'Calm before storm' may foreshadow climatic tipping point
By Lisa Zyga, Space & Earth science / Earth Sciences
http://www.physorg.com/news140866561.html
Now, a recent study has shown that there might be an early warning signal that heralds climatic tipping points. By analyzing the geological records of eight ancient abrupt climate shifts, scientists have found that each shift is each preceded by a period in which the system becomes increasingly slower in responding to natural perturbations, which is reflected as a decrease in the rate of change.
The scientists, from Wageningen University in The Netherlands and the Potsdam Institute for Climate Impact Research in Germany, have published their study in a recent issue of the Proceedings of the National Academy of Sciences.
Because the researchers wanted to see if this information could be used as an early warning signal in the future, they only used data from before the actual transitions. They found that, while some of these ?slowing down? periods were more extreme than others, it is highly unlikely that such behavior would appear randomly for the combined eight examples (less than a 0.3% chance).
?Our study has a dual significance,? co-author Marten Scheffer of Wageningen University told PhysOrg.com. ?It shows that climate has tipping points, and it shows that the theoretically predicted early warning signal can really be detected in a large complex system.?
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Here's the study:
http://intl.pnas.org/content/early/...ract?sid=b81854a5-3d59-4462-8693-c22fedf7b400
Abstract
In the Earth's history, periods of relatively stable climate have often been interrupted by sharp transitions to a contrasting state. One explanation for such events of abrupt change is that they happened when the earth system reached a critical tipping point. However, this remains hard to prove for events in the remote past, and it is even more difficult to predict if and when we might reach a tipping point for abrupt climate change in the future. Here, we analyze eight ancient abrupt climate shifts and show that they were all preceded by a characteristic slowing down of the fluctuations starting well before the actual shift. Such slowing down, measured as increased autocorrelation, can be mathematically shown to be a hallmark of tipping points. Therefore, our results imply independent empirical evidence for the idea that past abrupt shifts were associated with the passing of critical thresholds. Because the mechanism causing slowing down is fundamentally inherent to tipping points, it follows that our way to detect slowing down might be used as a universal early warning signal for upcoming catastrophic change. Because tipping points in ecosystems and other complex systems are notoriously hard to predict in other ways, this is a promising perspective.
By Lisa Zyga, Space & Earth science / Earth Sciences
http://www.physorg.com/news140866561.html
Now, a recent study has shown that there might be an early warning signal that heralds climatic tipping points. By analyzing the geological records of eight ancient abrupt climate shifts, scientists have found that each shift is each preceded by a period in which the system becomes increasingly slower in responding to natural perturbations, which is reflected as a decrease in the rate of change.
The scientists, from Wageningen University in The Netherlands and the Potsdam Institute for Climate Impact Research in Germany, have published their study in a recent issue of the Proceedings of the National Academy of Sciences.
Because the researchers wanted to see if this information could be used as an early warning signal in the future, they only used data from before the actual transitions. They found that, while some of these ?slowing down? periods were more extreme than others, it is highly unlikely that such behavior would appear randomly for the combined eight examples (less than a 0.3% chance).
?Our study has a dual significance,? co-author Marten Scheffer of Wageningen University told PhysOrg.com. ?It shows that climate has tipping points, and it shows that the theoretically predicted early warning signal can really be detected in a large complex system.?
----------------------------------------------------------------
Here's the study:
http://intl.pnas.org/content/early/...ract?sid=b81854a5-3d59-4462-8693-c22fedf7b400
Abstract
In the Earth's history, periods of relatively stable climate have often been interrupted by sharp transitions to a contrasting state. One explanation for such events of abrupt change is that they happened when the earth system reached a critical tipping point. However, this remains hard to prove for events in the remote past, and it is even more difficult to predict if and when we might reach a tipping point for abrupt climate change in the future. Here, we analyze eight ancient abrupt climate shifts and show that they were all preceded by a characteristic slowing down of the fluctuations starting well before the actual shift. Such slowing down, measured as increased autocorrelation, can be mathematically shown to be a hallmark of tipping points. Therefore, our results imply independent empirical evidence for the idea that past abrupt shifts were associated with the passing of critical thresholds. Because the mechanism causing slowing down is fundamentally inherent to tipping points, it follows that our way to detect slowing down might be used as a universal early warning signal for upcoming catastrophic change. Because tipping points in ecosystems and other complex systems are notoriously hard to predict in other ways, this is a promising perspective.