In the south-western English town of Totnes, its inhabitants are trying to power a "transition" of their small town. Their guide is a Transition Manual, which is illustrated by two depictions of Totnes on its cover.
On one side is a grey, empty street, shrouded in smog. There are a row of houses, a supermarket, a row of parked cars, a traffic jam and a petrol station.
On the other side, the sky is clear. The same houses sport small wind turbines and solar panels, people can be seen chatting in front yards that have been converted into vegetable gardens, and the petrol station is covered with vegetation.
This second depiction of the future represents the dreams of the 7,500 inhabitants of Totnes.
It is also the birthplace of a movement that is transforming hundreds of cities throughout the world.
Eight years after permaculture teacher Rob Hopkins started designing a strategy with his students to tackle the twin crises of climate change and peak oil prices in 2005, there are more than 500 Transition initiatives, led by citizens who have decided to initiate their own "local resilience" and "energy descent" action plans.
"The key to our success will be our ability to generate positive visions of the future," said Mr Hopkins.
The example of Totnes shows the importance both of how ground-up initiatives can help save the environment, and how urban centres lie at the heart of such efforts - the same centres where the problems often start.
The United Nations agency for human settlements estimates that cities are responsible for 70 per cent of the world's greenhouse gas emissions - despite covering only 2 per cent of global land area.
Over the years, increasingly disillusioned with the lack of public commitment on environment issues, citizen groups have emerged, determined to cut greenhouse gas emissions at a local level, decrease their dependence on oil and reduce their carbon footprint.
This has seen movements such as Transition Towns and the Voluntary Simplicity movement in Quebec, Canada, all taking up the challenge to face a future that they believe can be transformed through collective action.
Many of the proposals are pragmatic - for instance, urban agriculture and bike- and car-sharing systems. In many cities, city dwellers have started growing fruit and vegetables on sidewalks, in vacant lots and rooftops.
In Totnes, a local currency was even launched to re-localise the economy: The "Totnes pound" is used by many consumers to shop and pay small local businesses, which encourages local trade and promotes local resilience.
Said Mr Hopkins: "If we are able to turn things around on the scale we need to turn them around on, to replace vulnerability, carbon intensity and fragility with resilience, it will be an achievement our children will tell tales about, sing songs about.
"I hope I am there to hear them."