Calculating Our Real Carbon Footprint

Image courtesy of Ellie Gabriel.

It has become increasingly clear that greenhouse gas emissions are contributing to an unsustainable future. In the United States, environmentally extended input/output analysis (EEIO) has been used to track environmental footprints, but this method has its limitations. Yale Ph.D. candidates Peter Berrill, Reed Miller, and their research team have produced an extension to the existing EEIO model for the U.S., facilitating a more comprehensive analysis. In the current analysis model, the environmental cost of long-term capital assets used to produce certain goods are neglected, underestimating the true environmental impact. To address this, the researchers incorporated these neglected capital assets, drawing on data from multiple government sources. Their new modified version is called environmental life-cycle assessment:. “It’s not physical process data that is used, but rather economic transactions between sectors in a given year,” Berrill said. Their analysis reveals the importance of capital assets to environmental footprints, and identifies which sectors are most affected. For instance, housing, federal defense, state and local services, as well as personal transport fuels were found to have the largest overall footprints related to capital consumption. In the future, their approach and data could be utilized to enable more accurate calculations of footprints, and better estimation of the impacts due to government regulations. This new model could drastically shift the way in which environmental action is taken, and serve as the catalyst for a cleaner future.

The results from the new system used on the 2007 and 2012 EEIOs can be accessed through a publicly-accessible spread-sheet based tool, ‘CIFT-US’ produced by Reed Miller and Peter Berrill.

Works Cited

Berrill, P, Miller, TR, Kondo, Y, Hertwich, EG. Capital in the American carbon, energy, and material footprint. J Ind Ecol. 2019; 1– 12.

Dennehy, K. (n.d.). Capital Costs: Yale Research Offers Truer Calculation of ‘Footprint’ of Purchases. Retrieved from

Incorporating Capital in American Carbon, Energy, and Material Footprints. (n.d.). Retrieved February 2, 2020, from

Miller, T. Reed, Peter Berrill, Paul Wolfram, Ranran Wang, Yookyung Kim, Xinzhu Zheng, and Edgar G. Hertwich. 2019. “Method for Endogenizing Capital in the United States Environmentally-Extended Input-Output Model.” Journal of Industrial Ecology. DOI: 10.1111/jiec.12931.