China is outsourcing much of its carbon emissions to the interiors of the country, according to Steve Davis, UC Irvine climate change researcher, and his colleagues.

Researchers say that rich, coastal provinces such as Beijing and Shanghai import steel, heavy machinery and industrial equipment from regions in the country that have highly polluting factories. The Western countries have been outsourcing their carbon emissions to China; according to a related study, exports account for about a third of the country's carbon emission.

The latest study shows that China is shifting its carbon emission burden on a few of its provinces.

This domestic outsourcing is likely to continue in the future, as these regions don't require cutting carbon emission. China has province-specific pollution abatement targets that were adopted in 2009 as part of the Copenhagen Accord.

"This is regrettable, because the cheapest and easiest reductions - the low-hanging fruit - are in the interior provinces, where modest technological improvements could make a huge difference in emissions. Richer areas currently have much tougher targets, so it's easier for them to just buy goods made elsewhere. A nationwide target that tracks emissions embodied in trade would go a long way toward solving the problem. But that's not what's happening," said Davis, a UC Irvine Earth system scientist and attorney specializing in climate policy, according to a news release.

For the study, researchers assessed carbon emissions associated with goods that were manufactured in China and in other parts of the world by using a global model. The team then looked at carbon emission from 30 sub-regions in China that included 26 provinces and four cities.

"As the world's largest emitter of carbon dioxide, China is a prominent and important example, struggling to balance rapid economic growth and environmental sustainability across provinces that are in very different stages of development," the authors concluded.

The study is published in the journal Proceedings of the National Academy of Sciences.