[By Zhou Tao/Shanghai Daily ]

Green living environments can play an important role in making cities more equitable for their residents.

A number of cities in western Europe, the United States and Canada have pioneered green strategies.

Freiburg, a city of 200,000 inhabitants in Germany, has a long tradition of sustainable building and investment in recycling and it reduced CO2 emissions per capita by 12 per cent between 1992 and 2003.

Several cities in developing countries, especially in South America, have also branded themselves green. Authorities in Curitiba, Brazil, introduced policies to integrate land-use and transport planning and by the 1970s the city was equipped with an innovative bus rapid transit system.

Challenges for green cities include the rapid pace of urbanization and related pressure on the environment and social relations if it continues on the same trajectory.

Opportunities for green cities include the possibility to design, plan and manage their physical structure in ways that are environmentally advantageous, advance technological innovation as well as profit from synergies that exist between the constituent elements of complex urban systems.

In 2007, for the first time in human history, 50 percent of the global population lived in urban areas. Only a century ago, this figure stood at 13 percent but it is now predicted to reach 69 per cent by 2050.

In some regions, cities are expanding rapidly, while in others, rural areas are becoming more urban.

A significant part of this urbanization is taking place in developing countries as a result of natural growth within cities and large numbers of rural-urban migrants in search of jobs and opportunities.

Rapid urban growth tends to overwhelm cities where the struggle to develop infrastructure, mobilize and manage resources has negative consequences for the environment.

India and China

The scale of the problem comes into sharp focus in India and China.