PBS Nova. It took all of human history until 1800 for the world’s population to reach its first billion. Now we add a new billion nearly every dozen years. Over the next half century, 98 percent of that growth will take place in our planet's poorest regions. And as the global total swells to nearly 9 billion by 2050, the social and environmental strains will be enormous. In this groundbreaking, worldwide investigation of humanity’s future, NOVA shows how decisions made now will change the fate of everyone over the next fifty years.