Today, glaciers are found on all of Earth's continents except Australia. The two largest -- the Antarctic and Greenland ice sheets -- contain approximately 90% of the world's supply of freshwater. If they melted, they would raise global sea levels by about 60 meters (200 feet).

One reason scientists study glaciers is to learn more about their past so that they can better predict how glaciers will respond to climate change in the future. In addition, glacial sediment deposits archive data that can be used to reconstruct environmental conditions in the past. Bands of light and dark snow in ice cores indicate seasonal changes - light layers are deposited in summer and dark layers in winter. The layers vary in color because of the difference in density between summer and winter snow. Looking at this record, scientists can learn about changes in solar radiation reaching Earth, the presence of atmospheric dust and our atmosphere's chemical composition, which in turn tells us about changes in air temperature and volcanic eruptions.

If sea levels were to rise one meter (which would occur if global temperatures increased by 1 ºC (2 ºF)), millions of people would be displaced in coastal cities islands. For example, almost all of the agricultural land in Bangladesh would be covered with water. Glaciers in mountain valleys would melt, creating massive flooding. Rivers that are currently fed by glaciers would eventually dry up, impacting agriculture and other economic activities, as well as drinking water supplies.

In this interactive lesson, explore what would happen to the coastlines of southeast Asia, the east coast of the United States, Florida, and northern Europe if parts of the Antarctic Ice Sheet melted. It is estimated that sea levels would rise approximately 20 feet if the Western Antarctic Ice Sheet melted and up to 200 feet if the Eastern Antarctic Ice Sheet melted. It also shows glacial extent approximately 20,000 years ago, when sea levels were estimated to be about 400 feet lower than today, to provide a frame of reference for how much water is stored in Earth's glaciers.



Source: Teachers' Domain, Mountain of Ice: If the Ice Melts, published December 17, 2005, retrieved on August 9, 2010, http://www.teachersdomain.org/resource/ess05.sci.ess.watcyc.icemelt/