There is a recognised lack of reconciled estimates of global glacier mass changes and its impact on sea-level change. While an increasing number of regional estimates from various sources have become available, previous assessments were hampered by spatial and temporal limitations and the heterogeneity of existing data series, resulting in large variations between those assessments. 

GlaMBIE-1 (2022-2024) aimed to tackle these limitations and associated challenges through a joint effort across the scientific community to collect, homogenize, combine, and analyse glacier mass changes from in situ and remote-sensing observations at regional to global scales with the intention to understand the differences and produce a reconciled estimate of glacier mass change globally and regionally. The GlaMBIE project built on nascent efforts within the IACS working group on Regional Assessments of Glacier Mass Change (RAGMAC) to setup and coordinate an intercomparison exercise of regional glacier mass changes from glaciological in-situ measurements and various remote-sensing sources, including geodetic DEM differencing, altimetry, and gravimetry.

The GlaMBIE-1 consortium was made up of a team from the University of Zurich, University of Edinburgh, and Earthwave, with expertise in a wide range of earth observation techniques, in particular to the assessment of glacier mass changes. An assessment framework, algorithm, and environment were developed to compile and analyse the regional glacier mass-change results from the active research groups and to come up with a joint paper of a new community estimate of regional and global glacier mass changes and related uncertainties. The community was involved through an open data call, the engagement in two workshops, and different promotion activities.

The new community estimate of global glacier mass changes elaborated within GlaMBIE
yielded a global glacier mass-change rate of −273±16 gigatonnes per year from 2000 to 2023,
with an increase in loss rate of 36±10% from the first (2000−2011) to the second (2012−2023) half of the period. Since 2000, glaciers have lost between 2% and 39% of their ice mass regionally and about 5% globally. This glacier mass loss is about 18% larger than the loss from the Greenland Ice Sheet and more than twice that from the Antarctic Ice Sheet. 

The results from GlaMBIE-1 provide a new observational baseline for calibrating model ensembles, which will help to narrow down the projections for the 21st century. This underpins the IPCC’s call for urgent and concrete actions for tangible measures to prevent further man-made climate change and limit the impacts of glacier vanishing.