There’s something a little eerie about having a functioning biosphere in your home; something rather more disturbing about finding the thing has gone belly up while you were out at work. SimEarth lets you choose from a number of energy sources, including biomass, hydro-electric, solar, nuclear or fossil fuelled. It also lets you program a range of energy uses, including science, agriculture, medicine, and the arts. Each of these has different effects. If you expend energy on agriculture, population increases rather more rapidly. If you devote more resources to science, technological change accelerates. Some of the assumptions here are of course crude, but not unreasonable. Naturally, a home biosphere has to run a relatively simple algorithm compared to the heavy duty model.

The curious thing about it is how fiddling around with these crude variables gives you a feel for the global impact of fundamental choices about what economists call resource allocation. For instance, you start it up one midweek morning with settings which devote a lot of resources to agriculture. This seems a reasonable approach to creating a minimalist atopia. Theodor Adorno: “There is tenderness only in the coarsest demand: that no-one should go hungry any more. Every other seeks to apply to a condition that ought to be determined by human needs, a mode of conduct adapted to production as an end in itself.” And yet it doesn’t quite work out. When you come home from work you find the population shot through the roof. That one was predictable. What you hadn’t counted on, though, was that increasing agriculture pumped out more greenhouse gasses. The temperature was ever so slowly rising, threatening to toast everything, unevenly but very crisply brown. And all because of that troubling phrase, ‘human needs’…

Like any patient confronted with a terminal diagnosis, you wanted a second opinion. So you set SimEarth running at home before driving off to work, where you steal a little time to fire up your browser and go web surfing. The urgent problem is to find out why increasing the amount of food being grown has this lethal effect. The prognosis is not good. It seems that methane is one of the gasses that causes global warming. A bit too much methane in the air and heat gets trapped in the atmosphere. By dialing up more agriculture, you also upped the amount of methane going into the atmosphere. Rice paddies, for instance, are one of the sources of methane. It seems that deep in the muck at the bottom of rice paddies are little bacteria that produce methane as a byproduct. Great! There you were, only this morning trying to see to it that all the people on your biosphere are get enough to eat, and by the time you come home for dinner you’re cooking the biosphere.

This is all a bit too much, but fortunately the next day is the end of the working week and you are going out to dinner afterwards with friends. You imagine this might take your mind of SimEarth, but all that food on the table makes you loose your appetite. That big silvery dish with all that rice in it smells like over-cooked biosphere. The beef, delicious though it tastes, only makes things worse. It seems that one of the other sources of methane in the world is, of all things, cow farts. Yes, cow farts. It never occurred to you that there was the slightest global significance in the fact that cows are a bit gassy. The problem is, they fart (and belch) methane. Well, not the cows exactly, but the bacteria in their stomachs that break down all that grass. Those bacteria, like their teeming little prokaryote relatives in the rice paddies, also make methane.