cavelamb wrote:
In case you might have missed it, I think this one is important...


Predicting tipping points before they occur


http://www.usatoday.com/tech/science...ng-point_N.htm



By Elizabeth Weise, USA TODAY

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.

"We began to realize that there was really pretty cool and fundamental
thing going on here," says Stephen Carpenter, one of the paper's authors
and a lake ecologist at the University of Wisconsin-Madison.

Discerning these tipping points before they happen would be huge, says
Carpenter.

"Managing the environment is like driving a car in the dark in the fog
on the edge of a cliff. You know the edge is out there, but it's dark
and foggy," he says. "We're really great at knowing where thresholds are
after we fall off the cliff, but that's not very helpful."

What's fascinating about this concept of bifurcation points is that like
fractals (shapes and patterns that reoccur at different sizes throughout
systems and in nature), once you know about it, you realize that it's
everywhere, you just hadn't realized it before.

Examples of systems that these critical transitions have been found in
include:

•algae blooms in lakes
•asthma attacks
•climate change
•desertification
•epileptic seizures
•fisheries collapse
•migraines
•financial systems

...

Not yet predictive

While their work can't predict all transition points, they've begun to
tease out universal principles, says Scheffer.

What the researches have shown is that these early warning signals seem
to occur differently in different kinds of systems, but there's some
regularity to them within a set of systems.

Systems can also being to "flicker," rapidly oscillating between to
states before finally settling into a stable one.

There's also an interesting finding that as a system gets close to
tipping, it becomes more like systems around it. This is seen often in
financial markets and in social settings where the attitudes of
individuals towards certain issues are affected by what their peers think.

Another warning signal is variability — a lot of change back and forth.

...

Reminds me of an article I read in some scientific publication long time
ago calling the point of no return between one state and the next the
catastrophe point.

cheers
T.Alan