The Garde Shurbeck is a professor in population and family health at Columbia University. She recently published a book called Decline and Prosper about how we can adapt to a world with fewer children. Population issues have been discussed throughout history and across societies, she says. We are likely to see a population increased to a level around 10 billion before we will see stagnation and eventual decline in the global population numbers,. Thank God, it seems like population size raises concerns, almost whatever it's doing, whether it's rising or falling.