By: Dr. Zawwar Hussain
There is a tendency to think of extreme heat as an unavoidable act of nature, something to be endured until the arrival of cooler winds. Yet Karachi’s increasingly oppressive summers tell a different story. While climate change is undeniably making heatwaves more frequent and severe across the world, the intensity of heat felt in Pakistan’s largest city is also the product of decades of human decisions. The relentless expansion of concrete, the disappearance of green spaces and the neglect of sound urban planning have transformed what was once a naturally ventilated coastal city into one that increasingly traps and amplifies heat.
Karachi enjoys a geographical advantage that many large cities would envy. Resting on the shores of the Arabian Sea, it has historically benefited from cooling sea breezes that moderated temperatures even during the hottest months of the year. Today, however, those natural advantages are steadily being eroded. Unchecked construction, poorly planned high-rise developments and shrinking open spaces have interrupted the movement of coastal winds that once acted as the city’s natural cooling system. The result is a city where even relatively moderate temperatures can feel dangerously high because humidity prevents the human body from cooling itself effectively.
This is not merely a question of discomfort. Heat has become one of the most pressing public health challenges facing urban Pakistan. Medical experts repeatedly warn that prolonged exposure to extreme temperatures increases the risks of heatstroke, dehydration, cardiovascular complications, kidney disease and respiratory illnesses. Those who suffer the greatest burden are often the people who contribute most to keeping the city functioning. Construction workers, sanitation staff, traffic police, delivery riders and countless labourers spend long hours outdoors with little protection from the blazing sun. Children, elderly citizens and pregnant women remain particularly vulnerable whenever temperatures climb.
Scientific evidence has consistently shown that cities absorb and retain far more heat than surrounding rural landscapes. Asphalt roads, concrete buildings, steel structures and glass façades store solar energy throughout the day before releasing it slowly after sunset. This phenomenon, known as the urban heat island effect, means that city residents continue to endure elevated temperatures long after daylight has faded. Karachi exemplifies this pattern with increasing severity. Instead of allowing nature to regulate the urban environment, development has often prioritised commercial expansion and transport infrastructure while treating trees and green spaces as optional luxuries rather than essential public assets.
This imbalance reflects a broader misunderstanding of what modern urban development should achieve. Roads, bridges and commercial centres undoubtedly support economic growth, but cities are ultimately built for people rather than vehicles or buildings. Healthy neighbourhoods require shaded streets, accessible parks, green belts and natural drainage systems just as much as they require efficient transport links. When every available piece of land is covered by concrete, the city gradually loses its ability to cool itself.
The disappearance of Karachi’s trees has been particularly costly. Mature trees perform services that no machine can replicate economically or sustainably. Through transpiration they release moisture into the atmosphere, naturally lowering surrounding temperatures. Their canopies provide shade, reduce surface heating, improve air quality, absorb carbon dioxide, support biodiversity and contribute to better mental health. Around the world, neighbourhoods with abundant tree cover consistently record lower surface temperatures than densely built districts with little vegetation.
Karachi remains fortunate in one important respect. Its climate offers a relatively long planting season, presenting an opportunity that should not be wasted. Large-scale plantation drives can certainly help, but success depends not on the number of saplings planted during ceremonial campaigns, but on the commitment to nurture them for years afterwards. A neglected sapling offers little environmental benefit. A healthy mature tree becomes an investment in the city’s future.
The challenge also demands a different philosophy of urban planning. Climate resilience can no longer remain an afterthought considered only after new developments are approved. Every housing scheme, commercial project and public building should incorporate green corridors, permeable landscapes, rainwater harvesting, reflective construction materials and designs that preserve natural airflow. Many coastal cities around the world have already embraced such approaches because they recognise that adapting to a warming climate is no longer optional but essential.
Individual responsibility matters as well. During periods of extreme heat, simple precautions such as remaining hydrated, limiting outdoor activity during the hottest hours, wearing light clothing and checking regularly on elderly relatives can save lives. Yet personal action alone cannot compensate for structural failures in city planning.
Karachi stands at a decisive moment. Continuing to replace nature with concrete will only deepen the city’s vulnerability to rising temperatures. Choosing instead to restore green spaces, protect coastal ventilation, preserve native vegetation and integrate environmental science into every stage of urban development would not simply reduce heat. It would improve public health, strengthen resilience against climate change and create a more liveable city for generations to come. The future of Karachi will depend not on how many buildings it constructs, but on how wisely it rebuilds its relationship with the natural environment that once sustained it.
(The writer is a PhD scholar with a strong research and analytical background and can be reached at news@metro-Morning.com)
