ANNOUNCER: A CNN viewer wants to know "Is Antarctica melting?"</s>JOHN YIN, ASSISTANT PROFESSOR OF GEOGRAPHY, GEORGIA STATE UNIVERSITY: That is a complicated question. Because of its huge size, the ice sheets in Antarctica respond very slowly to any long- lasting climatic changes. Currently, there is about 30 feet to 40 feet of net accumulation in Antarctica. With increasing temperature, Antarctica will probably grow in size to balance out the effect on global sea level resulting from the Greenland ice sheet. We're faced with a lot of uncertainties. Somebody has proposed the idea that if the west Antarctica ice sheet should melt, it would cause a sea level rise of about 20 feet. That would be a quite catastrophic event.
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