China's carbon emissions: how much are ours?

One of the big hangups in a global climate agreement has been the interest of the United States in holding developing economies accountable for their climate emissions.  But there's one big problem - a lot of the carbon emissions in China and India serve their export businesses, ones that U.S. firms often set up to obtain cheap labor and more relaxed environmental standards. 

In other words, we own a great deal of China's carbon emissions, because they serve U.S. consumption.  In fact, at least 23% of China's emissions are from exports to industrialized countries. 

I think our share is a bit bigger than we've admitted.