Urban Heat Island Effect Essay

It is a common experience to walk in urban park, then few steps away, you just turn the corner, pass through lined tall buildings in a narrow street paved with asphalt and you clearly feel that the temperature is higher than in the park. Or maybe, you can recall one day in your life when the city was really hot, that you decided to spend some time in a shading park where you found some relief. Most of you didn’t know but you experienced what in climate science is called the urban heat island effect. In scientific terms, it is the difference between the temperature recorded in the urban environment and the temperature recorded in its rural surroundings.
Heat waves will become more frequent in the next years. The urban heat island effect is
2000, Gaffin et al. 2007).
Cooling cities would be cool since, in the last years there is an excess in heat-related deaths and an aggravation of cardiovascular and respiratory diseases. Urban heat island coupled with heat waves and global warming provoke an increase in deaths and hospitalization, with at about 1000 people dying every year in the United States (Changnon, Kunkel, & Reinke, 1996). In fact, the increase in urban temperature itself is detrimental for urban population, especially for the elderly and the socially vulnerable people such as homeless. Nevertheless, the increase of urban temperature entails an increase in the time of residency of pollutants that can aggravate respiratory diseases especially in children. A further effect of the increase in urban temperature is the contemporary increase in the use of air conditioning that, in turn, feeds climate change, initiating a vicious circle. The Heat Island Group has estimated an increase of the use of energy in Los Angeles correspondent to 100 million of US dollars (Chang, 2000). The Environmental Protection Agency suggests that in the US cities, the increase in the peak of urban electric
In fact, in densely urbanized cities available spaces which might be converted into parks can be hardly found and the increase in surface albedo might result annoying for citizens. Therefore, some decision makers decided to use rooftops as available urban surfaces to be converted into green and cool roofs. Some administrations already developed by-laws and initiatives to incentivize the wide deployment of green roofs. For instance, in 2005 in Toronto, Mayor Miller, during the meeting “Making Green Roofs Happen”, affirmed the will to make Toronto the “showcase for the world on green roof initiative”. In 2009, the Toronto City Council adopted the green roof by-law to direct the installation of green roofs in the city [76]. The city of Chicago sponsored grants for some years for the deployment of green roofs [66]. The city of Portland offers floor area ratio bonus for who installs green roofs [175]. Also the city of Waterloo in Ontario, Canada, has developed some projects to support the installation of green roofs and to transform the rooftop of public spaces – such as the City hall and the roof of the Eastview Community Centre – into green roofs [176]. In Switzerland, green roofs constitute a legal requirement in many cantons, while, in the U.K., although no policies have been applied in the last years, it has been observed an increase of 300% of green roof deployment