Since the great Chicago heat wave of 1995, the city government has enacted a large number of policies under the pretense that it is combating its urban heat island. While much investigation on the subject thus far has focused on either the local benefits of policies or broad descriptions of the entire region, few studies have evaluated whether the small-scale benefits of policies have begun to collectively impact the larger heat island.
This study addresses this issue by using LANDSAT imagery to observe changes in Chicago’s vegetated and reflective surfaces in relation to changes in surface temperature since 1995. Thus far, investigation has used two images from early June of 1995 and 2009 with similar air temperature and atmospheric conditions. Results from this initial observation indicate that reflective policies (especially reflective roofs) were very successful and increased the overall albedo of the city from .150 to .173 in addition to cooling certain neighborhoods by 2°C to 3°C.
Vegetation policies produced noticeable results but their overall impact was slightly less impressive, generating a weaker correlation to temperature decrease and often affecting small areas instead of the larger region. Also, the fact that the number of vegetated pixels in Chicago decreased by 9,727 since 1995 indicates that an optimal current urban heat strategy would probably involve a restraint of development over vegetated areas in conjunction with good reflective policies. Research will continue by developing more evidence to support the aforementioned claims and by taking a closer look into the impacts of specific reflective roof policies.