As the administration moves forward with plans to sign a treaty in December imposing legally binding, internationally enforceable limits on the production of greenhouse gases, questions continue to be raised as to whether such a far-reaching step is justified in light of existing scientific understanding of climate change.
In a review of the copious literature available on the subject, H. Sterling Burnett, environment policy analyst for the Dallas-based National Center for Policy Analysis (NCPA), points out that there is no scientific consensus that global warming is a problem or that humans are its cause. While ground-level temperature measurements suggest the earth has warmed 0.3 to 0.6 degrees Celsius since 1850, global satellite data, the most reliable of climate measurements, show no evidence of warming during the last 18 years, Burnett points out. And, he adds, even the slight warming that ground-level thermometers show is well within standard variations over the last 15,000 years. “The earth experienced greater warming between the 10th and 15th centuries,” Burnett notes, “a time when vineyards thrived in England and Vikings colonized Greenland and built settlements in Canada.”
As to the often-repeated charge that humans are causing global warming, Burnett observes that scientists most directly concerned with climate conditions reject the theory of global warming by a wide margin.
- A Gallup Poll found that only 17 percent of the members of the Meteorological Society and the American Geophysical Society think that the slight warming experienced in the 20th century has been the result of man-made greenhouse gas emissions–principally CO2 from burning fossil fuels.
- Only 13 percent of the scientists responding to a recent survey conducted by Greenpeace believe catastrophic climate change will result from continuing current patterns of energy use.
Another argument often raised in support of global warming is that steadily rising temperatures will lead to more frequent and more violent hurricanes. But recent data show no increase in the number or severity of tropical storms, and the latest climate models suggest that earlier models making such connections were simplistic and thus inaccurate. Burnett points out that:
- Since the 1940s, the National Oceanographic and Meteorological Laboratory has documented a decrease in both the intensity and number of hurricanes.
- From 1991 through 1995, relatively few hurricanes occurred, and even the unusually intense hurricane season of 1995 did not reverse the downward trend.
- The 1996 IPCC report on climate change concluded that a worldwide significant increase in tropical storms was unlikely; some regions may experience increased activity while others will see fewer, less severe storms.
Even if a slight overall warming of the planet did occur, Burnett says, the effect would likely be positive. “[I]t would primarily affect nighttime temperatures, lessening the number of frost nights and extending the growing season,” he writes. “Thus some scientists think a global warming trend would be an agricultural boom. Moreover, historically warm periods have been the most conducive to life. Most of the world’s plant life evolved in a much warmer, carbon dioxide-filled atmosphere.”
PF: For more on global warming, see “A Better Way to Slow Global Climate Change,” written by Warwick J. McKibbin and Peter J. Wilcoxen and released in June 1997 by the Brookings Institution. Call PolicyFax at 847/202-4888 and request document #2329421 (8 pages).
