As a business and fundraising consultant, Pat Castleman drives about 1,000 miles a month. So when the Mill Valley, Calif., resident heard that she could "neutralize" the greenhouse gas pollutants emitted by her new Infiniti sedan, she jumped at the opportunity.
By signing up with DriveNeutral, a nonprofit launched in October by students at the Presidio School of Management in San Francisco, Ms. Castleman was able to calculate her "climate change footprint," using simple online calculators. To neutralize that footprint, she bought greenhouse-gas emissions reductions, also known as "carbon offsets." Castleman paid $25 to compensate for about five tons of carbon emissions a year - plus a DriveNeutral decal proclaiming her vehicle's carbon-free status.
"I always feel slightly guilty when I'm driving around the Bay Area," says Castleman. "This seemed like a great way to contribute until we can develop alternative energy."
Although the United States is not a signatory of the Kyoto Protocol, an international treaty that imposes mandatory greenhouse-gas reductions beginning in 2008, a growing number of cities, states, and businesses are developing market-based programs to buy and sell pollutants that contribute to global warming. These initiatives include underwriting clean energy technology or purchasing carbon offsets generated by planting forests or recapturing methane gas released from cow manure.
DriveNeutral and its competitors signal a new, consumer-oriented approach to the fledgling greenhouse-gas emissions market. But although most climate-change analysts support the concept of buying individual offsets, they are quick to point out the pitfalls.
"It's 'buyer beware,' " says Mark Trexler, president of Trexler and Associates, a climate services company in Portland, Ore. Without a government-imposed cap on emissions, he says, it's difficult for consumers to know if the pollution reductions they paid for actually took place.