In May this year, Karachi fell victim to another heat-wave as the temperature rose as high as 43 degrees Celsius. Climate change is a global phenomenon that has escalated the average temperatures of the world. In Pakistan, none of the cities are affected as intensely as Karachi. The episodes of the 2015 heat-wave still represent shock and horror in the public consciousness. The World Meteorological Organization (WMO) states that, ‘a heat-wave occurs when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by five degrees Celsius’. Hence, we can conclude that heat-waves are infrequent phases of hot and humid or hot and dry conditions, which last from three to five days during a summer season.
The three days of horrific heat-wave in 2015 costed more than 1200 human lives. However, the Daily Times posted a startling revelation that according to independent estimates, more than 10,000 people perished just in three days of the heat wave due to heat-strokes and de-hydration. On the heat index scale during those days, the reported extreme temperature was at 44.8 degrees Celsius while the heat index was around 66 degrees Celsius at its peak i.e., 20 June, 2015. This was accompanied by low air pressure and wind speed with very high humidity.
Due to ill-conceived policies and rampant corruption in related government departments, the city is deemed as fifth most polluted city in the world according to findings of World Economic Forum in 2015.
A population boom has expanded the city of Karachi both vertically and horizontally, which has made it an Urban Heat Island (UHI). Technical reports on Karachi heat-waves in June, 2015 by the Ministry of Climate Change revealed that UHI has largely exacerbated the intensity of heat wave and led to a large number of fatalities in Karachi. It was stated, ‘many urban and suburban areas experience elevated temperatures compared to their outlying rural surroundings; this difference in temperature is what constitutes an urban heat island’.
The main cause of UHI is the loss of trees and vegetation in urban areas. These urban centers are now characterized by dry impervious surfaces such as straight roofs, sidewalks, roads and parking areas. And because the city continues to grow with the passage of time, much of the greenery has been lost and it is, therefore, responsible for lower surface temperatures. As greenery plays its part in the reduction of air temperatures via a process known as evapotranspiration, the paucity of vegetation and trees contributes to the elevation of surface and air temperatures. Moreover, the characteristics of various urban materials like the solar reflectance, thermal emissivity, and heat capacity also influence UHI, as they determine how the sun’s energy is reflected, emitted, and absorbed. Darker surface reflects less solar energy than a lighter one, but it is obvious that most of the material used for construction in Karachi has a darker surface.
In addition to this, high-rise buildings are generally conceived as a solution to provide housing facility to an overgrowing population in cities. However, such buildings have problems of their own as they also act as a bulwark against cool sea breezes from sea towards the city. They also reflect less and absorb more of the sun’s energy due to dark surface and contribute to the formation of UHI. The heat capacity of material used in construction is another cause of UHI development. Construction materials like steel and stone have higher heat tendency which is the reason why metropolitan areas can absorb and store twice the amount of heat in stark contrast to rural surroundings.
In case of Karachi, the authorities have failed to make proper arrangement for almost 12,000 tonnes of garbage which is produce daily in the city. The garbage heaps also emit a plethora of harmful gases, adding more heat in the atmosphere. Furthermore, the ownership of vehicles and bikes is growing at a rate of approximately 14 per cent per year (over 500 new vehicles joining the road network each day), which means that more smoke is being injected into the environment with the passage of time.
Due to ill-conceived policies and rampant corruption in related government departments, the city is deemed as fifth most polluted city in the world according to findings of World Economic Forum in 2015. Moreover, ‘Climate Change Action’ is among the 17 Sustainable Development Goals of the United Nations. However, the Environmental Protection Law was finally enacted in 2014, four years after the protection of environment was placed under the responsibilities of the provinces under the 18th Amendment. But deteriorating environmental condition of the city has revealed that much is left wanting when it comes to the implementation of this law.
Karachi, being a pivot of national economics, cannot absorb the shock of natural calamities as it directly affects the productivity of manpower and significantly disturbs the overall equilibrium of the economy. With implementation of rules and regulations, some measures should be opted by authorities and citizens. Urban forestry is considered as the best way to cope with environmental hazards by environmental experts. According to the Forest Department of the Government of Pakistan, 15 tonnes of harmful particles from the air can be removed yearly by one hectare of mixed forest. Hence, a country or city must possess 20 to 25 per cent of forest for a clean environment.
In addition to this, research has also revealed that energy consumption in a house with trees can be 20 to 25 per cent lower per year than that for the same house in an open area. Therefore, Urban Forestry is the best solution to fight rising temperature. is quite famous for its abundant trees (8.4 million), which cover 20 per cent of the city and eliminate 2241 tonnes of pollution per year. Moreover, about 132.7 million pounds worth of benefit a year is also provided by these trees to the British capital. Chicago is another success story of urban forestry with 3,585,000 trees capable of removing 888 tonnes per year pollution from the air, which is valued $6.4 million per year. Barcelona has 150,000 trees (3,611 hectares of green infrastructure covering 35.3 per cent of the city land), which eliminate 305 tonnes of air pollutants. Toronto is another triumph of urban forestry as it owns 10.2 million trees which provide at least $28.2 million in ecological amenities each year.
According to the Forest Department of the Government of Pakistan, 15 tonnes of harmful particles from the air can be removed yearly by one hectare of mixed forest. Hence, a country or city must possess 20 to 25 per cent of forest for a clean environment.
One would assume that by learning from these instances, the government ought to plant more trees. However on the contrary, it chose to cut the existing trees especially for the construction of Bus Rapid Transport system (BRT). A report on Environmental Impact Assessment (EIA) states that 16,637 trees of 72 species have been cut for the development of Green Line Bus project. Liaquat Ali Khan, CDGK’s Former Executive Director for parks and horticulture, revealed that Karachi had four million trees which are fading rapidly. A recent study draws up the curtain that Karachi has only 10 species of birds, which shows that most species of birds have either vanished or migrated since there is a severe lack of trees in the city.
It is not hard to understand that coping with heat waves and UHI is not just the responsibility of government rather, the citizens should be partners to serve and maintain the city’s ecology too. Corporate sector is obligated to fulfill its corporate social responsibility (CSR) to plant more trees in the city. If local administration of the city is running out of budget, they should work with the corporate sector. NGOs, in tandem with government, should engage themselves in these activities as well. Moreover, Conocarpus trees were planted in plentiful in the past in spite of the fact that they are not apt for Karachi. So other types of trees like Neem, Peepal, Gulmohar and fruit trees should be planted instead of Conocarpus. Likewise, vertical gardening is another new technique to reduce elevated temperature. Additionally, masses should choose a ‘cool-roof’ for their houses and offices and should paint their houses from outside with greenish paints.
Lastly, the concerned regulatory departments should also cut off taxes which are levied on those materials that can curtail UHI. By embarking upon the measures above, we can take concrete steps to make our city breathable and live-able. Otherwise, the current scenario and developmental trajectory suggests that we will be leaving a desert for our future generation.