Glaciology is the study of ice in the environment. Important components are seasonal snow, sea ice, glaciers, ice sheets and frozen ground. The extent of these types of ice reflects the present and past climate.

Examples are: hemispheric snow cover in winter, thickness of sea ice on the polar oceans, depth of frozen ground, volumes of glaciers and the physical and chemical properties in layers cored from ice sheets.

The ice also affects climate. For example, the large areas covered by snow and sea ice reflect solar radiation away from the Earth's surface and thereby influence the heat balance of the earth.

Because these ice components are only decimeters to meters thick, they can change on time scales as short as seasons and can influence climate at all time scales. Glaciers and ice sheets are hundreds to more than one thousand meters thick and change significantly only on decadal or much longer time scale. On these longer time scales they can influence atmospheric circulation and global sea level. More locally all of these types of ice influence hydrology, geomorphic processes and pose various natural hazards.