Definition (Encyclopedia of Global Warming)
Deglaciation is the uncovering or exposure of a land surface that was previously covered by glacial ice. It results from ice melting or subliming (transforming from solid directly into vapor). Deglaciation, therefore, accompanies the end of a glacial stage. As deglaciation occurs, several processes take effect. Among these processes are meltwater stream flow, development of meltwater lakes, addition of water to the world’s oceans (raising the global sea level), exposure of the land, and rebound of the land (lifting of the land’s elevation as a result of the removal of the weight of the overlying ice). In addition, faunal and floral changes accompany deglaciation in response to changes in landscape and ecology.
Glaciers have a seemingly infinite capacity to entrain and transport sedimentary material, from tiny clay particles to giant rock boulders. Glaciers move these materials within and upon the ice, but when they melt all this sediment is deposited in the area where the ice melts. For this reason, areas that have experienced deglaciation are typically covered by glacially transported sediment. Alternatively, glaciers may sweep an area clean of loose material, creating deglaciated areas of bare bedrock. Where deglaciation has formed modern shorelines, those shorelines tend either to be laden with glacial sediment or to present bare bedrock to the waves. In some places, rebound has lifted the land along the modern shore,...
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Significance for Climate Change (Encyclopedia of Global Warming)
Deglaciation accompanies climate change and can be a cause of climate change. The geological record indicates that, when deglaciation commences, there is typically a climatic turn toward global warming. In other words, after climatic warming initiates deglaciation, the deglaciation itself can create a positive feedback loop engendering further warming. Glaciers are highly reflective of sunlight, contributing to Earth’s albedo (the percentage of sunlight reflected back into space from the planet’s surface). As glaciers melt, white ice and snow are replaced with darker surface elements. Earth’s albedo decreases, and more solar radiation is absorbed and retained by the planet. As the planet warms, more glaciers melt, the albedo decreases even further, and the process continues. Melting glaciers also contribute water to lakes and oceans, which help retain atmospheric heat. Rising sea levels due to glacial meltwater contribute to global climate change as well.
Using the modern deglaciation as an example, loss of glacial ice cover on the land has had and continues to have profound consequences for global climate change. For example, release of water locked up in glaciers has affected the amount of water in the oceans as well as on land, in rivers and streams, and in the form of groundwater. This has affected coastal and interior ecosystems, which are dependent upon water for life. Changing patterns in the...
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Further Reading (Encyclopedia of Global Warming)
Alley, R. B., and P. U. Clark. “Deglaciation of the Northern Hemisphere.” Annual Reviews 28 (2000): 149-182. One of the best references for a complete understanding of the current deglaciation, its chronology, and its overall effects. Well illustrated.
Ehlers, J., and P. L. Gibbard, eds. Quaternary Glaciations: Extent and Chronology. 3 vols. San Diego, Calif.: Elsevier, 2004. Massive, comprehensive compendium of studies of the glaciations and deglaciations of the Quaternary period. Includes five CD-ROMS of digital maps and other supporting material.
Stanley, Steven. Earth Systems History. 3d ed. New York: W. H. Freeman, 2009. Lays out the history of Earth, including the factors affecting global climates and climate change, over the vastness of geological time. Selected chapters focus on climate change in terms of glaciation and deglaciation.
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