he's the executive director of united nations population fund in washington we cross the martyr madison campbell sees a lecture at the school of public health at the university of california berkeley and in gainesville we have matthew conley he's a professor of history at columbia university all right folks this is cross talk that means you can jump in anytime you want i very much encourage it but first moshe where does the world stand right now well it's seven billion people and still counting today's world population is that what it was in one thousand nine hundred fifty seven and seven times what it was only ten centuries ago by mid century a projected growth will put that figure at nine point three billion people concerns are mounting that such sustained expansion for human kind threatens to run dry this planet's already overstretched resources. the business as usual scenario predicts that humanity will be using renewable resources and land at the rate of two planets each year by twenty thirty and just over two point eight planets each year by twenty fifty in addition to medical progress and