Since the failure of the 2009 climate summit in Copenhagen, both the United States and China have largely retreated from big international agreements, each waiting for the other to move first. This week’s bilateral accord sets the stage for future international discussions. That would seem to be a big deal.

Early analyses of the U.S.-China climate deal have ranged from wildly enthusiastic to cautious to dismissive. But beyond the pleasantries of a signing ceremony, how serious are the agreement’s achievements?