If you read only the major newspapers and watched only the network news, you would believe that global warming is unquestioned and as certain as any other scientific conclusion. Do a little probing and you quickly discover the wealth of contrarian views available. There are web sites devoted to debunking the mainstream media's sacred cow, respectable books by prominent authors, and scholarly articles chock full of doubts. This would all be interesting diversion and debate were it not for the policy implications present. If the federal government believes the global warming hype, actions could be taken that would cripple the economy and lower our standard of living. It is thus important to discover which side is right.
The basic claim by proponents of global warming is that greenhouse gases like carbon dioxide and methane are building up in the atmosphere. This buildup, called the greenhouse effect, traps ultraviolet radiation and its consequent heat in the lower reaches of the atmosphere, causing the global temperatures to rise. This rising temperature leads to desertification, food shortages, and melting of the polar ice caps. Millions of people die from starvation and drowning. Supporters of this scenario call for government-mandated carbon dioxide emission reduction. They believe that reducing the amount of carbon dioxide produced will stem the greenhouse effect and save humanity.
They have held international conferences that have resulted in global accords like the Montreal Protocol—which banned chlorofluorocarbons—and the Kyoto Protocol—which seeks a hefty reduction in carbon dioxide emissions by the economic superpowers. Debate is squelched by cries of impending doom and universal consensus. "We must act now before it is too late," they clamor. Or they say, "No one questions the validity of global warming." A more careful investigation reveals just how wrong they are.
Global warming predictions are based on global climate models that are run on supercomputers. The advantage of computer modelling is that it allows a climatologist to tweak variables and see possible outcomes. The disadvantage of computer modelling is that it is far from clear whether a simulation can ever take account of all of the variables that make up our climate. In other words, the knowledge required to accurately portray the global climate approaches omniscience. For example, no one can accurately determine the effect of the earth's oceans and sea currents on the climate. Nor can they accurately estimate the effect of clouds or cataclysmic events like volcanic eruptions. The sun's role in the earth's climate is largely mysterious. And these are just the natural influences. Human influences, such as pollution and carbon dioxide production, have been quantified, but their causative relationship with climate is indeterminate. This is not to say that climate is unknowable, just currently unknown.
Due to the presently impossible incorporation of these variables into a computer model, researchers are left to guessing at impacts and hypothesizing causal relationships. The models are so rough that they entirely miss the effect of mountains1 and they treat the climate of heavily-forested Oregon and the Nevada desert the same.2 The output of the models they build become foregone conclusions because they are built on certain suppositions assumed by the author. Given that these models are used to predict climate in the near-future (within the next hundred years), they should be able to provide accurate predictors of the past. However, they cannot. Projections by computer models show that there should have been a 0.4°C rise in temperature over the last twenty years due to large increases in CO2 and other greenhouse gases, but satellite measurements for the years 1978-97 show no temperature rise at all. In fact, no reliable global temperature records show the rise predicted by the computer models.3 Also, when supplied with the relevant variables for the Pleistocene era, advanced computer models fail to predict glaciers.4 As James Hansen (the NASA scientist who started the global warming debate in 1988) said in the October 1998 issue of Proceedings of the National Academy of Sciences, "the forcings that drove long-term climate change are not known with an accuracy sufficient to define future climate change."5 With the current uncertainty of weather forecasts of weeks into the future, it is sheer folly to presume that we can understand (at present) weather patterns decades and centuries from now.
Another problem the global warming advocates face is the troublesome climate record. Satellite measuring only came into widespread use in 1978. Ground-based temperature measurement extends back about one hundred years. These ground-based readings show a global rise of 1°F this century, with a surge in the eighties. Satellite readings do not show this, however. Which set of data should one believe? The ground-based readings—though accurate—have been collected mostly in the Northern Hemisphere around urban centers. They don't record ocean temperatures—a particularly startling fact given that three-quarters of the earth's surface is ocean—and urban centers are prone to the heat-island effect. Satellite readings, on the other hand, are more accurate and cover the entire earth. Unfortunately, as noted earlier, they only date from the late 70s—too soon for real impact. With an imperfect dataset it is difficult to make accurate assessments.
Finally, by being quick to blame man and specifically the "developed" nations, global warming supporters cast a blind eye to other plausible explanations for temperature fluctuations. Serious research is underway into the strong correlation between the sun's 11-year sunspot cycle and global temperature changes. When plotted side by side, the graphs for temperature change and solar magnetic cycle appear very similar.6 In fact, the Maunder Minimum—a century-long period when the sun "dropped to very low levels of magnetism."7 This Maunder Minimum occurred at the same time as the Little Ice Age. While the causal relationship has not been established, it seems certain that the sun must have considerable influence on the earth's climate.
Even if the global warming advocates were correct and the global temperature was going to rise as much as their ever-revising-downward temperature predictions indicate, there is much to lead one to doubt their prophecies of global catastrophe. There are several scientists who believe that rising levels of carbon dioxide would be beneficial to plant growth and would herald an agricultural time of plenty.8 Also, a recent study indicates that "warming may actually increase the volume of ice stored in the large Antarctic ice sheets."9 The melting of ice sheets due to warmer sea surface temperatures would result in a net increase in ice accumulation due to increased precipitation. Finally, S. Fred Singer states that "any future moderate warming, from whatever cause, will slow down the ongoing sea-level rise, rather than speed it up."10 In short, the dire predictions of the global warming proponents would not necessarily be the end of the world—no pun intended—even if they were true.
2 Jastrow, Robert, William Nierenberg, and Frederick Seitz. "An Overview." Scientific Perspectives on the Greenhouse Problem. (San Francisco: Pacific Research Institute, 1992), 23, quoted in Sanera, 155.
6 Postrel, Virginia. "Stars in Her Eyes: An Interview with Astronomer Sallie Baliunas." Reason (October 1998): 46.
7 Ibid., 44.