US told to go green on carbon emissions or lose EU flights

From this article:

US airlines must pay for their carbon dioxide emissions or face a curb on flights to the European Union, the EU transport commissioner warned yesterday.
...
All airlines flying in and out of the EU must subscribe to the scheme but the International Air Transport Association has warned that 170 countries oppose the move.

European carriers want foreign rivals coopted on to the scheme because airlines who refuse to buy carbon credits will offer lower fares...