NCPA - National Center for Policy Analysis


May 15, 2006

Scientific debate continues regarding the extent to which human activities contribute to global warming and what the potential impact on the environment might be. Importantly, much of the scientific evidence contradicts assertions that substantial global warming is likely to occur soon and that the predicted warming will harm the Earth's biosphere, says David R. Legates, an associate professor of geography and director of the Center for Climatic Research at the University of Delaware.

Global warming alarmists have attributed increases in hurricanes, floods, droughts, tornadoes, hail storms and heat waves to global warming caused by human activities. However, the evidence does not support their claims, says Legates. In recent months, for instance:

  • The unprecedented destruction caused by Hurricanes Katrina and Rita was blamed on climate change -- but experts say recent, more powerful storms are part of a natural cycle, and greater hurricane damage in North America is due to increased coastal populations and development rather than more severe storms.
  • Similar claims have been made about other weather phenomena in North America; but, in fact, there is no evidence of an increase in the frequency or severity of floods, droughts, tropical cyclones, tornadoes, hail storms or other severe weather events.

Some have attempted to link the present warming trend to secondary effects, such as species extinction. However, the relationship between species extinction and climate change is even more tenuous, says Legates.

The complexity of the climate and the limitations of data and computer models mean projections of future climate change are unreliable at best. In sum, the science does not support claims of drastic increases in global temperatures over the 21st century, nor does it support claims of human influence on weather events and other secondary effects of climate change, says Legates.

Source: David R. Legates, "Climate Science: Climate Change and Its Impacts," National Center for Policy Analysis, Policy Report No. 285, May 2006.

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