Back to the story...Climate Debate

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It would be inaccurate to blame global warming on purely greenhouse gases, Balling said, because too many factors come into play -- everything from dust storms to ozone depletion to solar activity impact temperatures. For example, the ozone map of the Antarctic shows that the ozone is thinning, and ozone is a greenhouse gas. "The list of elements that impact temperatures is getting longer, and nobody can pinpoint with any consistency that one factor is more influential than another," Balling said. "Even James Hansen, who as then-director of NASA's Goddard Institute for Space Studies fueled the greenhouse effect debate in 1988 when he said before a government committee that he was 99 percent sure that warmer temperatures were partly a result of greenhouse gases, now believes a variety of factors impact temperature change."

Hansen recently said "the forces that drive long-term climate change are not known with an accuracy sufficient to define future climate changes."