Urban Heat Islands – UPSC Prelims

Urban Heat Islands:
  • It is defined as the rise in temperature of any man-made area, resulting in a well-defined, distinct “warm island” among the “cool sea” represented by the lower temperature of the areas nearby natural landscape

  • Though heat islands may form on any rural or urban area, and at any spatial
scale, cities are favoured, since their surfaces are prone to release large quantities of heat.
  • Urbanization negatively impacts the environment mainly by the production of pollution, the modification of the physical and chemical properties of the atmosphere, and the covering of the soil surface. Considered to be a cumulative effect of all these impacts is the UHI.
  • On an average the annual air temperature of a heat island in a city with 1 million people or more can be 1-3°C warmer than its surroundings which goes upto 12°C in evenings.
  • Heat islands can affect communities by increasing summertime energy demands, air-conditioning costs, air pollution and greenhouse gas emissions, heat-related illness and mortality
  • The major causes are vehicle, dark pavements, multi-storey buildings and air conditioners. Among these the use of ACs is most adverse as it creates a vicious cycle.
  • The effects of a heat island can be reduced by developing efficient cooling systems, adding vegetation to buildings, cooling paved surfaces with reflective paint etc.
  • The United Nations Environment Programme (UNEP) report titled “Sustainable Urban Cooling Handbook” stated that cities will be the hotspots as global warming continues unabated.

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