Wednesday, March 28, 2007

More on Irreversibility and its Importance

Cumulative Effects
by J.B. Ruhl

As my last post was quite a while back, I'll remind readers that I've been exploring the phenomenon of large-scale cumulative effects, a category of "wicked problems" that I contend plagues many of our environmental and social issues of the day. I define these as having several key properties: (1) massive agent numbers; (2) nonlinear aggregation thresholds; (3) agent resistance to change ("roots"); and (4) interaction with other systems ("tentacles"). My most recent post added "irreversibility" to that list and said I would move on to explore how successful two management approaches--unrestrained markets versus cost-benefit regulation--are likely to be in defying this inherent challenge.

Before going there, however, a few more thoughts on irreversibility based on some discussions with Neil Manson, a philosopher at the University of Mississippi doing some interesting work on the precautionary principle. My concern arises from the growing use of "irreversibility" as a buzzword in discourse on looming issues such as global climate change, sustainable development, and the precautionary principle. The term is being thrown around a lot without much precision as to its meaning. And it is usually portrayed as a "bad" thing, when in fact it is normatively neutral in the systems sense.

Irreversibility in the sense used in complex systems theory is a matter of degree. All systems are irreversible--you can't unwind time. What we're really talking about when we use it in practical applications is whether a perturbation has thrown the system off trajectory in a way that makes it very difficult to get back on approximately the same trajectory as before. Getting "back on track" is more difficult as the attributes described above for cumulative effects are increasingly in play. Some cumulative effects phenomena, in other words, exhibit what I will call high-resistance irreversibility--the effort it would take to get back on track, if one even could figure out how, may be beyond our social and economic capacity.

Global climate change is, in my view, the net product of numerous human and physical systems going through cumulative effects events with high-resistance irreversibility. The problem is that "irreversibility" as used in much of the literature on global climate change, as well as in the debates over sustainability and the precautionary principle, suggests that its causes are simple, known, predictable, and that its effects are uniformly negative. None of these claims is true.

The precautionary principle, for example, teaches us to avoid taking steps that will lead irreversibly to bad effects. Sustainable development is premised on the assumption that we can know which set of actions taken today will be sustainable versus which will lead us irreversibly into oblivion. While I find much of value in the ideas of the precautionary principle and sustainable development, they're trying to sell us too much in these claims about the predictability and effects of irreversibility in the context of cumulative effects. My concern is that the distortion of irreversibility as a predictable, bad event is often used to lead to the prescription of policies which, purportedly, will help us avoid it or control it. Rather, it strikes me that we need to come to grips with irreversibility as an unpredictable threshold with mixed effects and ask ourselves what system of governance is most likely to be able to cope with it over the long haul. That is what is leading me, soon, to the discussion of markets and cost-benefit analysis.


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