A European Union parliamentary committee on Tuesday backed a Commission plan to suspend for a year a law that would make all airlines using EU airports pay for their carbon emissions, and urged US President Barack Obama to accelerate a global deal.
International fury at the EU law led Climate Commissioner Connie Hedegaard last year to propose a temporary exemption for intercontinental flights.
The European Parliament's Environment Committee on Tuesday voted for her proposal, dubbed "Stop the Clock". The move needs the endorsement of a full parliamentary session in April, but has so much support that it is unlikely to be overturned.
The committee strengthened the wording to underline the fact that the suspension could be prolonged beyond a year only if "clear and sufficient" progress were made at the ICAO, the UN body seeking an alternative plan to curbing airline emissions.
"There's no excuse any more. Nobody can say now that the EU is obstructing any agreement," said German Christian Democrat Peter Liese.
"I appeal especially to US President Obama, who has been awarded the Nobel Peace Prize among other things for his commitment to tackle climate change, and to Secretary of State (John) Kerry," he added. "They could lose all the credibility if they continue opposing a solution in this important area."
Obama's appointment of Kerry, a long-time champion of action on climate change, raised EU hopes that the United States would step up its environmental ambitions.
So far, campaign groups say Washington's position paper ahead of the next ICAO-sponsored talks in March shows it is proposing a measure that would cover only a small part of airline emissions.
The International Air Transport Association said the EU law had been an obstacle to a global deal.
"With that roadblock removed, we are well positioned for a breakthrough on market-based measures," said Tony Tyler, IATA's director general.
But he said "the devil will be in the details" and it was crucial to have an agreement that preserved "fair competition".
Green campaigners welcomed the vote.
"Now the ball is in ICAO's court and, if it fails, Europe has other options up its sleeve," said Aoife O'Leary, a policy officer at the campaign group Transport & Environment.
The EU Emissions Trading Scheme continues to apply to flights between EU airports, which some airlines maintain is an unfair cost burden, given the intercontinental freeze.
The Commission argues that the cost is in fact minimal - only about EUR€2 per passenger per long-haul flight given the current price of carbon permits, which have fallen to a record low of less than EUR€3 per tonne.
Exclusion of international flights on a permanent basis could weaken the market even more.
A report from international energy consultants IHS CERA published on Monday said the permanent exclusion of intercontinental flights could deprive the EU ETS of more than 500 million tonnes of potential allowance demand to 2020.