Watch your ass(umptions)
Studies such as the Millennium Ecosystem Assessment have given us a rough picture of how much human activity impacts the rest of the biosphere. Answer: approximately as much as a live-in gang on PCP would impact your house. Many industrial groups and others trying to reduce their environmental impact have done studies on a finer scale. Known as life cycle assessments, these studies try to determine, say, exactly how much water is needed to produce one Australian pig, or how much pesticide is used to produce a kilogram of cacao beans. This is a serious step toward making improvements, marginal though they often are in the grand scheme of things.
Now it turns out that even companies trying to measure their environmental impact (at least in terms of land use–forests lost, carbon not sequestered, water not recharging the aquifers) are probably underestimating, according to a study in the International Journal of Life Cycle Assessment. This is because, when people conduct life cycle assessments, they often consider the land from the perspective of its current use. If you’re going to knock down a forest to build a new factory, that impact is counted. However, if you have already built a factory, an LCA (at least, an attributional LCA, the form commonly used for quantifying the impacts of current practices) doesn’t normally consider the fact that your factory could still *be* a forest, or could return to being a forest if given the chance. This is akin to having a home inspector come in while your house is occupied by the PCP-gang and make note of the conditions, then go away. If he returns and finds the gang still there, his response is to nod amiably, since there has been no change. He never saw the hydrangea bushes *before* they were on fire. Maybe he even thinks things are better now, since someone put a tarp over the hole in the roof.
The paper, by Sampo Soimakallio of the Finnish Environmental Institute and several colleagues, argues that an LCA should use a baseline that takes into account natural succession. The impact of your cacao farm on the surrounding ecosystem should be considered on the basis of what would happen if the cacao farm stopped operating. Instead of what is there, you try to take into account what could be there. Obviously a cacao farm isn’t going to turn back into a rainforest overnight, but nature could do something with your farm if you weren’t farming it. Land permanently occupied, then, is land that cannot be (re)occupied by natural ecosystems, and an LCA that fails to recognize this is underestimating our ongoing impact on the land.