"To stop global warming and avoid the worst effects of climate change, humans need to stop adding greenhouse gases to the atmosphere.

This sounds difficult, because it will be. The world has never done anything quite this big. Every country will need to change its ways, because virtually every activity in modern life—growing things, making things, getting around from place to place—involves releasing greenhouse gases.

If nothing else changes, the world will keep producing greenhouse gases, climate change will keep getting worse, and the impact on humans will in all likelihood be catastrophic.

But things can change. We already have some of the tools we need—and as for those we don’t yet have, everything I’ve learned about climate and technology makes me optimistic that we can invent them, deploy them, and, if we act fast enough, avoid a climate catastrophe.

This book is about what it will take and why I think we can do it."

—Bill Gates