Social Sustainability
Urban Heat Island (UHI)
Definition
The urban heat island is the temperature difference between urban areas and their rural surroundings, caused by dark, heat-absorbing surfaces (asphalt, roofing), loss of vegetation and evaporative cooling, waste heat from vehicles and air conditioning, and canyon geometry trapping heat. Differences reach several degrees — strongest at night, when stored heat releases — and UHI amplifies heatwave mortality, raises cooling energy demand and worsens smog; climate warming and UHI combine additively in city heat risk.
References
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This reference provides supporting context for how “Urban Heat Island (UHI)” is defined and used.
Overview
How it is used
The concept structures heat action plans, cool city programmes, urban greening investment and heat-health vulnerability mapping.
Why it matters
The urban heat island is where global warming lands on actual bodies; fighting it is among the most cost-effective adaptations cities own.