. >> woodruff: brandon wu, would you agree that was one positive that came out of this?i think that's one positive. that's the political reality. the political reality is the negotiations are incredibly challenging. it's very difficult to get countries to agree to, say, ambitious targets to reduce greenhouse gas emissions. but there is a scientific reality that we're on track for a world that is going to be massively warmer than it was before the industrial era, and we know-- we at least have some sense of how catastrophic some of the impacts of that might be. so we have a scientific reality where we need to deal with this member urgently, and then we have a political reality where we can't and we need to shift that political reality. >> woodruff: i hear you. so let's talk about the specifics, robert stavins of what didn't happen here. for one thing, there was a massive walkout. some 800 participants just walked out of the meetings one day. what was the main disagreement there over? >> well, i think there was rampant it disappointment, particularly from members from civi