01 · The problem
What is happening
Karachi experiences high temperatures combined with coastal humidity, which limits the human body's ability to cool by sweating. The 2015 heatwave caused widespread heat-related illness and deaths, documented by Pakistani authorities and in peer-reviewed public health literature. Risk is concentrated among outdoor workers, people without reliable electricity for fans or cooling, and residents of dense, poorly ventilated housing with little shade.
High severity. Serious, widespread effects requiring sustained action. Severity is descriptive editorial metadata summarising documented effects. It is not a measured index or a score.
02 · Causes
Why it is happening
- 01
Humid coastal climate
High humidity limits evaporative cooling, so the body struggles to shed heat even at moderate air temperatures.
- 02
Urban heat island
Dense construction, dark surfaces and limited vegetation keep built-up areas warmer than surroundings, especially at night.
- 03
Unreliable electricity supply
Power interruptions during peak demand remove access to fans and cooling exactly when risk is highest.
03 · Impacts
Who and what it affects
- 01
Heat-related illness and death
The 2015 heatwave produced mass casualties, with hospitals overwhelmed by heatstroke and dehydration cases.
- 02
Occupational risk for outdoor workers
Construction workers, street vendors and transport workers face sustained exposure with limited opportunity to rest or cool.
- 03
Strain on power and water systems
Cooling demand peaks at the same time as water demand, stressing both networks simultaneously.
04 · Solutions
Documented approaches
Heat action plans
Early warning, public advisories, cooling centres and pre-positioned medical response before forecast heat events.
Expected effectReduces heat-related illness and death; the approach is proven in several South Asian cities.
Shade, water points and cool surfaces
Shade structures, public drinking water and reflective or vegetated surfaces in high-exposure areas.
Expected effectLowers exposure for outdoor workers and pedestrians at relatively low cost.
Reliable power during heat events
Prioritising supply continuity for vulnerable areas and health facilities during heatwaves.
Expected effectMaintains access to cooling exactly when risk peaks.
05 · Key indicators
What can be measured
- 2015 heatwave
- Mass casualty event2015
The June 2015 heatwave caused a documented surge in heat-related deaths in Karachi. Reported totals vary by source and counting method.
- WHO heat-health guidance
- Heat action plans recommended2021
WHO and WMO recommend heat-health warning systems for cities exposed to dangerous heat.
06 · Sources
Where this comes from
- [1]Heatwaves: health topic and heat-health warning guidanceWorld Health Organizationwho.int(opens in a new tab)
- [2]Heat and health fact sheetWorld Health Organizationwho.int(opens in a new tab)
Links open the publishing organisation's site. Some point to the publisher's main page, where the named report or dataset can be found.