Glaciers are vital stores of fresh water. Their melt during dry seasons provides water for billions, and their loss reduces seasonal availability while raising sea levels, threatening coastal communities.\n\nThe World Glacier Monitoring Service tracks 31 years of glacier mass balance, which has been consistently negative. Since 1976, the cumulative loss equals 20m of water equivalent.

This shrinkage is driven by temperature, snowfall, and other climate factors, with the IPCC AR5 stating high confidence that human influence is a substantial cause.\n\nGlacier mass balance is measured via stakes in the ice to track melting and accumulation, as well as satellite radar, altimetry, and gravity missions like GRACE. These methods map height changes and large-scale ice loss. Each glacier responds uniquely to local climate drivers, but the long-term global trend is clear: glaciers have been retreating since the 19th century.