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From: Rod Deline
Date: 10/29/02
Time: 9:04:12 AM
Remote Name: 204.29.69.78
This is my week to post. Everything should be done by Sunday night.
Hydrosphere and Ice Shelf Disintegration
The hydrosphere is made up of all the planet's water. The hydrosphere contains all the solid, liquid and gaseous water of the planet. The hydrosphere extends several kilometers below the surface of the Earth and reaches heights of 12 kilometers into the atmosphere. The hydrosphere interacts with, and is influenced by, all other earth spheres.
Event>Sphere Interactions:
E>H: Changing the volume of an ice shelf does not change the sea level because floating ice already displaces a volume of water equal to the volume of water it contains. However, if ice currently resting on the continental surface were to flow into the coean more rapidly as a result of the removal of the fringing ice shelves, then sea levels would rise.
E>H Scientist say the melting of the West Antarctic ice sheet will cause sea levels to rise at a rate of 1cm per decade for a total of 20ft over the next 7,000 years. Scientist from the University of Maine and the University of Washington studying this process, predict the 360,000 square mile ice sheet will completely melt due to global warming.
E>H Ice streams are fast moving river like currents of ice that move through an ice sheet, carrying large volumes of ice out inot ice shelves. A complete collapse of an ice sheet is unlikely at this point. However, due to global warming ice streams may accelerate their flow, increasing the discharge of ice and contributing to the disintegration of the entire ice sheet.
E>H Nature recently published an extensive review of climate and ice sheet stability whcih reveals that human-induced global warming might compound cyclical melting within the West Anarctic Ice Sheet, causing the sheet to collapse over the next one hundred to one thousand years. The author of the article, Dr. Michael Oppenheimer, concludes, "Atmospheric accumulation of greenhouse gases over the next 100 years could irreversibly affect the future of the WAIS." "The future of WAIS, " he added, "will be determined by internal responses of the ice sheet to millennia-scale trends in global climate and sea level, coupled with changes in the accumulation and discharge of ice due to global warming."
Dr. Oppenheimer does not conclude that the West Antarctic Ice Sheet will collapse, only that it could. He believes that we might still be able to avert catastrophe if we reduce greenhouse gases now. Dr. Oppenhemimer's data suggests that collapse of the West Antarctic Ice Sheet would likely raise sea levels by 20 feet. It could take more thatn 10,000 years for the ice sheet to reform.
E>H Ice streams are fast moving river like currents of ice that move through an ice sheet, due to global warming ice streams may accelerate their flow, increasing the discharge of ice and contributing to the disintegration of the entire ice sheet.
E>H The breaking ice shelves could be loaded with all types of pollutants etc. As the glaciers disintegrate and return to a liquid form, they could pollute the water supply.
E>H Warm summer temperatures on the Ross Ice Shelf in Antartica could have very dire consequences because that ice shelf is part of the braking system for some very large glaciers. According to Ted Scambos of the University of Colorado at Boulder, "If we begin to get significant water ponding there, and the shelf is eventually destroyed, we would likely have ice pouring off the Antarctic at a much faster rate. This would increase sea level significantly."
Sphere>Event Interactions
H>E Increases in ocean water temperatures and ocean currents might increase the rate of discharge of ice sheets into the ocean. If ice flows into the ocean more rapidly then melting, then sea level increases would occur more rapidly. Heavy rains and storms also would erode ice sheets gradually over a period of time.
H>E According to Slawek Tulaczyk, an assistant professor of earth sciences, ice streams flowing across ice sheets may slow down and stop moving altoghether. Stoppage of the ice streams may lead to thinning and shrinking of the ice shelves they nourish, most notably the large Ross Ice Shelf that covers the Ross Sea. Loss of the ice shelf over the Ross Sea could, in turn, trigger changes in global ocean cirvulation and climate.
H>E As more of the ice shelves disappear, the water temperature in the oceans would continue to rise. As a result, more of the shelf would continue to disappear. According to Professor Bill Budd of Australia's Co-operative Research Center, atmospheric armign can lead to surface melting that in turn, cause the shelf to break. Budd and his research assoiciates also have evidence of warming of the ocean below floating ice which shows that even one or two tenths of a degree make a significant difference. In other words, both atmospheric temperature and the water temperature can greatly affect the composition of the ice shelves.