[QUOTE=marshmallow]
I agree with the overall thrust of your posts that things will have to change and we have many unsustainable/idiotic practices, but I’m wondering about the transportation of water (mainly due to my ignorance). From what I understand, all you need to move water around (assuming no gravity assist) is electricity. And there are many states and nations which dedicate large chunks of their electrical production to that task (5-20% of their total pie). So as long as we increase our total electrical production, is it really that big of an economic loser? Aren’t we right now regularly transporting oil and natgas over hundreds and hundreds of miles through pipes? Or is that different somehow?
I just don’t see why when push comes to shove we couldn’t set up desal plants on the Gulf of Mexico and pump that water to the interior states, powered by renewables in the long run – unless, of course. some other nation can replace our contribution to the world’s food supply at a cheaper price.
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It’s not just a matter of energy, though you’re going to need a hell of a lot of that–a couple of orders of magnitude more than we currently produce for residential and industrial use now–as well for desalination and pumping losses, bringing its own problems with pollution and waste. (Even renewable energy is going to produce waste heat if it uses any thermodynamic cycle, as will nuclear fusion.) The sheer amount of water needed to irrigate food crops is overwhelming, even though it is invisible to the end user. We’re talking about several thousand gallons of water per bushel of grain or legume. Most of these areas are substantially inland and often hundreds of feet above sea level, and it’s not just a matter of getting from a wellhead to a refinery as with oil and gas; you’ll have to deliver water directly to every field via a vast network of lines that makes the most elaborate refinery complex built by Bechtel look like a small box of Tinkertoys. Anyone with experience in the oil industry will know how difficult it is to make even a modest refinery and distribution installation work reliably; now imagine billions of acres, each requiring thousands of gallons per day during growing season. And of course there will be losses from evaporation, broken pipes, et cetera.
That is what it will take to replace the normal hydrological cycle processes that are normally powered by the Sun’s natural energy at 1kilowatt per square meter. This isn’t a problem to pass off as soluable by simple, predictable evolutionary advances in technology; this is a massive logistical nightmare, even if you could come up with the necessary energy sources. It’ll be much easier to change agriculture methods and relocate populations, even with all of the disruption that will cause.
[QUOTE=BrainGlutton]
[QUOTE=Tuckerfan]
My understanding is that the optimum sustainable population for the Earth is 2 billion people . . .
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Based on what?
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I don’t know where Tuckerfan is getting his number, but estimates of sustainable population vary all over the place, based upon what set of assumptions you use regarding resource depletion, average resource footprint, advances in energy and agriculture technology, et cetera. This is not a simply bounded problem with static resources, and so any estimate that anyone chokes out has to be qualified by the bounding assumptions. The physical space argument (“See, there’s plenty of room in flyover country,”) is as specious as is the notion that technology will be static, or that a population living at a mere sustainment level will be stable and healthy. Reasonable estimates vary from around 1B (assuming a world population enjoying a modern industrial lifestyle with modest degrees of recycling and eventual transition to mostly non-fossil fuels) to ~16B (assuming sustainence agriculture and effectively infinite resources of energy and water). If you make some speculative assumptions about advances in energy and an essentially infinite expansion of agriculture capability you can get estimates upward of 100B (I’ve seen 1T, though that would cover most readily habitable landmasses with urban concentrations of people) but I don’t think this is a reasonable assumption, nor is the population likely to grow to this density unchecked by the internal economics of the population.
For a long time the limiting parameter was assumed to be oil, and it may still be a driving economic force limiting expansion, but as detailed above, I suspect that water will be the limit for much of the current population growth, and likely one that such populations and governments are manifestly unprepared for.
Stranger
