If reports are to be believed, the US still holds the dubious distinction of being the world's largest emitter of carbon dioxide (CO2) emissions.
According to a report in New Scientist, the Carnegie Institution for Science in Stanford, California, reports that in 2004, 23 per cent of global CO2 emissions - some 6.2 gigatonnes - went in making products that were traded internationally.
AdvertisementMost of these products were exported from China and other relatively poor countries to consumers in richer countries.
Some countries, such as Switzerland, "outsourced" over half of their carbon dioxide emissions in this way because they have a high import-to-export ratio of such energy-intensive goods as consumer electronics, motor vehicles and machinery.
The average European is responsible for adding more than 4 tonnes of CO2 to the atmosphere in the manufacture of goods imported from other countries.
For people in the US, the figure was nearly half that - 2.5 tonnes - thanks to US exports of emissions-intensive goods that offset much of the C02 it imports.
"If we want to understand our footprint of emissions, we have to understand that others are emitting on our behalf to make our goods and services," said study co-author Ken Caldeira.
"The US and Europe are responsible for a bigger percentage of emissions, because it is emissions that go into the production of goods coming out of China that are supporting our lifestyle," he added.
The study draws on detailed economic data from the Global Trade Analysis Project based at Purdue University in West Lafayette, Indiana, which takes into account the CO2 emissions intensity of manufacturing in different countries and different sectors of the economy.
Another study, which Glen Peters of Norway's Center for International Climate and Environmental Research in Oslo is to publish soon, uses similar trade data to analyse consumption-based emissions up to 2008 and also tracks how the global movement of CO2 emissions has changed since 1990.
Based on Peters's findings, the US still leads the world in CO2 emissions because although US exports offset some of its territorial emissions, taken as a whole it is still emits the most.
"China surpassed the US around 2006 in terms of territorial emissions, but in terms of consumption, you'll find that the US is still the biggest emitter," he said.