Q. How many Australians does it take to change all the light bulbs?

A. One - Prime Minister John Howard, who banned incandescent light bulbs yesterday, making Australia the first country to take such direct action to stop global warming

After almost a decade as a pariah in the battle against global warming because of its refusal to join the Kyoto Protocol, Australia scored an environmental first yesterday by becoming the only large economy to ban the traditional incandescent lightbulb.

In a move that environmentalists hope will spark a similar move in Britain, the government Down Under said the sale of all incandescent bulbs will be phased out by 2010 and replaced with low-energy versions to cut greenhouse gas emissions.

The enforced switch to new high-efficiency fluorescent bulbs will cut Australia's carbon emissions by four million tons by 2012 and reduce domestic power bills by up to two-thirds, the Environment Minister, Bill Turnbull, claimed. Mr Turnbull, whose right-of-centre government is a recent convert to action on global warming, said: "It's a little thing but it's a massive change. If the whole world switches to these bulbs today we would reduce our consumption of electricity by an amount equal to five times Australia's annual consumption of electricity."

The initiative follows a study by the International Energy Agency last year which found that a global switch to fluorescent bulbs would prevent 16 billion tons of carbon dioxide being pumped into the world's atmosphere over the next 25 years. It would also save £1,300bn in energy costs.

Traditional incandescent bulbs, based on the 19th-century designs of Thomas Edison and Joseph Swan, produce light by passing electricity through a thin wire filament. They are inefficient because up to 90 per cent of the energy is wasted in the form of heat. The new generation of compact fluorescent bulbs are more expensive that the incandescent version but use only 20 per cent of the power to produce the same amount of light. Manufacturers say economies of scale mean they will soon be comparable in price to traditional bulbs and last much longer.

Artificial light accounts for almost 20 per cent of world's electricity consumption, significantly more than the output of all nuclear power stations in the world. Overall, lighting generates 1.9 billion tons of carbon a year, about three-quarters of the amount produced by all cars on the planet.

Australia is the first major economy to ban incandescent bulbs, although the American state of California is also considering a similar move.

But it is not first time a country has made an enforced switch to energy-efficient lighting: Cuba launched a similar scheme two years ago.

In Britain, the Government has yet to move far beyond a symbolic gesture to low-energy lighting by Tony Blair when he ordered the bulb in the lamp outside Number 10 to be changed to a fluorescent one. The Department for Environment, Food and Rural Affairs said it was working within a European Union scheme to promote the use of low-energy products within the home.

The reductions in greenhouse emissions from moving to low-energy bulbs are nonetheless small. The four million tons of CO2 that the Australian government expects to save must be compared with the 565 million tons that it produces annually.

Despite the recent conversion of the Australian Prime Minister, John Howard, to environmental issues, he has refused to ratify the Kyoto Protocol. Mr Howard said the deal would do too much damage to Australia's coal-based energy production.

But campaigners welcomed the ban on incandescent bulbs as one of a number of concrete measures which all countries, including Britain, should be taking as part of their response to global warming.

Friends of the Earth (FoE) said a wholesale conversion to fluorescent bulbs would cut UK electricity consumption by 2 per cent - equivalent to a large power station. Nick Rau, FoE's energy campaigner, said: "We would certainly like to see Britain follow the Australian example. There is no magic bullet for global warming and switching to low-energy bulbs is one significant step among many that we would like to see the Government take."

The failure to achieve a global swap from incandescent to fluorescent bulbs has been a source of frustration and bemusement to experts and campaigners.

The Lighting Industry Federation in Britain estimates that the majority of lights in this country still use inefficient bulbs despite an average reduction of 30 per cent in electricity bills from using low-energy bulbs.