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Explain the nature of Urban Climate and its impact on Global Environmental Change. | UPSC geography optional paper 1 2019

Explain the nature of Urban Climate and its impact on Global Environmental Change.
(UPSC geography optional paper 1 2019, 15 Marks)


The urban climate is a set of climatic conditions that exist in large metropolitan areas or densely populated cities and that is different from surrounding rural areas. 

Urban Climate
Urban Climate

Nature of urban Climate: 

The following are the nature of urban climate:
  • It is warmer areas approximately 2 degrees centigrade than surrounding rural areas.
  • Central areas of the city have a higher mean temperature than surrounding areas.
  • Due to warmer areas, it is also called Urban Heat Island (UHI).
  • The average humidity in Urban areas is lower than in the surrounding rural area.
  • Vegetation and Wildlife in the urban area are certainly lower than in the surrounding areas.
  • Due to heating, air rises in an urban area, rainfall occurs if has sufficient moisture in the atmosphere. Convention rainfall is common in urban areas.
Reasons for warmer temperature in Urban Area:
The urban climate is warmer due to:
  • The use of concrete, tar, and bricks in city infrastructure reduces the albedo and makes it opaque to outgoing terrestrial radiation but has a high heating capacity and conductivity.
  • Lack of Evapotranspiration in the city leads to a higher temperature in urban areas.
  • Industrial, automobile, transportation sectors release greenhouse gases, dust, particulate matter in the atmosphere which leads to traping of more insolation.
 Impact of  Urban Climate on the global environment: 
The following are the impacts of urban climate:
  • Urban or cities are hotspots of greenhouse gases. As per UNEP, urban cities are responsible for 75% of global greenhouse gases.
  • Urban cities are converting Urban Heat Island(UHI).
  • The higher temperature in urban areas leads to an increase in the colonization of species related to a higher climate.
    • For example, lizards, insects, ants are found more prominent in urban areas than rural areas.
  • More heat in urban areas resulted in adversely affect human and animal health.
  • It leads to a shortage of water as water demand increases and evaporation of water in water bodies also get increased.
  • High temperature leads to high electric consumption as needed AC  to cool and higher electric consumption leads to a further increase in temperature and creates a vicious cycle of temperature.
  • Due to relatively warmer as compared to surrounding rural areas in all the years, it creates low pressure and winds flow from surrounding rural areas in urban areas. Due to the convergence of air and friction, air rises. Upper rises air moves towards rural and make circular air circulation from rural to urban areas.

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