The signal before the collapse

What do earthquakes, heart attacks, seizures, and the collapse of stock markets and fisheries have in common? They’re all examples of what scientists call “tipping points” or “regime shifts.”

A regime shift is a large, sudden, and often catastrophic change in the state of a system. Once it occurs, it can be expensive or even impossible to reverse. If we could anticipate regime shifts in advance, it might be possible to prevent, or at least minimize their damages.

To this end, scientists have been working to develop ways of predicting the early warning indicators of regime shifts. Results are promising. Prior to most regime shifts, there is an increase in the variability of key components of the system at hand.

Consider fluctuations in the Dow Jones average prior to a stock market collapse or changes in brain activity that precede an epileptic seizure. With other colleagues at the Cary Institute, scientist Jon Cole is working to identify the warning signals that herald regime shifts in freshwater lakes.

“Through manipulating entire lakes in Wisconsin, we are using intensive monitoring to identify the environmental signals that precede shifts in things like fish populations and algal blooms. The results have been promising so far. We found that chlorophyll-a – which is the pigment that tells you how much algae is there – is a very good predictor of the shifts in fish communities. So it’s several trophic levels away, and we can monitor it with automated instruments, but we can tell that the shift in the fish is occurring.   And we are using the same monitoring approach and modeling approach to look at the conditions that lead up to toxic blooms.”

Such early warning signals will be important tools for today’s resource managers.


Produced in collaboration with WAMC Northeast Public Radio, this podcast originally aired on August 2, 2013. To access a full archive of Earth Wise podcasts, visit:

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