25 Mar 2009

Water and Population

In response to this post, JR writes:
You've said many times that there is no water "shortage" in the southwestern U.S., and that instead there is only a failure to set sufficiently high prices for water and market it appropriately. The implication seems to be that all water-related problems would be solved by raising prices and facilitating water markets.

Respectfully (and I mean that), I believe that conclusion is wrong. I agree that it could be very useful to raise prices for water (when the amount used is beyond a certain minimum allocation that everyone should get for basic sustenance and health needs -- your principle of "some for free, pay for more"); and I agree that well-conceived, well-managed water markets could be very useful in addressing many water management issues in the western U.S. (and elsewhere).

But I disagree with your exclusive focus on prices and markets. While useful, those measures won't solve all our water problems as we move forward into a future where population grows way beyond the carrying capacity of our natural resources, and climate change substantially increases aridity and decreases the supply of freshwater available for the western states.

Today you said that laying the blame for western water problems on overpopulation is "not valid". But I'm sure you don't believe that population can continue to grow indefinitely in the arid and semi-arid western states at the rate it is currently expanding without eventually leading to dire, and very real, shortages of freshwater. Even if we raise water prices and implement water markets, there are limits to the size of the population that can be supported in the desert and semi-desert (or anywhere, for that matter) due to a finite, and shrinking, water supply.

It's not "politically correct" to talk about population, but if we don't start addressing that issue as a society, we're in deep trouble. You touched on the population issue briefly today vis-a-vis carbon, and yet you explicitly indicated the issue doesn't apply vis-a-vis water. I strongly disagree.

California and the desert southwest aren't alone in facing a future with an insufficient supply of freshwater to support our exponentially growing populations. The exploding human population world-wide is going to cause precisely the same problem around the globe. See this article.
To which I replied:
Water "shortage" will NOT occur if water is expensive enough. The population in the SW would not have come (and would not be here) but for the cheap water we have provided. Note the small population in another desert -- the Sahara. (As economists would say "water is necessary, but not sufficient, for human settlement")
To which JR replied:
I certainly agree that the population in the southwest would not have grown to its current level, and many of today's cities wouldn't exist at all, if "cheap water" hadn't been provided.

So, basically, your view is that a future water shortage (a real one) will not occur if water is made sufficiently expensive, because when people realize how much it's going to cost for them to sustain their desired southwestern lifestyle, the population won't continue to grow beyond the carrying capacity of the resource? But if every person gets "some for free," isn't there still a limit on how many people can be drawing upon that free allocation before the limited resource is tapped out?
...and then I said:
Good point (if everyone gets some for free), but I think we'll hit other constraints before that point (e.g., population density like NYC...)
... and then JR said:
Ah, population density like NYC; precisely (not) what people were seeking when they decided to settle in CA and the southwest... Fundamentally, we need to decide what kind of a future we're unwilling to have, and strive to avoid it.

I'd really love to see you use your considerable blogging skills to focus more attention on the population issue.
...and NOW here's what I say...

Population is NOT something that we can "manage" to an efficient level. (Note how the Chinese one-child policy cut population growth but led -- via selective abortion -- to a "shortage" of women, a problem that has fed a growing business of kidnapping women from elsewhere.)

Population will rise and fall as the cost and benefit of children changes. The "demographic transition" begins (population rising quickly) when babies stop dying, food is cheap, and adults live to 60+ years. The transition ends (population stabilizes) when women can choose how many children to have and bear a cost (i.e., lost work time) for additional children.

Note that the Green Revolution saved many from starvation but also facilitated today's 6+ billion world population -- via cheaper food.

Putting aside population magnitude, population distribution is the result of the costs and benefits of living locations. As many of you are aware, the population of Zimbabwe has fallen (through emigration and premature death) by 25% because the government there is so venal, corrupt and incompetent.

Population in the American southwest increased for the opposite reason -- immigration and a healthy, WET environment (at least initially) that attracted people from elsewhere (in the same way that the Thirteen Colonies attracted the poor and huddled masses from Europe).

The cheap water policies that politicians ordered and the Bureau and Corps delivered was part of our "Manifest Destiny" to fill the continent with white people (no PC in the 1800s), and those policies were VERY successful. A lot of land developers got rich, and a lot of people got happy, and everyone enjoyed the cheap water brought from there to here. On page 84 of my dissertation, I write:
Beeson et al. (2001) find that precipitation has a significant positive effect on population density in the United States of 1840. By 1990, this significance disappears. In fact, precipitation has a negative correlation with population growth in the 150 years after 1840. These results correspond to what we know about water in the western US: As infrastructure has brought water to arid regions, people have moved from wet, colder areas to dry, warmer areas.
Bottom Line: I predict (as others have) that the southwestern population will get denser as expensive water leads to smaller lawns and shrink as desert living becomes more expensive. As usual, those predictions may be swamped by other considerations (the same way that New Yorkers are happy to pay high rents in exchange for the "good life"), but I have no doubt that water shortages (or expensive water) will dampen the appeal of the Southwest.

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