gletscher

Gletscher (German for glacier) refers to a large, persistent mass of ice that forms on land from the accumulation, compaction, and recrystallization of snow over many years, and that slowly moves downslope under its own weight. Glaciers form where snowfall exceeds ablation over long periods, creating an accumulation zone at higher elevations or latitudes. The ice mass deforms plastically and flows, with basal sliding facilitated by meltwater that reduces friction at the bed.

Glaciers come in different forms. Alpine or valley glaciers flow through mountain valleys, while continental ice sheets cover extensive areas. A glacier is bounded by a terminus and bounded above by the equilibrium line (snowline), which separates accumulation and ablation zones. Surface features such as crevasses, seracs, and moraines record stress, flow, and past ice dynamics.

Glacial erosion and deposition shape landscapes, creating U-shaped valleys, fjords, and sharp ridges. Glaciers store large amounts of fresh water and influence regional hydrology, acting as reservoirs during warm periods. They are also sensitive indicators of climate, responding to temperature and precipitation changes with thinning, retreat, or, in some cases, advance. In recent decades, many glaciers have retreated and thinned globally due to warming, contributing to sea-level rise in part through loss of land-based ice. Researchers monitor glaciers with field measurements, satellite imagery, and isotopic analyses to study past and present climate dynamics. Glaciers thus remain essential for understanding Earth’s climate system and freshwater resources.