The world's most eco-friendly cities

Since 2008, and for the first time in human history, the majority of the world's population lives in cities. Pollution and environmental degradation are some of the biggest challenges to urban living. But the following cities have adapted their environment as well as to the needs of the environment beyond their limits to become the world's most eco-friendly cities:
San Francisco (United States): A city that recycles almost everything, champions locally sourced produce and heavily invests in renewables.
Amsterdam (Netherlands): Where bikes outnumber people and the government encourages citizens to generate renewable energy at home.
Stockholm (Sweden): Remarkably clean, an abundance of green space and the first city to be awarded with the European Green Capital Award.
Vancouver (Canada): A modern metropolis which also boasts low emissions, fantastic air-quality and vast green public spaces.
Copenhagen (Denmark): The nordic city best known as a cyclist's paradise aims to be carbon-neutral by 2025.
Reykjavik (Iceland): The city is unique like Iceland itself, which produces all its heating and electricity from renewable sources.