very day we burn energy that took millions of years to produce. It took that long for countless billions of plants and creatures to decompose and be turned by heat and pressure into the oil, gas and coal that now go up in smoke. And almost all of it took place more than 285 million years ago, during the Carboniferous period, long before even the dinosaurs roamed the Earth.

We cannot go on much longer bingeing on the energy laid down by the sun so long ago. What we take is not being replaced and will one day run out. Experts predict that within a few decades - maybe even within a few years - oil production will peak, turning 145 years of growth in its use into decline. At that point, ever-increasing and generally cheap supplies will turn into shrinking, increasingly expensive ones. If the world is not properly prepared, economies will slump and conflicts erupt as nations tussle over what is left.

The binge is all the worse because only a minority benefits from it. Roughly a fifth of the world's people have grown rich - in both developed and developing countries - by using up the Earth's fossil fuel capital. The poorest 2.5 billion people have virtually no access to it at all. Instead they have to burn wood and dung, ruining their health and the environment in the process.

And even greater damage is being done by the fossil fuels bonanza itself. For the carbon dioxide that they release when they are burned is the main cause of global warming, which threatens to change the world beyond recognition. It looks as if we may be the last generation to benefit from the benign, stable climate that has allowed civilization to take root and flourish over the last 11,000 years.

Fortunately the solution is known, and to hand. The answer, as the song put it, really is blowing in the wind - and shining in the sun, too. Natural, renewable, clean sources constantly provide the world with far more energy than we will ever need, and we are increasingly developing sophisticated ways of harvesting them. They do not run out, they do not cause climate change, and they are available to the poor as well as the rich, because nature distributes them free.

Ours has to be the generation that moves from plundering millions of years of fossil fuels to harnessing the energy that is constantly on tap. It is a huge transition, but achievable - particularly if we cut down on the massive present waste of energy. It will enable us both to tackle dire poverty and to increase prosperity, to advance technology and yet combat climate change. It is time to turn on the sun.