Targets for reducing aircraft noise will have to be sacrificed to halve the climate change emissions of a new generation of airliners, easyJet said yesterday.

The budget airline unveiled a model of what it described as an “eco-jet”, which would use open rotor engines invented in response to the oil crisis of the 1970s.

It hopes that these engines will generate 50 per cent less CO2 than those used on its current aircraft.

Manufacturers abandoned the design in the 1980s because the oil price fell and fuel efficiency became less important.

The engines would be much more efficient than existing ones, but also noisier because they would have no outer shell around the rotating blades.

Rolls-Royce is among several manufacturers working on open rotor engines, which are double the diameter of existing engines and produce the same amount of thrust with half the fuel. The eco-jet would also be designed to fly more slowly to save fuel, adding five to ten minutes to most journeys within Europe.

Andy Harrison, chief executive of easyJet, said: “There is a trade-off between noise and carbon dioxide emissions. We think reducing CO2 should be the priority.”

The aviation industry has agreed a target with the European Commission to reduce noise from new aircraft by 50 per cent by 2020.

Mr Harrison said that the new jet would not be able to meet this target, but could achieve a 25 per cent reduction in the noise perceived on the ground by attaching the engines at the rear of the aircraft and using the tailfin to direct the noise upwards.

Speaking at a conference in London, he said: “This is not Star Trek. This is the future.

“We at easyJet think that global warming is a near certainty and that this generation need to take action now.

“Aircraft technology is an important component to achieving improvements and efficiency, and particularly environmental efficiency.”

He said that the new jet could enter service by 2015 but airlines would first have to persuade the leading manufacturers, Boeing and Airbus, to develop it. “We are currently spending £4 billion on aircraft – they are listening to us,” he said.

Mr Harrison added: “The aircraft example we have unveiled today represents the next major step forward in airframe and engine technology.”

The lightweight structure and open-rotor engines are based on technologies that are being developed by manufacturers. The wings of the eco-jet are swept forward rather than back in order to reduce drag.

“This is realistic and it is achievable. If it were to be made available today, we would order hundreds of them for fleet replacement and to achieve the green growth that our industry has committed to.”

Airbus promised yesterday to increase its research budget by 25 per cent from next year and said that by 2020, all of its new aircraft would produce 50 per cent less CO2.

Budget airlines have been under fire recently from environmental groups and politicians for their contribution to global warming. According to figures from the Intergovern-mental Panel on Climate Change, airlines contribute only 2 per cent of global carbon emissions.

But aviation is the fastest growing source of emissions and has no credible alternative source of fuel.

Mr Harrison said that low-cost airlines were generally more environmentally efficient than other carriers, pointing to the low average age of easyJet aircraft and a higher number of passengers per flight.

He also announced that easyJet would shortly introduce a carbon offsetting scheme and had already called for 600 of Europe’s oldest aircraft to be banned from the skies.

He said that easyJet’s contract with Airbus ran to around 2014, and would be in the market for its next generation of aircraft from 2015.

“The environmental performance will be a crucial consideration in the design that we select,” he said.

Richard Dyer, Friends of the Earth’s aviation campaigner, said: “It is important that the aviation industry looks at ways to significantly reduce its impact on climate change.

“But unless this includes massive cuts in the anticipated growth in air travel, it is unlikely to be achieved.”