When the Conference of the Parties meets in Paris in the coming weeks, it will mark the 21st time the nations of the world have met to try to strike a deal to combat climate change. Given existing tensions between nations, and given that each country has a unique capacity to contribute to a comprehensive deal, we ask the question, "how can we measure success at the Paris negotiations?" Stanford researcher Aaron Strong and New York Time reporter Andy Revkin walk us through the history of previous negotiations to explore what went wrong, what we've learned, and why many are so optimistic about Paris. They point out the areas where progress has already been made and where the potential sticking points lie. As anthropogenic climate change continues to affect the world around us, success in Paris might look a little different than people have previously thought.