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National Science Foundation

Ice | Background

Ice has a significant impact on global climate, influencing the amount of solar radiation reflected back into space; the exchange of heat between the polar oceans and the atmosphere; the amount of freshwater entering the sea; and, indirectly, the strength of the global ocean's overturning circulation. Snow and ice cover about 10 percent of the land surface of Earth, including virtually all of the landmasses of Greenland and Antarctica, and seasonal sea ice spans much of the Arctic and Antarctic Circles during winter in each hemisphere.

Snow and ice factor into Earth's climate in a number of important ways. The amount of land-based ice determines global sea level--the geological record shows that higher sea levels occurred during "greenhouse Earth" periods in the past. The reflectivity, or albedo, of snow and ice introduces climate sensitivity, particularly in Earth's polar regions; as ice disappears, less solar energy is reflected away and more is absorbed, heating the surface, which causes the remaining ice to become more susceptible to melting. Ice also plays an important role in the circulation and currents of the world's ocean, because the formation and melting of sea ice affects the temperature and salinity of the surrounding seawater, which are important factors driving global ocean circulation.

Snow and ice at high elevations at temperate, and even tropical latitudes, affects local ecosystems and regulates local climate. In many parts of the world, human drinking water supplies depend on reliable and predictable patterns of glacial accumulation and thaw, which are threatened by alterations in global temperature and weather patterns. High-altitude glaciers around the world face uncertain futures. They also serve as powerful visual illustrations of a changing climate, as historical photographs reveal the dramatic extent to which many of them have receded. In some cases, they've already disappeared.

Ice is disappearing around Earth's poles as well. In 2007, satellite images confirmed what was plain enough to the researchers and indigenous people on the ground: Arctic sea ice cover shrank to a record new low.

Because of the importance of ice to Earth's climate, and because of its sensitivity to climate feedbacks, constant monitoring and observation is critical--both on the ground and from satellites above. Through decades of support of basic research, NSF has advanced our understanding of the physical, chemical and biological processes that make interpreting observational data possible. NSF's contribution to 'ice' research, particularly in the polar regions, has led to substantial advances in what we know about Earth's changing ice and snow, and how those changes may lead to further changes.

International Polar Year

The International Polar Year (IPY) 2007-2008, a world-wide scientific effort in which participating government agencies sponsor heightened activities in their polar research programs, aims to increase the public's knowledge of and benefit from research conducted at Earth's northern and southernmost extremities.