By Richard Black
Environment correspondent, BBC News website
EU emissions are much higher if goods made overseas are included
Rich countries including several EU nations are "importing" about a third of their CO2 emissions, says a study.
US-based researchers used a global trade database to track goods and services, and assigned emissions to the countries where they were used.
Nearly a quarter of China's emissions come from goods exported to the West.
Writing in the journal PNAS, the researchers say this is an ethical reason why rich countries should lead global attempts to cut emissions.
"We expected to find this net flow from developing countries to the developed world," said lead researcher Steve Davis.
"But what stood out was how much of the global flow is accounted for by bilateral trade between China and the US."
China recently passed the US to become the most highly-emitting country.
But 22.5% of China's emissions are generated during production of goods and services consumed overseas, and 7.8% are embodied in exports to the US alone.
However, when countries' emissions are calculated this way, the US is less of an "emissions importer" than some European countries.
The study found that Austria, France, Sweden, Switzerland and the UK import about a third of their emissions.
Under the UN climate convention, greenhouse gas emissions are allocated to the countries where the gases are generated.
But increasingly, academics and environmental groups have argued that this is unfair. It means, for example, that a Briton can buy goods made in China; he or she gets the benefits of these goods, but the emissions are assigned to China.
The EU currently produces just under 10 tonnes of CO2-equivalent per citizen.
But in some EU nations, imported goods and services account for a further four tonnes per head of population, this latest study found.
The counter-argument is that making the goods benefits the countries where they are produced as well, by providing jobs and income.
A few years ago, the dispute had little practical significance because academics struggled to produce comprehensive figures for consumption-based emissions.
Dr Davis acknowledged that things are still far from perfect. The Middle East is one region, he said, where the supply of data is poor.
But, he pointed out, his study uses the most recent year for which data is available - 2004 - and is able to split the world into 130 units, many of them individual countries.
Dieter Helm, the Oxford University professor of energy policy who has conducted a lot of research in the same field, observed: "What all these exercises show is that production-based figures are highly misleading and in particular flatter Europe and the US.
"What the authors fail to conclude is that the Kyoto-based approach [using production-based emissions] is fatally flawed, and that the case for border carbon taxes is very considerable."
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