Without Better Calculations, It’s Just Carbon “Toe Prints”

Corporations typically underestimate their carbon footprints by an average of 75 percent, according to a new study from Carnegie Mellon researchers. One of the major blind spots is in calculating the total greenhouse gas emissions from myriad supply chain inputs, as opposed to the direct emissions involved in primary operations. The study authors told Christa Marshall at ClimateWire (subscription) that “most companies focus solely on direct emissions from their operations, such as those spewing from headquarters and accompanying facilities, and from purchased energy.”

As a result, study author H. Scott Matthews suggested that “most companies were calculating ‘toe prints’ rather than carbon footprints.”

The study indicates that another problem is that the term “carbon footprint” itself does not have a fixed meaning:

The definition of “carbon footprint” is surprisingly vague given the growth in the term’s use over the past decade. The term itself is rooted in the literature of “ecological footprinting” (3): attempting to describe the total area of land needed to produce some level of human consumption. Because the land use to make most consumer products is fairly distant in time and space from the final consumer, the ecological footprint is inherently a full life-cycle calculation. However, this does not seem to be true for the term’s new successor, the carbon footprint; Wiedmann and Minx (4) found a large variety of definitions that differ in which gases are accounted for, where boundaries of analysis are drawn, and several other criteria.

The researchers have developed an “Economic Input-Output Life Cycle Assessment” that utilizes publicly available data on various economic sectors. But they are careful to note that any lifecycle GHG calculation will be imperfect, regardless of model or input data. Moreover, the accuracy of a company’s calculations hinges on the firm’s own accountability:

We argue that the footprints should be useful in pursuing more effective climate change policies. However, the information contained in a carbon footprint varies depending on how it was calculated and how much responsibility the entity being “footprinted” is willing to take on. There is an inherent trade-off between comprehensiveness (i.e., the percentage of total world GHG emissions included in a system) and participation (i.e., the percentage of businesses or consumers taking part in the system). Because consumers can influence the carbon footprints of goods and services through their purchase decisions, a broad estimation of carbon footprints including supply chain effects is appropriate. Similarly, as a corporation can influence its suppliers, a broader estimation can similarly motivate more effective corporate climate change policies

Modeling lifecycle carbon emissions is not a trivial matter. The Environmental Protection Agency is currently working with a variety of complex models as they move forward with the rulemaking process for the Renewable Fuels Standard. GreenWire reports that the four major consulting firms are all moving to help corporations with their emissions calculations. Having accurate, well-understood models will be critical for many industries when Congress and the next administration move ahead with comprehensive climate change legislation.

Tags: Climate Change, economics, Energy

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