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Model probes how planetary systems collapse

Publicado em 27 março 2017

Por José Tadeu Arantes, da Agência FAPESP

Speed read

  • Model probed what happens when systems like water resources get close to disappearing
  • Even when irreversible change is afoot, ‘residual effect’ can make systems look stable in short-term
  • In practice, tipping points are difficult to spot and should be examined closely, authors say

A mathematical model of how natural and social systems collapse when they reach their ‘tipping point’ suggests how signs of stability in the short-term can give a false sense of security.

Tipping points — loosely defined as the point at which systems transition from one stable state to another — have been the subject of much scientific study for ocean, atmospheric, ecological and economic systems, among others. A tipping point is reached when restoration of a dynamic system is not possible by reversing the trend that caused its collapse.

new study aims to give a better understanding of what happens when a plant or animal species reaches a tipping point after which it will inevitably disappear.  It also helps to understand other natural and social phenomena such as depletion of water resources or the financial crash of institutions.

It was published in Scientific Reports journal (February 2017) as part of postdoctoral research, supported by FAPESP, by Everton Santos Medeiros, a researcher of University of Sao Paulo Physics Institute.

According to Medeiros, the main contribution of the research is to show how in certain cyclical phenomena the transition to a tipping point can be masked by the dynamics of the system itself. 

“For instance, an endangered species is doomed to inevitably disappear when it crosses its tipping point. However, individuals within that species may continue existing and reproducing in nature even for a short time after that point is reached. This transitory effect hides the fact that in the long-term, the species will be extinguished”, Medeiros told FAPESP’s newsletter.

This means that although a tipping point is set to bring irreversible change, due to a ‘residual effect’ the system appears to keep its original characteristics in a transition phase that masks the transformation which has already occurred.

“Extinction of an animal species, depletion of a water reservoir, melting of a big glacier — they all follow this pattern: when the tipping point is reached, damage will be irreversible,” Medeiros said.

But in real life it is difficult to say whether or not a tipping point has been reached, according to professor Luiz Iberê Caldas, co-author of the article and supervisor of Medeiro´s research.

“For example, can we recover the Atlantic rainforest in the Sao Paolo-Santos region or have we lost it inevitably? As there is still much vegetation in this area, it seems we can recover it with some initiative to remedy the damage. But is this really the case? Or is this leftover vegetation just a transitory effect unable to reverse the forest’s collapse?” he asked.

Medeiros studied this type of transition by creating a model to simulate tipping points through a simple differential equation.

“The lesson we have drawn from our study is that we need to be very careful when the first symptoms of impairment appear, because not all of them can be reversed”, Caldas concluded.

Taken from a newsletter by FAPESP, a SciDev.Net donor, and edited by our Latin America and the Caribbean desk.