Middle class rising

Moreover, a middle-class lifestyle in these developing countries, even if more frugal than what is common in rich nations, is more energy-intensive. In 2006, China added as much electricity as France's total supply. Yet millions in China lack reliable access to electricity; in India, more than 400 million don't have power. The demand in India will grow fivefold in the next 25 years.

And we know what happened to oil prices. Oil reached its all-time high of $100 a barrel not because of supply constraints but because of unprecedented growth in consumption in poor countries. China alone accounts for one-third of the growth in the world's oil consumption in recent years.

The public debate about the consequences of this global consumption boom has focused on what it means for the environment. Yet its economic and political effects will be significant too. The lifestyle of the existing middle class will probably have to drastically change as the new middle class emerges. The consumption patterns that an American, French or Swedish family took for granted will inevitably become more expensive; driving your car anywhere at any time, for example, may become prohibitively so. That may not be all bad. The cost of polluting water or destroying the environment may be more accurately reflected.

But other dislocations will be more painful and difficult to predict. Changes in migration, urbanization and income distribution will be widespread. And expect growing demands for better housing, healthcare, education and, inevitably, political participation.

The debate about the Earth's "limits to growth" is as old as Thomas Malthus' alarm about a world in which the population outstrips its ability to feed itself. In the past, pessimists have been proved wrong. Higher prices and new technologies that boosted supplies, like the green revolution, always came to the rescue. That may happen again. But the adjustment to a middle class greater than what the world has ever known is just beginning.

As the Indonesian and Mexican protesters can attest, it won't be cheap. And it won't be quiet.