Heat islands, areas whose average temperatures are higher than what would be natural because of an increase of energy absorbing materials and a decrease of energy reflecting materials, are increasing temperatures of major cities worldwide, creating an increased need for energy use (cooling), that in turn increases the heat island effect, causing a vicious cycle of economic waste and environmental damage. Though heat islands are most obvious on large, urban to rural scales, the causes of heat islands can be reduced to individual alterations of an otherwise natural landscape. According to the International Council for Local Environmental Initiatives, during the warm summer months, some cities will be up to eight degrees (Fahrenheit) hotter than the neighboring rural surroundings, and research has been done in the Lake Wingra Watershed that supports these findings. The ICLEI (International Council for Local Environmental Initiatives), along with publishing its heat island data, makes broad scale suggestions for how to mitigate the heat islands in major cities. However, many of these actions are difficult to conceive or execute for small-scale organizations or groups (For example, a certain type of paint is less reflective than another, and the ICLEI suggests that this type of paint be used universally in major cities).
WHAT CAUSES HEAT ISLANDS?
· Paved surfaces & manmade objects: Many paved surfaces and manmade objects are not sufficient at reflecting incoming sunlight. As a result, that heat energy is absorbed in those objects and temperatures and ozone levels rise.
· A lack of vegetation: Vegetation reflects most heat energy (and the energy that is not reflected is used in photosynthesis), which is why highly vegetated areas will tend to be cooler than an area that is less green in a similar climate.
· Urbanization: Cement's unique absorbency of heat causes it to generate heat very easily and quickly and then cool very slowly-the exact opposite of what normally occurs. For this reason, cities will heat up very easily during the day and will not cool as easily as a rural area would at night.
· Buildings: The density of buildings also plays a role in the increase of temperatures in cities. When streets are condensed with buildings, the heat energy of the sun has little physical space to escape.