Global Warming: Enjoy it While You Can

Published June 1, 1998

Policymakers have been arguing for nearly a decade over what to do about global warming. Noticeably missing from their debate has been any mention of the fact that natural fluctuations in the Earth’s temperature, not humans, are the likely explanation for any recent warming.

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 warming the planet. Said warming, they contend, will cause disastrous flooding, severe storms, disease, and a mass exodus of environmental refugees.

To address the “crisis,” 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 an estimated $3.3 trillion over 20 years. But the apocalyptic predictions by which they justify those drastic steps are unsubstantiated and ignore many 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, that lasts 10,000 to 12,000 years. The last ice age reached its coolest point 18,000 to 20,000 years ago, when the average temperature was 9 to 12.6° F cooler than today. Earth is currently in a warm interglacial called the Holocene, which 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 3,000 years, others as short as 650.

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. 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.

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 one thousand 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. That 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 humankind faired during the era is instructive. Most strikingly, it was during this period that the Agricultural Revolution began in the Middle East, laying the foundation for civilization. Yet, greenhouse theory proponents today claim the planet will experience severe environmental distress if the climate is that warm again.

Since the Holocene Maximum, the planet has continued to experience temperature fluctuations. In 900 A.D., the Earth’s temperature roughly approximated today’s temperature. Then, between 900 and 1100, the climate dramatically warmed. During this period, known to scientists as the Medieval Warm Period, the temperature rose by more than 1° F, reaching an average of 60° or 61° F–as much as 2° F warmer than today.

Again, the temperature during the Medieval Warm Period was similar to what greenhouse theory predicts for 2100, a prospect theory proponents insist should be viewed with alarm. But judging by how Europe prospered during this era, there is little cause for concern The warming that occurred between 1000 and 1350 caused the ice in the North Atlantic to retreat, permitting Norsemen to colonize Iceland and Greenland. Back then, Greenland was actually green. Europe emerged from the Dark Ages in a period that was characterized by bountiful harvests and great economic prosperity. So mild was the climate that wine grapes were grown in England and Nova Scotia.

The major climate change that followed the Medieval Warm Period is especially critical as it bears directly on how to assess our current warming period. Between 1200 and 1450, the average temperature plunged to 58° F. After briefly warming, the climate continued to get dramatically colder after 1500. By 1650, the temperature hit a low of 57° F. This is regarded as the coldest point in the 10,000-year Holocene geological epoch. The era between 1650 and 1850 thus is known as the Little Ice Age.

It was during this period that mountain glaciers advanced in Switzerland and Scandinavia, forcing the abandonment of farms and villages. Rivers in London, St. Petersburg, and Moscow froze over so thoroughly that people held winter fairs on the ice. There were serious crop failures, famines, and disease due to the cooler climate. In America, New England had no summer in 1816. It wasn’t until 1860 that the temperature sufficiently warmed to cause the glaciers to retreat.

The significance of the Little Ice Age cannot be overestimated. The 1.5° F temperature increase over the last 150 years, so often cited as evidence of man-made warming, most likely represents a return to normal temperatures following a 400-year period of unusually cold weather. Even the United Nation’s Intergovernmental Panel on Climate Change (IPCC), the chief proponent of the Kyoto Protocol global warming treaty signed in December 1997, concluded that: “The Little Ice Age came to an end only in the nineteenth century. Thus, some of the global warming since 1850 could be a recovery from the Little Ice Age rather than a direct result of human activities.”

Leading climate scientist Dr. Hugh Ellsaesser of the Lawrence Livermore National Laboratory says we may be in for an additional 1.8° F warming over the next few centuries, regardless of human activities. The result would be warmer nighttime and winter temperatures, fewer frosts, and longer growing seasons. Since CO2 stimulates plant growth and lessens the need for water, we could also expect more bountiful harvests over the next couple of centuries. This is certainly not bad news to the developing nations of the world struggling to feed their populations.

Thus, far from being a self-induced disaster, global warming is likely the result of natural changes in the Earth’s climate–changes that promise to yield significantly positive benefits. In the geological scheme of things, the warming is not even particularly dramatic compared to the more pronounced warming trends that occurred during the Agricultural Revolution and the early Middle Ages. Moreover, there is strong evidence that this long-needed warming is moderating.

All things considered, global warming should be viewed for what it is: A gift from the often fickle force of Nature. Enjoy it while you can.

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].