John Carlisle

In the following viewpoint, John Carlisle contends that the global temperature increase of 1.5 degrees Fahrenheit over the last 150 years has been caused by natural fluctuations in the earth’s temperature and has not been the result of human activity. Carlisle describes periods from the earth’s geologic history that had temperatures warmer than the present average of 59 degrees Fahrenheit, illustrating a continually changing climate system. The author believes that humanity will benefit from a warmer planet, enjoying longer growing seasons and higher-yield harvests. Carlisle is the director of the Environmental Policy Task Force of the National Center for Public Policy Research, a conservative/free market foundation in Washington, D.C.

As you read, consider the following questions:

1. How long do the interglacial periods following ice ages typically last, according to Carlisle?
2. What was the average temperature...