Decline of variability when approaching bifurcation point: an alternative view of charting

One of the significant problems facing climate scientists is how to predict when the system is about to undergo a major change in organization. This point is important because a precise prediction of what is going to happen in response to continued alteration of the atmosphere is unlikely. What we may be able to do is look for signals of an impending global reorganization in the hopes that we will recognize same before the change suddenly occurs.

The basis of this discussion is that the climate system acts to resist external forcings, but if the forcing is strong enough, the system then evolves very rapidly towards some new equilibrium. We may or may not be able to predict what the new equilibrium will be.

It is generally viewed that a change in climate equilibrium would be bad for us as our entire system of global agriculture is geared towards our present equilibrium, which has lasted for about ten thousand years (which, come to think of it, is about as long as we have been practicing agriculture). We haven't put much effort into planning for agriculture in a new equilibrium state.

Once again, understanding the past is the key to predicting the future.

A number of papers have been presented recently, in which the authors have looked at climate signals prior to major climate shifts in the paleoclimate record. And they have noticed that prior to a major change in climatic regime, the short-term variability declines dramatically.

Carbonate content of marine sediments during a "climate tipping" event from greenhouse conditions to icehouse conditions ca. 34 million years ago. From Thompson and Sieber (in press). The lower figure tracks the rise of an autoregressive parameter--essentially an inverse measurement of variability.

The reason for this decline in variability is unclear, however it appears in both models and in observed time series. Given the detailed observations made of present-day climate, it is theoretically possible to anticipate when a sudden climate change is about to occur.

There are counter-arguments, however. Climate measurements are normally easier to make than ecological measurements.

What does this mean for the stock market?

Some well-known charting patterns show the same behaviour; most notably the triangle pattern.

This does seem to be at odds with some conclusions I've drawn earlier. I may have to reconsider.

Consider it evidence that dynamic systems are hard.






Reference

Thompson, J. M. T. and Sieber, J., in press. Predicting climate tipping as a noisy bifurcation: A review. International Journal of Bifurcation and Chaos.