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Environment Magazine September/October 2008


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Editors' Picks - September/October 2008

The Dawn of an Urban Millennium
Nancy B. Grimm et al., “Global Change and the Ecology of Cities,” Science 319, no. 5864 (8 February 2008): 756–60

For the first time in history, more than half the human population—some 3.3 billion people—live in urban areas. This number is projected to double by 2050, and as urban areas continue to push outward while facing an overlay of environmental challenges, including climate change, the global urban expansion looms large as a factor determining a successful transition to sustainability. Fortunately, the field of urban ecology, too, has grown. It is increasingly contributing to an understanding of how urban centers respond to and affect the environment and the practice of urban development.

In an article in Science, international researchers describe the influence urban areas have on environmental change. Cities are not only hot spots of production, consumption, and waste generation; their outward expansion is creating, according to some planners, “megapolitan” regions across the globe where multiple urban centers connect as the areas between them grow increasingly more dense. The “footprint” analogy becomes perceptibly inadequate at such scales of environmental tread.

The authors’ main task, however, is to review how the field of urban ecology has illuminated five areas of urban human-nature interactions and change: land-use and land-cover, biogeochemical cycles, climate, hydrosystems, and biodiversity. They credit national investments in urban research programs, such as the National Science Foundation’s expansion of its Long Term Ecological Research Program into studies of human-dominated ecosystems, for beginning to change the discipline of ecology. Such programs are integrating theory and methods of both the social and natural sciences to study the links between ecosystem services and environmental change at multiple scales. The article pulls together a great deal of interesting research to describe the human-urban-nature nexus and poses critical questions for further investigation.

The authors reveal some attention-grabbing implications for urban planning, policies, and management—including the unintended consequences of increasing housing densities in Seattle (it encouraged low-density sprawl in neighboring rural and wild areas); the potential substitution of high-nutrient, treated wastewater for commercial fertilizers; and the implication that urban aquatic systems should be designed to reflect their altered ecology rather than restored to an ideal state. They also suggest that collective behaviors creating daily and weekly driving patterns with commensurate loading of atmospheric particulates and pollutants are more important than localized, individual behaviors, and they highlight the critical importance of mitigation and adaptation as strategies for cities to respond to climate change, particularly the most vulnerable areas, coastal cities.

Will the dawn of an urban millennium fade into a dusk of glowing sustainability? The authors suggest urban ecology will play a pivotal role. Continuing to support the field’s evolution is essential. And bringing together urban ecologists with the planners, builders, and financiers of future cities should turn the pivot on a promise of sustainable practice.

Sherburne B. Abbott
University of Texas
Austin, T

Food Equity in U.S. Neighborhoods
Samina Raja, Changxing Ma, and Pavan Yadav, “Beyond Food Deserts: Measuring and Mapping Racial Disparities in Neighborhood Food Environments,” Journal of Planning Education and Research 27, no. 4 (Summer 2008): 469–82

Long ignored by U.S. planners, neighborhood “food environments” are becoming an increasing focus of attention for practitioners and academics, especially given the recent publicity surrounding the food crisis. One important element is how low-income and minority households compare with middle-class white households for access to healthy, affordable food. The food security literature has posited the existence of “food deserts,” a particularly evocative term, but shifting definitions and scarce empirical data have underscored the need for more research. Addressing this gap, a recent study of predominantly black, white, and mixed-race communities in Erie County, New York, suggests a more complex picture than the metaphor conjures.

Using data from 897 census block groups in the county, researchers from the State University of New York (SUNY) at Buffalo found that while both minority and white neighborhoods offer access to food destinations, the type of establishments differ. For instance, predominantly black neighborhoods have slightly less than half the supermarkets within a five-minute walking distance but 1.15 times the number of smaller grocery stores and 1.37 times the convenience stores as their predominantly white counterparts.

This specialization reveals a disparity in the availability of healthy food options in white and minority neighborhoods: a 2003 survey of 25 Erie County supermarkets, groceries, and convenience stores found that the latter two were considerably less likely to carry fresh produce and whole grains than supermarkets. Raja, Ma, and Yadav were encouraged to find, however, that a weekly basket of food that feeds four and meets the USDA’s Thrifty Food Plan standards costs about the same in the grocery stores and supermarkets.

Despite the inequitable distribution of supermarkets in Erie County, the authors argue, “[I]t would be a mistake to overlook the existing extensive network of small grocery stores and their potential role in providing healthful, affordable, and culturally appropriate foods in minority neighborhoods.” They suggest that supporting small grocery stores—for instance, by funding refrigeration and other retrofits and providing incentives for grocery owners to partner with local food producers—may be a more efficient strategy than recruiting supermarkets. This, they say, is a call for local governments to adopt a “third wave” strategy of economic development: developing what’s already there rather than assuming a (new) supermarket is the only solution.

Julian Agyeman
Tufts University
Boston, MA


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