Eating the seed grain

Alex Steffen at World Changing frames our problem well.

One way to wrap our brains around the implications of that many people sharing a small planet is to do some math, divide up the usable part of the globe by the number of folks who want to use it. This would give us a sense of what a fair share would be for each of us.

To be really fair, though, we should probably not use up everything right away. Our kids and grandkids may want to eat, drink and breathe, too. So, we should probably only take as much as we can while allowing nature to renew itself.

It's like when people plan for retirement. You save money — build up a investment portfolio, say — and then try to live on the revenue those investments create. In this case, our natural “capital” is a gift we've inherited simply by having the good luck to evolve on such a bountiful planet. And in using that capital, we should leave enough nature undestroyed that future generations can draw upon it as well. We should leave the capital alone and live off the interest.

So, really, we don't have an entire planet to use, if we're being fair about it. We don't even have a quarter of the planet to use. What we have, if we're being fair, is that portion of the planet that we can use without trashing nature so badly that our grandkids are reduced to grubbing for withered tubers in a world of cockroaches and weeds — divided by the number of people who want to use it.

How much nature is that per person? Well, luckily, some ecogeeks have worked that out for us. They've found a way to measure the impacts of our lives on the planet, what they call our “ecological footprints.” In a fair and sustainable world, these ecological footprints would work out — in Matthis Wackernegel's equations, which really smart people seem to think are pretty accurate, if not perhaps a bit optimistic — to about 1.9 hectares per person (that's 4.7 acres). In other words, if you divided the usable part of the world up by the number of people who want to use it, we'd each have find a way to meet our needs sustainably from the bounty of a little under 2 hectares.

Unfortunately, we're already using an average 2.3 hectares per person, planetwide. To make matters worse, our sustainable share of the planet is shrinking. Part of this is a natural result of population growth: divide the planet by more people and you get a smaller piece of land.

But the planet is shrinking for another reason: we're using it up. We each get 1.9 hectares, and we're already using 2.3. Where's the extra half a hectare coming from? It's coming from nature's capital. Every year, we cut more forests, graze more cows, drive more miles, dump more trash — gobble up more stuff, and spit out more waste. And since we're already gobbling and spitting more than the planet can sustainably take, the result is that every year nature has less to offer us. To make matters worse, this spiral seems to be accelerating and the gap between sustainability and reality widening.

Here too, really geeky guys with supercomputers have gone to work, and one thing they've found is pretty shocking: as they'd put it, we're already using between 40 and 50% of the world's “net primary productivity.” What that means, for those of us whom math makes sleepy, is that humans are using about half of all the life on earth — that about half of all the plants, insects, microbes and mammals alive on the earth are being sucked into the systems that go to feed our needs.