By Roger Harrabin
Environment analyst, BBC News
The committee says aviation needs to be included in the carbon target
The UK government's official climate change advisers have raised the bar on ambitions to cut emissions.
The Committee on Climate Change (CCC) said a cut in greenhouse gas emissions of at least 80% by 2050 should include international aviation and shipping.
It said other industries would have to make up any shortfall in those areas.
Prime Minister Gordon Brown has intimated at an 80% cut, but ministers have been wary of counting aviation and shipping, where cuts are difficult.
Mr Brown hinted at the Labour Party conference that the UK would need to cut emissions to just one fifth of the current amount - a task of staggering ambition.
The committee, led by the former CBI head Lord Adair Turner, says that if CO2 cannot be cut sufficiently from shipping and flying, some other sector will have to make up the shortfall to ensure the overall target of 80% is met.
The expert committee was set up to advise on how far the UK needed to cut emissions to contribute to a fair agreement to keep greenhouse gases below what official scientists consider to be a dangerous level.
They said that the target was achievable at an affordable cost of between 1-2% of GDP in 2050.
In a statement, Lord Turner said: "Climate change poses a huge potential threat to human welfare.
"If we do not act soon, in developed and developing countries, it will become too late to avoid serious and potentially catastrophic consequences," he added.
"That is why it is so vital that a global deal is reached on climate change and that the UK contributes significantly towards this.
"But we have the potential to reduce our emissions by 80% or more by using energy far more efficiently, by investing in developing new energy sources and by making relatively minor lifestyle changes."
Lord Turner said using energy more efficiently made economic sense as well as benefitting the environment.
Parliament is expected soon to pass the Climate Change Bill, which will provide for the setting of carbon budgets for the UK.
The first such budget will be published by the Climate Change Committee at the beginning of December.
The committee's insistence on the inclusion of international aviation in the targets ensures that flying will remain a source of controversy for years to come - particularly among Labour MPs.
It is the richest in society who fly most yet it is the poorest who will suffer most from high energy prices if the power sector needs to de-carbonise even more to make extra room for aviation.
Friends of the Earth's executive director, Andy Atkins, said: "The committee's advice is fantastic news - climate change is the biggest threat the planet faces.
"The Climate Change Bill is a trail-blazing piece of legislation - but the government must now strengthen it to help make Britain a world leader in developing a low carbon economy."
Mr Atkins added that leaving international aviation and shipping outside of the target was not an option.
"The bill currently has a loophole allowing future governments to continue to ignore these emissions - ministers must act to close it."