I wish to make one point though. My perusal of the various reports on historic temperatures has shown me that these numbers were cobbled together using various proxies and at the time and place represented at best a best guess. They have not necessarily been overly reviewed and even when reappraised, the former information, usually in chart form, lingers for a long time.
Once a position is accepted for any length of time, it is natural for critical analysis to fade and for that position to be given more credence than even the authors intended. In the game of climate analysis we have an uncommon amount of speculation been accepted too easily as fact. After all, I have the same problem. I need true proxies for global temperatures at any point in time and I have no choice but to accept the reported consensus. It is a little maddening to see this consensus shifting around.
The best most recent example is the infamous 'hockey stick' which is still been trotted out and will be with us so long as anyone watches Al Gore's documentary.
Thus while a six degree swing may be the experience in much of the Northern Hemisphere, the rest of the globe experienced a more modest half degree swing between the two hemispheres.
Today we are in the middle of a northern warming upswing that is lifting Europe to at least a couple more degrees of warmth before it is over. It appears to be very explainable as a rebound from the very real Little Ice Age which principally impacted Northern Europe. At least they complained the most.
Global Warming: Enjoy it While You Can
Policymakers have been arguing for nearly a decade over what to do about global warming. Noticeably missing from this debate has been any mention of the fact that natural fluctuations in the Earth's temperature, not Man, is 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 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.
Since the Holocene Maximum, the planet has continued to experience temperature fluctuations. In 900 A.D. the planet's temperature roughly approximated today's temperature. Then, between 900 and 1100 the climate dramatically warmed. Known as the Medieval Warm Period, the temperature rose by more than 1° F to an average of 60° or 61° F, as much as 2° F warmer than today. Again, the temperature during this period is similar to Greenhouse predictions for 2100, a prospect global warming theory proponents insist should be viewed with alarm. But judging by how Europe prospered during this era, there is little to be alarmed about. The warming that occurred between 1000 and 1350 caused the ice in the North Atlantic to retreat and permitted 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 temperature plunged to 58° F. After briefly warming, the climate continued to dramatically get 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. That is why the era between 1650 and 1850 is known as the Little Ice Age. It was during this time 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, concludes 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 of warming over the next few centuries, regardless of Man's 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 the result of natural changes in the Earth's climate that promises to yield humanity positive benefits. In the geological scheme of things, the warming is not even that 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 JCarlisle@nationalcenter.org.