Glaciers are indicators of ongoing anthropogenic climate change^1. Their melting leads to increased local geohazards^2, and impacts marine^3 and terrestrial^4, 5 ecosystems, regional freshwater resources^6, and both global water and energy cycles^7, 8. Together with the Greenland and Antarctic ice sheets, glaciers are essential drivers of present^9, 10 and future^11–13 sea-level rise. Previous assessments of global glacier mass changes have been hampered by spatial and temporal limitations and the heterogeneity of existing data series^14–16. Here we show in an intercomparison exercise that glaciers worldwide lost 273 ± 16 gigatonnes in mass annually from 2000 to 2023, with an increase 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 regionally and about 5% globally. 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^17. Our results arise from a scientific community effort to collect, homogenize, combine and analyse glacier mass changes from in situ and remote-sensing observations. Although our estimates are in agreement with findings from previous assessments^14–16 at a global scale, we found some large regional deviations owing to systematic differences among observation methods. Our results provide a refined baseline for better understanding observational differences and for calibrating model ensembles^12, 16, 18, which will help to narrow projection uncertainty for the twenty-first century^11, 12, 18.
A Wed, study studied this question.