Filed under: livable future, Real Science Content, science fiction, Speculation, sustainability, Uncategorized | Tags: future, green, sustainability
This one’s inspired by this NPR story, about sustainability.
What does sustainability look like? In The Ghosts of Deep Time, I have one character say that civilization is cool, quiet, and green, and that’s still my thumbnail for a sustainable city. To unpack that a bit:
Cool. Forests are cooler than grasslands, not because they get less sunshine, but because they catch more of that sunlight and do things with it. Scientists can actually determine how stressed a forest is by measuring how hot it is. Efficiency translates into less energy loss, which means less heating.
In cities, we tend to waste a lot of energy, which is why they are hot. Most of the sunshine gets reflected, or absorbed into surfaces that it heats up. Most of our equipment runs hot, which means we have to get rid of that heat too. A sustainable civilization doesn’t waste much energy, so it’s going to be cool.
Quiet goes with cool. Much of the noise of modern civilization is wasted energy, gone to making sound waves instead of useful work. An efficient civilization is going to be quiet as well as cool.
Green. This is both in philosophy and color. Plants can perform a large number of functions, from cleaning water to providing shade and cooling air. Moreover, we humans aren’t so far from our evolutionary roots that we don’ enjoy having plants around, even if our thumbs are scummy black rather than green. Obviously, a sustainable city will be ethically green as well, but from a simple design standpoint, I think it’s difficult to have a sustainable city without having a lot of functional plants around.
Anything else? Or can we do without one of these?
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Putting the life back in science fiction 
I would enjoy living in a place that is cool, quiet, and green. In fact I once did, in a pleasant older neighborhood in Portland, OR. That said, I think there are significant weaknesses with all 3 points.
1. Only a small fraction of sunlight absorbed captured by healthy plants goes to anabolic activity. All other sunlight absorbed is immediately wasted as heat or is used to support metabolic activity that also releases heat with a modest time-shift. I believe it is enhanced evapotranspiration that makes forests cooler than grasslands. Large forested areas can modify the climate to produce a virtuous cycle of enhanced water availability, forest growth, and local cooling. In fact it has been proposed that the Sahara desert could be reforested by human intervention, and that after the forest area grows large enough it will be self-sustaining with sufficient natural rainfall induced by the change in land cover.
Stressed forests are hotter because transpiration is impaired or (reversing cause and effect) they are water-deprived, which is a stress in itself that will also be detected by reduced transpiration.
2. There’s at best a weak correlation between noise and energy waste. The ear is very sensitive; even something as loud as a chainsaw only dissipates about 0.1 watt as acoustic energy. No street-legal car can run as loud as a chainsaw in the US, but even the smallest car will waste several times as much energy as one. Better to promote quiet for our own human comfort than as any sort of efficiency measure.
3. Counterpoint: what of desert regions that predate any written records of human-induced desertification? Should they all be fair game for local ‘terraforming’ to make them leafy and green? Should people be compelled to move to greener places and leave the deserts as-is? Some have been inhabited since before any written history of the area. I wouldn’t be enthusiastic about giving Navajo land or Phoenix, AZ a makeover to look like Seattle, even if you had a way to do it without relying on unsustainable tapping of fossil water or river diversion. Of course I think that should ultimately be up to the people who live there, but I also think that a lot of evo-psych is questionable and “people all want to live where it is green” strikes me as more of the same. I actually moved away from Portland to a drier region because I like sunshine even more than I like lush green vegetation. But I don’t foolishly live like it’s Portland here: I’m not going to try to maintain a green lawn or other thirsty plants.
Comment by Matt November 11, 2011 @ 10:05 pmExcellent counterpoints!
I’ll have to disagree about the forests. You’re right about individual plants, of course. The thing is that there are typically more layers of leaves in a forest, so the light that gets wasted by one leave gets caught by the next. Also, while individual leaves are warm, they are horrible at transferring that heat to someone under them, unlike the sun. Mostly they warm the boundary layers around their leaves. Finally, the real comparison I wanted to draw was between a forest and a city. There’s a lot of energy banging around in cities, both solar and fossil, and we waste most of it, even compared to a grassland. Our cities would be much cooler if our energy efficiency was in the range of a forest. At least, that’s my opinion.
