China, the world's most populous nation, is a rich and diverse melting pot which is expected to one day be the world's largest economy.  Burdened by the environmental costs of rapid expandsion fueled by coal power, China leads the world in carbon emissions and emissions of many other airborne pollutants.  The air quality is so bad that often major cities are blanketed by a thick smog that is enough to trigger asthma attacks and breathing problems in those not prepared with masks.

With such problems, few questioned recent reports from NASA, which placed the blame for 15 percent of the air pollution over the U.S. on China, blown across the Pacific by the jets stream.  While the critical report certainly seems accurate, a new report from Carnegie Mellon puts this picture in a new light and shifts the blame away from China.

According to the report, much of China's chronic air pollution problems are not the fault of domestic endeavors, but rather it places culpability on international corporations that have outsourced their production to China.  According to the report, 1.7 billion metric tons of carbon or 33 percent of its emissions are the result of producing exports to sell abroad.

In total, six percent of China's pollution, according the study, can be attributed to the U.S. as 18 percent of Chinese exports head to the U.S.  This amount adds up to a sizable 300 million tons of carbon.  Such conclusions are controversial, but some say they illustrate that the U.S. should not be so quick to blame China for international climate problems.

The "export emissions" are expected to grow as well.  China, like the U.S., is unfettered by having committed to global air quality pacts such as the Kyoto Treaty.  Thus it is literally free to pump as much pollution into the air as it wants. 

This report and others are causing some to call for changes in the way greenhouse gases are measured, particularly when considering national and international legislation.  They say only domestic production should count against a nation, and export production should be distributed to other countries' metrics proportional to their percentage of outsourcing to the nation.  Furthermore, some say companies should not merely look at current carbon emissions, but should rather focus on carbon emissions by products, over the entire product lifetime.

Christopher L. Weber led the team from Carnegie Mellon and worked with colleagues Glen P. Peters of the Norwegian University of Science and Technology, Dabo Guan of the University of Cambridge and Klaus Hubacek of the University of Leeds in the analysis.  He states, "We found that in 2005, fully one-third of China's greenhouse gas emissions were due to production of exports. This proportion has risen quickly, from 12 percent in 1987 and only 21 percent in 2002."

While he says China is responsible for fixing this problem, in part, he says the international community, including the U.S., also bears responsibility.  He states, "It is clear that urgent improvements are needed, especially in China's electricity sector.  Installing more renewable power and overcoming the financial and technological hurdles involved with new technologies such as carbon sequestration should be the first priority of both China and its export partners."

Whether China will follow his advice remains uncertain.  While China has vowed to squelch all its carbon pollution within a couple decades and is adopting alternative energy sources, its emissions continue to soar yearly, just like its economic growth.