Large scale catastrophic shifts have been documented for ecosystems, climate systems, oceanic circulation patterns and socio-economic systems. Such shifts may be related to loss of resilience, in the sense that the basin of attraction of the present state of a system is shrinking and the probability that a small disturbance can tip the system into the basin of attraction of a contrasting state increases. Recent theoretical findings suggest that the shrinking of the basin of attraction has fundamental effects on the dynamical behavior of the system. Such effects appear to change with a consistent way as the system approaches the point where the catastrophic transition takes place. Apparently, being able to decipher these effects into measurable quantities of some sort of leading indicators can enhance our ability to assess the risk of upcoming catastrophic shifts, or to manage systems for enhanced resilience to such transitions.

1. Vasilis Dakos
Aquatic Ecology and Water Quality Management Group
Wageningen University, The Netherlands
vasileios.dakos@wur.nl, (www.aew.wur.nl/UK/)
Expecting the unexpected:
Leading indicators of regime shifts
Nordwijk March 2010

2. [transitions]
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

3. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Clear lakes get turbid
Scheffer and Carpenter, 2003
algae dominated state
macrophyte dominated state

4. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Cod in North Atlantic crashes

5. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
deMenocal et al, 2000
The Sahel turned into desert

6. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Earth climate systems shift

7. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Financial markets collapse

8. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Averagejourneytime
We get stuck in traffic jams

9. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Humans get epileptic seizures

10. Can we foresee if a system approaches a transition?
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

11. Can we foresee if a system approaches a transition?
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Even if we do not understand the system?

12. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Same shift different causes:
Small changes big surprisesBig changes big surprises
Critical transition
It depends…
Scheffer 2009

13. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Critical Transitions workshop 2007

14. Early Warning Signals
for critical transitions
as Indicators of Resilience
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

15. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

16. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Scheffer and Carpenter, 2003
Why should we expect early-warning signals?
Bifurcation point
Eigenvalue goes to zero

17. Critical slowing down prior to a transition
Van Nes & Scheffer, 2007
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
What does the “eigenvalue goes-to-zero” mean?

18. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Consequences of critical slowing down

19. Indicators of transitions in time
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

20. Indicators of transitions in time
Rising variance
Carpenter & Brock, 2006
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

21. Indicators of transitions in time
Guttal & Jayaprakash, 2008
Increasing skewness
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

22. Held & Kleinen, 2004
Indicators of transitions in time
Increasing autocorrelation at-lag-1
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

23. Indicators of transitions in space
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

24. Indicators of transitions in space
pattern formation
Rietkerk et al, 2004
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts

25. Indicators of transitions in space
Kéfi et al, 2007
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Increasing grazing
Truncated power law

26. Spatial
Variance
Spatial
Skewness
Indicators of transitions in space
Guttal & Jayaprakash, 2008
Spatial
Mean
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
overexploited
underexploited

27. Dakos et al, early online
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Indicators of transitions in space
Increasing spatial correlation
Turbid state
Clear state

28. Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
The indicators seem to work well on models…

29. 23 juni 2005
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Do the indicators work in reality?
But…

30. 23 juni 2005
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Slowing down precedes ancient climate shifts
Shutdown of thermohaline circulation
Model prediction Data
end of Younger Dryas
Dakos et al, 2008

31. 23 juni 2005
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Slowing down precedes ancient climate shifts
Dakos et al, 2008
…more examples

32. 23 juni 2005
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Increasing variance precedes epileptic attacks
McSharry et al, 2003; Scheffer et al, 2009

33. 23 juni 2005
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Increased spatial variance prior to community reorganization
Litzow et al, 2008

34. Indirect estimates of resilience
(indication of proximity to transition not predictive tools)
Tools for verifying past regime shifts
(indication in establishing a sudden change as a critical transition)
Limitations in their estimation in real systems
(data length, data resolution, scale issues)
Practical applicability: may work better in spatial than temporal
context
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Few concluding points

35. How can we identify false positives? (need for proceedures to
increase statistical power)
What kind of monitoring schemes that can capture the indicators
do we need to design?
Can we develop empirical tests for the indicators next to
monitoring for probing the resilience of the system?
Are they only relative measures? Or could an one-time sampling
estimate indicate how much fragile the system is?
How much early is early enough?
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Challenges

36. 23 juni 2005
vasileios.dakos@wur.nl
Thank you for your attention!
Vasilis Dakos Wageningen University Expecting the unexpected: Leading indicators of regime shifts
Scientists Seek Warning Signs for Catastrophic Tipping Points
Nordwijk March 2010