Added: 03/14/2006 |
The Cryosphere System and its Role in the World's ClimateThe cryosphere system plays an undoubtedly important role in the climate system and in global-change research. But before examining the influences of cryosphere system on the global climate, let's define what the cryosphere is. The cryosphere is one of the Earth's spheres of irregular form existing in the zone of interaction of the atmosphere, hydrosphere and lithosphere, distinguished by negative or zero temperature and the presence of water in the solid or super-cooled state.
In other words, it's the frozen part of the Earth's surface. The cryosphere system consists of the great ice sheets of Antarctica and Greenland; the sea ice of the Arctic and Southern Oceans; frozen stretches of Canada, Siberia, and other lands within the Arctic Circle; and mountain glaciers.
Snow and ice, along with frozen ground or permafrost, have far-reaching effects on Earth's climate. The white crystals have a high albedo. That means that they reflect most of the sunlight they receive. By reflecting most solar radiation back into space, snow and ice have an essential cooling effect on the atmosphere. The excessive emissions of carbon dioxide and other greenhouse gases from human activities including industrial processes, fossil fuel combustion, and changes in land use, such as deforestation cause the thinning of the cryosphere, are potentially allowing more solar radiation to stay in the atmosphere and further warm the planet.
With the gradual melting of the snow blanket there is a possibility of covering this territory with the northern forests. If the northern forests encroach on areas that are now covered by tundra or ice, the dark trees will tend to absorb solar radiation, thereby accelerating the warming cycle.
The disappearance of the ice formed on the ocean also can have the disastrous effects as it reduces the movement of humidity and energy into the air, thereby affecting climate patterns and atmospheric circulation. More quantity of melted ice - water - can evaporate to form more clouds and precipitation. This can also influence the global circulation of oceans by affecting the ratio of fresh water to salt. According to the numerous recent researches and studies melting of one or more big ice sheets may be reached if available fossil fuels are burned too rapidly.
Climate scientists observe the intense retreat of mountain glaciers and the thinning of ice sheets as possible signs of global climate change. The consequences of cryosphere changes are watched and studied all over the world. Even now we can see the results of cryosphere thinning.
For instance, Asian cryosphere is considerably changing. The climate of modern Central Asia has been characterized by a lot of fluctuations. They were especially sharp during the second half of the 20th century. The long-term precipitation changes are mostly connected with the physico-geographical features of the total atmospheric circulation that are changing under the influence of green house effect.
So, the cryosphere system - sea ice and snow blank - is the important factor in global climate for numerous reasons:
1) Sea ice isolates the ocean from the cold atmosphere. The amount of sea ice affects heat, local clouds and precipitation.
2) Sea ice and snow blank have high albedo that reflects most of the sunlight (warming causes less ice, less sunlight reflected back to space, enhanced warming). Satellite observations show that Arctic sea ice concentrations have significantly decreased over the last 25 years. Submarine observations also suggest that the Arctic ice pack has thinned dramatically (by about 1/3) in the last 20-30 years.
It is important for human activities and biological habitats:
A) Shipping, oil exploration;
B) Arctic mammals (seals, polar bears) hunt, breed, and feed on the ice.
As you see, the problem of the global warming is a sticking point of the present. Perhaps it's too late for this generation to do anything to halt its progress. But certainly the next generation and the ones after tat have inherited a heck of a problem.
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