A recent update of our study on the carbon footprint of nations highlights the role of China, Russia, the USA and the EU.

Steven Davis and Ken Caldeira have  just published an analysis of the carbon footprint of nations using the  GTAP 7 database, allowing for a comparison of the years 2004 and 2001.  The paper published in the prestigious Proceedings of the National Academy of Sciences (PNAS  for short) uses the same methods, research questions and data sources  as our 2008 and 2009 papers. It highlights the role of the most  important polluters and largest trade flows by emissions embodiment.

According to Davis and Caldeira, 23% of the global CO2 emissions from  fossil fuel burning were connected to the production of goods  ultimately consumed in a different country. The largest trade flows in  terms of pollution required to produce the goods traded (embodied  emissions) were from China to the United States, Europe, and Japan. The  flows from Russia at Europe and from the Arab Middle East to EU and US  were also significant, as was the trade between US and EU (see figure).

News stories on the article in the New Scientist and the BBC emphasize  the point that many European countries have a larger difference in  emissions between the consumption and production perspectives than the  United States, measured per capita. In other words, the difference in  emissions embodied in imports and emissions embodied in exports is  larger. In my opinion, this is really not a relevant way of interpreting  the results. What counts is the fraction of the national carbon  footprint (consumption based emissions) outsourced to other countries.  Europe can hardly be criticized for having a much lower emissions  intensity than the United States, which is the reason for why the net  trade balance is higher for the EU than the US.

I think that Davis and Caldeira do a particularly nice job  highlighting the increasing specialization of production in the global  economy and the differences in the imports and exports of different  countries. It is striking that the emissions intensity of exports from  Russia, China and India are more than 2 kg of CO2 per $ traded, while  those of European countries listed are between 0.17 and 0.25 kg per $.  The reason for this difference is most likely a combination of the  difference in the emissions intensity of the energy mix, the energy  efficiency and the value of the products produced.

The split of emissions embodied in trade by traded commodities also  indicates the importance of global value chains. The largest flows for  most countries shown are “intermediate goods”. The logical next step  will be to investigate the makeup of global value chains, analyzing the  through-trade of carbon of countries. Given global value chains, how are  the carbon footprints of specific products distributed across  countries?

Davis and Caldeira did not go through the trouble of adding the  emissions of non-CO2 greenhouse gases and could also not assess  emissions from land use change. As a result, the emissions in some poor  countries are very low – 0.12 tons per capita in Ethiopia and Malawi,  compared to 22 tons per capita in the United States. As we have observed  in our analysis, for such poor countries, the emissions of methane and  nitrous oxide from food production are much more important than the  emissions of CO2 from fossil fuel consumption. The lower limit for  carbon footprints including these emissions are around 1 ton  CO2-equivalent per capita.

For Norway, the analysis shows that Norway had more emissions  embodied in imports than in exports. This is a reversal from 2001, when  the emissions embodied in exports were still dominating. The reason for  this is a steady increase in import volumes and associated emissions.  Emissions embodied in exports remain constant over time, as we will show  in a future time series analysis.

The paper by Davis and Caldeira, allowing a comparison with our  numbers, underlines the importance of emissions embodied in trade. As  this paper confirms, rich countries risk fooling themselves by focusing  on territorial emissions while their carbon footprints are growing. The  objective of climate policy should be to reduce carbon footprints, and  not to reduce territorial emissions. This can only be achieved by paying  attention to carbon footprints!