The biggest threat to global stability is the potential for food crises in poor countries to cause government collapse.

No civilization has survived the ongoing destruction of its natural support systems. Nor will ours.

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.

In the Middle East, where populations are growing fast, the world is seeing the first collision between population growth and water supply at the regional level. For the first time in history, grain production is dropping in a geographic region with nothing in sight to arrest the decline. Each day now brings 10,000 more people to feed and less irrigation water with which to feed them.

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.

The transition from coal, oil, and gas to wind, solar, and geothermal energy is well under way. In the old economy, energy was produced by burning something - oil, coal, or natural gas - leading to the carbon emissions that have come to define our economy. The new energy economy harnesses the energy in wind, the energy coming from the sun, and heat from within the earth itself.

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.