Trees are Karachi’s natural defense against deadly heat, climate change and an increasingly unlivable city
By: Ramesh Raja
Hats off to the Karachi Press Club Environment Committee for bringing together environmental experts, climate activists, senior journalists and conservation professionals under the timely theme, “Karachi Without Trees: Environmental Degradation, Climate Change and the Future of Our City.” The initiative rightly warns that a “Karachi Without Trees” represents a dangerous future. In my view, Karachi’s environmental crisis can no longer be dismissed as a beautification issue. The disappearance of mature trees, shrinking green spaces, expanding concrete, traffic, air-conditioning and unplanned urbanization are converging with global warming to create a dangerous phenomenon: the Urban Heat Island (UHI).
The Jewel Must Not Become Coal
Karachi is the capital and most precious city of Sindh, its jewel and the economic heartbeat of Pakistan. A jewel must be protected, polished and preserved, not allowed to turn into coal. Sindh has already lost its ancient urban masterpiece, Mohenjo-daro, whose decline is associated with complex environmental, climatic, hydrological and other factors. The comparison does not mean Karachi will meet the same fate, but the historical warning is powerful: cities cannot remain sustainable when their relationship with nature is neglected.
An Urban Heat Island occurs when built-up areas become hotter than their less-developed surroundings. Concrete, asphalt, buildings and roofs absorb solar radiation and release it slowly, while vehicles, industries, generators and air-conditioning add waste heat. The removal of vegetation eliminates shade and evapotranspiration. British meteorologist Luke Howard documented London’s urban temperature differences in The Climate of London, first published in 1818, providing one of the earliest scientific accounts of the phenomenon. Karachi Is Already Getting Hotter
A 2026 study of major Pakistani cities found Karachi had the highest urban-rural temperature differential, approximately 4.5°C, compared with 4.1°C in Lahore, 3.8°C in Faisalabad and 2.5°C in Islamabad. It also found a strong inverse relationship between vegetation and land-surface temperature.
This local heat problem is occurring against unprecedented global warming. The World Meteorological Organization reports that 2015-2025 were the eleven warmest years on record, while 2025 was approximately 1.43-1.44°C above the 1850-1900 pre-industrial average. In 2024, atmospheric concentrations reached approximately 423.9 ppm CO₂, 1,942 ppb methane and 338 ppb nitrous oxide, around 52%, 166% and 25% above pre-industrial levels respectively.
The Paris Agreement seeks to keep warming well below 2°C while pursuing 1.5°C. A 1.5°C pathway requires global emissions to fall approximately 43% by 2030 from 2019 levels. The implication for Karachi is clear: global warming raises the temperature baseline, while UHI adds a locally manufactured heat burden.
Trees Are Infrastructure, Not Decoration
A mature tree is living urban infrastructure. Its canopy provides shade, evapotranspiration and cooling while improving air quality, biodiversity and human comfort. Removing a mature tree and planting two or three saplings cannot immediately replace its environmental value because a sapling requires years to develop comparable canopy.
The issue has already reached the Sindh High Court, which directed authorities to avoid unnecessary tree cutting and ordered a survey of Karachi’s trees. During proceedings, the Sindh Environmental Protection Agency reported that more than 3,800 trees had been cut for the Red Line project.
Satellite data also need careful interpretation. Global Forest Watch records about 5 hectares of tree-cover loss in Karachi from 2001-2025, equivalent to 0.69% of its 2000 tree-cover area, while recording approximately 320 hectares of tree-cover gain between 2000 and 2020. These figures are not a complete count of individual urban trees, demonstrating why Karachi urgently needs a transparent GIS-based tree and canopy inventory.
The wider Sindh picture is equally important. The Sindh Forest Department reports 14.099 million hectares of provincial land, with 1.384 million hectares under the Forest Department. Riverine forests and irrigated plantations account for only about 2.29% of total provincial land. Sindh has approximately 0.595 million acres of riverine forests, 0.202 million acres of irrigated plantations, and 1.5 million acres of mangroves and 1.129 million acres of rangelands. Estimated wood-energy demand is 6.4 million cubic meters against 1.68 million cubic meters of sustained supply, leaving a deficit of about 4.72 million cubic meters.
Trees Alone Cannot Cool Karachi
Trees are essential, but they are not the only UHI solution. Karachi is too densely developed to depend on plantation alone. International practice combines urban forestry, cool roofs, green roofs, cool and permeable pavements, shaded pedestrian routes, reflective surfaces, energy-efficient buildings, urban ventilation, cleaner transport and blue-green infrastructure.
This is particularly important where land is unavailable. Karachi has enormous roof area, making cool roofs a major opportunity. The US EPA reports that cool roofs can reduce maximum indoor temperatures in non-air-conditioned buildings by approximately 1.2-3.3°C. Green roofs can provide additional cooling where structural capacity and maintenance permit. Cool pavements can reduce surface temperatures, while shaded walkways, bus stops and pergolas can protect pedestrians where trees cannot be planted.
The city should also reduce waste heat through efficient buildings, air-conditioning, transport and energy systems, while protecting mangroves, wetlands and other blue-green infrastructure.
From Plantation Drives to a Cool Karachi
Karachi needs a permanent Urban Heat Island Management and Heat Resilience Program, beginning with a Karachi Urban Heat Atlas using satellites, GIS, weather stations, drones and field measurements to identify the hottest and most vulnerable neighborhoods. Every major road, flyover, BRT corridor, bridge and development project should undergo a Tree and Urban Heat Impact Assessment, with mature trees retained wherever design modifications can make that possible.
The city should establish neighborhood-level tree-canopy targets, legally protect existing parks and green belts, and judge plantation programs by five- and ten-year survival and canopy growth, not the number of saplings planted on launch day. Public buildings, schools and hospitals can become cooling zones through shaded grounds, cool roofs and better ventilation. A permanent Heat Action Plan should provide early warnings, cooling centers, water access and protection for outdoor workers and vulnerable populations.
Ultimately, Karachi must change its definition of development. A road is infrastructure, but so is a mature tree; a bridge is infrastructure, but so is a park; and a building is infrastructure, but so is a mangrove forest. Karachi cannot stop global warming alone, but it can stop unnecessarily manufacturing additional heat through unchecked concrete expansion, loss of vegetation, inefficient buildings and poorly planned urbanization. The warning is before us, the science is available and the solutions are known. Karachi is the jewel of Sindh, and a jewel must be protected, not allowed to turn into coal. The real question is therefore no longer whether Karachi can afford to protect its trees, but whether Karachi can afford to lose them.
Read: Every AI Answer Costs the Environment
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The author of this article, Engr. Ramesh Raja, is a Civil Engineer, visionary planner, PMP certified and literary enthusiast with a passion for art and recreation. He can be reached at engineer.raja@gmail.com
