In this essay, Malthus argued that population ... to grow from 8.2 billion people to 9.8 billion in 2050. According to the World Bank, more than half of the world’s population (4.4 billion ...

Half of the global population already lives in cities, and by 2050 two-thirds of the world's people are expected to live in urban areas. But in cities two of the most pressing problems facing the ...