Quick Answer: The cryosphere is an umbrella term for those portions of Earth's surface where water is in solid form. This includes sea ice, ice on lakes or rivers, snow, glaciers, ice caps, ice sheets, and frozen ground. Thus, there is an overlap with the hydrosphere. The cryosphere is an integral part of the global climate system. It also has important feedbacks on the climate system. These feedbacks come from the cryosphere's influence on surface energy and moisture fluxes, clouds, the water cycle, atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in the global climate and in climate model response to global changes. Approximately 10% of the Earth's surface is covered by ice, but this is rapidly decreasing. Current reductions in the cryosphere are measurable in ice sheet melt, glaciers decline, sea ice decline, permafrost thaw and snow cover decrease.