What is an ice age? The term ice age refers to a period when the earth’s temperatures remain below freezing long enough to form ice sheets like those at the north and south poles. As long as those ice sheets remain in any form, we are still technically in an ice age. When those ice sheets disappear, the ice age is over.

What many people really fear is something that geologists say has happened only once in all of earth’s history. That is the snowball earth theory. In the snowball earth scenario, the entire planet is covered by ice and no land is visible. If the theory is correct, this event would have been the most devastating to life on earth, in whatever form that may have been. When people today think of an ice age, what they really fear is a snowball earth.

Are we entering an ice age? We are currently in an ice age by definition, although we are also in an interglacial period. Are we in danger of experiencing a snowball earth? No way. Here’s why. For a new ice age to begin, the flow of warm water from the equator northward and southward would have to stop, the earth’s orbit around the sun would have to change and the continents would have to shift to alter the tectonic plates. Granted, previous ice ages are believed to have been assisted by the build-up of greenhouse gases from volcanoes. However, many other factors must be in place to bring about an ice age. The events required to bring about a snowball earth are so complex that it is likely impossible that humans could be the cause.

Nonetheless, humans cannot ignore the fact that the earth is warming and the ice sheets are shrinking. In past ice ages, the increase of carbon dioxide gas in the atmosphere was a factor. The earliest known ice age occurred some 2.7 billion years ago. The most recent, and the one we are still in, began some 50 thousand years ago. Ice ages occur in cycles of about 40,000 to 100,000 years. It is predicted that earth will enter another ice age in about 50 thousand years.

With that in mind, it is not the next ice age that humans should fear. It is the global warming caused by excessive carbon dioxide caused by human activity. The excessive warming of the planet will be the problem our children and grandchildren will have to deal with. Any prospect of a new ice age will be something to worry about thousands of generations from now.