Posted for Richard Van Noorden from The Great Beyond

More than one-fifth of the carbon dioxide produced by China in 2004 was emitted to provide goods and services for non-Chinese consumers, mainly in western Europe, the United States and Japan.

The statistic comes from the latest study to look at an alternative style of carbon accounting — one that assigns CO2 emissions to the consumers responsible for them. By contrast, inventories such as those reported under the United Nations Framework Convention on Climate Change (UNFCCC) simply tally the amount of gas each country produces.

Ken Caldeira and Steve Davis, of the Carnegie Institution of Washington, in Stanford, California, published their findings this week in PNAS. The most comprehensive of its kind, the analysis takes trade figures from 113 countries across 57 industry sectors and finds that 23% of global CO2 emissions (or 6.2 billion tonnes of CO2) was traded internationally in 2004.

“Instead of looking at carbon dioxide emissions only in terms of what is released inside our borders, we also looked at the amount of carbon dioxide released during the production of the things that we consume,” says Caldeira (press release). “Just like the electricity that you use in your home probably causes CO2 emissions at a coal-burning power plant somewhere else, we found that the products imported by the developed countries of western Europe, Japan, and the United States cause substantial emissions in other countries, especially China.”

In some wealthy countries, including Britain and France, more than 30% of consumption-based emissions are imported; in the United States, the figure is 11%. Caldeira thinks that the UNFCCC’s production-based inventories should be supplemented with figures that track where the carbon is ultimately being consumed.

Dieter Helm, an economist at the University of Oxford who has previously published papers showing that much of the UK’s carbon footprint is produced overseas, says that the new study “highlights that Europe and the US are flattered by their CO2 production numbers”.

“What the authors fail to conclude is that the Kyoto based approach is very badly flawed, and that at Copenhagen the European and US offers for production reductions did not reflect their full carbon footprint,” says Helm. “Such considerations also make the case for a border carbon tax very strongly.”

Image: flow of emissions among major exporting and importing countries (megatons) / Steven Davis/Carnegie Institution for Science.