Wednesday, November 24, 2010

Three dimensions of risk – Part One: Severity

A few posts ago I introduced the concept of risk in climate change in, it must be said, a very simplistic way:

Suppose there is a revolver to your head with a thousand cylinders (it's a big revolver). For a 3% raise, how many chambers are you willing to have loaded before your boss pulls the trigger? One? Maybe if you're hard up. One in a thousand's not a huge chance to take. Ten? Probably not, if you have anything to live for. A hundred? Never in a million years.

The problem with Russian roulette as a metaphor for climate change is that while a bullet to the head will usually* result in instant death, the effects of climate change on you personally and on society as a whole are a bit (OK, a lot) more complicated than that.

Effects vary in terms of how likely they are to come to pass, ranging from already happening and unstoppable (coral bleaching) to unlikely (massive near-instantaneous releases of methane hydrates). But they also very according to three other important terms: one is severity, a measure of how destructive the change is likely to be; another is distribution, which I will explain in part two, and finally time – when will it start and how fast will it progress?

Severity is self-explanatory, although neither severity nor any of these other factors are easy to quantify. A minimal severity impact would be that harder rains in late spring shred, simply shred, your prize-winning geraniums. A maximal impact, on the other hand, would be something like what happened at the end of the Permian: massive anoxia in the oceans, brought on by global warming, led to overgrowth of sulfate-reducing bacteria, which caused a massive release of poisonous hydrogen sulfide gas that suffocated the majority of life on earth; most of the survivors of the gas itself were done to death by UV radiation when the gas destroyed the ozone layer. That, in the immortal words of Egon Spengler, "would be bad."

Usually impacts are assessed in terms of monetary cost – what will be the impact on GDP? This is a good way to assess low-severity events which progress relatively steadily. As sea levels rise, for example, we can simply ("simply") add the damage caused by submersion of land, increased erosion, salinization of water tables, increased storm surges, and flood defenses for major cities we can't afford to lose (young people may see the day when the rest of New York joins Manhattan as a series of islands.)

More severe impacts, however, are difficult to estimate in this way. If you imagine a degree of drought in many locations around the world which cuts food production by two-thirds, you cannot simply value that food at today's market prices and assign that loss as your risk. Lose that much productivity, and many millions of people will starve. A simple calculation of the value of the food won't begin to capture the destructive potential of such an event.

And as argued here, when estimating the risks of such events, we have to recognize the frailty of our political and economic systems. For several centuries now, the world's population has been rising on a massive wave of economic growth and scientific progress. Much of that was created and is maintained by sound(er) national and international political systems (not perfect by any means, but much better than what came before). Free trade. Open economies. Stable governments with a limited amount of corruption that maintain comprehensive educational systems, public health, and physical infrastructure.

But stress people enough and, very predictably, all of this will come crashing down. Free trade will give way to protectionism. Governments will divert resources from research and entrepreneurship to maintaining the living standards of restive populations. Environmental protection, ironically, will suffer as people burn more and more of their ecological "capital" in order to compensate for diminishing "returns."

This is a critical and under-studied aspect of climate change; the effect it will have on our institutional strengths, and hence, our adaptability. We often assume adaptation will accelerate as the damage of global warming becomes more severe, because the urgency of the problem will be better recognized. This is no doubt true, but we also have to recognize that the process often reverses itself in failing societies, from Easter Island to pre-Bolshevik Russia; they turn inward, give way to corruption, seek refuge in nativism, extremism, and pursue scapegoats rather than solutions. There is a point – a deer-in-the-headlights point – at which trauma and terror of the future make us less adaptable, because adaptation depends on cooperation, trust, and shared burdens, and when societies confront a crisis, they will eventually lose all of these to an unpredictable degree.

This is the second major reason – and to my mind the most important reason – we must not wait to act on climate change until the damage is massive and the need to act is apparent to all. The first reason, which everyone knows, is that our climate has great inertia, and by waiting to act we lock in a dangerous level of future impacts. But reason number two is little discussed (Jared Diamond started the conversation in "Collapse"): As the damage mounts, we will reach a point where we lose the ability to act together on a long-term project like climate change. We will lose the will to help each other, and it will first become a matter of each country for itself, and then each community, and eventually, perhaps, each person. Today, we stand at the helm of a human civilization with more wealth, more knowledge, and strong bonds of union among peoples than ever seen in the world before. We must turn the wheel and start correcting our course before we are damaged to the extent that the controls no longer respond.

Soon: Risk, Part Two: The discount rate

*Though if anyone out there is considering it, I have to warn you that a significant percentage of the time it goes horribly wrong. Shooting yourself in the head is a great way to transform yourself from a suicidally depressed person into a suicidally depressed retarded person with no face.


  1. While the prose is at times inpenetrable, you might consider picking up a copy of Ulrich Beck's "Global Risk Society" if you aren't already aware of it.

    Love your posts so far. Keep it up!