What is Cryosphere ?

One of the interrelated components of the Earth’s system, the cryosphere includes snow cover, floating ice, glaciers, ice caps, ice sheets, seasonally frozen ground and

perennially frozen ground (permafrost)
It is thus distinguished by negative or zero temperature (°C), and the presence of water in the solid or super-cooled state. Fluctuations in the volume of the cryosphere cause changes in ocean sea-level, which directly impact the atmosphere and biosphere. It interacts with the atmosphere, hydrosphere, biosphere and lithosphere.

More information on the web : Cryosphere and IPCC