Sound is a similar issue. If you’ve been through a major power outage in a city, you’ve probably noticed how much quieter it is when the power’s off. We throw a lot of energy out as noise. While yes, we block quite a lot of noise, it’s also a sign of inefficiency.
As for green, I absolutely agree that we shouldn’t (and probably can’t) turn deserts into forests in a sustainable way, at least not right now. Again, the issue is what a city should look like. Cities in the desert are often full of green plants, because they are often situated on or near water sources. Contrast that with a modern concrete, steel and glass city. In our cities, the water use is still huge, but there’s not a lot of green. I’d suggest that’s a problem, not a virtue.
Comment by heteromeles November 12, 2011 @ 12:59 amNo, really, we don’t throw off much energy as noise. We are just sensitive to the (tiny amount of) energy that is lost that way. The noise:waste correlation is too weak to use as any guide to energy intensity or efficiency. A noisy corner in Mumbai is as loud as anything you’d find in an American city but the American city is using an order of magnitude more energy. A Peltier cooler is completely silent but considerably less efficient than a humming compression refrigerator. An incandescent light bulb is no louder than an LED lamp but much less efficient.
On the subject of cities: yes, where it is appropriate we should use green plants to beautify our surroundings and modulate the elements. A big shade tree near a building is both more pleasing to the eye and more energy efficient than running an air conditioner to compensate for the direct glare of the sun. But let’s first be sure that the city is using water in a sustainable way, THEN use that water to turn the city green (if warranted). Don’t just say “as long as we’re using too much water anyhow, let’s use it for this nice thing…” This is the same sort of lazy justification that runs “as long as we’re wasting a trillion dollars on unfunded wars anyway, why can’t I have a mere hundred billion for my Mars expedition?”
Why am I so obsessed with this distinction between signs and signals of goals vs. the goals themselves? It’s because you will get what you optimize for, and if it’s easier to optimize the surface indicator than the underlying thing you were really after, you will get the letter (but not the spirit) of your request in spades. If you act to reduce noise instead of inefficiency you will get (e.g.) direct resistance electrical heating instead of heat pumps — inefficient to operate, but cheap and silent! You will get regulations targeting cars’ stereo systems and mufflers instead of their fuel economy.
I’m afraid that the idea “sustainable cities look green” is far too easily misinterpreted, accidentally or cynically. It allows a branding exercise to substitute for an analytical exercise. It is practically begging to be co-opted by some consulting agency that says any city anywhere can look woodsy and green (like Seattle!), which will show its concern with sustainability (like Seattle!) and thereby attract a hip, affluent demographic (like Seattle!) You will get arid cities promoting a profligate and inappropriate explosion of greenery in their streets. You will get frigid environs trying to imitate the look of temperate forests. Australian aboriginal dwellings and surroundings didn’t look like those of the Incas or Inuit, nor would it have been appropriate. What’s appropriate and sustainable depends greatly on regional circumstances and can change with time. The city as leafy green forest is just one possible template for sustainability, not appropriate everywhere.
Comment by Matt November 13, 2011 @ 3:40 amI thought of “noise” as signifying more broadly the low-level energy lost obeying the law of entropy. However, we can “harvest” more of our lost energy than we used to think possible. That’s what the stillsuits did in Dune, and the Prius hybrid does today.
Comment by Joan S. November 17, 2011 @ 3:04 pmAbsolutely Joan. The Prius is a good example, with its regenerative braking. The stillsuit? It always sounded so intelligent, until someone pointed out that wearing a water-tight plastic suit is not smart in a hot environment. A large black parasol would work better on Dune, I suspect. It keeps the sun off the skin, so you walk in the shade, and it’s one of my favorite tricks for working in the desert.
Comment by Heteromeles November 17, 2011 @ 4:15 pm