Community estimate of global glacier mass changes from 2000 to 2023

Abstract 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$^{11,12,18}$.