For hundreds of millions of years the entire Earth was covered with tropical rainforest. There were no ice sheets anywhere on the planet. Then about 40 million years ago the Earth began to cool. First slowly, then extremely rapidly until almost the entire Earth was covered with ice. The Earth was covered with so much ice, sea levels dropped 400 ft. Since that time the ice sheaths have ebbed and flowed on a pretty regular schedule. About two million years ago the ice sheets began a major retreat. Man had nothing to do with any of this climate change. The following podcast was originally recorded live on YouTube.