Medium-sized ice caps covering thousands of square kilometers in sub-polar and Polar Regions are also considered to be glaciers. The world's largest glaciers include the huge ice shelves that
stretch out hundreds of kilometers over the oceans and seas of the Arctic and Antarctic. In recent geologic times there have also been enormous ice sheets as thick as four kilometers that blanketed most of Antarctica and Greenland.
have been working to understand the mysteries surrounding the world's glaciers for over a century and a half, By examining the physical and chemical properties and geologic record of glaciers, and creating advanced computer models to simulate glacial growth, flow and melting mechanisms , our understanding of ice on earth has vastly improved, inspiring new questions and necessitating more research into the power and dynamic qualities of glacier.
This image compares modern day glacier and ice coverage of the northern hemisphere with the same region 18,000 years before present. Note that the modern sea ice coverage is during the summer months; winter coverage is more extensive.