All Commentary
Tuesday, May 1, 2001

Unprecedented Global Warming?

Global Warming Is Both Common and Natural

One of the most contentious issues of the day is global warming. Those who openly discuss the subject fall into one of two camps. First, there are the environmental alarmists who only see the world in terms of urban sprawl, deforestation, and pollution. For this group, global warming provides the much-needed justification to curtail, or reverse, our current level of earth-unfriendly economic activity. The other group sees no evidence of harmful global warming. They view the draconian anti-business remedies as both unjustified and misguided.

Given the high stakes (from both a monetary and an emotional perspective), it should come as no surprise that there is a temptation for the first group to play fast and loose with the available scientific data. Findings that support global warming are highlighted, and those that do not are downplayed, omitted, or politicized. Global-warming computer models are frequently little more than high-tech “crystal balls.” With the multitude of variables and assumptions that come into play, these computer models become highly suspect. In deciding which model to use, the critical question becomes: “How scary do you want the future to be?”

Ground zero in the global warming debate is the 1997 Kyoto Protocol Agreement. This treaty, yet to be ratified by the United States, calls for a reduction in greenhouse gases and fossil-fuel emissions to a level 5 to 7 percent below the 1990-benchmark year by 2012.1 The estimated compliance cost for the United States will be $300 billion a year.2 But the global solidarity to end global warming had a temporary setback last November at The Hague. Participating countries were unable to work out the details.

The Kyoto Protocol seems to be built on the following two assumptions: First, global warming is a function of human activity (with the biggest villains being automobiles, factories, and power plants), and second, we are currently experiencing unprecedented levels of global warming. However, a review of the earth’s most recent “geological history” brings into question both assumptions and puts the entire subject in a different light.

For over a million years, the earth has undergone a succession of glacial and interglacial periods. Each glacial period lasted anywhere from 70,000 to 100,000 years. In the most recent one, ice covered all of what is now Canada and the northern third of the United States.3 To date, each glacial period has been followed by a very warm, yet much shorter, interglacial period of 10,000 to 30,000 years. In some of these interglacial periods, ice covered less area than today.

The last ice age ended approximately 10,000 years ago. This was followed by a period of significant global warming that lasted —5,000 years. The average temperature in this time frame was 2 to 3 degrees Celsius higher than we find today. This caused the sea level to rise over 100 feet. The warmer climate also made it possible for broad-leafed forests to grow in latitudes much farther north than they do currently. In the most recent 5,000-year period, there have been numerous periods of distinct global warming and global cooling.4 However, the overall long-term climatic trend indicates that the earth has been getting cooler, not warmer.

Agriculture Flourishes

There was a very pronounced medieval warm period from 700 AD to 1400 AD. Indirect evidence suggests that the average temperature was as much as 1.5 degrees Celsius warmer than today. In Europe, agriculture flourished at latitudes farther north and at higher elevations than today. Vineyards, which require sunny and warm conditions, existed in areas 300 miles north of the present limits. The cultivation of grapes for wine-making was extensive throughout the southern portions of England from about 1100 to around 1300. The amount of English wine produced was enough to provide significant competition with the French. As further evidence of a much warmer climate, the tree line in the Alps was 300 meters higher than we find today.5

This warm period made it possible for the Vikings to establish colonies in Greenland and Iceland. Greenland, which could honestly be called a green land, was settled near the end of the tenth century. The colony flourished with between 5,000 and 6,000 residents.6 Sheep and dairy cattle were able to graze in areas that are today—icebound.7

By about 1400 the climate had cooled to temperatures that approximate what we see today. However, evidence from a number of sources—glacial sediments, tree rings, and written records—shows that from the beginning of the fifteenth century until the mid-nineteenth century major cooling continued to take place in most parts of the world. This period came to be known as the “Little Ice Age.” Glaciers around the globe in Europe, New Zealand, North America, and Greenland advanced and have only recently started to recede. The freezing of the Baltic Sea and the Thames River in England became a regular occurrence. London had its first “Frost Fair” on the river in 1607. This winter festival was an annual event until it was discontinued in the 1800s with the return of warmer winters.

The settlements in Iceland and Greenland were especially hard hit by this period of global cooling. Iceland lost half its population. In Greenland, farms were abandoned as the permafrost level rose and glaciers advanced. We do not know exactly how the Greenland colonies came to an end because growing sea ice cut off all contact with the outside world in 1410.

More Global Warming

During the last 150 years there has been another fairly sustained period of global warming amounting to an increase of about 0.7 degree Celsius. In spite of rhetoric to the contrary, the majority of this warming took place naturally before 1940. This warming trend was interrupted by a 35-year cooling period from 1940 to 1975. This caused many climatologists to actually predict that we were entering another ice age.8 At that time the public was obsessed with “global cooling.” Today, our obsession is “global warming.”

This review of the post–ice-age epoch shows that global warming is, in reality, both common and natural. In fact, for most of this period, the temperatures were much warmer than we see today. While our current level of industrial activity probably contributes to global warming to some degree, the increases that we have seen in the last 25 years are by no means unprecedented.

After viewing global warming from this alternative perspective, it is hard to justify the strong medicine prescribed by the Kyoto Protocol. Ironically, given the fact that the long-term climatic trend suggests global cooling, rather than global warming, our industrial/economic activity may actually serve to impede the natural cooling process. Under these circumstances, the environmental alarmists may want to adopt a new warning label: Enjoy the warm weather, while it lasts!


  1. Jerome Socolovsky, “Climate Delegates Reject Compromise,” Associated Press, November 24, 2000.
  2. “Global Warming’s Polarized Debate,” Detroit News, September 1, 2000.
  3. Thomas J. Crowley, “Remembrance of Things Past: Greenhouse Lessons from the Geological Record,” Consequences, Winter 1996.
  4. “Holocene Epoch,”, 1999–2000.
  5. Richard D. Tkachuck, “The Little Ice Age,” Origins 10(2), 1983, pp. 51–65.
  6. Kathy A. Svitil, “The Greenland Viking Mystery,” Discover, July 1997.
  7. Alan Cutler, “The Little Ice Age: When Global Cooling Gripped the World,” Washington Post, August 13, 1997.
  8. Science Update—August 28, 1997, “Climate Change in Perspective,”

  • Michael Heberling is the Chair of Leadership Studies in the Baker College MBA program in Flint, Michigan. Prior to this, he was President of Baker's Center for Graduate Studies for 16 years. Before Baker, Dr. Heberling was a Senior Policy & Business Analyst with the Anteon Corporation. He also had a career in the Air Force retiring as a Lieutenant Colonel. Dr. Heberling has over 75 business and public policy publications. His research interests focus on leadership, military history and the impact of public policy on the business community. He is a member of the FEE Faculty Network.