Though home to us all, the earth is mute. It doesn't get a vote in any congress or parliament. It doesn't own blocks of shares in the market. It doesn't rise up at a protest rally. It can't even buy a hybrid car. The earth has no voice — so someone must speak for it.
We call the men and women on the following pages heroes, but they could just as easily be called speakers for the planet, a planet that is hanging, as one of them put it years ago, in the balance. Some are prophets of peril, like Australian scientist and activist Tim Flannery, who has ceaselessly warned of the dangers of climate change. Others diagnose our planet's ills, like D.P. Dobhal, who scales the shrinking glaciers of the Himalayas to track the globe's warming in real time. There are those ready with solutions, like Abul Hussam, a Bangladeshi chemist who found a simple, life-saving way to purify poisoned water. And there are those with a gift for bringing such solutions to the wider world, like solar tycoon Shi Zhengrong, who became one of the richest men in China by tapping the power of the sun.
They range from one end of this endangered earth to the other — from Kenya to Korea, Britain to Brazil, Canada to China. By their words and their actions, by their votes and even their checkbooks, TIME's environmental heroes have stepped into the silence, and in doing so, have given the earth a voice. It remains for the rest of us to listen — and join them.