The history, location and population of Curitiba are typical of many Latin American cities. Its population has swelled from 150,000 in the 1950s to the present 1.7 million, in a metropolitan area of three million. Curitiba has its share of squatter settlements with over 50% illiteracy, yet it boasts 17 new parks, thousands of trees, 150 kilometers of separate bicycle lanes (not shared with cars or buses) that link the parks, and traffic and garbage systems that officials from other cities worldwide come to study. When Curitiba's then-mayor sponsored a contest for a citywide master plan in the 1960s, Lerner was on the winning team of young architects who rejected the municipal habit of borrowing money for highways, shopping malls and other showy projects. In 1971, Lerner was appointed mayor by Brazil's military government. As mayor, he made a case for planning that took into consideration both the environment and human needs. During his 12 years in office, Lerner reportedly had a 92% approval rating. "I remained an architect and urban planning consultant throughout my terms as mayor," he says. Brazil was in a dire economic situation and Lerner was forced to think small, cheap and participatory. The visionary mayor provided 1.5 million tree seedlings to neighborhoods for local residents to plant and care for, and solved the city's flood problems by diverting water from lowlands into lakes in newly created parks. Unemployed teenagers were hired to keep the parks clean. Lerner says that the parks were an important component in revitalizing Curitiba's fortunes. "Curitiba has 51.5 square meters of green areas per resident. It's better to preserve existing green areas than build new parks. We bought out two-thirds of privately owned green spaces for a relatively small price. The remaining land values shot up, so it's a win-win situation. Small woods and disused quarries were converted into parkland. Now the city is dotted by hundreds of small, natural parks," he explains. One section of landfill was converted into the woodland campus of the Free University for the Environment, inaugurated in 1971 by the late marine explorer Jacques Cousteau. Lerner also introduced financial incentives. Builders in Curitiba, for example, receive a tax break if their projects include green areas. Focused local actions have a knock-on effect, he notes. "Relatively small, beautiful places can affect their surroundings look how the Pompidou Center gave Paris a new energy." When he met resistance from shopkeepers after he proposed converting the downtown shopping district into a pedestrian zone, Lerner suggested a 30-day trial. Soon shopkeepers on other streets asked to be included in the zone. Lerner's innovative ethos emphasized recovering degraded areas of the city. "There are no bad areas," he says. "A city functions 24/7, so we promoted night-time street fairs a portable nightlife, because mobility is an important issue." "The city is not a problem, the city is a solution," Lerner adds. "I love cities, and have met many mayors. Many of them complain that their cities are too big, or lack financial resources. I reply that every city in the world can improve its quality of life within two years. There is no excuse. You can do it. All you need is a good strategy. I often ask them two simple questions: where is their city growing and how are the people making their money. Are they are moving from industrial to service economies, for example. "I would say to any mayor in the world that if you want to have a sustainable city, start with three single issues: use your car less, NOW; separate your garbage, NOW; and induce people to live closer to their work, because this saves energy. If you cannot live closer to your work, at least use public transport. I've heard many definitions for sustainable cities. To me, it is a simple equation: save more than you waste. If you waste zero, your sustainability is infinite," says Lerner. Curitiba recycles two-thirds of its refuse. Curitibanos separate their trash into organic and inorganic waste. A recycling plant (constructed itself from recycled materials) employs handicapped people, recent immigrants and alcoholics to separate the bottles, cans and plastic. Styrofoam is shredded and used as quilt stuffing for poor residents. In squatter settlements unreachable by trucks, the poor exchange their trash bags for bus tickets or basic commodities at neighborhood food centers. The recycling program has resulted in a cleaner city with less landfill, lower unemployment, and food and transportation for the poor. Lerner describes how he instigated such a change in Curitiba: "We did not use sophisticated government-sponsored PR campaigns, rather we started with the children. For six months we taught them how to deal with garbage, and why it's important garbage is energy. Only after that we started the campaign, which is why it was successful. "In my experience, parents do listen [to their children]," he adds. "Every child knew that 50 kilos of paper, when recycled, is the equivalent of a tree. They knew that we could save 1,500 trees per day. If every city in my country would do the same, we'd save 600 woods a day. One of the biggest sources of energy is what we waste. They know that metal is energy, and they can save energy. Glass is 100% recyclable. "These simple messages affected all the population. Since 1989, 70% of people have been separating their garbage, and the city has cut its waste by some 40%."