Redirected from Urban heat island effect
Scientists believe this effect is caused mostly by the difference in albedo between the generally dark surfaces of a city - tarmac from roads, etc - and the vegetation that the city/suburbs has replaced. These dark surfaces absorb sunlight, heat up, and retain more of this heat than the suburban areas. A contributing factor is the lack of evapotranspiration from vegetation. Finally, hot air from vehicle exhausts and from industry heats up the air further.
One consequence of urban heat islands is the increased energy required for air conditioning and refrigeration. This is particularly true for cities that are already in comparatively hot climates. The Heat Island Group estimates that the heat island effect costs Los Angeles about $100 million per year in energy.
The heat island effect can be countered by using white or reflective materials to build houses, pavements, and roads. This is a long established practice in many countries. Another option is to increase the amount of well watered vegetation.
The view of the Intergovernmental Panel on Climate Change is that the effects of urban heat islands on the recorded temperature "do not exceed about 0.05°C over the period 1900 to 1990". This rests on various sources, contributing reasons being [1] (http://www.grida.no/climate/ipcc_tar/wg1/052.htm#222):
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