Predicting tipping points before they occur
Scientists try to detect early warning system before a system changes.
— -- Say you're in a canoe on a lake, dry and firmly seated. A fish swims by and you lean over to take a look. You lean a little further, and a little further still, until, with a surge of panic you realize you're starting to fall over. You being to flail your arms, causing the canoe and you to rock wildly back and forth, but it's no good: Over the side you go.
Now you're in a new stable state — treading water next to an upside down canoe. And getting back to your former state — un-waterlogged in an upright canoe — will take a lot more work than falling out did.
You've just experienced a tipping point.
However, if you've been following work over the past 30 years in systems theory, you'll recognize this scenario as what scientists call a bifurcation point — the moment when a stable system flips over into a new stable state, after a period of rapid change.
Now some of the most prominent scientists in that field have published a new paper on detecting early warning signals before a system changes. Titled "Early-warning signals for critical transitions," the review paper is in this week's issue of the journal Nature.
Though exceedingly complex, the gist of their work is simple: detecting patterns that tend to emerge in systems just before they hit a tipping point, hopefully in time to stop the process.
"This is a very important paper," says Brian Walker, a fellow at the Stockholm Resilience Center at the University of Stockholm in Sweden.
"The big question they're trying to answer is, how the hell do you know when it's coming? Is there any way you can get an inkling of a looming threshold, something that might be a warning signal that you're getting to one of the crucial transition points?"
"The fascinating thing is that we found that very different systems react the same way and appear to obey the same universal laws as they are getting close to a tipping point," says Marten Scheffer, lead author on the paper and an ecologist at Wageningen University in the Netherlands.
Work on these theories began in the 1970s. At a meeting of researchers looking at these signals convened by Scheffer in Holland in 2007, scientists began to see examples in all sorts of places.
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