UN-Habitat: Few coastal cities to be spared by climate change

UN-Habitat Press Release

All too soon, the harsh reality of climate change is upon us and the facts are becoming common place. But at a time when over 50 percent of humanity lives in urban areas, UN-HABITAT’s new State of the World’s Cities Report 2008/9: Harmonious Cities sets out to determine which cities are in danger and which communities might well be drowned out.

In the 20th century, sea levels rose by an estimated 17 centimetres, and global mean projections for sea level rise between 1990 and 2080 range from 22 centimetres to 34 centimetres. The low elevation coastal zone – the continuous area along coastlines that is less than 10 metres above sea level – represents 2 per cent of the world’s land area but contains 10 per cent of its total population and 13 per cent of its urban population.

There are 3,351 cities in the low elevation coastal zones around the world. Of these cities, 64 per cent are in developing regions; Asia alone accounts for more than half of the most vulnerable cities, followed by Latin America and the Caribbean (27 per cent) and Africa (15 per cent). Two-thirds of these cities are in Europe; almost one-fifth of all cities in North America are in low elevation coastal zones.

Concerned about the prospect of large scale devastation, in his foreword, Ban Ki-moon, the Secretary-General of the United Nations states that, “Cities embody some of society’s most pressing challenges, from pollution and disease to unemployment and lack of adequate shelter. But cities are also venues where rapid, dramatic change is not just possible but expected.”

Aimed at policymakers and planners, the new UN report warns that few coastal cities will be spared.

In the developed world (including Japan), 35 of the 40 largest cities are either coastal or situated along a river bank. In Europe, rivers have played a more important role in determining the growth and importance of a city than the sea; more than half of the 20 largest cities in the region developed along river banks. Quoting a report by Organisation for Economic Cooperation and Development, the authors note that the populations of cities like Mumbai, Shanghai, Miami, New York City, Alexandria, and New Orleans will be most exposed to surge-induced flooding in the event of sea level rise.

In Asia, 18 of the region’s 20 largest cities are either coastal, on a river bank or in a delta. 17 per cent of the total urban population in Asia lives in the low elevation coastal zone, while in South-Eastern Asia, more than one-third of the urban population lives there. Japan, with less than 10 per cent of its cities in low elevation zones, has an urban population of 27 million inhabitants at risk, more than the urban population at risk in North America, Australia and New Zealand combined.

The report points out that by 2070, urban populations in cities in river deltas, which already experience high risk of flooding, such as Dhaka, Kolkata, Rangoon, and Hai Phong, will join the group of most exposed populations. Also, port cities in Bangladesh, China, Thailand, Vietnam, and India will have joined the ranks of cities whose assets are most exposed. Major coastal African cities that could be severely be affected by the impact of rising sea levels include Abidjan, Accra, Alexandria, Algiers, Cape Town, Casablanca, Dakar, Dar es Salaam, Djibouti, Durban, Freetown, Lagos, Libreville, Lome, Luanda, Maputo, Mombasa, Port Louis, and Tunis.

An assessment of the vulnerability of Alexandria, the most important economic and historic centre along the Mediterranean coast (the cities of Alexandria, Rosetta and Port Said) suggests that, with a sea-level rise of 50 cm, more than 2 million people would have to abandon their homes, 214,000 jobs would be lost, and the cost in lost property value and tourism income would be over US $35 billion, which does not include the immeasurable loss of world famous historic, cultural and archaeological sites.

Researchers studying the impact of climate change on Dhaka predict that the city will be affected in two major ways: flooding and drainage congestion, and heat stress. The elevation of Dhaka ranges between 2 and 13 metres above sea level. This means that even a slight rise in sea level is likely to engulf large parts of the city. Moreover, high urban growth rates and high urban densities have already made Dhaka more susceptible to human-induced environmental disasters. With an urban growth rate of more than 4 per cent annually, Dhaka, which already hosts more than 13 million people, is one of the fastest growing cities in Southern Asia, and is projected to accommodate more than 20 million by 2025. The sheer number of people living in the city means that the negative consequences of climate change are likely to be felt by a large number of people, especially the urban poor who live in flood-prone and water-logged areas.

The report points out that Lagos, with a total population of nearly 10 million inhabitants, lacks adequate infrastructure to cope with flooding. “Normal” rainfall brings flooding to many areas of the city, largely as a result of inadequacies in sewers, drains and wastewater management. Any increase in the intensity of storms and storm surges is likely to increase such problems, as much of the land in and around Lagos is less than 2 meters above sea level. Many low-income settlements are built in areas at high risk of flooding (many on stilts), largely because safer sites are too expensive.

Observing the worrying prospects for cities facing climate change, in her forward, Anna Tibaijuka, Executive Director of UNHABITAT, calls on cities and national governments to address these challenges and opportunities by adopting innovative approaches to urban planning and management that are inclusive, pro-poor and responsive to threats posed by environmental degradation and global warming. She continues to say, ‘From China to Colombia, and everywhere in between, national and local governments are making critical choices that promote equity and sustainability in cities. These governments recognize that cities are not just part of the problem; they are, and must be, part of the solution.’