"Cities are an environmental paradox. As dense centers of commerce and industry, they are responsible for more than their population share of global environmental impacts," said journal Editor-in-Chief Reid Lifset. "On the other hand, their compactness provides opportunities for economies of scale in transportation, wasgte and water services and infrastructure."

The environmental impact of cities extends beyond their borders. Cities produce greenhouse gases whose impact is global. More subtly, urban residents stimulate resource extraction and manufacturing-with all the attendant environmental pressures- beyond the city boundaries.

The topics in the special issue, Industrial Ecology and the Global Impact of Cities, range from the prospects for addressing global warming in urban policy to resource flows in cities. Contributors examined the environmental impacts in Singapore, Barcelona, Toronto, China and Southeast Asia as a whole.

"We have always known that cities are a fundamental piece of the environmental equation, as a source of both challenges and opportunities," says Gus Speth, dean of the Yale School of Forestry & Environmental Studies. "What is new here is recognition, front and center, that they have a global role to play."

"Industrial ecology, an emerging field that examines the relationship between industry and the environment, is especially adept at analyzing the flows of resources-materials and energy and their environmental impacts-at many scales," said Lifset, who is a member of the faculty of the Yale faculty of Forestry and Environmental Studies, and is Associate Director of the Industrial Environmental Management Program. "The application of industrial ecology to cities is beneficial at both ends-it provides powerful analytical tools and it enriches the field of industrial ecology." -Yale University