Hello ladies and gents this is the Viking telling you that today we are talking about

SAVERS OF THE WORLD

Carlo Petrini

Food activist

Carlo Petrini, 58, is the only anti-McDonald's activist who has been welcomed to the offices of David Cameron, David Miliband, Prince Charles, Al Gore and Barack Obama. The founder of the international Slow Food movement, nominated here by Vandana Shiva, is idolised by rich and leisured foodies for promoting high-quality, small-scale farming and organising a relaxed life around long lunches. But Petrini, an Italian leftie of the old school, has a far more serious purpose than saving the pilchard or Parma ham. The Slow Food movement has now expanded across 100 countries and is throwing poisoned darts at the whole fast food culture and the multinational food producers that between them have wrecked so much of the environment.

Tewolde Egziabher

Scientist

Tewolde Egziabher, 67, a slight, Gandhian figure, is a UK-trained biologist who runs Ethiopia's environment protection agency and has proved himself an extraordinarily effective negotiator. At 2am at the 2002 Earth Summit , he made one of the most impassioned speeches heard at a global meeting. It had looked certain that the world's politicians would back a US proposal giving the World Trade Organisation the power to override international environment treaties, but he shamed the ministers into voting it down. No one could remember a personal intervention having such an impact, and his battles on behalf of developing countries to protect them from patents, unfettered free trade and GM crops are legendary. He was nominated by Vandana Shiva.

Amory Lovins

Physicist

Think of a world where cars burn no oil and emit drinking water - or nothing at all. Where central power stations are redundant and buildings and parked vehicles produce enough energy to drive factories. Where no house is built that cannot generate electricity for others. Where carbon emissions have long been declining, and industries no longer waste almost all their material. This is not a pipe dream, but an increasingly likely scenario, here within a generation or two; that is the prediction of Amory Lovins, 60, an experimental physicist turned energy reduction pioneer who has had as profound an influence on the way people use energy as any man alive.

From a base in the Rockies, Lovins and his team of engineers and analysts show governments and large car, aviation and energy companies, as well as the likes of Walmart and Monsanto, how to profit from using less energy by applying knowledge of composite materials, engineering, design and energy storage. He says: "Optimism beats fear or despair any time. There are excellent reasons to be encouraged. The global consciousness is higher at all levels. Revolutionary changes are taking place."

The car industry is speeding towards solutions Lovins proposed nearly 20 years ago, when he developed the idea of a "hyper car" - a carbon fibre hybrid petrol- and electricity-run machine that weighs next to nothing, has far fewer parts than conventional cars, does 150-200mpg and emits practically nothing. Last November, Toyota unveiled just that: a four-door carbon fibre model the same size as its green Prius but about a quarter of the weight of some Minis. It emits only one third of the Prius's greenhouse gases and does more than 100mpg. Now most car makers, with one eye on $100 dollar a barrel oil prices and an understanding that there is a vast market for green, are playing catch-up with Lovins' ideas.

While at Oxford in the 70s, Lovins helped set up Friends of the Earth in Britain and stopped Rio Tinto digging up Snowdonia. By the age of 28, he had worked out that the US could phase out fossil fuels not at a cost, but at a profit. "We stand here confronted by insurmountable opportunities," he wrote. Now the revolution he helped shape is coming, and Lovins says the US can eliminate all oil use by 2050, "and know unprecedented prosperity".

"We're finding in the auto sector speed of change at a fundamental level," he says. "Change is coming out of fear and the car makers are gazing into the abyss. It is widely understood that incremental change is a high-risk strategy. Those who take the opportunity to change will do very well. We can save half the oil we use and the rest we can save with advanced biofuels."

He dismisses nuclear power as the fantasy of control and command states stuck in the 50s. "New nuclear plants are so costly that spending the same on micropower can save two to 10 times more CO2, and sooner. In 2005, renewables produced one sixth of the world's total electricity and a third of new electricity. This revolution already happened - sorry if you missed it!"

Lovins works by seeking efficiency at every point. Take the most energy-efficient existing hybrid car, he says. Drive it carefully and you can double efficiency. Make it ultra-light, and you can redouble it. Run it on an advanced biofuel, and you can quadruple its oil efficiency again. If you then give it batteries that can be recharged by connecting a plug to an electric power source and have a good economic model to pay for the batteries, then you at least double efficiency again. Put all this together, and you can be down to about 3% of the oil per mile you started with. And Lovins says he has never known any company invest in energy and not make a profit.

He's working with the Pentagon, which spends nearly a third of its vast budget on moving troops and equipment around. If it invested in really energy-efficient goals, in the same way as, say, it invested in the internet, GPS and chips, Lovins says it would shift the entire global energy landscape. The knock-on effect would transform civilian car, truck and plane industries, too. The cost? It's a $180bn investment, he reckons - or roughly what the UK spends on its health service in a year.

And as always have a chilled day from the Viking