Michigan summers are often the main weather attraction of the year, with bumper crops for farmers and millions of tourists joining Michiganians to enjoy the natural beauty of the state. What could possibly spoil the party? Global warming, say today’s Chicken Littles. The sky may not be falling but according to environmental alarmists, it is getting too hot.

Modern transportation, housing, and other energy-intensive industrial activity use power provided mostly by the burning of fossil fuels such as coal, natural gas, and oil. This combustion has increased atmospheric carbon dioxide by about 30 percent over the past century. Carbon dioxide is a "greenhouse gas" suspected of trapping so much heat in the atmosphere that it results in world-wide temperature increases. Activists who spread alarm about global warming argue that this is the primary source of a heating trend and disaster looms if government fails to take corrective action.

Is our planet really getting warmer? Reliable temperature data for the past 150 years do show that average temperatures have increased by about one degree Fahrenheit. But scientists, citizens, and policy makers must look for the reasons this has occurred and ask whether this is due to forces in nature or in human activity.

By the same token, the findings of environmental scientists like Patrick J. Michaels of the University of Virginia ought to be considered. In a May 1998 study for the Cato Institute, Michaels writes that since 1986, "the mean temperature of the earth has shown no significant warming, despite perceptions to the contrary. Three independent measures—temperature measured at the earth’s surface, temperature of the lower atmosphere measured by weather balloons, and temperature of the lower atmosphere measured by orbiting satellites—all show no statistically significant change."

In spite of scientific disagreement over the nature and causes of global warming, the United Nations is pushing a treaty that requires countries to make major changes to reduce greenhouse gases. For the United States, the resulting restrictions on the use of fossil fuels over the next 15 years would severely limit economic growth and require major lifestyle changes in Americans’ transportation, homes and offices, and leisure activity. One responsible economic forecasting firm, WEFA, Inc., puts the likely impact of the global warming treaty on American families at $2,700 annually.

For nearly 20 years scientists have been studying climate changes using computer models designed to make predictions of temperature and rainfall. One major assumption is that carbon dioxide levels are a major factor affecting temperature. Some models predicted increases of six degrees by the year 2100. The worst case scenarios expect melting polar ice caps, coastal flooding, and more severe storms such as hurricanes and tornadoes. Recent forecasts have predicted a more moderate one to three degree increase with less dire consequences.

Computer models have been tested to compare today’s information with known data from the past but have shown poor results. A time-honored computer adage says "garbage in, garbage out," meaning that poor input will yield poor results. For global climate modeling this means that assumptions are difficult to make and yield inaccurate information. There is no agreement on whether the effect of clouds leads to heating or cooling, for example. Experts say the models need at least 10 more years to become reliable.

Are scientists any better at predicting short-term environmental impact than they are at predicting the distant future? In 1991 during the Gulf War, Saddam Hussein set over 600 oil wells on fire in Kuwait. Renowned scientist Carl Sagan predicted effects similar to "nuclear winter"—not global warming—with major consequences for the planet and years needed to extinguish the fires. However, with modern technology, oil well firefighters put out the blazes in a few months with no major effects outside a 200-mile radius of the wells. This human activity of a very destructive nature had little or no apparent long-term effect on the planet.

Natural events such as volcanic eruptions at Mount Pinatubo have caused major temperature and rainfall changes around the globe. During the 1997-98 winter, warmer water temperature in parts of the Pacific Ocean created "El Niño," which created major weather changes for North and South America. California experienced major rainfall while the Midwestern United States experienced a mild winter. In these cases, the forces of nature far outweighed the impact of any human activity on global climate changes.

A thorough public debate is needed before the United States signs the UN global warming treaty. That debate must be informed less by politics and emotion and more by reliable physical evidence, sound environmental science, and the economic implications of proposed regulations.