Cryosphere

The cryosphere is the collection of regions of Earth where water exists as ice or snow. It includes sea ice, glaciers, ice sheets, snow cover, permafrost, and frozen ground in lakes and rivers. The cryosphere stores freshwater, shapes landscapes, and interacts with global climate and hydrological systems.

Key components are ice sheets in Greenland and Antarctica, mountain glaciers, seasonal snowpack, permafrost, sea ice in polar oceans, and frozen water in lakes and rivers. Snow cover and sea ice exhibit strong seasonal cycles, while ice sheets and permafrost respond to climate change over longer timescales.

The cryosphere influences the climate system through albedo effects, insulating properties, and momentum transfer at interfaces. Snow and ice reflect solar radiation, helping to cool the planet; melting reduces albedo and can drive further warming. Glaciers and ice sheets are major freshwater reservoirs whose melt contributes to sea level rise; permafrost thaw releases carbon and methane.

Because of climate change, the cryosphere is undergoing rapid changes in many regions. Arctic sea ice has declined in extent and thickness; many glaciers are retreating; permafrost is thawing, risking infrastructure and releasing greenhouse gases. Monitoring relies on satellites, airborne measurements, and ground observations to track extent, thickness, and volume.