If China emit more than US or today, or if it will take an extra year or two is less important. The big question is if these numbers actually tells us anything meaningful that can help us guide our action, or if we need to add information to get something useful. Judge for yourself.
FACT 1: Numbers for Simple emissions
China: 6 billion tonnes
US: 6 billion tonnes
That is probably not too far off, however looking at the actual situation using some rough numbers, gives us a very different perspective.
First of all about 25% of the emissions in China are embedded in net export that mainly feed (over) consumption in OECD. So from Chinas emissions we can subtract about 1,5 Gigaton. For US the situation is reversed as it has outsourced a lot of polluting industries and have a net export of approximately 0,5 Gigaton each year.
UPDATE 25th Augusti: New numbers indicate that 30% of China's CO2 emissions are embedded in their export. That would take us to almost 2 Gigaton in the export... (That is about 50% of EUs total emissions so quite a significant number).
FACT 2: Numbers including embedded emissions in import and export
China: 4.5 billion tonnes (due to net export of 1.5 billion tonnes in products)
US: 6.5 billion tonnes (due to net import of 0.5 billion tonnes in products)
Then we should not forget that people are important, it is not countries that emit CO2 but people. So the question is how big the emissions are per capita. China’s population is about 1.3 billion people and US is 0.3 billion people.
FACT 3: Numbers based on per capita emissions from consumption
China: 3.46 tonnes/ person
US: 21.67 tonnes/ person
Another fact that is often forgotten by media in OECD is that it is not only the emissions today that matters. The infrastructure that US (and the rest of OECD countries) have built up exist thanks to massive use of fossil fuel. If we compare the cumulative emissions between 1850-2000 in order to capture the whole industrialization we can see that US have emitted about 30% of the world’s emissions during this time, compared to Chinas 7%. During this time Chinas population has grown from 400 millions to 1 300 and US from 25 millions to 300 millions. So China has been hosting a population between 10 and 4 times larger than US. So not only has US contributed 4 times more historically, per capita we can assume that it is at least 5 times more, resulting in 20 times greater emission through history. Talking about emission trading today without acknowledging the historic pollution from US/OECD is not very credible.
FACT 4: The proportional responsibility from a historic perspective