Carbon trading is a business arrangement in which someone who produces CO2 pays a fee, which in turn is used to support a project that reduces CO2. The carbon trading market is a measurable and deliverable means to offset emissions for which a person is responsible. If all airline passengers paid a "carbon tax", for example, it could have a broad impact on carbon reduction projects around the world.

e2 is an ongoing PBS documentary series that chronicles efforts to solve the world's most pressing ecological challenges. From energy consumption to design efficiency, policy to industry, the series documents the innovators whose work is reducing humans' impact on the environment. Interviews with experts, policymakers and pioneers across a variety of disciplines offer a firsthand account of the complex environmental challenges that we face, as well as the possibility that pragmatic solutions are within reach. The series is narrated by Brad Pitt and Morgan Freeman. Each episode is supplemented by a video podcast that features new footage and unseen interview excerpts, providing further insight into the social and environmental issues that series examines. Produced by kontentreal, new episodes of e2 release on PBS member stations every Tuesday beginning September 2, 2008. Check your local listings. Major corporate support for e2 is provided by Autodesk.