Explain How The Earth's Climate Naturally Changes Over Extended Periods Of Time

The earth's climate naturally changes over extended periods of time. Temperatures have been much warmer for 80 to 90 percent of the last 500 million years than they are today. The polar ice caps, for example, are actually a relatively new phenomenon. They were formed 15 to 20 million years ago in the Antarctic and perhaps as recently as 3 to 5 million years in the Arctic. The climate is still dominated by natural cycles of warming and cooling. The most influential of these natural weather patterns is the 180-year cycle. The 180-year cycle predicts that temperatures in the Northern Hemisphere reach a minimum every 180 years. (Climate records for the Southern Hemisphere are incomplete.) The bottom of the last cycle was in the early 1800s, which