"An Urban Heat Island, or UHI, is a metropolitan area that's a lot warmer than the rural areas surrounding it. Heat is created by energy from all the people, cars, buses, and trains in big cities like New York, Paris, and London. Urban heat islands are created in areas like these: places that have lots of activity and lots of people.



There are many reasons for UHIs. When houses, shops, and industrial buildings are constructed close together, it can create a UHI. Building materials are usually very good at insulating, or holding in heat. This insulation makes the areas around buildings warmer."- As described on National Geographic

The scenario in India

India?s two major cities, Delhi and Mumbai have been adversely affected by the Urban Heat Island effect. The population has almost doubled in the past 25 years as inflow of migrants from rural areas of the country. Findings show that temperatures in both cities have risen by 2C-3C in only 15 years. The ongoing study by NASA shows that the cities are 5C-7C warmer as compared to the surrounding rural areas. The UHI phenomenon is recognized as a direct consequence of urbanization

Scientists expect urban heat waves to increase in both intensity and frequency as cities in developing countries grow. A study of 30 years' weather records by the Shanghai Urban Environmental Meteorology Centre shows that warming differs according to the degree of urbanization, and that many more people die from extreme heat in built-up areas than in areas surrounding a city.

The Urban Heat Island effect is directly related to and has been worsened by climate change, where it is expected that an increase in the average temperature will have a stronger effect on the health of people living in cities, and particularly of the vulnerable groups like the sick and elderly.

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