gavin schmidt, welcome to the "newshour". significance of this accord, when even the president of the united states who's a supporter says it's only going to get us part of the way we need to go? >> well, like the old proverb says, a journey of a thousand miles starts with a single global agreement, and this is where we're at. we have an agreement now that encompasses every country in the world. every country in the world is thinking this is something they need to get behind. every country has promised to reduce emissions to the level that they signed up for. while president obama is correct that in and of itself, this is not going to stop global warming, that's a much bigger task, but this is a step in that right direction, and what the hope is, is that, with experience, with seeing the best practices that other countries have adopted, great ideas, new technologies, the people will be able to increase their commitments under this agreement at each of the next update stages, which come every few years. >> woodruff: how confid