John Kerry: “We had the environment community at the table; we had the faith-based community at the table.”

The message is, let's find a way to be able to make sure when we fly, we're not leaving emissions that we cannot capture.

It is not fair for us to be reducing.

It's a matter of mathematics and physics, not politics, not ideology. It is a response to the science.

The U.N. Finance Analysis suggests that it will cost trillions of dollars. Maybe $2.5 to $4.5 trillion a year between now and 2050.