"I actually think we're going to solve this thing."
That's what President Obama said in a news conference just before he left a United Nations summit on climate change.
"Climate change is a massive problem," Obama said. "It is a generational problem. It's a problem that by definition is just about the hardest thing for a political system to absorb, because the effects are gradual, they're diffused. And yet despite all that ... I'm optimistic. I think we're going to solve it."