Icebergs in the Southern Ocean Click on image for full size (27 Kb) Ute Kaden/PolarTREC

Frozen water is found in many different places on Earth. Snow blankets the ground at mid and high latitudes during winter. Sea ice and icebergs float in the chilly waters of polar oceans. Ice shelves fringe lands in Earth’s polar regions. Glaciers and larger ice sheets move slowly over land in polar regions. Glaciers are also found on high mountaintops around the world. The soils of polar regions, called permafrost, are filled with frozen water. Together, these different types of frozen water are known as the Earth’s cryosphere. Approximately three-quarters of the world’s fresh water is frozen in the cryosphere.

Some parts of the cryosphere, such as snow and the ice on ponds and lakes in mid-latitude locations, are only around during winter months. Other parts of the cryosphere, such as glaciers and ice sheets, stay frozen year-round and, in fact, can stay that way for tens of thousands or even hundreds of thousands of years. Some of the ice in the ice sheet that covers most of the continent of Antarctica has been there for nearly a million years.

The cryosphere is tied to the other parts of the Earth system. Here are some examples!

• Because snow and ice are light in color, they reflect more of the Sun’s energy back into space. When snow and ice melt, darker ocean and land are exposed. The darker colors absorb and then radiate more of the Sun’s energy, warming the atmosphere.

• When ice and snow melt, the water becomes part of the hydrosphere. For example, in the state of Washington in the western United States, melting snow and glaciers during summer provide 470 billion gallons of water each summer. The amount of snow and ice that melts each summer is increasing because of global warming.

• Many different living organisms within the biosphere rely on parts of the cryosphere for water and habitat. Polar bears roam across Arctic sea ice as they hunt for seals. Arctic cod take shelter in areas underneath the sea ice. Some penguins rely on ice during their breeding season. Snow and ice that melt seasonally, provides the freshwater that many different plants and animals need to survive.

• Glaciers and ice sheets shape the land surface. They erode rocks of the geosphere as the ice moves slowly across the land and then the eroded sediments are deposited in other places. In the tundra ecosystem, soils stiff with ice, called permafrost, sequester greenhouse gases from the atmosphere.