42. Pay For Your Carbon Sins

Feeling full of climate-change guilt, Americans are snapping up carbon offsets from Web-based retailers and nonprofits. Unlike mandatory allowances, offsets allow consumers to pay voluntarily to reduce carbon emissions by a quantity equal to their estimated contribution. The money typically funds clean-energy projects, pollution control, tree planting and forest conservation. But offsets are picking up skeptics along with customers. Critics say consumers have little assurance that the projects they underwrite really reduce emissions and warn that those buying offsets may sometimes pay for improvements that would have happened anyway. They also argue that carbon-offset trading distracts from the urgent need to change U.S. policies to address global warming.

Are these criticisms fair? "There needs to be more standardization, more verification and more assurances for the consumer that the offsets are real," concedes Ricardo Bayon, director of Ecosystem Marketplace. A number of organizations, including the Center for Resource Solutions in San Francisco and the Climate Group, based in Britain, are racing to establish certification standards. Even supporters of offset trading agree that it's no substitute for comprehensive national policies. "This voluntary stuff is an interim measure," says Judi Greenwald of the Pew Center on Global Climate Change. "But it is certainly better than doing nothing."