Essay by Jason Nu

The urban environmental transition (UET), as formulated by Peter Marcotullio and Gordon McGranahan in Scaling Urban Environmental Challenges: from Local to Global and Back, is a framework that describes how the environmental burdens generated by cities change in quality, impact, and spatial and temporal scales as cities transition economically from less developed to more developed (M&M, Chps. 1-3). The concept of “development” as used by Marcotullio involves a broad range of social and economic indicators, including per capital GDP adjusted by purchasing power parity, the number of consumer goods such as televisions and telephones per capita, and access to social services such as education, health care, and police protection, etc. (M&M, Chp. 3). The overall argument that the UET framework makes is that as individual cities move from developing status to developed status, the environmental burdens they create shift in nature from “brown,” to “grey” to “green,” and that the resulting health impacts of these burdens transition from those that are immediately life-threatening to those that threaten global life support systems in the long run. Furthermore, as cities develop, negative environmental externalities get pushed out spatially from a local scale to a global scale, and stretched out temporally from immediate to longer term impacts.

Historically, as industrializing cities exploded in size in the 19th century, the primary environmental challenges they faced involved access to clean water supplies and the development of an effective and sanitary sewerage system, concerns that Marcotullio calls “brown” problems. An example of one of the solutions to these brown problems developed by cities in the 19th century includes New York’s construction of the Croton reservoir and aqueduct system which helped solve the city’s pressing water access needs (Gandy, Chp. 2). Another example is London’s construction of a comprehensive sewer system that efficiently removed human waste from homes while keeping it separated from the city’s drinking water supply, which greatly reduced the number and severity of the cholera outbreaks that were a frequent scourge of the city in the past (See Steven Johnson’s The Ghost Map, 2006). These brown problems tended to be localized in nature, affecting only parts of the city and nearby surrounding areas, and also tended to cause very immediate health threats. Lack of clean drinking water, along with the associated diseases and dehydration problems, could cause thousands of deaths in a matter of days. Marcotullio goes on to describe that after many of these brown problems were solved during the sanitation revolution of the 19th century, developed cities began to face “grey” problems. These include environmental issues such as air pollution from industrial and automobile exhaust, as well as chemical pollution from various manufacturing processes. These grey problems tended to affect a wider geographic area around the city than the old brown problems. Air pollution can affect the health and quality of life for an entire region around a city, and dirty air can even cross state and national boundaries. The negative health consequences of these grey problems play out in a somewhat longer timeframe than brown problems. For instance, asthma exacerbated by air pollution is not as immediately life threatening as cholera, but can instead result in chronic ill health, lasting for years. Marcotullio goes on to describe how developed cities mostly solved these problems by enacting stringent legislation on automobile and industrial emissions, as well as by exporting these burdens to far away locales. In the present day, cities in developed countries are primarily faced with “green” problems. These are long-term, global problems related to changes in atmospheric composition and climate change. The health challenges associated with green problems, although less immediate and furthest removed from any particular city, are perhaps of the greatest urgency. Environmental impacts related to climate change have the potential of damaging entire global life support systems.

Marcotullio goes on to describe how developing cities in today’s world often have to deal with all three kinds of environmental problems (brown, grey and green), on all scales (local, regional and global), at the same time. Marcotullio calls this phenomenon time-space telescoping, or compression. Due to 21st century communication and transportation technologies, the increasing connectivity of markets around the world, and massive economic growth and human migration, all phenomena which can be said to fall under the rubric of globalization, developing cities in the present day are confronted with the daunting task of having to deal with multiple environmental problems that cut across several spatial scales, in a short amount of time. To confront these challenges successfully, political and institutional instruments must work together across spatial and temporal scales. Local institutions will have to collaborate with regional and national institutions, which in turn have to collaborate with international and supranational organizations. Information and ideas must flow in both directions, from global to local as well as local to global, and short term priorities will have to be balanced by long term ones.