Urban Innovators on List of Planet Heroes

"But who are the people who can bring about change, the pioneers coming up with radical solutions? We can modify our lifestyles, but that will never be enough. Who are the politicians most able to force society and industry to do things differently? Where are the green shoots that will get us out of the global ecological mess?"

-Ken Livingstone

London mayor

"Ken Livingstone, 62, has dragged the capital to the top of the major world cities' environment league. He shocked the more timid Tony Blair and Gordon Brown when he set an ambitious 60% CO2 reduction target by 2025 - and now he is championing renewables, energy from waste, heat and power systems, and ways Londoners can adapt their homes. The capital has seen a huge increase in cycling, and from this month most of the city's public buildings will be 'retrofitted' to save energy. It's beginning to work, he says: four years ago, more than one in three Londoners used their cars every day; now fewer than one in five do."

-Peter Head

Civil engineer

"Peter Head, 60, is an unlikely man to be leading a cultural revolution. The soft-spoken Englishman, a director of Arup and one of the world's leading bridge builders, is now the master planner of the world's first true eco city.

His brief from the Shanghai city authorities may have been simple, but in building and design terms it was the equivalent of a moonshot: to build on an island at the mouth of the Yangtze a city for 500,000 people that can lead the world's fastest growing economy out of the industrial age into the ecological one. Dongtan will cost $50bn or more, and be a prototype for 400 or more similar Chinese cities over the next 30 years."

-Jockin Arputham

Urban activist

"Jockin Arputham, 60, has lived in a slum outside Mumbai since 1963. As president of the National Slum Dwellers Association and Slum Dwellers International, he is rallying the world's poorest city dwellers to improve their environment. Urban squalor is one of the biggest problems of the age, and by 2030 the number of slum dwellers is projected to reach two billion - a recipe for poverty, disease and political instability. Arputham has pioneered a way to help the poor negotiate with city authorities to secure land ownership - the greatest barrier to improving slums."