Weighting Environmental Impact Categories

To make those tradeoffs, we have to decide how important each impact category is compared to the others. Sometimes we do this implicitly as we make choices. To communicate about our decisions, however, it helps to express our priorities through weighting factors. These factors can be used to combine multiple scores into one aggregate score, making comparisons easy. Getting to that simple comparison, however, is a process fraught with assumptions and simplifications.

When you have to assign weightings, you have several options. A common approach is to simply poll a group of people and ask them how important each category is. But when people answer that question, they usually have some arbitrary scale of impact in mind. It’s easy to say that avoiding climate change is more important than avoiding ozone depletion, for example, but are you willing to accept drastic ozone depletion to avoid a small amount of climate change? Probably not—but where do you draw that line?

Published January 2, 2009

Malin, N. (2009, January 2). Weighting Environmental Impact Categories. Retrieved from