The cryosphere is the frozen water part of the Earth system. Snow and ice, including sea ice, lake and river ice, snow cover, glaciers, ice caps and sheets, and frozen ground, make up the cryosphere (the Greek word for cold) the places on Earth where water exists in solid form.
The cryosphere is a lifeline. With nearly 70% of Earth’s freshwater stored in glaciers and ice caps, more than a billion people around the world rely on the cryosphere as a source of drinking water.
In Arctic regions, sea ice provides a home for animals like seals and polar bears, feeding and breeding areas for a variety of migrating species, and hunting grounds for local communities. Although most of Earth’s frozen water is found near the poles, snow and ice can actually be found on all seven continents.
Acting like a highly reflective blanket, the cryosphere protects Earth from getting too warm. Snow and ice reflect more sunlight than open water or bare ground. The presence or absence of snow and ice affects heating and cooling over the Earth’s surface, influencing the entire planet’s energy balance.
Changes in snow and ice cover affect air temperatures, sea levels, ocean currents, and storm patterns all over the world. Just as changes in the cryosphere can influence climate, changes in climate can also dramatically alter the Earth’s snow- and ice-covered areas. Unlike other substances found on the Earth, snow and ice exist relatively close to their melting points and can easily change back and forth between solid and liquid.
With just slight variations in Earth’s temperature, thousands of square miles of snow and ice can accumulate or melt, making the cryosphere one of the most powerful indicators of climate and climate change. Today, scientists also use satellites to observe the cryosphere and monitor changes. Using these data, they are able to make predictions about what the cryosphere and Earth’s climate might look like many years from now.