U.K. goes offset-crazy, but how much is it helping the planet?

Carbon offsets are all the rage in the U.K. these days — but are they a dangerous distraction from the need to slash greenhouse-gas emissions at the source, or simply a savvy strategy for efficiently addressing a global problem? Forum for the Future, a British sustainability group, had some feisty internal debates over this question when presented with the opportunity to help energy giant BP develop a consumer offset scheme. Peter Madden reports on the lessons learned.