Whether cities or neighborhoods, communities can provide the means for their residents to reduce CO2 emissions and live more sustainably.

• Densely populated communities reduce land use and encourage walking.
• Public green spaces enhance the quality of life.
• Public transportation cuts traffic and pollution.
• Pedestrian and bi
  king zones reduce driving and parking needs and curb pollution.
• Reuse of building sites reduces new construction.

Public buses and bus stop shelters, part of the environmental efforts of the city of Curitiba, Brazil.

Ron Giling/Peter Arnold, Inc.

Some Examples:

New Songdo City, South Korea, will accommodate 65,000 residents, about 250,000 incoming daily commuters, over 300 acres of parks, as well as businesses and cultural centers, all within 1,415 acres. It is being built to meet the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED®) standards.

Curitiba, Brazil, has a bus system with high-capacity loading stations, transporting nearly 2 million riders each day and replacing some 40,000 cars

An electric delivery truck in the Bahnhofstrasse area of Zermatt, Switzerland, where only electrically powered vehicles are allowed. The truck is powered by electric batteries.

Martin Bond/Photo Researchers, Inc.

Zermatt, Switzerland, bans fossil-fuel-powered vehicles within city limits. Trains bring people in, and electric taxis transport them around town.

The Thoreau Center for Sustainability, San Francisco, California, inhabits a historic hospital building from 1902.