5 Causes of Urban Heat Island Effect Explained
Causes of urban heat island are; deforestation and de-vegetation, urbanization, industrial activity, overpopulation, and climate change.
This article discusses the causes of urban heat islands, as follows;
1). Deforestation and De-Vegetation (as one of the Causes of Urban Heat Island Effect)
Loss of vegetation is one of the early steps or processes that lead to urban heat island formation.
Studies of urban heat island effect using satellite imagery and other technologies, have shown that there is a direct correlation between urbanization, regional temperature, and deforestation [3].
Deforestation causes urban heat island effect because it diminishes the presence of vegetation which plays an important role as a natural carbon sink and producer of oxygen.
Removal of this carbon sink therefore results in lower carbon sequestration, higher greenhouse emission, global warming, and climate change rates.
The impact of deforestation on the formation of urban heat island, is further compounded and intensified by the process of urbanization itself; whereby natural soil and vegetation are replaced by manmade infrastructure.
2). Urbanization
The process of urbanization causes urban heat island effect by replacing natural ecologic components of the environment like soil and vegetation with manmade alternatives like asphalt and concrete [2].
In the course of urbanization, infrastructure like water dams, roads, buildings, and bridges are usually constructed.
These infrastructures are seldom constructed using sustainable materials, and the process of their construction itself may cause greenhouse gases to be released into the environment.
Asphalt, concrete, and other building materials that are extensively used in urban development, are capable of absorbing large amounts of solar energy in form of heat.
This heat is subsequently (slowly) released and circulated by convection current within the immediate environment.
Such mechanism generally results in higher regional temperature in urban areas compared to adjacent rural or even semi-urban areas.
Urbanization can be considered a very central factor with regard to the cause of urban island effect, as it facilitates other causes like energy resource exploitation, commerce, and electricity generation; which are all known causes of urban island effect.
3). Industrial Activities (as one of the Causes of Urban Heat Island Effect)
Industrial activities cause urban heat island and pollution dome.
This is due to the fact that heated-air convection mechanisms that occur in urban heat islands, tend to reduce air circulation rates and facilitate air pollution among other forms of environmental degradation [4].
The role of industrial activities in urban heat island formation is directly linked to the large-scale combustion of fuel and other carbon-intensive energy resources, in order to produce electricity and heat for industrial processes.
Waste energy from these industrial processes is also often released into the urban ecosystem in form of heat, that can contribute to the heat island effect.
Other major causes of urban heat island that are related to industrial activities include; transport, manufacturing and infrastructure development.
4). Overpopulation
The main cause of urban heat island is human activity; and the simultaneous conversion of natural ecosystems into manmade ecosystems in order to support these activities.
Based on the above, it is not difficult to predict that overpopulation can contribute to urban heat island occurrence.
Overpopulation itself is a recurrent factor in scenarios involving urban heat island conditions, due to the fact that urban centers are often densely populated compared to rural areas [1].
With population increase, natural ecosystem encroachment also increases as the ecosystem is progressively converted into residential, commercial and industrial zones.
Overpopulation is associated with higher demand for both water and energy resources. The high rate of exploitation and risk of absolute resource depletion, all contribute to environmental degradation that often involves global warming and emission of heat-trapping gases.
Lastly, overpopulated areas usually contain more manmade infrastructures in the form of buildings and roads among others. The heat-absorbing attribute of these infrastructures, alongside lower rates of air circulation, both facilitate urban heat island effect.
5). Climate Change (as one of the Causes of Urban Heat Island Effect)
The relationship between climate change and urban heat island is a cause-and-effect type.
Because climate change often involves temperature rise, it can facilitate the formation of urban heat islands.
Aside climate change itself as a phenomenon, other climate change-induced factors including hazards like heat waves, can help establish the conditions necessary for heat island effect to occur.
In turn, urban heat island can worsen the effects of climate change in metropolitan areas, meaning that it is itself a facilitator of climate change.
Conclusion
Causes of urban heat island are;
1. Deforestation and De-Vegetation
2. Urbanization
3. Industrial Activities
4. Overpopulation
5. Climate Change
References
1). Elsayed, I. (2012). “Effects of Population Density & Land Management on the Intensity of Urban Heat Islands: A Case Study on the City of Kuala Lumpur, Malaysia.” Application of Geographic Information Systems (pp.267-283). Available at: https://doi.org/10.5772/47943. (Accessed 17 December 2022).
2). Mohajerani, A.; Bakaric, J.; Jeffrey-Bailey, T. (2018). “The Urban Heat Island Effect, its Causes, and Mitigation, with Reference to the Thermal Properties of Asphalt Concrete.” Available at: https://www.sciencedirect.com/science/article/pii/S0301479717303201. (Accessed 17 December 2022).
3). Ogle, J.; Seong, J. (2012). “Urban Heat Islands, Deforestation, and Sprawl.” American Association of Geographers – 2012, Los Angeles, CA. Available at: https://doi.org/10.13140/RG.2.2.22142.69442. (Accessed 15 December 2022).
4). Ulpiani, G. (2020). “On the linkage between urban heat island and urban pollution island: Three-decade literature review towards a conceptual framework.” Science of The Total Environment 751(38):141727. Available at: https://doi.org/1016/j.scitotenv.2020.141727. (Accessed 17 December 2022).
