The Chinese were having a merry time sticking fingers in Obama’s eye for several reasons.
First of all, it’s fun. He’s a jerk, and they know it. They also like to watch him squirm.
Second, their own scientists have undoubtedly told them that man-made, CO2-based AGW is the biggest load of horse manure to be foisted on the world to date, and while they are not above attending these things to see what kind of freebies they can pick up, they never had any intention of agreeing to a single thing that would cost them one yuan.
Third, anything that reduces Obama’s international stature is good in Chinese eyes because it increases their relative clout worldwide, but most especially in the developing world, where they are busy working to supersede both European and American interests — and are doing it quite well.
Fourth, they wanted to clearly remind Obama and the entire administration that THEY have the whip hand because of their purchases of US debt. Putting Obama into the junior position by keeping Hu Jintao away from the talks and forcing Obama to deal with a flunky made that point quite clearly.
There are probably more reasons than that. But those are the biggies.
Not only that, Obama is being treated by the ChiComs as a toy, as a plaything, as a punching bag.
And a big bit is payback for ObiWankaNewbie barging into a meeting of the G4 as if his skin colour entitled him to be there.