In recent decades, the world has experienced unprecedented urban growth. In 2015, close to 4 billion people — 54 per cent of the world’s population — lived in cities and that number is projected to increase to about 5 billion people by 2030. Rapid urbanization has brought enormous challenges, including growing numbers of slum dwellers, increased air pollution, inadequate basic services and infrastructure, and unplanned urban sprawl, which also make cities more vulnerable to disasters. Better urban planning and management are needed to make the world’s urban spaces more inclusive, safe, resilient and sustainable. As of May 2017, 149 countries were developing national-level urban policies.
- The proportion of the urban population that lives in developing country slums fell from 39 per cent in 2000 to 30 per cent in 2014. Despite some gains, the absolute number of urban residents who live in slums continued to grow, owing in part to accelerating urbanization, population growth and lack of appropriate land and housing policies. In 2014, an estimated 880 million urban residents lived in slum conditions, compared to 792 million urban residents in 2000.
- As more and more people move to urban areas, cities typically expand their geographic boundaries to accommodate new inhabitants. From 2000 to 2015, in all regions of the world, the expansion of urban land outpaced the growth of urban populations. As a result, cities are becoming less dense as they grow, with unplanned urban sprawl challenging more sustainable patterns of urban development.
- The safe removal and management of solid waste represents one of the most vital urban environmental services. Uncollected solid waste blocks drains, causes flooding and may lead to the spread of water-borne diseases. On the basis of data from cities in 101 countries from 2009 to 2013, 65 per cent of the urban population was served by municipal waste collection.
- Air pollution is a major environmental health risk. In 2014, 9 of 10 people who live in cities were breathing air that did not comply with the safety standard set by WHO.
Source: Report of the Secretary-General, "Progress towards the Sustainable Development Goals", E/2017/66
- More than half the world’s population lives in cities. By 2030, it is projected that 6 out of 10 people will be urban dwellers. Despite numerous planning challenges, well-managed cities and other human settlements can be incubators for innovation and ingenuity and key drivers of sustainable development.
- However, as more people migrate to cities in search of a better life and urban populations grow, housing issues intensify. Already in 2014, 30 per cent of the urban population lived in slum-like conditions; in sub-Saharan Africa, the proportion was 55 per cent, the highest of any region. Globally, more than 880 million people were living in slums in 2014. This estimate does not include people in inadequate or unaffordable housing (defined as costing more than 30 per cent of total monthly household income).
- As population growth outpaces available land, cities expand far beyond their formal administrative boundaries. This urban sprawl can be seen in many cities around the world, and not only in developing regions. From 2000 to 2015, the ratio of the land consumption rate to the population growth rate in Eastern Asia and the Oceania was the highest in the world, with developed regions second. Other regions, such as South-Eastern Asia and Latin America and the Caribbean, showed a decrease in that indicator over the same time period. Unfortunately, a low value for this ratio is not necessarily an indication that urban dwellers are faring well, as this can indicate a prevalence of overcrowded slums. Unplanned urban sprawl undermines other determinants of sustainable development. For example, for every 10 per cent increase in sprawl, there is a 5.7 per cent increase in per capita carbon dioxide emissions and a 9.6 per cent increase in per capita hazardous pollution. This illustrates the important interlinkages across the goals and targets.
- Likewise, managing solid waste is often problematic in densely populated areas. In fact, in many developing regions, less than half of solid waste is safely disposed of. As per capita waste generation continues to rise, the collection and safe disposal of solid waste will continue to require serious attention.
- Urban air pollution also challenged cities around the world, causing illness and millions of premature deaths annually. In 2014, around half the global urban population was exposed to air pollution levels at least 2.5 times higher than maximum standards set by the World Health Organization.
- The quest for sustainable and coordinated urban development starts with national policies and regional development plans. As of 2015, 142 countries had a national urban policy in place or under development. Those countries are home to 75 per cent of the world’s urban population.