Reuters had a piece a couple of weeks ago about the growing pressure on corporations to hire independent auditors to validate their “green cred” and stave off claims of greenwashing:

Green audits - which for medium-sized companies can easily cost more than $100,000 - are helping a growing number of corporations assert their environmental responsibility in the face of scrutiny from the government, as well as consumers. Regulators are making more demands. For example, companies that label their products as eco-friendly likely will face tougher oversight from the U.S. Federal Trade Commission under guidelines proposed a year ago. Environmentalists make demands also. Overly positive green claims regularly trigger protest campaigns by such groups as Greenpeace. Green audits can also help companies find energy savings, fend off publicity nightmares and attract investors concerned about climate change.

The piece also points out some of the limitations of these kinds of audits:

Some auditors only verify numerical data, such as carbon emissions, and do not check the accuracy of the glowing narratives about companies' environmental achievements and goals that often dominate reports. Moreover, there are no firm rules for environmental reports comparable to the U.S. generally accepted accounting principles (GAAP) and SEC requirements for financial statements.

Auditing has been quicker to catch on in Europe than in the U.S., largely out of compliance with an emissions trading program. (h/t Two Sides)