Definition and extent

The cryosphere is the term which collectively describes the portions of the Earth’s surface where water is in its frozen state – snow cover, glaciers, ice sheets and shelves, freshwater ice, sea ice, icebergs, permafrost, and ground ice. The word kryos is Greek meaning icy cold. Dobrowolski (1923, p.2; Barry et al. (2011)) introduced the term cryosphere and this usage was elaborated by Shumskii (1964, pp. 445–55) and by Reinwarth and Stäblein (1972). Dobrowolski and Shumskii included atmospheric ice, but this has generally been excluded. The cryosphere is an integral part of the global climate system. It has important linkages and feedbacks with the atmosphere and hydrosphere that are generated through its effects on surface energy and on moisture fluxes, by releasing large amounts of freshwater when snow or ice melts (which affects thermohaline oceanic circulations), and by locking up freshwater when they freeze. In other words, the cryosphere affects atmospheric processes such as clouds and precipitation, and surface hydrology through changes in the amount of fresh water on lands and oceans. Slaymaker and Kelly (2006) published a study of the cryosphere in the context of global change, while Bamber and Payne (2004) detailed the mass balance of glaciers, ice sheets, and sea ice. The discipline of glaciology encompasses the scientific study of snow, floating ice, and glaciers, while the study of permafrost (cryopedology) has largely developed independently.