Political leaders are gathered in Kyoto, Japan, working away on an international treaty to stop "global warming" by reducing carbon dioxide emissions. The debate over how much to cut emissions has at times been heated--but the entire enterprise is futile or worse. For there is not a shred of persuasive evidence that humans have been responsible for increasing global temperatures. What's more, carbon dioxide emissions have actually been a boon for the environment.
The myth of "global warming" starts with an accurate observation: The amount of carbon dioxide in the atmosphere is rising. It is now about 360 parts per million, vs. 290 at the beginning of the 20th century, Reasonable estimates indicate that it may eventually rise as high as 600 parts per million. This rise probably results from human burning of coal, oil and natural gas, although this is not certain. Earth's oceans and land hold some 50 times as much carbon dioxide as is in the atmosphere, and movement between these reservoirs of carbon dioxide is poorly understood. The observed rise in atmospheric carbon dioxide does correspond with the time of human release and equals about half of the amount released.
Carbon dioxide, water, and a few other substances are "greenhouse gases." For reasons predictable from their physics and chemistry, they tend to admit more solar energy into the atmosphere than they allow to escape. Actually, things are not so simple as this, since these substances interact among themselves and with other aspects of the atmosphere in complex ways that are not well understood. Still, it was reasonable to hypothesize that rising atmospheric carbon dioxide levels might cause atmospheric temperatures to rise. Some people predicted "global warming," which has come to mean extreme greenhouse warming of the atmosphere leading to catastrophic environmental consequences.
Careful Tests
The global-warming hypothesis, however, is no longer tenable. Scientists have been able to test it carefully, and it does not hold up. During the past 50 years, as atmospheric carbon dioxide levels have risen, scientists have made precise measurements of atmospheric temperature. These measurements have definitively shown that major atmospheric greenhouse warming of the atmosphere is not occurring and is unlikely ever to occur.
The temperature of the atmosphere fluctuates over a wide range, the result of solar activity and other influences. During the past 3,000 years, there have been five extended periods when it was distinctly warmer than today. One of the two coldest periods, known as the Little Ice Age, occurred 300 years ago. Atmospheric temperatures have been rising from that low for the past 300 years, but remain below the 3,000-year average.
Why are temperatures rising? The first chart nearby shows temperatures during the past 250 years, relative to the mean temperature for 1951-70. The same chart shows the length of the solar magnetic cycle during the same period. Close correlation between these two parameters--the shorter the solar cycle (and hence the more active the sun), the higher the temperature--demonstrates, as do other studies, that the gradual warming since the Little Ice Age and the large fluctuations during that warming have been caused by changes in solar activity.
The highest temperatures during this period occurred in about 1940. During the past 20 years, atmospheric temperatures have actually tended to go down, as shown in the second chart, based on very reliable satellite data, which have been confirmed by measurements from weather balloons.
Consider what this means for the global-warming hypothesis. This hypothesis predicts that global temperatures will rise significantly, indeed catastrophically, if atmospheric carbon dioxide rises. Most of the increase in atmospheric carbon dioxide has occurred during the past 50 years, and the increase has continued during the past 20 years. Yet there has been no significant increase in atmospheric temperature during those 50 years, and during the 20 years with the highest carbon dioxide levels, temperatures have decreased.
In science, the ultimate test is the process of experiment. If a hypothesis fails the experimental test, it must be discarded. Therefore, the scientific method requires that the global warming hypothesis be rejected.
Why, then, is there continuing scientific interest in "global warming"? There is a field of inquiry in which scientists are using computers to try to predict the weather--even global weather over very long periods. But global weather is so complicated that current data and computer methods are insufficient to make such predictions. Although it is reasonable to hope that these methods will eventually become useful, for now computer climate models are very unreliable. The second chart shows predicted temperatures for the past 20 years, based on the computer models. It's not surprising that they should have turned out wrong--after all the weatherman still has difficulty predicting local weather even for a few days. Long-term global predictions are beyond current capabilities.
So we needn't worry about human use of hydrocarbons warming the Earth. We also needn't worry about environmental calamities, even if the current, natural warming trend continues: After all the Earth has been much warmer during the past 3,000 years without ill effects.
But we should worry about the effects of the hydrocarbon rationing being proposed at Kyoto. Hydrocarbon use has major environmental benefits. A great deal of research has shown that increases in atmospheric carbon dioxide accelerate the growth rates of plants and also permit plants to grow in drier regions. Animal life, which depends upon plants, also increases.
Standing timber in the United States has already increased by 30% since 1950. There are now 60 tons of timber for every American. Tree-ring studies further confirm this spectacular increase in tree growth rates. It has also been found that mature Amazonian rain forests are increasing in biomass at about two tons per acre per year. A composite of 279 research studies predicts that overall plant growth rates will ultimately double as carbon dioxide increases.
Lush Environment
What mankind is doing is moving hydrocarbons from below ground and turning them into living things. We are living in an increasingly lush environment of plants and animals as a result of the carbon dioxide increase. Our children will enjoy an Earth with twice as much plant and animal life as that with which we now are blessed. This is a wonderful and unexpected gift from the industrial revolution.
Hydrocarbons are needed to feed and lift from poverty vast numbers of people across the globe. This can eventually allow all human beings to live long, prosperous, healthy, productive lives. No other single technological factor is more important to the increase in the quality, length and quantity of human life than the continued, expanded and unrationed use of the Earth's hydrocarbons, of which we have proven reserves to last more than 1,000 years. Global warming is a myth. The reality is that global poverty and death would be the result of Kyoto's rationing of hydrocarbons.
Arthur Robinson and Zachary Robinson are chemists at the Oregon Institute of Science and Medicine.