As of 2012, all flights into or out of the European Union will be subject to regulations that require airlines to buy carbon offsets to compensate for the greenhouse gases emitted by their aircraft.  The airlines’ costs will probably be passed along to passengers in the form of added  fees.  This infographic illustrates the additional cost (in euros and US dollars) for a one-way ticket to various destinations.  Note, however, that estimates vary: the chart below shows emissions and costs as calculated by five different carbon-offset brokers.

The Cost Of Carbon Offsets

Source: Synoptical Charts