http://www.declineoftheempire.com/2015/11/note-on-chinese-coal-consumption.html

It seems that China's coal consumption figures for this century are probably under-reported.

By 17%.

It would also seem that China's GDP growth for the same period is probably over-reported. But nobody really knows by how much.

Given the sheer scale of all this it's going to cause quite a few problems. Not just for forecasting generally, but for the upcoming climate talks. And for those claiming some kind of technology driven de-coupling of global GDP from energy usage rates. If we can't measure this stuff accurately, then how can we expect to manage it or draw conclusions from it? It's enough to make you think we really have no idea what's going on. And if we don't know what's going on now, how can we set targets for the future. That 17% extra coal is also 17% extra CO2. 

17% !