The perceived consensus is that global warming is real and is a clear and present danger to human civilization and the planet as a whole. According to environmental alarmists, the planet is warmer now than ever before. The leading theory holds that human industrial activity is causing carbon dioxide (C[O.sub.2]) and other greenhouse gases to be pumped into the atmosphere causing abnormal, runaway warming. The result, alarmists say, will be more drought, famine, pestilence, species extinction, and extreme weather events of unprecedented violence. Are these predictions true? An examination of the science behind global warming paints a very different picture.
QUESTION: Is the planet warmer now than in the past?
ANSWER: The planet is either warmer or cooler now than in the past, depending on what time in the past is being referred to, for the simple reason that the temperature fluctuates. Nearly everyone is familiar with the idea that most of the Northern Hemisphere was once covered with ice. The vast ice sheets of the Ice Age reached as far south as Wisconsin. They melted when the climate warmed substantially. According to the Oak Ridge National Laboratory's Environmental Sciences Division, at the end of the Ice Age, "Forests quickly regained the ground that they had lost to cold.... Ice sheets ... began melting.... The Earth entered several thousand years of conditions warmer and moister than today." In fact, those warmer, moister conditions coincided with the rise of agriculture and the increase in food production that made city life possible. Simply put, human civilization was made possible by a warmer climate.
Q: Yes, but we've had more warming recently. Doesn't this point to human influence?
A: Since the end of the Ice Age, the planet has been in a long-term, several-thousand-year period of relative warmth. Within that long-term period, there have been shorter periods in which the temperature has fluctuated from the average. Scientists and historians, using both historical records and data from ice cores and tree rings, have pinpointed two such deviations within the last 1,000 or so years. The first is the Medieval Warm Period, a time of warmer than average temperatures. According to Dr. Philip Stott, professor emeritus of bio-geography at the University of London, "During the Medieval Warm Period, the world was warmer even than today, and history shows that it was a wonderful period of plenty for everyone." It was during this time that the Vikings were able to take their remarkable journeys to North America, which they called Vinland, and Greenland. The slightly warmer climate made normally icy Greenland a place where, for a time, Viking colonies were able to thrive.
The Medieval Warm Period was followed by the Little Ice Age, when the climate cooled to temperatures that were not only lower than those of the preceding Medieval Warm Period but that were also somewhat cooler than the average for the longer, several-thousand-year period. In short, there have been times both when the climate was warmer than today and when it was cooler than today. In all such instances, the climate changed independently of human activity.
Q: Still, land-based temperature readings tend to show an increase in temperatures since the beginning of the industrial era. Surely this points to a human-induced warming?
A: In a sense, it does, because weather stations where temperatures are monitored are typically located in and around cities. The growing concrete and asphalt jungles of today's big cities warm faster, hold the heat of the day, and release it in the evening, raising temperatures. Moreover, "Cities tend to grow up around their weather stations," notes climate scientist Patrick J. Michaels in his recent book Meltdown. "Bricks and concrete retain the heat of the day and are especially adept at warding off late spring and early fall chilis." This accounts for the …