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What Is An Urban Heat Island?

GS Paper 3:

Syllabus: Environment and Pollution related issues.



Several sections of the country are experiencing extreme temperatures. Cities, in particular, are significantly hotter than rural places. The reason for this is a phenomenon known as –urban heat island effect”.


What is an urban heat island?

It’s a localised and temporary phenomenon that occurs when particular parts of a city receive more heat than the rest of the city on the same day.

  • The differences are primarily due to heat being trapped within environments that resemble concrete jungles.
  • The temperature variation can range between 3 to 5 degrees Celsius.


What are the Causes of Urban Heat Island?

  1. Carbon-absorbing materials such as asphalt and concrete are required for the constructing buildings in cities. They trap a lot of heat, which raises the average surface temperature of cities.
  2. Many structures in urban areas have dark surfaces, which reduce albedo and increase heat absorption.
  3. Tall buildings, as well as the small streets that commonly accompany them, obstruct air circulation, diminish wind speed, and hence reduce any natural cooling effects. The effect is known as the Urban Canyon Effect.
  4. Use of fossil fuels adds up to the heat effect.
  5. Reduced tree cover and green areas.


How can Urban Heat Islands be Reduced?

  • Increase Area Under Green Cover.
  • To reflect heat and prevent absorption, roofs and terraces should be painted white or with light colours.
  • Kitchen gardening and terrace vegetation should be encouraged.



Prelims Link:

  1. Urban Heat Island.
  2. Green House Gasses.
  3. Green house effects.
  4. Climate Change and its impact.
  5. NASA’s Ecosystem Spaceborne Thermal Radiometer Experiment (Ecostress).

Mains Link:

Discuss about the Causes and Impact of Urban Heat island.

Sources: Indian Express.