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 April 1998

Global Warming: Enjoy it While You Can

by John Carlisle



Proponents of the global warming theory repeatedly cite a 1.5° F temperature increase over the last 150 years as evidence that man-made CO2 is dangerously heating up the planet and will cause huge flooding, severe storms, disease and a mass exodus of environmental refugees. Based on this, the Clinton Administration and its environmental allies want Congress to ratify a treaty that will hike consumer prices 40 percent and cost the American economy $3.3 trillion over 20 years. But the apocalyptic predictions on which they justify these drastic steps are totally unsubstantiated and ignore some fundamental truths about the Earth's climatic behavior.

The fact is, the planet's temperature is constantly rising and falling. To put the current warming trend in perspective, it's important to understand the Earth's geological behavior.

Over the last 700,000 years, the climate has operated on a relatively predictable schedule of 100,000-year glaciation cycles. Each glaciation cycle is typically characterized by 90,000 years of cooling, an ice age, followed by an abrupt warming period, called an interglacial, which lasts 10,000-12,000 years. The last ice age reached its coolest point 18,000 to 20,000 years ago when the average temperature was 9-12.6° F cooler than present. Earth is currently in a warm interglacial called the Holocene that began 10,700 years ago.

Although precise temperature readings over the entire period of geologic history are not available, enough is known to establish climatic trends. During the Holocene, there have been about seven major warming and cooling trends, some lasting as long as 3000 years, others as short as 650. Most interesting of all, however, is that the temperature variation in many of these periods averaged as much as 1.8° F, .3° F more than the temperature increase of the last 150 years. Furthermore, of the six major temperature variations occurring prior to the current era, three produced temperatures warmer than the present average temperature of 59° F while three produced cooler temperatures.

For example, when the Holocene began as the Earth was coming out of the last Ice Age around 8700 B.C., the average global temperature was about 6° F cooler than it is today. By 7500 B.C., the climate had warmed to 60° F, 1° F warmer than the current average temperature. However, the temperature fell again by nearly 2° F over the next 1,000 years, settling at an average of 1° F cooler than the current climate.

Between 6500 and 3500 B.C., the temperature increased from 58° F to 62° F. This is the warmest the Earth has been during the Holocene, which is why scientists refer to the period as the Holocene Maximum. Since the temperature of the Holocene Maximum is close to what global warming models project for the Earth by 2100, how Mankind faired during the era is instructive. The most striking fact is that it was during this period that the Agricultural Revolution began in the Middle East, laying the foundation for civilization. Yet, Greenhouse theory proponents claim the planet will experience severe environmental distress if the climate is that warm again.







John Carlisle is director of the Environmental Policy Task Force, a project of The National Center for Public Policy Research. Comments may be sent to him at [email protected].


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