Daniel Hoornweg

What a Waste (2012), the World Bank report he lead-authored with Perinaz Bhada-Tata, is the global reference diagnosis on municipal solid waste. Its central finding is a simple, hard correlation: the richer a city, the more waste it generates per head, and at the same time the better it manages it. The problem appears in the middle, in cities growing rich fast, where waste generation outpaces collection capacity.

Hence his warning about pace. Across much of Africa and South Asia the quantity of waste will multiply in the coming decades while collection still fails to reach entire districts, with the known consequences: uncontrolled dumping, blocked drains, flooding and disease. Hoornweg argues that waste management is the worst-funded urban infrastructure in the world relative to its direct impact on health.

A Canadian engineer, Hoornweg was for years the World Bank's lead urban specialist and is a professor at Ontario Tech University, where he works on urban sustainability, energy and long-term city projections.

In 2013 he published in Nature, with Mehdi Hosseini and others, an analysis estimating when global waste generation would peak: not before 2100 on current trends, and considerably earlier if cities densify and economies dematerialise. His practical conclusion is that urban form determines waste as much as income does: a compact city generates less and collects it more cheaply.