52.    Today, the majority of people live in cities. Over the past 20 years, the urban population has grown by more than 60 per cent worldwide, and over the next two decades, the population living in urban areas is projected to grow by another 1.4 billion — from 3.5 billion in 2010 to 4.9 billion in 2030 — with most growth taking place in medium-sized cities (those with populations of between 500,000 and 1 million people) in developing countries.

53. All over the world, people are moving to cities in search of jobs and opportunities that are unavailable in their places of origin. The world’s urban areas are also powerhouses for research and innovation. But the global shift towards cities is also creating new challenges. Cities enable middle-class lifestyles that place greatly increased demands on resources and ecosystems. The physical expansion of built-up areas leads to urban sprawl and the expansion of slum areas at the expense of arable land and ecologically vulnerable areas. Informal settlements (“slums”) with no basic amenities are becoming a permanent fixture and a way of life for migrants in some developing countries, leading to health and security risks, exposure to natural disasters and other environmental risks.

54. The present report focuses on three areas where the need for justice, sustainability and resilience is the most urgent, providing concrete recommendations on how a transition to sustainable development can be triggered: (a) empowering people to make sustainable choices (sect. III); (b) working towards a sustainable economy (sect. IV); and (c) strengthening institutional governance to support sustainable development (sect. V).