Temperature of Karachi city
The temperature of Karachi City is due to the urban heat island (UHI), a phenomenon where urban areas experience significantly higher temperatures than surrounding rural areas due to the concentration of heat-absorbing surfaces, human activities, and urban infrastructure. The more population, the higher the use of vehicles and their exhaust, and the more industrial units that produce heat and greenhouse gases that are the main cause of heat in the urban areas. The urban area has fewer plants to absorb heat and carbon dioxide produced from industries and vehicles on the road. This leads to a microclimate with elevated temperatures, often 1-3°C (1.8-5.4°F) higher than in nearby rural areas. However, the rural area has plains or is irrigated with crops and trees that may release water vapor and absorb heat, and heat can’t be retained in the plain or on watery areas.
Causes of Urban Heat Island (UHI)
Heat-absorbing surfaces
Dark-colored pavement, buildings, and roofs absorb solar radiation, heating up the surroundings. Urban areas have more populated buildings and congested buildings that retain more heat and get cities hotter than rural areas.
Urban canyons & the temperature of Karachi city
Tall buildings and narrow streets create canyons that trap heat and reduce airflow. Cities should be made according to air flow and ventilation in homes or buildings to minimize heat retention and protect the environment from higher temperatures and environmental pollution due to population.
Vehicle emissions & Temperature of Karachi city
Vehicles emit heat and pollutants, contributing to the Urban Heat Island (UHI) effect. According to some research, 40 percent of air pollution is due to vehicular emissions, mainly in urban areas.
Industrial activities Results Temperature of Karachi city
Industrial processes, such as manufacturing and energy generation, release heat into the environment. Urban areas have more industries due to the facilitation of raw materials and dispatch of products. Industrial units in urban areas create more heat and air pollutants in the atmosphere that create or help to increase the urban heat island.
Population density Results Temperature of Karachi city
High population density leads to increased human activity, energy consumption, and waste heat generation. Higher pollution in urban areas also creates more waste and pollution and low awareness of the disposal of waste from homes and even in industrial units. Industries are bound through the environment department of the state for proper disposal of waste, which is either incinerated or recycled.
Lack of green spaces results Temperature of Karachi city
Limited vegetation and green areas reduce the cooling effect of evapotranspiration. Urban areas have less space for plantation and irrigation of crops that also increase the heat and affect the Urban Heat Island (UHI).
Effects of Urban Heat Islands UHI
Heat-related illnesses and mortality Increased energy consumption and costs, Air pollution and poor air quality, Heat stress on urban infrastructure and buildings, Impacts on urban ecosystems and biodiversity
Economic and social disparities, as vulnerable populations are often more affected
Less life of building and materials
Diseases due to air pollution like asthma and lung problems
Mitigation strategies for the temperature of Karachi city
Green infrastructure
Plant trees, green roofs, and urban gardens to increase evapotranspiration and shading. Every home and building should have a green belt area for vegetation and plantation to reduce heat in urban areas. Roads should be planted with trees because the emission exhaust of vehicles is covered and absorbed at the road to reduce pollution.
Cool materials
Use light-colored, reflective materials for pavement, roofs, and buildings because that may reduce the amount of light absorbed by the material and building. Dark colors absorb more heat than lighter color shades.
Urban planning for urban heat island (UHI)
Design cities with green spaces, parks, and public squares to reduce urban density. Every building should have a green belt area, and societies or residential societies should have parks and playgrounds to reduce heat absorption, and societies should be well ventilated because of green areas, evaporation of water, and absorption of heat.
Energy-efficient buildings
Implement energy-saving technologies and designs to reduce heat generation. Even all the appliances should be energy-saving, and buildings should be well ventilated, while the design of buildings should be advanced.
Transportation & Urban Heat Island UHI
Promote public transportation, walking, and cycling to reduce vehicle emissions. Cycling is an important step to reduce vehicular emissions; for long routes, use of public transport is feasible. The government should increase public transport and facilitate the public so they don’t use separate or their own vehicles.
Climate-sensitive urban design
Consider local climate conditions and heat island effects in urban planning and development. In the less developed countries no one is using this technology to save the environment and reduce the heat by using climate-sensitive building designs and maps. Furthermore, it should always follow environmental law to reduce the effects of global warming and urban heat islands. Additionally, small cities may develop to reduce heating of buildings and effects of urban population and all other matters faced by the public.