"Global Warming" is something that has been happening for a long time. The temperature of the earth has been increasing more or less continuously since the time of the cave man.
Approximately 18,000 years ago the earth began a gradual process of warming up after more than 100,000 years of Ice Ages. Much of North America, Europe, and Asia lay buried beneath great sheets of glacial ice.
By about 15,000 years ago the earth had warmed sufficiently to halt the advance of glaciers, and sea levels worldwide began to rise.
By 8,000 years ago the land bridge across the Bering Strait was drowned, cutting off the migration of men and animals to North America.
Since the end of the Ice Age, Earth's temperature has risen approximately 16 degrees F and sea levels have risen a total of 300 feet! Forests have returned where once there was only ice.
From a geological perspective, global warming is the normal state of our accustomed natural world. Technically, we are in an "interglacial phase," or between ice ages. The question is not really if an ice age will return, but when.
Don't panic when you hear global alarmists warning the earth may have warmed almost 1 degree in the last 200 years. Although this still hasn't yet been proven, it is in fact exactly what should be happening if everything is normal.
If Global Warming stops, then you can start worrying! It means our warm interglacial phase is over and we may be heading into another Ice Age!
ANIMATED GLACIER: Courtesy of Illinois State Museum