The United Nations estimates that rich countries throw away nearly as much food as the entire net production of sub-Saharan Africa--about 230,000,000 tons per year--but is it any less a waste to eat the excess food? Morally, it is equivocal. Nutritionally, it depends. However: the land, water, and carbon footprints are the same.
In fact, researchers in Italy have proposed a way to measure the ecological impact of global food wastage due to excessive consumption. First, they estimate the net excess bodyweight of each country's population--based on BMI and height data--and distribute its energy content among foods groups according to national availability. The results suggest that direct food waste--thrown away or lost from field to fork--is a mere hors-d'oeuvre.
"Excess bodyweight corresponds to roughly 140,000,000,000 tons of food waste globally," reports study leader Maura Serafini, professor of human nutrition at the University of Teramo. This figure is a snapshot of the current world population's accumulated dietary excesses, not a rate of overconsumption. It is, though, orders of magnitude higher than current annual direct food waste, estimated at 1,300,000,000 tons.
The disproportionate impact of Serafini's so-called "metabolic food waste" grows when its ecological costs are calculated, using per-kilo values from thousands of food lifecycle assessments. Fruits, vegetables, roots, and tubers have the highest direct wastage rates, but excess energy consumption is dominated by more calorie-dense foods. These typically entail more land, water, and greenhouse gases to produce--so much so that growing the world's metabolic food waste would be expected to generate the equivalent of 240,000,000,000 tons of C02. This is roughly the amount mankind released burning fossil fuels over the last seven years combined. Notably, the EU, North America, and Oceania together contribute as much to this estimate as the rest of the...