A paper, called Growing Cities Sustainably , was recently published in the Journal of the American Planning Association, which generated much debate on the benefits and disadvantages of the “compact” city model. The paper argues that for three studied regions in Britain, the current policy trend of promoting compact cities is actually economically and environmentally unsustainable. Britain has been very successful in implementing anti-sprawl policies, starting with the 1947 Town and Country Planning Act. The new paper compares the compaction model with planned expansion models in three urban regions and concludes “Smart growth principles should not unquestioningly promote increasing levels of compaction. In many cases, the potential socioeconomic consequences of less housing choice, crowding, and congestion may outweigh its very modest CO2 reduction benefits.”
While arguments of the paper are well-developed, there is a risk for other cities to aim at applying the same findings to their urban policies. For example, the paper argues that the CO2 emissions will not increase substantially in the dispersal or expansion model, while many other studies  on other cities have confirmed that low-density suburban development in general is more energy- and GHG-intensive than dense urban cores and downtowns. Another study  also has shown that emissions vary by an order of magnitude in various neighborhoods of the city of Toronto, concluding that variation in total auto and building-related emissions is quite significant between census tracts of Toronto, ranging from 3.1 to 13.1 tonnes of CO2 equivalents per year. With a robust methodology and rigorous analysis, they show that the ten census tracts of Toronto with the highest GHG emissions are located in the lower-density suburbs, attributing the high emissions to private auto use.
Several pro and anti-sprawl arguments have been presented in the past several decades, when the increased use of automobiles had stimulated the rate of suburbanization and sprawl, especially in higher income countries. Now this model is being replicated in emerging middle-income countries, which seem to be following the road travelled by the developed countries in the mid-20th century. One of the most famous pro-sprawl books  claims that sprawl is the result of the free market and has been going on for centuries. It also claims the harmful effects of sprawl are over-stated by an “elitist” anti-sprawl movement. The book also asserts that sprawl cannot be limited without government regulations that artificially constrict the housing supply and raise prices. Other pro-sprawl advocates also have long argued that housing prices and living expenses in the suburbs are more affordable for the lower and middle-income population, which the Growing Cities Sustainably paper echoes (by asserting that density would exacerbate the shortage of housing in outer areas and will result in higher rents and cost of living). However, at least in the United States, the proliferation of poor communities in low-income suburbs indicates otherwise. A report  by the Brookings Institution shows that by 2008, suburbs were home to the largest and fastest-growing poor population in the United States.
In addition, building denser cities has many other social and economic benefits. The urban economist Edward Glaeser advocates the connection between spatial organization and economic growth. He argues that cities have a role in generating ideas, accumulating human capital and fostering innovation through proximity and competition. Richard Florida’s concept of the “creative class”, which he argues is the driver of economic development, can flourish only in dense urban environments. Density, if planned inclusively, can also become a tool for social integration and upward mobility.
While the Growing Cities Sustainably paper is a good read and contributes to the rich debate between urban thinkers, it has the potential to negatively affect the way developing countries view urbanization. The big risk here is that the conclusion — which is definitely specific to the very small sample of cities studied — could be politicized and blindly generalized to other regions and contexts. City leaders in the developing world need to tailor solutions to their individual city, considering environmental, economic, and social issues systematically. The difference between the findings of the Toronto paper and Growing Cities Sustainably reinforces the fact that for each city, a robust analysis of empirical data can determine the trends and illuminate the path for future urban development.