Based on the economic principle of demand management, London’s congestion charge challenges the 20th century notion that cities should be designed around cars, and asks drivers to pay for access to public roads and parking spaces. Thanks to visionary municipal leaders like former Deputy Mayor Nicky Gavron, this plan is the core of a sweeping push to transform London into a transit-efficient and pedestrian-friendly megacity in time for the 2012 Olympic games.

Paris’ ambitious public-private Vélib’ bike initiative encourages residents to forgo cars for bikes and public transportation. In the process, the program has fostered a unique popular culture, complete with its own language, jokes and pick-up lines. If imitation is the sincerest form of flattery, Paris Mayor Bertrand Delanoe has undoubtedly taken heart: Its success has inspired cities like Rome, San Francisco and London to begin adopting similar programs of their own.

In the 21st century global food economy, most foods travel an average of 1,500 miles from farm to plate. As renowned author Michael Pollan elaborates, the impacts of this fossil fuel-driven system are detrimental to the environment, but also to our health and social well-being. Writer Michael Shuman argues that investing in local food systems lessens the distance between who we are and what we eat, and creates wealth in the community.

In 2003, the city of Seoul took a rare step “back in time,” demolishing a major downtown freeway to uncover and restore the ancient Cheonggyecheon stream that once flowed beneath it. An impressive feat of engineering, the project re-purposed more than 75 percent of the dismantled highway material for reconstruction and rehabilitation of the stream’s banks and commercial corridor. The Cheonggyecheon is now a vital part of the city’s commercial and tourism sectors, and has proven that environmental restoration can revive culture and community, as well.

Thanks to a progressive public transportation portfolio that includes train, streetcar, bus and aerial tram, Portland has become a global model of transit-oriented development (TOD). For more than 40 years, city planners have uniquely integrated transport decisions into urban growth and development efforts. The result: Portland is consistently ranked as one of the country’s most livable cities, boasting a healthy two percent population growth annually — and the second lowest per capita transportation spending of the 28 largest U.S. metropolitan areas.

Even if regional transportation becomes more efficient, people and goods will still need to travel the world. This episode looks at new technologies and policies that could offset the aviation industry’s substantial greenhouse gas emissions, such as Amyris Biotechnologies’ new synthetic jet fuels, and Hybrid Air Vehicles’ second generation of dirigible airship. To reduce fuel emissions, industry leaders like Boeing are also advocating towing planes on runways and implementing smarter air traffic control systems.