We are witnessing the beginning of one of the great tragedies of history. The United States, in a misguided effort to reduce its oil insecurity by converting grain into fuel for cars, is generating global food insecurity on a scale never seen before.

In today's integrated world economy, ... eradicating poverty may contribute as much to U.S. security as eradicating terrorism.

Among the environmental trends undermining our future are shrinking forests, expanding deserts, falling water tables, collapsing fisheries, disappearing species, and rising temperatures. The temperature increases bring crop-withering heat waves, more-destructive storms, more-intense droughts, more forest fires, and, of course, ice melting. We are crossing natural thresholds that we cannot see and violating deadlines that we do not recognize.

Farmers...can no longer keep up with rising demand; thus the outlook is for chronic scarcities and rising prices.

The problem with water, though, is that the shortfalls don't show up until the very end. You can go on pumping unsustainably until the day you run out. Then all you have is the recharge flow, which comes from precipitation. This is not decades away, this is years away. We're already seeing huge shortages in China, where the Yellow River runs dry for part of each year. The Yellow River is the cradle of Chinese civilization. It first failed to reach the sea in 1972, and since 1985 it's run dry for part of each year. For 1997 it was dry for 226 days.

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.

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.