Predicting Catastrophe

| Wed May 23, 2007 2:32 PM EDT

What makes a tipping point finally tip? New research reveals a fascinating mechanism. Complex systems, like the earth's climate, coral reefs, oceans, and social-economic systems, often react in a surprising way to change. When conditions change gradually, the system may respond little until a critical tipping point is reached, after which the system may collapse completely. After collapse, it's nearly impossible to restore the original state of the system. Yet managers have had difficulty predicting catastrophic transition without a deep knowledge of the underlying mechanisms.

But now, Egbert van Nes and Marten Scheffer have analyzed models concluded there's a simpler way to predict a catastrophic transition. Their work, in the June issue of The American Naturalist, shows that after small disturbances the system recovers much more slowly if a collapse is near. They argue that this slower recovery serves as an early warning signal for upcoming shifts. In practice, the recovery rate can be determined from small experiments, or by analyzing the natural variations in a time series.

So, will we do it? It's kind of like taking a DNA test to see if you're going to inherit a fatal disease or not. Few at risk do. --JULIA WHITTY

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