For the cynics who think events like COP26 are a vacuous talkfest, these criteria provide a concrete way to measure success. Taken together the three components would mean a market-based solution to internalise the externalities caused by emissions, in a way that provides appropriate incentives for all countries to drive emissions reductions, and do so in a way that is not too late to stop irreversible warming of the planet.
Whether or not the world community can come together, let alone work together, remains to be seen. A lot will rest on what the United States and China do.