Looking at climate history over the last 3,000 years of human existence, there is nothing that would lead us to expect that warmer temperatures in the future - should they occur would trigger a global catastrophe. The geologic record already shows natural temperature changes that were larger and more rapid than those predicted by many climate models - and certainly larger than what can be extrapolated from observed temperature trends.
We know from recorded history that warm periods are beneficial for human populations and that cold periods bring disaster. The "climate optimum" around 1100 A.D. facilitated Viking settlement of Greenland, and saw wine grapes grown in England and Nova Scotia. The "Little Ice Age," between 1450 and 1850, brought glaciers down out of the mountains and led to crop failure, famine and disease. So, in general, the effects of even a modest rise in global temperature would be positive. One would even expect bouts of severe weather to be less frequent because models predict a reduced equator-to-pole temperature difference.
The most feared consequence of warmer temperatures - a dramatic rise in sea level, resulting in coastal flooding and perhaps even the disappearance of some islands - does not appear to pan out. Sea level has been rising over the last century, and likely over several centuries, at the rate of about 1.8 millimeters per year (7 inches per century). This, for the most part, is not due to glaciers melting as the Earth recovered from the Little Ice Age but to tectonic changes in the shape of the ocean basins.
It has been impossible to predict, from theory alone, whether this ongoing sea level rise would accelerate or slow down as a result of warmer temperatures.
Certainly melting glaciers and thermal expansion of ocean water would raise sea level more rapidly. But increased evaporation of ocean water would lead to increased precipitation, which would in turn thicken the snow pack at the poles and slow the sea level rise. The puzzle was, which was the greater effect?
In a recent analysis of sea level and temperature data over this century, increased precipitation won out. The warming that occurred in the early part of this century showed an inverse correlation with sea level: When temperature went up, sea level rise slowed down.
As far as agriculture is concerned, a modest warming is bound to be beneficial for several reasons. The increase would register largely as warmer nighttime and winter temperatures, leading to fewer frosts and longer growing seasons, while increased CO2 will stimulate plant growth and lessen the plants' need for water. Indeed, a "greening" of the Earth and a slightly earlier spring have already been reported because of higher CO2 concentrations in the atmosphere. And farmers, whose occupation is highly sensitive to climate, can easily adapt through careful crop selection.
Recently, concerns have been raised by environmental lobbyists that warmer temperatures would spread insect-borne tropical diseases, such as malaria. But authoritative scientists report in scientific journals that insect control and public health measures are the primary determinants of such diseases. Further, with cheap and rapid mass transportation, the human vector is becoming increasingly important.
One is reminded that frequent epidemics of malaria and yellow fever occurred in the United States and even Northern Russia when the climate was much colder. Moreover, today, wealthy Singapore, situated at the equator, does not share the widespread tropical diseases so prevalent in poverty-stricken Africa.
Government bureaucrats and their Big Environment allies have raised unnecessary alarms about climate change by failing to consider two factors: Climate is always changing and human beings adapt, just as they do when they move from Chicago to New Orleans or New York to Miami. If global warming does materialize as a result of higher levels of CO2, recent successful experiments with ocean fertilization show much promise for drawing CO2 out of the atmosphere, and at much less cost than energy taxes.
So, the global climate doesn't seem to be warming, causing considerable embarrassment to scientists who are banking their reputations on computer models that show large warming trends. And if it does warm, the overall results would seem to be positive, causing some embarrassment to economists whose cost-benefits analyses automatically assume disbenefits.
Politicians, of course, manage to avoid embarrassment altogether by ignoring both science and economics. They continue to preach policies of mitigation, ranging from fantastic to technologically trivial, from economically neutral to extremely damaging.
Based on existing assessments, human-induced climate change over the next century will be much less important to the environment than other agents of global change, including population growth. Successful adaptation then requires specific actions that will stimulate economic growth and continued technological advances. Meeting these twin goals is not on the agenda when delegations from some 150 countries meet in Kyoto next month. But they should be.
S.Fred Singer, president of the Science & Environmental Policy Project in Fairfax and former director of the U.S. Weather Satellite Service, chaired the US. government panel investigating possible climate effects from supersonic transports (SSTs). This series is adapted from his latest book, "Hot Talk, Cold Science: Global Warming's Unfinished Debate," published this month by the Independent Institute, Oakland Calif.