isbre

An isbre is a glacier, a large, persistent body of ice that forms on land from the accumulation, compaction, and recrystallization of snow over many years. Glaciers move slowly under gravity, deforming internally and, where meltwater is present, sliding at their base. They transport ice, rocks, and sediment, shaping landscapes by carving valleys and leaving moraines.

Glaciers originate in accumulation zones in high mountains or polar regions. Snow gradually becomes firn and then ice, thickening to tens or hundreds of meters. Their flow is driven by gravity and modulated by bed conditions, temperature, and seasonal melt. They are commonly categorized as alpine or mountain glaciers, ice caps and ice sheets, depending on size and geometry.

The terminus of a glacier can be land-terminating or calving into a body of water, in which case icebergs may form. Glaciers erode, transport, and deposit material, creating features such as U-shaped valleys, moraines, and outwash plains. They also act as freshwater stores and sources for rivers.

Global climate warming has altered many glaciers, causing retreat or advance in some places. Changes in mass balance affect sea level, freshwater availability, and regional hydrology. Scientists monitor glaciers with field measurements and remote sensing to track changes in length, area, thickness, and velocity.

The term is derived from Norwegian isbre, combining is (ice) and bre (glacier). In English, the general term is glacier. Notable glaciers include Vatnajökull (Iceland), the Aletsch Glacier (Switzerland), and the Perito Moreno Glacier (Argentina).