URL: https://user.geo.uzh.ch/idussa/Dussaillant_etal_ESSD_data/.

In 2004, we painstakingly measured the thinning of a single glacier tongue (the Mer de Glace, Mont-Blanc) from pairs of SPOT (CNES) satellite optical stereo-images. It then took us nearly 20 years before we managed to up-scale such observations to the global scale. In this presentation, I will illustrate the advances (in terms of data availability and processing) and all the collaborative work that led to a spatially-resolved and almost complete estimation of mass changes for the more than 200,000 glaciers on Earth. These new data paint a global picture of accelerating glacier mass loss since 2000 and pave the way toward improved projections of future glacier mass and sea level contribution.

Glaciers distinct from the Greenland and Antarctic ice sheets are currently losing mass rapidly with direct and severe impacts on the habitability of some regions on Earth as glacier meltwater contributes to sea-level rise and alters regional water resources in arid regions. In this review, we present the different techniques developed during the last two decades to measure glacier mass change from space: digital elevation model (DEM) differencing from stereo-imagery and synthetic aperture radar interferometry, laser and radar altimetry and space gravimetry. We illustrate their respective strengths and weaknesses to survey the mass change of a large Arctic ice body, the Vatnajökull Ice Cap (Iceland) and for the steep glaciers of the Everest area (Himalaya). For entire regions, mass change estimates sometimes disagree when a similar technique is applied by different research groups. At global scale, these discrepancies result in mass change estimates varying by 20%–30%. Our review confirms the need for more thorough inter-comparison studies to understand the origin of these differences and to better constrain regional to global glacier mass changes and, ultimately, past and future glacier contribution to sea-level rise.

Abstract Modeling the short‐term (<50 years) evolution of glaciers is difficult because of issues related to model initialization and data assimilation. However, this timescale is critical, particularly for water resources, natural hazards, and ecology. Using a unique record of satellite remote‐sensing data, combined with a novel optimisation and surface‐forcing‐calculation method within the framework of the deep‐learning‐based Instructed Glacier Model, we are able to ameliorate initialization issues. We thus model the committed evolution of all glaciers in the European Alps up to 2050 using present‐day climate conditions, assuming no future climate change. We find that the resulting committed ice loss exceeds a third of the present‐day ice volume by 2050, with multi‐kilometer frontal retreats for even the largest glaciers. Our results show the importance of modeling ice dynamics to accurately retrieve the ice‐thickness distribution and to predict future mass changes. Thanks to high‐performance GPU processing, we also demonstrate our method's global potential.

Retreating and thinning glaciers are icons of climate change and impact the local hazard situation, regional runoff as well as global sea level. For past reports of the Intergovernmental Panel on Climate Change (IPCC), regional glacier change assessments were challenged by the small number and heterogeneous spatio-temporal distribution of in situ measurement series and uncertain representativeness for the respective mountain range as well as by spatial and temporal limitations and technical challenges of geodetic methods. Towards IPCC SROCC and AR6, there have been considerable improvements with respect to available geodetic datasets. Geodetic volume change assessments for entire mountain ranges have become possible thanks to recently available and comparably accurate digital elevation models (e.g., from ASTER or TanDEM-X). At the same time, new spaceborne altimetry (CryoSat-2, IceSat-2) and gravimetry (GRACE-FO) missions are in orbit and about to release data products to the science community. This opens new opportunities for regional evaluations of results from different methods as well as for truly global assessments of glacier mass changes and related contributions to sea-level rise. At the same time, the glacier research and monitoring community is facing new challenges related to the spread of different results as well as new questions with regard to best practises for data processing chains and for related uncertainty assessments.In this presentation, we introduce the Glacier Mass Balance Intercomparison Exercise (GlaMBIE) project of the European Space Agency, which is building on existing activities and the network of the International Association of Cryospheric Sciences (IACS) working group on Regional Assessments of Glacier Mass Change (RAGMAC) to tackle these challenges in a community effort. We will present our approach to develop a common framework for regional-scale glacier mass-change estimates towards a new data-driven consensus estimate of regional and global mass changes from glaciological, DEM-differencing, altimetric, and gravimetric methods.