The European Union said it won’t back down and ease the carbon-reduction burden on airlines by assessing only one leg of flights in its emissions trading system, the world’s biggest.

“The European Commission is not considering only one leg of flights as an option,” Isaac Valero-Ladron, climate spokesman for the commission, the EU regulatory arm, said by email on Friday.

The expansion of the European cap-and-trade programme into aviation triggered opposition from countries including the US, China and Russia.

Chinese and Indian airlines failed to meet an EU deadline to submit carbon-dioxide emissions data for 2011, the commission said May 15.

The 27-nation EU decided in 2008 that flights to and from European airports should be included within the bloc’s carbon programme as of this year after airline emissions in the region doubled over two decades.

Countries opposing the expansion of the EU cap-and-trade into aviation argue Europe should let the United Nations’ International Civil Aviation Organisation, or ICAO, regulate greenhouse-gas limits for the industry.

“We are devoting all our energy and efforts to accelerate progress at ICAO,” Valero-Ladron said. “Similarly, we are engaged in bilateral talks to explore possible equivalent measures.”

‘Equivalent measures’

The EU has said that while its law enables the exemption of incoming flights from a country if it implements “equivalent measures” to tackle pollution from aviation, the bloc won’t give up the inclusion of airlines in the cap-and-trade programme.

An EU consent to assess only one leg of a flight following a proposal of equivalent measures by the third country would avoid “heightened sovereignty and trade tensions even though the EU has a sound legal case of its actions”, Olivia Hartridge, a vice president at Morgan Stanley, said on Friday.

A dispute about the EU carbon curbs on airlines is creating distortions, Jonathon Counsel, head of environment at British Airways, told the CarbonExpo conference in Cologne, Germany.

“We certainly want to see this resolved,” he said. “It creates distortions and threatens retaliatory measures. It’s about sovereignty of airspace.”

European Union aviation permits for December closed down 2.3 per cent at €5.96 (Dh27.22) a tonne on the GreenX Holdings LLC exchange on Thursday.

The permits are influenced by the price of allowances issued to manufacturers and utilities, which airlines can also buy to comply with emissions limits.

The benchmark EU contract has fallen 63 per cent in the past year as the debt crisis damps demand amid an oversupply of permits.