If our civilization requires the resource equivalent of three earths to be sustainable, then we have to stop drawing on ecosystem services that are overstretched. In fact, maybe we should start acting like there are no ecosystem services available to us at all.
What's an ecosystem service? Here's Wikipedia's definition:
Ecosystem services are distinct from other ecosystem products and functions because there is human demand for these natural assets. Services can be subdivided into five categories: provisioning such as the production of food and water; regulating, such as the control of climate and disease; supporting, such as nutrient cycles and crop pollination; cultural, such as spiritual and recreational benefits; and preserving, which includes guarding against uncertainty through the maintenance of diversity.
Economically, ecosystem services provide us with assets that we would otherwise have to produce ourselves. The simplest example is water treatment, which is done for free by our aquifers. It's possible to directly measure the equivalent cost of a water treatment plant for a given set of wetlands or aquifer, which means you can exactly quantify the value of many ecosystem services. Pollination is another hugely important ecosystem service, which is provided largely for free by bees.
There's a lot of discussion about ecosystem services these days, and about our ecological footprint. The usual line is this: we're using three earths worth of resources, so we have to find a way to cut back or we're all sunk. This is true, but as I've pointed out before, there's a dramatic difference in terms of motivating people, between framing something as a positive, or as a negative. The "three earths" metaphor is good for scaring people, but it's a negative: it evokes images of austerity and sacrifice. If we want to motivate people to change things, it's always better to frame the change in terms of opportunity.
Charles Stross recently yanked the collective chains of the space advocacy movement with a little article entitled "The High Frontier, Redux." In this article he questions the practicality, and ultimately the value, of human colonization of other worlds. To make the point that there's "no there there" when it comes to space colonization, Charlie quotes Bruce Sterling:
I'll believe in people settling Mars at about the same time I see people settling the Gobi Desert. The Gobi Desert is about a thousand times as hospitable as Mars and five hundred times cheaper and easier to reach. Nobody ever writes "Gobi Desert Opera" because, well, it's just kind of plonkingly obvious that there's no good reason to go there and live. It's ugly, it's inhospitable and there's no way to make it pay. Mars is just the same, really. We just romanticize it because it's so hard to reach.
...And this is where I break ranks with Charlie and Bruce. Because the assumption both of them are making is that the only places worth settling are those that provide us with good ecosystem services. Quite apart from being a spectacularly lazy point of view, this stance takes for granted that alternatives to the Gobi desert (or Mars) are still available to us. But as the "three earths" metaphor makes clear, they aren't. In fact, if you ask where we should have been building our cities over the last century or so, the answer is in the Gobi desert, and the Sahara, and the barest and emptiest rocky plains we could find. (Even those have thriving ecosystems, of course.)
We should have been colonizing Earth as though it were a planet with no ecosystem resources to exploit.
Look at the difference between what we do when we settle a new area on Earth, compared to what we'd do on a planet like Mars. On Earth we'd take advantage of the free air and water, ready-made soils provided by local fauna, pollination provided by the local bees, all to minimize the costs of building and minimizing our colonies. This process is documented expertly by Jared Diamond in Guns, Germs and Steel; he points out that the conquest of the Americas was really the invasion of one ecosystem by another, rather than a simple matter of moving human populations. North America is the greatest success story of European expansionism because its ecology was most similar to that of Europe, more than for any political or social factors.
On Mars most of those services are unavailable. Mars is the most attractive local planet precisely because it does have some services, most notably a 24 (and-a-half) hour day, potentially fertile soil, and ready water from underground sources. Still, that's not much compared with even the Gobi desert. Our assumption on landing there has to be that the 24-hour day is about the only service we're going to get. Everything else--from air to agricultural production--has to be provided by us.
If we knew how to live on Mars, we'd know how to reduce our footprint on Earth. Space colonization is the Rosetta stone for earthly sustainability because it's entirely about living in the absence of ecosystem services. The Moon, Mars and the asteroids are a great experimental laboratory that we're ignoring at our own peril.
Back to the idea of framing something as a positive rather than a negative: we have the historic opportunity to colonize planet Earth, and do the same to our neighbouring planets at the same time. The effort to do one may necessarily involve the other. And doing this no longer has to be reactive, but can be a positive goal for our whole civilization.
If you read my Rewilding Canada entry, you might have figured out that I'm saying exactly the same thing here as I did there; I'm just using slightly different language. The ability to colonize other planets is the ability to rewild our ecosystems--to reforest our plains and mountains, and to restock our oceans. A mature vertical farming technology is precisely the technology needed to do agriculture on Mars, for instance. Grey-water and black-water recycling are necessary in exactly the same ways. Ditto for energy production and conservation.
I'm not suggesting that we all end up walking around our own planet in space suits--but I am suggesting that our industries and agriculture will ultimately need to do the equivalent. I don't expect Buckminster Fuller's domed cities to sprout up everywhere. I do think that chemical industries have to be closed-loop, taking nothing from the ecosystem and putting nothing into it. It would be fine for us to continue using coal and oil into the indefinite future, provided none of their byproducts ever enter the ecosystem. That would be equivalent to running industry under a dome.
Colonizing planet Earth--and therefore the rest of the solar system--is a recipe for a future of growth and opportunity that meets the exact same goals as programmes that emphasize austerity and conservation.
We don't want restraint. We don't want austerity. We want unlimited growth--just not at the expense of this glorious planet we live on. And we can have that, provided we start by reframing what we think of now as a crisis as, instead, an opportunity.