After the handshakes, photo-ops, and countless speeches at the Paris climate talks, it's time to face the hardest part: implementation and follow-through.

Hear the details of the agreement, explained by Jeffrey Sachs, director of the Earth Institute at Columbia University, special advisor to Secretary-General Ban Ki-moon of the United Nations on the Millennium Development Goals, and the author of The Age of Sustainable Development (Columbia University Press, 2015).

Sachs calls the agreement "a triumph of diplomacy" and gets into the weeds on a few specific details, including a worldwide $100 billion/year pledge for climate-related financing starting in 2020.