OSLO (Reuters) - The United States is by far the biggest greenhouse gas emitter ahead of China if consumers in rich nations are given responsibility for energy used to make imported goods, a researcher said on Wednesday.

A layer of smog can be seen above Manhattan through the Verrazano-Narrows Bridge in New York May 21, 2009. REUTERS/Lucas Jackson

Greenhouse gases, including by factories making goods such as cars or televisions for export, usually count toward the total of the country where they are made. Such data indicate that China has overtaken the United States as top emitter.

But adjusting emissions according to the country where consumers of goods live swells emissions by developed nations, said Glen Peters, a researcher at the Center for International Climate and Environment Research in Oslo (CICERO).

“The ranking makes a lot of rich countries look worse and a lot of poor countries look better,” he told Reuters.

In the ranking of 73 nations, Americans have the biggest annual “carbon footprint” at the equivalent of 29 tonnes of carbon dioxide per capita, ahead of Australians on 21 tonnes and Canadians on 20 tonnes.

Each Chinese citizen in the survey, based on 2001 data, accounts for just 3.1 tonnes. Adjusted for China’s much bigger population, U.S. emissions were 7.9 billion tonnes and China’s 3.9 billion.

“The U.S. is increasingly shifted toward a more service-based economy, importing more of its products from China,” Peters said of the ranking, published online last month in the journal Environmental Science and Technology.

“A lot of China’s emissions growth is production of exports,” he said of the ranking produced with the Norwegian University of Science and Technology. Economic trends since 2001 confirmed the United States as number one.

U.N. TREATY

Developing nations such as China have sometimes suggested that rich nations should take more responsibility for imported emissions in sharing out the burden of curbs under a new U.N. climate treaty due to be agreed in Copenhagen in December.

Peters’ rankings count emissions within each country, then add on imports and subtrace exports.

The study found that consumers in each country tended to have a bigger carbon footprint the richer they got, a depressing finding for governments trying to rein in emissions while promoting economic growth.

“Once you’ve bought your food and paid for your house what you do with your money is luxury consumption -- buying a second car, a CD player,” Peters said. “The more money you earn the more emissions you have.”

He said that governments could try to shift consumption toward more service-based activities that do not push up emissions so much -- for instance going to restaurants or paying for entertainment.