Statement by Dr. Joan Clos, Under-Secretary-General of the United Nations Executive Director of UN-HABITAT on the occasion of World Habitat Day, 3 October 2011

Each year on World Habitat Day, the first Monday in October, we bring to the world's attention a matter of great concern in our rapidly urbanizing world. This year we look at the impact of cities in creating climate change, and, in turn, the impact of climate disruption on cities, and what cities are doing about it.

We live in an age where the world's population will have grown to 7 billion by the end of this month and where more than half of them live in towns and cities. Projections indicate that this will increase to two-thirds in just over a generation from now. How we manage this rapid urbanisation is one of the greatest challenges facing us.

We must bear in mind that the greatest repercussions of climate disasters both begin and end in cities.

According to UN-HABITAT's Cities and Climate Change: Global Report on Human Settlements, it is estimated that by 2050, there could be as many as 200 million environmental refugees worldwide, many of whom will be forced from their homes by rising sea levels and the increased frequency of flooding or drought.

Prevention should be addressed through better urban planning and building codes so that city residents, especially the poorest, are protected as far as possible against disaster. Such measures can also help to keep their ecological footprint to the minimum.

Climate induced risks such as rising sea levels, tropical cyclones, heavy precipitation events and extreme weather conditions can disrupt the basic fabric and functioning of cities with widespread reverberations for the physical infrastructure, economy and society of cities. These include public health risks in urban areas.

We already know that the impacts of climate disruption will be particularly severe in low-elevation coastal zones where many of the world's largest cities are located. And always it is the urban poor, especially slum dwellers, who are most at risk when disaster strikes. We need to stress the provision of adequate adaptation measures based on urban planning.

Even though we are still trying to understand some of these extreme climatic events, we have the know-how and the strategies to take preventive measures.

Urbanization offers many opportunities to develop mitigation and adaptation strategies to deal with climate change. Given that most global energy consumption occurs in cities, roughly half of it from burning fossil fuels in cities for urban transport, the solution seems obvious.

This is due to the fact that the economies of scale produced by the concentration of economic activities in cities also make it cheaper and easier to take action to minimize both emissions and climate hazards.

The social, economic and political actors within cities must therefore become key players in developing these strategies.

Many towns and cities, especially in developing countries, are still grappling with climate change strategies, working out how to access international climate change funding and how to learn from pioneering cities.

We should reflect on this World Habitat Day on how we turn our cities – arguably the greatest achievements of human civilisation – into better cities for the future.