Nuclear power, once regarded as petroleum's natural heir, has become less and less attractive as its numerous drawbacks come to light. Coal, the other fossil fuel, is ultimately as exhaustible as oil.

Our numbers expand, but Earth's natural systems do not.

Today, more than ever, we need political leaders who can see the big picture, who understand the relationship between the economy and its environmental support systems.

Saving civilization is not a spectator sport.

The foundation is being laid for the emergence of both wind and solar cells as cornerstones of the new energy economy.

Each summer, for example, nitrogen and phosphate washing from farmlands in the Mississippi Valley enter the Gulf of Mexico, creating a massive algal bloom covering some 16,000 square kilometers. As the blooms die off, this area-roughly the size of New Jersey-is so deprived of oxygen that no fish survive.

Saving Greenland is both a metaphor and a precondition for saving civilization. If its ice sheet melts, sea levels will rise 23 feet. Hundreds of coastal cities will be abandoned. The rice growing river deltas of Asia will be under water. There will be hundreds of millions of rising-sea refuges. The word that comes to mind is chaos. If we cannot mobilize to save the Greenland ice sheet; we probably cannot save civilization as we know it.