So what do we do? everyone knows the planet is in bad shape, but most people are resigned to passivity. Changing course, they reason, would require economic sacrifice and provoke stiff resistance from corporations and consumers alike, so why bother? It's easier to ignore the gathering storm clouds and hope the problem magically takes care of itself.

Such fatalism is not only dangerous but mistaken. For much of the 1990s I traveled the world to write a book about our environmental predicament. I returned home sobered by the extent of the damage we are causing and by the speed at which it is occurring. But there is nothing inevitable about our self-destructive behavior. Not only could we dramatically reduce our burden on the air, water and other natural systems, we could make money doing so. If we're smart, we could make restoring the environment the biggest economic enterprise of our time, a huge source of jobs, profits and poverty alleviation.

What we need is a Global Green Deal: a program to renovate our civilization environmentally from top to bottom in rich and poor countries alike. Making use of both market incentives and government leadership, a 21st century Global Green Deal would do for environmental technologies what government and industry have recently done so well for computer and Internet technologies: launch their commercial takeoff.

Getting it done will take work, and before we begin we need to understand three facts about the reality facing us. First, we have no time to lose. While we've made progress in certain areasÑair pollution is down in the U.S.Ñbig environmental problems like climate change, water scarcity and species extinction are getting worse, and faster than ever. Thus we have to change our ways profoundly—and very soon.

Second, poverty is central to the problem. Four billion of the planet's 6 billion people face deprivation inconceivable to the wealthiest 1 billion. To paraphrase Thomas Jefferson, nothing is more certainly written in the book of fate than that the bottom two-thirds of humanity will strive to improve their lot. As they demand adequate heat and food, not to mention cars and CD players, humanity's environmental footprint will grow. Our challenge is to accommodate this mass ascent from poverty without wrecking the natural systems that make life possible.