THE UK could cut carbon emissions to zero in 20 years, but only if people accept a virtual end to air travel and stop using fuel-driven cars, a report claimed yesterday.

Meat would also need to disappear off many menus and an "armada" of wind turbines would be required to be built around the coast to achieve the goal, according to the new research.

Money would meanwhile be overtaken in importance by carbon credits traded by everyone using special smart cards.

The radical vision was put forward by researchers and scientists from the Centre for Alternative Technology (Cat) and was announced as details were revealed of the UK's longest protest march to call for action on climate change.

The 1000-mile trek around the UK will take in 70 towns and cities and involve an estimated 50,000 people.

The scientists from Cat set themselves the task of seeing if the UK could cut fossil fuel emissions to zero by 2027.

They claim achieving such a drastic cut in emissions is possible and may be the only way to tackle climate change.

Paul Allen, the development director of Cat, said: "What we are saying is that we need a huge programme, a bit like the US space project in the 1960s.

"When that was launched it was known to be a huge target, but the driving force to make it work was there. We think that zerocarbonbritain can do that again; it can give us a positive future."

In its report, CAT suggests people would be given their own carbon credits called Tradable Energy Quotas (TEQs) and carry them on the environmental equivalent of the London transport Oyster card. Each year the free allocation would decrease as the country moves towards zero carbon, with the effect that the value of the quotas will go up.

But every time consumers use fossil fuels, say by filling their cars up with petrol, they would lose valuable credits, forcing them to choose low carbon alternatives.

The resulting market would drive environmental change, providing the economic incentive to produce green products. One major effect, according to the authors, would be that electric, battery-operated cars would quickly overtake use of the internal combustion engine.

Households would be forced to invest in ways to make their homes energy efficient, and switch from gas to biofuels or renewable electricity.

But there would also be "negative" effects in terms of the lifestyle that people currently enjoy.

Air travel would become far too expensive unless the industry "pulls something out of the hat" and finds a green fuel.

And the diet of the country would have to change to include far more organically-grown, locally-produced vegetables, and less meat.

Tens of thousands of wind turbines would be built, mainly around the UK's shores, to provide 50% of the country's new energy needs.

The rest would come from a combination of biofuel "combined heat and power" stations, wave power, hydroelectricity and tidal schemes.

Meanwhile, walkers from around the world are preparing to embark on what organisers believe will be the UK's longest protest march to call for action on climate change.

Campaigners will set out from Northern Ireland next Saturday on a 1000-mile trek around the UK taking in 70 towns and cities, finishing at the London Stock Exchange 11 weeks later.

An estimated 50,000 people are expected to join the walkers at different points, gathering signatures for a petition calling on Gordon Brown to bring in a new law forcing companies to reveal their carbon dioxide emissions.

The event, organised by Christian Aid, will begin in Bangor, Co Down, on July 14 where the campaigners will gather at the marina and board a boat bound for Troon, Ayrshire, to begin their trek.

In another move to tackle climate change, Boeing has unveiled its new "green" 787 Dreamliner aircraft powered by Rolls-Royce engines. The 250-seat plane will fly for the first time this autumn and will go into passenger service in May 2008.

With Rolls-Royce Trent 1000 engines, the Dreamliner is 25% British-made.

Boeing boasts that the plane will use 20% less fuel per passenger than similarly sized aircraft, will produce fewer carbon emissions and will have quieter take-offs and landings.