Dear EarthTalk: I keep meeting people who say that human-induced global warming is only theory, that just as many scientists doubt it as believe it. Can you settle the score?
—Jon Proctor, London, UK
So-called “global warming skeptics” are indeed getting more vocal than ever, and banding together to show their solidarity against the scientific consensus that has concluded that global warming is caused by emissions from human activities.
Upwards of 800 skeptics (most of whom are not scientists) took part in the second annual International Conference on Climate Change—sponsored by the Heartland Institute, a conservative think tank—in March 2009. Keynote speaker and Massachusetts Institute of Technology meteorologist Richard Lindzen told the gathering that “there is no substantive basis for predictions of sizeable global warming due to observed increases in minor greenhouse gases such as carbon dioxide, methane and chlorofluorocarbons.”
Most skeptics attribute global warming—few if any doubt any longer that the warming itself is occurring, given the worldwide rise in surface temperature—to natural cycles, not emissions from power plants, automobiles and other human activity. “The observational evidence
suggests that any warming from the growth of greenhouse gases is likely to be minor, difficult to detect above the natural fluctuations of the climate, and therefore inconsequential,” says atmospheric physicist Fred Singer, an outspoken global warming skeptic and founder of the advocacy-oriented Science and Environmental Policy Project.