The recent Digging Beneath the Greenwash supplement in Building (page 30) carries an great definition of greenwash, a term often used on this blog.
Simply offset your carbon emissions with hot air emissions. Stick a picture of a giraffe on the cover of your annual report and inside be sure to point out that your company did not kill a single giraffe this year. Change the corporate logo to a fuzzy picture of a tree. Carry on as before.