The age group now in power has not achieved enough. It helped to turn environmentalism and concern for world poverty into a global force. It brought about social, economic and technological revolutions, and fought racism and sexism. But people in the developed world - and the comfortably-off in the developing one - became too set in their ways, too attached to a good life and to their own status, to bring about the switch to sustainable development that the world desperately needs.

We only need to look around. Nearly half the world's people still have to live on less than 2 dollars a day. Over 2 million people die every year because they cannot get clean water. Over a million children under five die from breathing in the smoke from burning wood and dung because their families can't get modern clean forms of energy. Nearly a quarter of the world's farmland has been degraded. Species are being driven to extinction alarmingly fast. And global warming is speeding up, melting glaciers and polar ice shelves, disrupting harvests and threatening catastrophe.

Can we possibly accept a future of increasing world poverty in a disintegrating global environment - and the violence and conflict that are bound to result?

We must act, and act now. We may not be in power, but we are not powerless. Businesses spend billions on advertising to us. Politicians seek our votes. We should think and buy what we need - but only products produced with proper care for the environment. And those who can vote should support people who really work for sustainable development.

As this magazine reports (page 11) young people meeting in Dubna, near Moscow, Russia, have drawn up ten practical commitments which give a guide to action. As other pages in the magazine show, such action can have a dramatic effect. Many other important steps have been taken because people were convinced by their children.

Above all we must not let our youthful radicalism fade into middle-aged complacency. We must tread lightly on our planet - keeping our consumption sustainable - while stamping on practices that endanger it.