Climate change and cities: a prime source of problems, yet key to a solution

Ahead of the COP21 UN climate summit, Nicholas Stern and Dimitri Zenghelis argue that the choices cities make today on transport and industry will determine whether the world can benefit from resource-efficient growth

Cities are home to half the world's population and produce around 75% of the world's GDP and greenhouse gas emissions. By 2050, between 65% and 75% of the world population is projected to be living in cities, with more than 40 million people moving to cities each year. That's around 3.5 billion people now, rising to 6.5 billion by 2050; a huge and singular event in human history.

This places cities at the centre of economic activity affecting how economies grow, how resources are allocated, how innovation takes place, whether innovation is used well or badly and, if badly, how much damage it inflicts on others now and in the future. They can also be very exposed and vulnerable to climate risks such as water shortages, floods and heat stress. The mass congregating of people and rising demand for resources, under poor organisation and governance, make cities prime sources of pollution, congestion and waste.

Cities are all about efficiency - it is why they are there in the first place

Stockholm reduced emissions by 35% from 1993 to 2010, but grew its economy by 41%

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