Paleo Slide Set: The Ice Ages

Southern hemisphere glacial and estimated sea ice coverage

Glaciers presently cover some 15.8 million square kilometers of the earth's surface, 
which is about 10% of the earth's land area (roughly the size of South America). 
In this image of the surface topography of the Southern Hemisphere, ice covered 
regions are white, and the rainbow colors depict different elevations.

15.8 million square kilometers may sound like a lot of ice but in the past glaciers 
occupied even more of our planet. Eighteen-thousand years ago, at the peak of the 
last ice age, scientists estimate that nearly 32% of the earth's land area was 
covered with ice, including much of Canada, Scandinavia, and the British Isles. 
In what is now the United States, huge sheets of ice even stretched as far south 
as southern Wisconsin and Long Island. In Europe, ice covered northern Germany, 
Poland, and the northern reaches of the former Soviet Union. These glaciers 
developed because the earth was in the midst of an ice age. What caused the earth's 
climate to change so dramatically? Why did ice ages begin, why did they end, 
and what can we expect the future to hold?

This image compares 18,000 years before present and modern day glacial 
and estimated sea ice coverage of the southern hemisphere.

Photo Credits:
Mark McCaffrey
Paleoclimate Program/NOAA