BRUSSELS A high-level group set up to devise a global solution to curbing international airline emissions is due to hold a second meeting at the end of this month.
The panel of experts was established in response to furious exchanges between the European Union and non-EU governments over an EU law that makes all aviation using EU airports pay for their emissions via its Emissions Trading Scheme (ETS).
Critics said the EU law breached national sovereignty and warned of a trade war.
Late last year, the European Commission proposed to "stop the clock" for a year to give U.N. body the International Civil Aviation Organization (ICAO) the chance to negotiate an alternative solution. The clock would restart automatically in the absence of an ICAO deal.
The Commission proposal must be agreed by EU member states, but endorsement, which is expected over the coming months, should be a formality, given the support of leading members Britain, France and Germany.
Well over a decade of ICAO talks has failed to deliver a plan, and analysts say even the increased pressure on the U.N. body might not be enough.
The European Union introduced its system in the first place only because the ICAO had not managed to agree on an alternative.
The EU Emissions Trading Scheme (ETS) makes air operators responsible for emissions on all flights both arriving into and departing from Europe.
Airlines are required to measure and collate data on fuel burn per flight and present this in an annual report that must be verified.
The following outlines possible alternative solutions:
1) All departing international flights from a state:
Considered the most realistic of the alternatives, this would involve charging just departing flights. They could be charged on the basis of fuel burn calculated using a standard conversion factor to translate fuel use into emissions.
2) All international flights carried out by operators registered in a given state:
For a global scheme, each country would be responsible for accounting for the emissions of all its registered operators worldwide, based on fuel burn.
It would require each country to agree to participate, something many observers consider extremely unlikely, given the extent of opposition to the EU law.
3) International flights on the basis of the nationality of airspace traveled through:
One of the weaknesses of this approach is that when aircraft are flying in international airspace, emissions would not be accounted for, leaving about 50 percent of global emissions unregulated.
(Reporting by Barbara Lewis; editing by Jane Baird)