Wednesday, March 28, 2007

Shock the Frog

Front stoops, no more houses. Plaquemines Parish, LA.

The way the urban legend went, the temperature of the water in the pot rose so gradually and evenly that the frog never noticed it getting hotter. He adapted as every degree was added and eventually succumbed, not aware that the water was too hot to support his life. We could apply that same model to humanity - that we might adapt to a slow, steady increase in temperature, or in rainfall, or in lack of rainfall, until conditions get so bad that no action will save our sorry asses.

But that's not how we're going to experience climate change. The best explanation I've read so far of how things are likely to unfold is in a report by the Global Business Network titled (what else?) Impacts of Climate Change. Originally written for the Pentagon, it raises some of the possible scenarios that are likely to play out as a result of how climate change manifests itself around the world.

Far from the slow and linear change of the "boiling frog" story, we'll see more climatic excursions from the linear -- record-breaking temperatures, droughts and storms, interspersed with years of relative normality. But the impacts of the intermittent extreme events will be devastaing and will last for years or even for generations. Huge populations may be displaced, tremendous losses of life may take place, witnessed virtually by millions or billions, just as Katrina and the Indonesian tidal wave were. Violent conflicts will break out as millions migrate in desperation across borders.

This is a particularly good paper to read because its authors acknowledge that impact studies about climate change are difficult to do.
...they are not predictable enough to be actionable because the exact nature of the event that will jar the planet in the near- and long-term future -- the wheres, whens and hows of climate change -- remains both unknown and unknowable.
So, the authors took another tack.
Instead of starting with climate change and working out toward impacts, we focus on systems that are already generally vulnerable first, and then consider what the geophysics of climate change may do to them.
It's a low-hanging fruit approach; make the easy predictions -- the ones with the highest level of confidence -- and see where that gets us. In this case, even with the relatively safe probabilities described in the report, there is enough potential damage to life, property, culture, politics and the global mood to guarantee that we'll be challenged on all levels in the decades to come.

This passage, I think, is the most succinct description of how the impact will land:
Finally, the high likelihood of extreme events and nonlinear excursions in global climate intersects with the question of threshold effects. As extreme events -- perhaps compounded by medium-term excursions -- take place, the chance that any given event will exceed the resiliency of a natural or human system rises dramatically. And when such a threshold is passed, the amount of damage also rises steeply.
Katrina was a perfect example.

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