Voluntary carbon trading markets in the United States have doubled in volume over the past year, demonstrating that companies and consumers increasingly seek to offset their role in creating greenhouse gasses by fostering reductions in carbon elsewhere. But the market lacks quality control and a reliable referee. Some companies may take more interest in pushing brand identity [3] than good works. A survey of 30 companies commissioned by the nonprofit, Clean Air-Cool Planet [4] (which promotes its own sponsors in the report), gave mostly low marks to the types of carbon offsets used by participating companies. "[T]here is the potential benefit of educating people through offsets," Dan Becker, director of the Sierra Club's [5] global warming division, told the Monitor. "On the other hand, if people view offsets like papal indulgences that allow you to continue to pollute, then it's probably not a good idea." Of course, if the U.S. had participated in the Kyoto Protocol [6], there already would be a national policy, national (rather than private) standards and potential penalties for not participating in carbon offsets.