Why do glaciers store such a large share of Earth’s freshwater?

Glaciers store approximately three-fourths of all the world’s freshwater because they act as massive, long-term reservoirs for precipitation. This storage occurs in regions where annual snowfall consistently exceeds the rate of summer melting, allowing snow to accumulate and transform into dense glacier ice over long periods.123

The process begins as snow is buried and compacted into firn, an intermediate stage between snow and ice. Under the pressure of overlying layers, this material undergoes recrystallization and densification, eventually forming impermeable ice that traps water in a solid state. Because these ice masses cover about 11 percent of the world’s land area, they effectively lock up a significant portion of Earth's water supply, releasing it slowly through meltwater and runoff rather than allowing it to cycle rapidly through the atmosphere or rivers.45162