Consider Japan. In the 1600's, the country faced its own crisis of deforestation, paradoxically brought on by the peace and prosperity following the Tokugawa shoguns' military triumph that ended 150 years of civil war. The subsequent explosion of Japan's population and economy set off rampant logging for construction of palaces and cities, and for fuel and fertilizer.

The shoguns responded with both negative and positive measures. They reduced wood consumption by turning to light-timbered construction, to fuel-efficient stoves and heaters, and to coal as a source of energy. At the same time, they increased wood production by developing and carefully managing plantation forests. Both the shoguns and the Japanese peasants took a long-term view: the former expected to pass on their power to their children, and the latter expected to pass on their land. In addition, Japan's isolation at the time made it obvious that the country would have to depend on its own resources and couldn't meet its needs by pillaging other countries. Today, despite having the highest human population density of any large developed country, Japan is more than 70 percent forested.

There is a similar story from Iceland. When the island was first settled by the Norse around 870, its light volcanic soils presented colonists with unfamiliar challenges. They proceeded to cut down trees and stock sheep as if they were still in Norway, with its robust soils. Significant erosion ensued, carrying half of Iceland's topsoil into the ocean within a century or two. Icelanders became the poorest people in Europe. But they gradually learned from their mistakes, over time instituting stocking limits on sheep and other strict controls, and establishing an entire government department charged with landscape management. Today, Iceland boasts the sixth-highest per-capita income in the world.

What lessons can we draw from history? The most straightforward: take environmental problems seriously. They destroyed societies in the past, and they are even more likely to do so now. If 6,000 Polynesians with stone tools were able to destroy Mangareva Island, consider what six billion people with metal tools and bulldozers are doing today. Moreover, while the Maya collapse affected just a few neighboring societies in Central America, globalization now means that any society's problems have the potential to affect anyone else. Just think how crises in Somalia, Afghanistan and Iraq have shaped the United States today.

Other lessons involve failures of group decision-making. There are many reasons why past societies made bad decisions, and thereby failed to solve or even to perceive the problems that would eventually destroy them. One reason involves conflicts of interest, whereby one group within a society (for instance, the pig farmers who caused the worst erosion in medieval Greenland and Iceland) can profit by engaging in practices that damage the rest of society. Another is the pursuit of short-term gains at the expense of long-term survival, as when fishermen overfish the stocks on which their livelihoods ultimately depend.

History also teaches us two deeper lessons about what separates successful societies from those heading toward failure. A society contains a built-in blueprint for failure if the elite insulates itself from the consequences of its actions. That's why Maya kings, Norse Greenlanders and Easter Island chiefs made choices that eventually undermined their societies. They themselves did not begin to feel deprived until they had irreversibly destroyed their landscape.

Could this happen in the United States? It's a thought that often occurs to me here in Los Angeles, when I drive by gated communities, guarded by private security patrols, and filled with people who drink bottled water, depend on private pensions, and send their children to private schools. By doing these things, they lose the motivation to support the police force, the municipal water supply, Social Security and public schools. If conditions deteriorate too much for poorer people, gates will not keep the rioters out. Rioters eventually burned the palaces of Maya kings and tore down the statues of Easter Island chiefs; they have also already threatened wealthy districts in Los Angeles twice in recent decades.