Can you be traveling green by buying offsets?

Buy an airline ticket online, and you’re increasingly likely to see this pitch: Add a payment of a few dollars, and finance save-the-Earth activities to offset environmental damage caused by your trip.

Travel companies such as British Airways and travel sites Travelocity and Expedia are giving ticket purchasers the chance to at least assuage guilt, and possibly help the planet, by selling so-called offsets to finance green activism. Cost: About $5 and up.

The travel companies pass along the money to a new breed of enterprises