How can a city become sustainable?

Sustainability in cities involves improving and developing cities whilst preserving the environment and resources. Sustainable cities must control the use of resources. This can be done by improving the efficiency of water, recycling and waste systems. CO2 emissions can be managed through improving public transport, using renewable energy sources and designing carbon neutral infrastructure. Sustainable cities should increase the number of parks and open spaces available to its inhabitants. Cities should be accessible for everyone and should control the number of inhabitants in order not to damage the environment. Ultimately, sustainable cities improve the quality of life for its inhabitants. Examples include Curitiba in Brazil and Copenhagen in Denmark, which aims to become carbon neutral by 2025.In line with sustainable cities, the term 'Eco-cities' has emerged. These are purposefully built new cities that are self-sufficient and eco-friendly. Eco-cities use advances in technology to create a clean and efficient environment. These include creating the city and buildings using eco-friendly and recycled materials and unique waste management systems which reuse waste to produce energy. There are plans to create Eco-cities in China and South Korea.