The cryosphere is an integral part of the global climate system with important connections and feedbacks generated through its influence on surface absorbed solar radiation, moisture fluxes, clouds, precipitation, hydrology, and atmospheric and oceanic circulation.
Through these processes, it also plays a significant role in the response to global climate change and its accurate modeling is a fundamental part of any climate model. Most of the world's ice volume is found in the Antarctic region, mainly in the East Antarctic Ice Sheet.
In terms of extent, however, winter snow and ice extent in the Northern Hemisphere covers the largest area, averaging 23% of the hemispheric surface area in January. The large extent of the area and the important climatic role of snow and ice, related to their unique physical properties, indicate that the ability to observe and model snow and ice cover extents, thickness, and physical properties (radiative properties and thermal) is of particular significance for climate research.
The thermal properties of cryospheric elements also have important climatic consequences. Snow and ice have a much lower thermal diffusivity than air. Thermal diffusivity is a measure of how fast temperature waves can penetrate a substance.
The importance of the cryosphere in the planet's climate balance
Snow and ice are an order of magnitude much less efficient at spreading heat than air. Snow cover insulates the land surface, and ice shelves insulate the underlying ocean, decoupling the surface-atmosphere interface with respect to heat and moisture fluxes.
The polar ice caps are the largest potential sources of fresh water, containing approximately 77% of the entire planet's resources. This is equivalent to 80m above sea level, with Antarctica leading the way, with reserves amounting to 90%.
Greenland accounts for the largest remaining 10%, with other ice masses and glaciers accounting for less than 0.5%. Due to their size in relation to annual variations in snow accumulation or melting, the residence time of water in ice masses can extend to 100,000 or 1 million years.
While changes in glaciers are likely to have minimal effects on global climate, their recession may have contributed one-third to one-half of the observed sea-level rise in the 20th century. Furthermore, such extensive glacier recession as is currently observed in the Western Cordillera of North America, where runoff from glacial basins is used for irrigation and hydroelectricity, is extremely likely, implying significant hydrological and ecosystem impacts.