Thursday, September 22, 2005

ThingsThat Begin with the Letter R

As everyone probably knows by now, it's very unusual (but still within the Gaussian) to get to named storms with the letter R in September.

I was talking to some folks in London yesterday and they asked if I thought it was climate change (or global warming, take your pick). I said I'm post a short piece with some references to explain what I was saying in the cab.

The terms climate change and global warming have become fungible in their common use although they do have different meanings. Global warming is a sub-set of the larger term climate change, and the outcome of global warming (what it causes) may be some other area of climate change (e.g. glaciers, "water world" etc.)

The current spate of hurricanes may or may not be a result of climate change (I know that's not real helpful). It turns out that the current models don't predict statistically more named storms, but do predict that that the storms occur will be stronger and more violent. Hurricanes are powered by the temperature of the surface water over which they travel. The warmer the water, the more evaporation, the stronger the storm (the contrapositive of this also appears to be true). If the ocean temperature is increasing due to surface warming, then storms will be stronger.

You won't get more storms because the forces that cause the storms are correlated with a lot of conditions besides ocean temps (wind patterns, weather in the Sahara, the jet stream and the deep ocean circulation pattern). Climate change may or may not cause more storms, it's not clear. The data so far though only suggest a high Gaussian season so far in the Atlantic, the Pacific and Indian areas seem to be closer to the norm, although there too the intensity is up.

Bill Gray does a good job of making the black art of hurricane prediction more approachable. Back in the day I met Dr. Gray at a AAS conference and have been a fan ever since. He's one of the folks that got me thinking about climate change in the first place.

A Note on Climate Change: The Earth's climate is very complex. The entire discipline of Chaos Theory was founded while trying to tease apart the complex, interacting systems of Earth's energy balance and turn it into a set of simple rules. It's not simple by any means and any conclusions based on simple cause and effect are more likely to be wrong than right and if, right, it's almost always by coincidence. It's roughly equivalent to taking digital computer operating systems and applying them to the analog human brain. Conceptually attractive, but denying the basic physics and certainly the wrong approach.

Real climate models predict strange things in response to surface temperature increases, in part based on the cause of those changes. It’s a complex set of interlocked differential equations, with sometimes odd answers. There are also a lot of factors invloved beyond just the surface temperature which could act as "force multipliers" to amplify some effects out of proportion. These amplified effects feed into other systems and the whole climate moves to a new state vector.

There seems to be two stable attractors in the equations; the current Warm Solution which humanity has mostly evolved in and the White Earth Solution. Neither are fully stable and it seems like the Earth lips back-and-forth between at least these two attractors (they may be more).

The point here is this: It’s a hard problem we don’t understand and, the Earth is not guarantee to be, at all times, habitable. At least not to humans. My advice (since I was asked yesterday), be suspicious of simple cause and effect explanations for or against climate change and, keep in mind the stakes are surprisingly high. In the end, there may be nothing at all we can do about it, except adapt.

Update: In the cab I mentioned some reference to the Martian Climate runaway. References here here and here

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