Green Cities: Urban Growth and the Environment (review)

According to Matthew Kahn, more than half the world's population will live in urban areas by 2030, and most of these cities will be located in capitalist economies. In Green Cities, Kahn explores the implications of these trends for the urban environment. In a clear and straightforward manner, he illuminates the complex relationship between humans and the environment and convincingly makes the case that growth can be expected to generate both positive and negative effects on environmental quality in cities. As an economist, Kahn is primarily interested in the environmental consequences of market-driven growth, but he also considers other aspects of urban growth, such as rising populations and sprawling development patterns. This book offers broad theoretical arguments linking urban growth and the environment rather than a detailed perspective on how growth plays out in any particular place. Along the way, Kahn presents an impressive array of empirical examples, primarily based on large-n quantitative analyses, drawn from virtually every region of the world.

Kahn begins by highlighting the difficulties encountered when we attempt to define and measure urban environmental quality. Chapter 2 presents three approaches to assessing a city's environmental quality—ecological footprints, public health, and price differentials—and notes that each provides a different and sometimes divergent picture of a city's "greenness." Subsequent chapters demonstrate that the effects of growth may positively affect some aspects of environmental quality while negatively affecting others. Chapters 3 through 5 focus on the significance of income growth, with the Environmental Kuznets Curve (EKC) serving as the central organizing framework. Kahn provides an excellent introduction to EKC theory in Chapter 3, including a discussion of factors that might help shift the curve, and careful consideration of some critiques of the EKC (such as the pollution haven hypothesis). In the two following chapters Kahn discusses factors that shape the trajectory of the EKC in urban areas. These include the role of the market, especially prices and technology development, and the importance of green governance.

Kahn concludes that the EKC is a "powerful idea" with a great deal of empirical support. Yet, he is quick to point out that it is also "more subtle" than often assumed in that it does not claim income growth automatically solves environmental problems. "Whether growth mitigates urban environmental problems hinges on the incentives for urban consumers, producers, and politicians" (p. 131), incentives that are generated through markets and governance. Kahn recognizes that the EKC provides a limited picture of the relationship between urban growth and environmental quality because it only focuses on income growth. He therefore also considers the links between population growth, urban sprawl and local environmental problems such as air quality, water quality and solid waste. In the final chapter, Kahn argues that urban environmental quality is a function of how income, population, and sprawl interact.

Green Cities contributes to the study of global environmental politics in a number of ways. It illustrates the complexity of pursuing environmental objectives and the trade-offs doing so may require. He also embeds urban areas in a multilevel context, noting that what can be done at the local level is frequently a function of higher-level policies and that local actions may have global impacts. Much of the empirical discussion focuses on local environmental problems, such as air quality, water quality, solid waste and land use. Kahn makes a brief attempt to address the issue of cities and climate change, but his treatment is not particularly sophisticated and does not draw on the growing literature that addresses this topic directly. The book makes a strong methodological contribution. In each chapter, Kahn meticulously moves from theoretical concepts to empirical tests, often discussing problems of data collection and limitations of existing datasets.

This ambitious project covers a great deal of terrain. As a result, some issues are not treated as thoroughly as they might have been. For example, the three approaches introduced in Chapter 2 could have been used to greater advantage. In subsequent chapters Kahn does make brief...