Interesting fact: Glaciers move even though they are solid ice, slowly flowing downhill under their own tremendous weight.
The answer: A glacier can weigh from millions of tons to trillions of tons depending on its size. Ice has a density of about 917 kilograms per cubic meter, so once a glacier reaches valley or ice-sheet scale, its mass becomes enormous.
Glaciers are easier to estimate than clouds because their boundaries can be mapped, but the total still changes with snow accumulation, melt, and internal flow. Their weight matters because it shapes valleys, affects sea level when ice is lost, and records climate change over long periods. Modern satellites now track glacier mass change much more precisely than older field methods could.
