Caldeira Lab Research:Energy, Global Carbon Cycle, and Climate

Accounting for carbon dioxide emissions: A matter of time

K. Caldeira & S. Davis

Carbon dioxide emissions happen where fossil fuels are burned to provide energy. But goods and services made with that energy are often exported to be consumed somewhere else. Because of this, policies that only account for emissions where they happen may not reduce global emissions, but instead encourage consumers to import goods from places that do not restrict emissions. Peters et al. (Proceedings of the National Academy of Sciences, 2011) published results showing that since 1990, developed countries have increasingly imported goods from developing countries. In fact, although emissions happening in developed countries decreased slightly between 1990 and 2008, the emissions related to goods consumed in developed countries has increased by 7%. This commentary on Peters et al. replots their results to show that developed country emissions still exceed developing country emissions when you consider imported goods. However, emissions per person in the developed world remain much greater than those of people in developing countries, even taking into account traded goods.

Caldeira K., and S. J. Davis (2011), Accounting for carbon dioxide emissions: A matter of time, PNAS May 11, 2011, doi: 10.1073/pnas.1106517108

Fig. 1: Consumption-based and production-based accounting of CO2 emissions by Peters et al. (2), divided into industrialized and industrializing countries. (Top) CO2 emissions to support consumption in developed countries exceeds CO2 emissions to support consumption in developing countries, despite the fact that more CO2 emissions are produced within the territory of developing countries. (Middle) On a per-capita basis, there is great disparity in consumption emissions between developed and developing countries. (Bottom) Consideration of a consumption-based perspective produces less of a difference in carbon intensity of economic activity (adjusted for purchasing power parity) between developed and developing countries.

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