Wednesday, August 30, 2017

Paradise Paved

Bison hunters bringing hides to market, Taylor County, TX, sometime around maybe 1870, via TexasBeyondHistory.
A huge landmark moment in media coverage of climate science occurred yesterday, but nobody seems to have noticed it, including the writer who did it, David Leonhardt ("Harvey, the Storm that Humans Helped Cause"), in The New York Times:

The daily surface temperature of the Gulf of Mexico last winter never dropped below 73 degrees. You can probably guess how many previous times that had happened: Zero.
This sort of heat has a specific effect on storms: Warmer weather causes heavier rainfall. Why? When the seas warm, more moisture evaporates into the air, and when the air warms — which has also been happening in Texas — it can carry more moisture.
The severity of Harvey, in other words, is almost certainly related to climate change.
Yes, I know the sober warning that’s issued whenever an extreme weather disaster occurs: No individual storm can be definitively blamed on climate change. It’s true, too. Some version of Harvey probably would have happened without climate change, and we’ll never know the hypothetical truth.
Not sure what the "hypothetical truth" is doing in that sentence, actually. I'd say the hypothetical truth is what we do know, and what we'll never know is whether it's wrong.

But that sober warning is no longer regarded as quite true, is the thing. I can't remember where I first saw it, sometime in the last few months, but the science is now there; the new scientific consensus is that, while you can't blame a particular extreme weather event on human-caused global warming, you can blame that for the extremity, within certain probability limits.

That is, the Galveston–Corpus Christi coast is on the Gulf of Mexico, and that's where hurricanes happen, so if a hurricane lands there we really should not be surprised. But when a hurricane is carrying that much water, enough to shatter the records of an entire continent (I heard more rain fell on Houston in four days than fell on famously wet Seattle for an entire year, and they say it was an unusually wet year up there), it is now no longer bad form to say we know why. We're not 100% certain, but, uh, we basically know, and we can say it.

The new approach is known as "attribution science", and it's been used recently to explain, for example, last year's Paris floods and Arctic heat wave, which you can read all about in an excellent report from Scientific American, January 2 2017. The case for the severity of Harvey as a consequence of global warming, laid out so clearly by Leonhardt, is an especially simple one; it ought to be obvious to anybody who's graduated from 9th grade, which is where you learn that rising water temperature leads to more evaporation and rising air temperature means air can hold more water vapor.

In other words, it's now legal for journalists to say this, about a storm like Harvey, or about this year's terrible monsoon floods in India, Bangladesh, and Nepal, the worst in many years, which have already killed some 1,200 people, and now shut down Mumbai. Like hurricane season in the gulf, the rains are something that happens every year—they'd starve without them—but never rains like this.

Bogra, Bangladesh, August 20. Photo by Reuters via CBS News.
I'm saying Leonhardt is among the first of the journalists in the standard-setting media like The Times to get that we finally have permission to talk about this, even if he doesn't fully understand it, and that's some immense progress.

Let us also praise Leonhardt for pointing out the responsibility of the city of Houston and the state of Texas for having no zoning laws, so that Greater Houston has been able to spread out over 1,660 square miles in a geographical pasta plate over the decades as a maze of ranch houses, pipelines and powerlines, and petrochemical plants mixed chock-a-block together, all paved so that there's no place for that fucking water to go, on the advice of experts like urban futurologist Joel Kotkin (a special bugbear of my own because he used to serve as a primary source for David Brooks) who told them this was going to be the model for the whole world henceforth. They paved something that wasn't quite paradise, put up a parking lot, and created hell. We're nowhere near learning yet how bad this could get.

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