There are folks who will equivocate. They'll say, 'You know, I'm not a scientist.' Well, I'm not either. But the best scientists in the world know that climate change is happening.
The biggest threat, when it comes to climate change and pollution, isn't going to come from us because we only have 300 million people. It's going to come from China with over 1 billion people and India with over 1 billion people.
We need to start by having a conversation about climate change. It would be irresponsible to avoid the issue just because it's uncomfortable to talk about.
We do not know how much our climate could or will change in the future. We do not know how fast change will occur or even how some of our actions could impact it.
There's one issue that will define the contours of this century more dramatically than any other, and that is the urgent and growing threat of a changing climate.
We are willing to uphold principles that have resulted in unprecedented prosperity and security throughout Europe and around the world. With the threat of climate change only becoming more urgent, Angela [Merkel] and I focused on the need for American and E.U. leadership to advance global cooperation.