Another agricultural trend of growing concern is the increased nutrient content of coastal waters resulting from fertilizer runoff in agricultural regions. Augmented by urban sewage discharge in some situations, this results in huge algal blooms, which, as they die and decay, deplete the oxygen content in the water, leading to the death of the fish.

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.

In this era of tightening world food supplies, the ability to grow food is fast becoming a new form of geopolitical leverage, and countries are scrambling to secure their own parochial interests at the expense of the common good.

The choice is ours-yours and mine. We can stay with business as usual and preside over a global bubble economy that keeps expanding until it bursts, leading to economic decline. Or we can adopt Plan B and be the generation that stabilizes population, eradicates poverty, and stabilizes climate. Historians will record the choice, but it is ours to make.

In Mexico City, Tehran, Kolkata, Bangkok, Shanghai, and hundreds of other cities, the air is no longer safe to breathe. In some cities, the air is so polluted that breathing is equivalent to smoking two packs of cigarettes per day.

Nations are in effect ceding portions of their sovereignty to the international community and beginning to create a new system of international environmental governance.

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.