The Debate over the Accuracy of GHG Footprinting

Authors

• Marshall Chase

  Former Associate Director, BSR

A recent Wall Street Journal article highlights concerns about greenhouse gas (GHG) footprinting: "The results have the appearance of precision. But... measuring carbon footprints is inexact. It is clouded by varying methodologies and definitions—not to mention guesses." While this is true, the article gets bogged down in a discussion of uncertainties and competing standards, and loses sight of a few important points.

First, as long as GHG measurements are rigorous and done the same way, then product comparisons can generally be made. Regardless of whether the comparison is made using the PAS 2050 standard or ISO LCA methodology cited in the article, the numbers should be accurate enough to determine whether one product has a larger GHG footprint than another. If two widely accepted methods result in different conclusions about which product emits more GHGs, then the difference is probably too small to matter for companies and consumers.

Second, companies and consumers can use these comparisons to inform their actions. As the article points out, there is agreement that the biggest source of emissions in dairy supply chains is methane from cows, even though there isn’t agreement on the exact GHG footprint of a gallon of milk. Given that, methane emissions can become a focus of GHG-reduction efforts.

Similarly, companies and individuals can make purchasing decisions based on product GHG data to help reduce their own GHG footprint (if they so choose). This holds true whether they are buying milk from Dairy A vs. Dairy B, or considering whether to have cheese or peanut butter on their lunchtime sandwich.

Finally, both precision and demand for GHG footprinting will grow with time. Governments and buyers increasingly encourage—and in some cases require—product GHG footprints. As more products disclose their footprints and standards evolve, increasingly detailed comparisons among products can be made. As a result, companies that currently dismiss footprinting as “complex and imprecise” may find themselves at a competitive disadvantage in the future.