CO2: The Debate Heats Up

Is carbon dioxide an air pollutant? That will be the key issue in any legal challenge to California's proposed rules to reduce CO2 in auto exhaust. Carmakers argue that carbon dioxide is naturally occurring and nontoxic. That, they say, means it's not a pollutant -- which, more importantly, means California can't cite its clean-air laws to restrict CO2. They point, too, to an Environmental Protection Agency ruling last summer in which the agency reversed a Clinton-era rule declaring CO2 a pollutant and said that it had no business regulating it.

The California Air Resources Board sees things differently. High levels of greenhouse gases, largely carbon dioxide, the board argues, are a major contributor to global warming. CO2 emissions, CARB adds, have "significant adverse effects" on ecological systems, human health, and the economy.

The CO2 question is already the subject of a federal lawsuit. A group, including 12 states and 14 environmental outfits, sued the EPA last year, challenging the agency's decision not to regulate CO2. The plaintiffs argue that the Clean Air Act instructs the EPA to act against threats to the "public welfare."

Lawyers say a win or loss in Washington could make the California dispute moot. Either way, plenty of debate is in store. And all that hot air means -- yup -- more CO2.

By Kathleen Kerwin in Detroit

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