Using LCAs, Part One: Comparing Costs and Impacts
Life cycle assessments are often used in two important ways. The first is to compare the costs or impacts of different products or production systems in a rigorous way, seen in Fig. 10.2.4 which compares the phosphorus water pollution resulting from three ways of producing pork meat in France (Basset-Mens and Van Der Werf, 2005). This “cradle to farm-gate” pork LCA includes the cropping used to produced pig feed as well as the animal raising methods at pig farms that use three different standard methods. In this example, two different ways of expressing LCA results show how different messages can emerge depending on how results are presented. The graph at left shows the impacts at a per-area of land used basis (per hectare), while the graph at right expresses the impact as a per-kg of food produced, which means that if a production method yields more on a per-area basis, its impact can be reduced compared to one with less productivity per hectare. Organic and red-label humane methods with straw-bedded barns pollute less on a per-hectare basis, but the organic methods are not less polluting than the conventional treatments on a per-kg of pig basis because more area is needed to both raise the pigs and grow the crops for feed in the organic system. Therefore if demand (in kg pork) remains the same for pigs while consumers switch from conventional to organic pork, total water pollution from phosphorus in pig production is unlikely to decline, at least according to this study. Rather, the red-label option seems to be able to shrink pollution per kg of pork consumed in the food system. Meanwhile, if you limited your viewpoint to a single watershed with a delimited area, you would say that both the red-label and organic methods reduce pollution. Despite some of the benefits of organic management generally, in reducing toxins in the environment and building soil quality (for example), this study can give us some pause in thinking about the particular system we are talking about (e.g. organic hog production versus organic apple production, for example) and the need to respect specific case analyses and the measures used in LCA analysis. When we talk about a whole food system, it may be best to employ a per-kg of food produced approach.