to cross-talk population levels i'm joined by babatunde or sitting here in berlin he's the executive director of united nations population fund in washington we cross to martha madison campbell she's a lecturer 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 musharraf where does the world stand right now with seven billion people and still counting today's world population is double what it was in one thousand nine hundred fifty seven and seven times what it was only two 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 of the humankind 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 a