Urban sprawl can be thought of as providing many positive effects on human society which includes decongestion of city centers and addressing inequities in residential availabilities. However, increased urban and suburban development and its subsequent sprawl can lead to huge environmental challenges. There have been many scientific studies conducted providing evidence that urban development is causing harm to the ecology of those areas which have been developed. Urban sprawl is responsible for the destruction of thousands of acres of habitat for flora and fauna. In Wellington and Halton, both of which are found in Canada, a dozen species have peen placed at risk of complete extinction. This includes the Great Egret, the Jefferson Salamander and the Green Snake. The sprawl occurring in Canada's highest bio-density forest zone is causing habitat loss and the destruction of its ecosystem. There is also the problem of replacement of native species by non-native species as reported by Blair (2001) which could dramatically alter the ecosystem of the area. One just need to remember the rabbit problem that occurred in Australia to know how much damage the introduction of non-native species could cause.
One might argue that most of urban sprawl claim farmlands and a little of forest zones only. While it is true that the bio-density of farmland is low compared to native wilderness, its windrows and forest cover nevertheless provides much habitat for a wide variety of species. Farmland is only one generation away from wilderness and if left untended, it reverts back to its native wilderness state in thirty or forty years as compared to never going back to its natural state when paved. According to Environmental Protection Agency (2005), the severity of the disturbance caused by urban sprawl is graver than the damage caused by deforestation because it is more permanent.
Further evidence of the detrimental effects of urban sprawl was found in the Great Lakes which contains almost 20% of the world's freshwater. The water levels in all five Great Lakes have been found to be below long-term averages and some are at record lows. As residential and commercial areas are established, watersheds are destroyed and the water needs of the community drains the aquifer in the area. Runoff from these communities can also pose a serious threat to the indigenous aquatic population as it may contain garbage and other sewage materials. (Benfield et al, 1999)
Perhaps the gravest threat to the environment by urban sprawl is the threat posed by increased greenhouse gas emissions. In destroying farmland, woodlands and wetlands and creating sprawl, we construct a high-carbon infrastructure system of highways and sprawling communities that will increase our greenhouse gasses emissions and lessen ways to decrease it. Urban sprawl also leaves at its wake, boarded up houses, vacant storefronts, closed businesses, abandoned and often contaminated industrial sites and traffic congestion stretching miles from urban centers which results to increased traffic congestion, longer commutes, increased dependence on fossil fuels, worsening air and water pollution and threatened surface and ground water supplies. (Pickett et al. 2001)
All of these leads the conclusion that urban sprawl does harm the environment.
Benfield, F. K., M. D. Raimi, and D. D. Chen. 1999. Once there were