The Wall Street Journal story False 'Green' Ads Draw Global Scrutiny (pd. subs. may be req'd) by Tom Wright notes that government agencies and even notoriously cautious industry self-regulatory bodies are stepping up efforts against greenwashing-- the practice of falsely claiming in ads that your polluting product is good for the Earth:

In Norway, government regulators in September banned all car ads from stating that their vehicles are "green," "clean" or "environmentally friendly" on the grounds that all car production leads to more, not fewer, carbon emissions. The Belgian industry-run, advertising-standard authority in October ruled that Swedish auto maker Saab Automobile, a unit of General Motors Corp., must pull a print campaign in which it claimed that its "Biopower" range of cars make the roads "finally turn green."

Carbon offsets fund projects designed to reduce greenhouse gas emissions in one place in order to counterbalance or "offset" emissions that occur elsewhere.