Travelers taking off or landing in countries in the European Union may notice a bump in airline fares, as U.S. Airways and American Airlines have joined Delta and United Continental in adding a $3 surcharge each way to help offset the cost of a new carbon emissions law.

Reuters says the law requires airlines airlines touching down or departing from the EU and three neighboring countries to acquire permits for the carbon they emit while flying.

Several countries, including the United States, have spoken up in opposition of the law, which went into effect January 1.

As airlines try to pay for the carbon emissions permits and pass the cost on to consumers, some experts say airfares between the U.S. and Europe could rise higher than the $3 each way surcharge, up to $90.

American, US Air add surcharges in wake of EU law [Reuters]

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