It’s a bit late now, but the article What should Obama say in Copenhagen? by Dean Baker (Politico) serves as a source for the U.S. requirement that the Chinese commit to ¼ of the per-capita CO2-output of the U.S.:
“The current view in the U.S. appears to be that the Chinese should forever commit themselves to emitting greenhouse gases at one-third or one-quarter the per capita rate as people in the United States.”
So, when you kept hearing the President say that the “deal is on the table” and that “countries should step up”, he knew full well that the deal was completely unacceptable to the Chinese. Hillary also made sure to very specifically note that the U.S. would only proceed with their deal if “all other parties” also signed on. Both Obama and his Secretary of State took the opportunity to try to look and sound good because they knew that the Chinese wouldn’t take the bait and force the U.S. to actually have to go through with the deal they’d offered.