The future will be green, or not at all. This truth lies at the heart of humankind's most pressing challenge: to learn to live in harmony with the Earth on a genuinely sustainable basis.

If something is sustainable, it means we can go on doing it indefinitely. If it isn't, we can't

The World Health Organization recently published some data showing that each overweight person causes and additional one tonne of CO2 to be emitted every year. With one billion people overweight around the world-of whom at least 300 million are obese-that's an additional one billion tonnes.

Many ideas have struggled over the centuries to dominate the planet. Fascism. Communism. Democracy. Religion. But only one has achieved total supremacy. Its compulsive attractions rob its followers of reason and good sense. It has created unsustainable inequalities and threatened to tear apart the very fabric of society. More powerful than any religion, it has reached into every corner of the globe. It is consumerism

A combination of very rapid population growth over the last 50 years and reckless economic growth during the same time has stored up massive problems for societies the world over. No nation is immune. The scientific evidence tells us all we need to know: carry on with business-as-usual growth-at-all-costs, and we're stuffed

Keeping people on side is a precondition of making any progress on sustainability issues

I am unapologetic about asking people to connect up their own responsibility for their total environmental footprint and how they decide to procreate and how many children they think are appropriate.