Caldeira Lab

Carbon dioxide emissions embodied in international trade: Ken Caldeira

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Typically, CO2 accountings are based on territorial emissions, so people look at emissions from China or the United States or the European Union. But another perspective is to think that the CO2 is emitted in order to produce goods and services, and those goods and services might be exported somewhere else and consumed someplace else. So we can ask how much CO2 was emitted in order to support consumption in one country versus another.

So a number of people have been working on this, notably Glen Peters and also myself working with my post-doc Steve Davis. So we had a perspectives piece in Proceedings of the National Academy of Sciences that summarized some work done by Glen Peters. What we found was that even though CO2 emissions in the developing world exceed those in the developed world, if we do a consumption-based accounting, still the developed world is responsible for more CO2 emissions than the developing world because, for example, a lot of China’s emissions are going to support consumption in the west. This disparity becomes much starker if we look on a per-capita basis because typically people in the developed world emit something like four times the amount of CO2 than do people in the developing world. And so even though there’s a rough parity in terms of developed versus developing world emissions when we look at a per-capita basis, we’re still emitting far more.

So this kind of analysis suggests that there are multiple ways to look at the drivers of CO2 emissions. We can think of the countries where you mine or extract fossil fuels as having economic motivation to keep the fossil fuel system going. People who buy cheap fossil fuels and produce cheap products also have a motivation to continue the system. Then also, the people who are buying cheap consumer products also benefit from low fossil fuel prices. So in the same way that all the people along the whole supply chain benefit from the fossil fuel system, will all likely feel the damage of the climate change and ocean acidification that follows on that. So we’re in a complex situation where there’s a whole range of drivers of CO2 emissions and a range of reasons to be reducing those emissions.

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

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