A NEW speed limit of 55mph should be imposed on drivers to help cut global warming, MPs said last night.

A Commons campaign, led by the chairman of the all-party group on climate change, also calls for a ban on internal flights by the end of next year and prime-time TV slots to be taken over by environmentalists.

Backers of the move insist it is time for politicians to set out specific measures to reduce harmful emissions, instead of simply signing up to high-minded targets.

One Westcountry MP warned "challenging lifestyle changes" lie ahead.

But any attempt to impose new rules on drivers would be keenly felt in the Westcountry, a region which depends on more heavily on the private car than any other.

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Labour MP Colin Challen has launched the parliamentary motion, which points to a "climate emergency". He said: "The catastrophic destabilisation of global climate represents the greatest threat that humanity faces."

The immediate action he says is needed includes redirecting money aimed at boosting the economy to "green measures", and assigning at least two hours of prime-time television per week to "explain the gravity of the crisis to the public".

He also said "domestic flights should be phased out by the end of 2010" while a "speed limit of 55 miles per hour should be introduced".

Mr Challen pointed to claims by the Independent Committee on Climate Chance that if all drivers obeyed the speed limit it would save 1.4 million tonnes of UK carbon emissions.

"If the speed limit was reduced that would be leading to further savings," he said. "It's worth looking at and it has to be the kind of collective thing government do."

Driving groups condemned the idea as "ridiculous" and Nigel Humphries, spokesman for the Association of British Drivers, said: "It is an admission that speed limits aren't about safety any more.

"People should have a choice – we pay enough fuel tax. Frankly, when you get on a motorway and there are a lot of trucks, the air is moving, the difference in fuel consumption between 55mph and 85mph is minimal."

He added that it was disputed "climate change is man-made anyway". Senior Liberal Democrat Andrew George, MP for St Ives, backed the call for specific ideas for cutting carbon emissions and said he wanted to promote a "mature debate". He said: "We need a melting pot of ideas and we need more ideas thrown in to see which ones enough people will support."

It will be "easy enough" for politicians to sign up to high-minded targets at the Copenhagen climate change talks next month, Mr George said, adding: "It is when you get down to specifics that people start backsliding.

"That's where the hard decisions need to be taken. Some challenging lifestyle changes may be required in order to be able to meet it."

Mr George said the hope of abolishing domestic flights by the end of 2010 is not achievable, but they could be phased out "in the medium term". But he rejected the idea of a 55mph speed limit, instead favouring using road pricing to fund the necessary improvements in public transport. He backed Mr Challen's calls for prime-time TV debates on the environment as part of a "functioning democracy". Mr George said: "It is all very well having celebrity gameshows and X Factors dominating the airwaves … but anything that can be done to promote an informed debate on issues can only be a good thing."

A spokesman for Exeter-based airline Flybe said: "Sat in his Westminster Ivory Tower, Mr Challen clearly has no idea how crucial aviation is to UK regional economies.

"Cornwall and Devon businesses rely on direct air services from airports like Newquay and Exeter to win new business and safeguard vital jobs in communities that need all the help they can get at the moment.

"Lets see him tell our passengers in the South West that they have to spend nearly eight hours, with two changes thrown in for good measure, on a train from Exeter to Glasgow, rather than 85 minutes on one of Flybe's environmentally efficient aircraft.

"Domestic aviation accounts for less than one half of one percent of the UK's CO2 emissions.

"For Mr Challen to put at risk tens of thousands of jobs for the sake of a throwaway headline is nothing short of scandalous.

"If he really wants to make a difference to aviation's carbon footprint, he'd be better off joining our campaign to get all aircraft over 15 years of age banned from UK airspace."