alan wiseman alan is an award winning journalist his reports of a period in a variety of publications including new york times magazine mother jones and it landed a finalist for the national book critics circle award winner of the prize of the national library of china ellen is also the author of several books including the national bestseller the world without us and his latest critically acclaimed countdown our last best hope for a future on earth alan joins me now in the studio alan welcome thanks for thanks for being with us to be here the essential story of countdown is the story of overpopulation it is it's something that i came to unexpectedly at the end of doing my last book the world without us which was really kind of a red herring because it was about how could we have a world with us theoretically wiped everybody off the planet so we could see how beautifully the planet would restore itself. hoping that readers would ask wow how do we add ourselves back to that picture of a healthy world only kind of in balance with nature not in combat with it but i discovered that every four and a half days we were adding a million people to the planet and we still are and that didn't seem like a sustainable figure at all so i just raised it at the end of the book and sort of left a day laying there and it became a really important talking point everybody wanted to talk about that's what friendly decided i should investigate it as a jour