So 80 heads of state, plus international celebrities like Al Gore and Arnold Schwarzenegger all came to the United Nations today. Great! What did they accomplish? Well, if you are looking for a single document committing UN member states to combat climate change, you are looking in the wrong place. Rather, the significance of today's meetings needs to be understood in the longer term.

In 2015, Kyoto will expire. As the thinking goes, it will take two years to negotiate a successor to Kyoto, then another four years for member states to actually ratify the treaty.

In December, the process of negotiating a successor to Kyoto will kick off with a meeting in Bali. This meeting will be largely technical in nature, i.e. what sort of carbon emissions targets should be achieved and how to set up a global carbon credit market. The purpose of today's meetings was not to talk about those technical issues, but to inject some desperately needed political will into the Bali meeting so that when negotiators descend on Indonesia in three months they will be empowered to push for robust climate change policies.

The elephant in the room, of course, is that for the Bali negotiations to be successful, the Kyoto non-signatories (namely the United States, China and India) need to be on board. And herein is the reason why the UN appropriate venue to hold these talks: In a body composed of 192 member states, it is very difficult--practically speaking--for a tiny group of nations to hold out against the will of the rest.

It is a basic negotiating tenet here at the UN that countries try to avoid being "isolated." (And conversely, that negotiating blocks strive to isolate hold-outs as a way of winning concessions.) That's why Security Council vetoes are so rare. It is also why so many UN issues (like the budget) are resolved by consensus, not majority vote. No country feels comfortable being a "spoiler" by positioning itself against the will of an overwhelming majority of UN member states. The decision to use the UN to host climate change discussions, therefore, is born out of a basic pragmatism. In smaller venues, like the G-8, it is simply harded to use "isolation" as an instrament of diplomatic pressure.