Many offsets sold on this market are what Ricardo Bayon, director of Ecosystem Marketplace, a San Francisco-based information provider on ecosystems services, calls "gourmet." Their value lies not in the compliance, but in the prestige of achieving carbon neutrality. At first glance, this type of offset appears more straightforward: A consumer pays for a carbon-removal service.
Dig a little deeper, however, and it gets more complicated. There are many ways to remove carbon from the air, each operating on a different time scale and all of them of different "quality." You can capture greenhouse gases by planting trees. You can also prevent greenhouse gas from entering the atmosphere by burning methane released from animal manure and landfills. (As a greenhouse gas, methane is 23 times more potent than CO2.) Or you can preempt its release by building alternative-energy sources such as wind- and solar-power devices.
Compounding an offset's inscrutability is its intangibility. Unless you're willing to visit Uganda in 20 years to verify the existence of a new tree, a carbon offset is arguably invisible. "The carbon market is particularly difficult because of that issue," says Mark Trexler, president of Trexler Climate + Energy Services in Portland, Ore., the firm commissioned to author Clean Air-Cool Planet's (CA-CP) guide to carbon offsets. "You're dealing with stuff in the future in many cases that hasn't happened yet."
CA-CP's "A Consumer's Guide to Retail Carbon Offset Providers" attempts to wrangle a semblance of order from what one industry insider calls the "Wild West." It ranks offsetting companies on factors like transparency, third-party certification, their efforts to educate consumers, and how well they prove they're not selling the same carbon offset more than once.