Traditional methods of determining CO2 emissions are based on energy production. The obvious drawback to this method is that the producing country can export the goods produced from the energy that causes the emissions. The exported goods are then consumed, or used in other countries. This is the final depository for "outsourced" manufacturing or other outsourced mechanisms. It means that countries like the U.S. and the European Union, who are very affluent relative to the rest of the world, can now consume even more fossil fuels than they emit from their own energy generation. The ratio is actually quite high. the U.S. is actually responsible for 10 percent more CO2 emissions than they create from the combustion of fossil fuels, The European Union is responsible for 30% more CO2 emissions that their fossil fuel burning reveals, and China is being blamed for 22% more emissions than they actually consume because this 22% is exported to the United States, European Union and the rest of the world.
Davis and Caldiera, Consumption-based accounting of CO2, PNAS, March 2010