Paleo Home Research Data Education What's New Features Paleo Perspectives Site Map Mirror Sites National Climatic Data Center, Asheville, North Carolina navigation bar
Educational Outreach - Glaciation

What is Glaciation?
What Causes it?

The map at left outlines in blue the extent of the Laurentide Ice Sheet 15,000 years ago. Geologists have found material left by the ice throughout this area, proving that virtually all of Canada and some of the northern US were once covered by thick glacial ice. Similar findings show that ice was also widespread in many other parts of the world. Scientists believe that changes in the earth's climate caused the ice sheets to grow.

The explanation for these climate changes is believed to be variations in the earth's orbit around the sun (The Milankovitch Theory), combined with positive feedbacks from albedo (reflection of sunlight from snow and ice) and decreases in Carbon Dioxide concentrations in the atmosphere.

Contact Us
28 January 2003