Sometimes the nature news is really depressing, and this is one of those times. (Maybe the rest of my life will be one of those times). This plot from the World Wildlife Federation attempts to classify the average “ecological footprint” for people living in various countries. The idea here is that it takes a certain fraction of the earth’s area to provide the food that we eat, the water that we drink, provide the forests that purify the air that we breathe, etc., and these people have attempted to quantify it. They express this in “hectares”; a hectare is 100 ares (I knew that would help) — a hectare is 10,000 square meters, or about 2.5 acres. If you believe the figure, then even without ANY fossil fuel buring, and ANY depletion of fish and other marine resources, we (in the U.S.) would be using more than the earth can sustain; if you include these things, we’d be off the chart if they didn’t extend the chart so far.
OK, but DO you believe the figure. I believe it, roughly speaking anyway. The Zoological Society of London claims (as discussed in a BBC report) to have compiled data that show that “Populations of land-based species fell by 25%, marine by 28% and freshwater by 29%” since 1970. As far as ecological timescales go that is incredibly fast, more than 25% losses in less than 40 years. But unfortunately, that’s a gradual change for people who see year-to-year differences: who would notice a decline of 0.5% from one year to the next? After a while, wildlife concentrations that were once common become rare, but it happens gradually enough that people don’t notice. Wildlife levels that were one considered “severely depleted” are accepted as the new norm, and another cycle of decline begins. It’s depressing.