[mailchimp_signup][/mailchimp_signup]This question arises after the failure of a voluntary scheme by the biggest UK airline British Airways. In late September it asked passengers to pay a “green fee” to compensate for greenhouse gases emitted by aircraft, with the amount dependent on the distance traveled (ranging from €7.50 for London-Paris to €36 for London-Sydney). The idea is to give the money raised to “carbon offsetting” projects in the developing world. Environmental groups criticised the scheme for underestimating the amount of greenhouse gas emissions at altitude. And even at underestimated levels, it is hardly proving a winner – last month BA admitted hardly anyone had volunteered to pay the fee. A spokeswoman said “less than 0.5%” of the three million passengers the airline carried in October had paid. The news magazine The Economist said: “Economists spy an example of what they call revealed preferences – the idea that talk is cheap and actions provide the best guide to somebody’s beliefs.” This news story is taken from the November 2005 edition of T&E Bulletin.