Nature's awesome powers have been on frightening display lately. As world leaders gather in Johannesburg to discuss global environmental threats, many parts of the planet are battered by floods, droughts, harvest failures, massive forest fires, and even new diseases. Man's relationship to nature is a theme as old as our species, but that relationship is changing in complex ways. The most important result of the Johannesburg Summit should be a recognition that more scientific research and much more global cooperation is needed.

Floods and droughts have been scourges from ancient times, yet the frequency, size, and economic impact of these disasters has grown in recent years. Insurance claims against natural disasters rose to unprecedented levels during the 1990s, suggesting that the social costs of environmental upheavals have intensified. Climate shocks such as the fierce El Nino of 1997-98 played a major role in recent economic upheavals. Indonesia and Ecuador, among other countries, succumbed to financial crises in 1997-98 that were linked (in part) to agricultural crises caused by the severe El Nino.

Part of the growing climate effect results from our sheer numbers. Largely as a result of technological successes in the past 200 years, the human population has grown seven-fold since 1800, from around 900 million in 1800 to more than 6 billion people today, crowding humanity into vulnerable spots throughout the world.

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