Our Scoring System
How do you compare one city's "greenness" with another's? We decided to rank our 50 biggest cities, along with the largest city in each state (if that state wasn't already represented). We gathered data for each city from Earthday Network's Urban Environmental Report,* SustainLane 2006 US City Ranking, the Standard Rate and Data Service, and other public data sources in these categories:
Scoring. We assigned each city points for each category—the city in first place received one point, second place two points, and so on. Then we gave each city an overall average score by dividing the total point count by the number of categories. The lower the final score, the better.
*A ranking based on a broad range of public data from the U.S. Census Bureau, U.S. Environmental Protection Agency, American Lung Association, Natural Resources Defense Council, U.S. Department of Labor, U.S. Geological Survey, and others.
On every continent, people are coming up with ideas for improving the environment. Here are a few of the most interesting.
Vancouver, Canada, manages growth while reducing its ecological footprint through its EcoDensity Plan. Smart transportation planning has resulted in a 44 percent increase in walking, a 180 percent increase in bike trips, and a 20 percent increase in transit use.
Mexico City suffers from traffic congestion and thick smog. Mayor Marcelo Ebrard launched the Plan Verde ("Green Plan") in 2007 to expand public transportation, create new parks and pedestrian-only zones, manage water pollution, and control the traffic problem.
Tuvalu, a tiny Polynesian island nation with just 10,500 inhabitants, is threatened by rising sea waters due to climate change. Tuvaluans and environmental groups have initiated a 10-year plan involving two biogas digesters, a bio-diesel project using copra (coconut palm), solar streetlights, composting toilets, and numerous wind projects.
Abu Dhabi, United Arab Emirates, has set a course to become the world's first zero-carbon, zero-waste city by creating a pedestrian-friendly environment, starting a national carbon dioxide capture and storage network to cut CO2 emissions, and investing $350 million in a 100-to-500-megawatt solar power plant (500 megawatts could generate power for 500,000 households).
Dongguan, People's Republic of China, won the International Awards for Liveable Communities competition last year. The city boasts 951 parks, totaling more than 7,000 acres, and a vegetation coverage rate of 41 percent.