Filed under: Altithermal, California, climate change | Tags: California, California water, Middle East
Yes, I had a nice, long road trip through the west, up the Central Valley to Oregon, back around through various national parks, and back in through the Imperial Valley. Now I’m back, just in time to bury myself in a bunch of environmental documents.
Still, I had fun. As usual, I made the fun weird by reading an (in)appropriate book, in this case Ronnie Ellenblum’s The Collapse of the Eastern Mediterranean: Climate Change and the Decline of the East, 950-1072. The premise here is that, when Europe was enjoying the Medieval Warm Period, eastern Europe and the Mediterranean were hit a couple of times by really bad droughts and associated famines due to regional cooling that extended well past the Black Sea. Ellenblum blames the collapse of the Byzantine Empire and the Caliphate and the rise of the Turks (who came in off the steppes) on this change in weather, and suggests that the reason the Crusades “worked” was that eastern Europe was suffering at a time when western Europe was booming. One can argue with this idea, but one can’t argue with a bigger point, which is that the reason this particular history isn’t better known is that the archives are spread across multiple languages, from Hebrew to Arabic to Greek to whatever, while the medieval history of western Europe is largely in Latin. Thus, you have to be multilingual (as Ellenblum is) to compile a regional history of the Near East and notice that so many people are complaining about famines and civil unrest at exactly the same times.
Given how much California is like modern Israel–climatically at least–I’m finding the book interesting as sort of a guide to what happens during major droughts, and Jerusalem is a great example. Up until the 10th Century, the city was watered by several Roman-built aqueducts that tapped springs in the nearby hills. As the droughts deepened, the big aqueducts fell out of service, and the city depended more on local aqueducts and on storing rain in big cisterns, as at the Temple Mount. As one might expect, the less dependable water was, the smaller the population of Jerusalem was. Ellenblum makes a case that it’s not a linear relationship between water and population, because Jerusalem’s rain fluctuates enormously between years. Rather, when the city was running solely on rainwater, and on perched springs fed by recent rainwater, the dry years seemed to be a really dominant driver in determining how many people were willing to live in Jerusalem.
That’s something I’m really thinking about, after driving past so many farms watered by groundwater and cities fed by enormous aqueducts. When we run out of usable groundwater and when the aqueducts fail, California’s population is going to fall by quite a bit. No surprise there, of course, but the pleasant(ish) thought is that, well, Jerusalem weathered some really bad spells, and it’s still accreting history today. Los Angeles could collapse from a population in the millions to a population in the thousands, but some part of it might remain,a dusty desert pueblo parked between Silver Lake and the LA River, for at least another thousand years.
That wasn’t the only history I saw. We puttered along State Route 49 through the California Gold Country. It was gorgeous with wildflowers (this was a few weeks ago), and we drove past some pretty empty reservoirs. Then there were the little towns, with the closed tourist shops and the broken down gas stations. As we got closer to Sacramento (past Ione, anyway), the ranches were going up for sale, and some had sprouted subdivisions and malls. There were at least three generations of California history packed in there, with the ranches (some broken down, some fine), the old towns from the horse days, the old gas stations from the early car days, the more modern towns where people had concentrated (often with their little strip malls and chain stores), and then the (often gated) subdivisions where the ranchers had sold out. Alan Schoenherr’s California progression of “the cow, then the plow, then the bulldozer” was happening all over, but kind of randomly, as some ranches held out longer than others.
Coming back to San Diego, we saw the same sort of development all around Coachella, where it really looked like an exercise in martian terraforming, with bland, walled suburbs and anonymous malls plopped on top of what had been creosote, after the farmers moved south. It’s amazing what you can do with some Colorado River water and developers with a vision to make the same homes over and over and over again. They’ll leave some neat ruins when the water runs out, at least until the sheet rock falls apart. The Colorado Desert doesn’t seem to be that kind to old buildings.
Going back to the Mid East, one reason the area work(ed?, s?) so well for civilization is that the croplands depend on not one, but two different rain regimes. The Middle East itself runs on a Mediterranean climate with winter rains and summer drought. The Nile in Egypt, though, is fed from the Ethiopian Highlands, which run partially on the Indian Ocean Monsoon. Either one can fail, but it’s historically rare for both the Nile and the Middle East to have simultaneous droughts. Unfortunately, when the double drought happened, empires tottered, because they couldn’t export grain from Egypt to feed hungry people elsewhere, nor could they import grain to feed hungry farmers along the Nile. Nowadays it looks like Egypt’s a net importer of wheat, and subject to global market forces instead of regional ones. I’m not sure what it does for global stability, having everyone tied together into one system like that, but that’s where we are right now.
Southern California kinda-sorta does the same thing as Egypt and the middle East used to do, by drawing water from the Rockies via the Colorado, and from the northern Sierra Nevada via the California aqueduct. Both these are long pipelines, though, and weather in Colorado and the Sierra are more linked than, say, the weather in Israel and Ethiopia. Still, there’s some parallel, and it’s one reason why farming in the Imperial Valley used to be so prosperous. Now the salt’s creeping in, so they’ve got their own problems (not least of which is the Salton Sea), but that’s another story.
In any case, if and when California collapses, it’s probably not the end of all the cities, just a radical downsizing. That might be bad news for Oregon, since I don’t think they’re ready for 35 million climate refugees heading north, but it’s better than total devastation.
And, in the meantime, if you take a car trip, you can look for signs of history as you drive too. It beats listening to books on tape, at least in my opinion.