Worldwide greenhouse gas emissions from flying must be limited as part of a global deal to tackle climate change, the committee set up to advise the Government on the issue said today.
Ahead of the UN meeting in Copenhagen in December designed to thrash out a new international agreement on cutting greenhouse gases, the Climate Change Committee said in a letter to ministers that aviation emissions must be capped under a wider deal to reduce greenhouse gases.
Rich countries should take the lead, making sure their aviation emissions are no higher - and possibly lower - than they were in 2005 by 2050, the committee urged.
The cap on aviation emissions could come through a global deal governing the whole industry or as part of national and regional targets for reducing greenhouse gases, the letter to Transport Secretary Lord Adonis and Climate Change Secretary Ed Miliband said.
Any deal to reduce emissions from flying should be "ambitious", and aim for no less than the EU's current plans which require a 5% reduction in emissions from 2013 to 2020.
But the committee's chief executive David Kennedy said such measures would not force people to fly less than they currently do.
"It is vital that an agreement capping global aviation emissions is part of a Copenhagen deal," he said.
"We are calling for a cap that would not require people to fly less than today, but would constrain aviation emissions growth going forward.
"Such a cap together with deep emissions cuts in other sectors would limit the risk of dangerous climate change and the very damaging consequences for people here and in other countries that this would have."
In the UK, bringing emissions from flying back to 2005 levels by 2050 could - alongside cuts of 90 per cent in greenhouse gases across the rest of the economy - deliver the 80 per cent cut in overall emissions to which the Government has signed up.
Without steps to stop growth in emissions from flying, planes could account for as much as a fifth of all carbon dioxide produced worldwide by 2050, the committee warned.
All aviation emissions should be capped, but there could be a period where flights in and out of rich countries would be targeted, while those between developing countries were exempt, the letter suggested.
The committee said it supported plans to include flying in the EU-wide emissions trading scheme, which would give the aviation industry a certain number of "carbon credits" to cover some of their output and let them purchase allowances from greener companies to make up the shortfall.
But all allowances must be auctioned to the industry rather than given away for free, to prevent them receiving the kind of windfall profits energy companies have benefited from under the free allocation system.
And in the long term real cuts must be made, rather than rich countries relying on "offsetting" their emissions by purchasing credits from poorer countries under international trading schemes.
Funding for research and development is needed under a global deal agreed on climate change, to deliver the innovative engine, aircraft and fuel technology that will be needed to cut emissions from flying.
The deal could also agree to use funding from the auctioning of carbon allowances to airline companies to help people, particularly those in poor countries, cope with the already-inevitable impacts of warming global temperatures.
A Government spokesman said: "The UK now has the toughest climate change regime for aviation of any country in the world and we will bring international pressure for aviation emissions to be part of global deal on climate change at the Copenhagen conference later this year.
"We will take full account of the Committee's advice as we continue to press for international aviation to tackle climate change at Copenhagen."
But environmental campaigners renewed their calls for an end to airport expansion in the wake of the advice from the committee.
Friends of the Earth's aviation campaigner Richard Dyer said: "International aviation emissions must be curbed as part of global plans to avoid catastrophic climate change."
Greenpeace climate change campaigner Vicky Wyatt said any government would find it "almost impossible" to build a third runway at Heathrow if it followed the committee's advice.
The chairman of aviation group FlyingMatters, Brian Wilson, said: "I'm delighted that the committee are not seeking to ensure people fly less than today - particularly as most people have only recently been able to afford foreign travel.
"Only an international agreement coupled with the technological advance to which the aviation industry is committed will effectively deal with aviation's emissions.
"Neither unilateral action by the UK nor trying to prevent people travelling will secure the public's support - support which is essential if we are to reach, and deliver on, a deal at Copenhagen."