In the deadly grip of heat waves again!
With an ongoing heat wave, Karachi is in a critical need of de-concretization to cool it off, or the regularity of such events will lead to further misery and mayhem in an already challenged city reaching a population of 30 million.
The price of unchecked development translating into nothing more than concrete all the way is becoming a self-evident truth in the form of heat waves in Karachi. Overall, not only has incessant industrialization and urbanization destroyed its natural environment, but ironically threatens the very existence of the people it supports.
Climate change is real, is happening and is a key global crisis we face. Countless on the planet are suffering due to increased disasters such as hurricanes, droughts, and heat waves. The impact on Pakistan in general is and will be quite severe, starting with floods and now the yearly droughts. Global warming is creating this havoc, which is the abnormal rise in temperature due to excess emission of greenhouse gases which lead to abnormal heating.
Karachi is particularly hard hit by this rise in temperature as well the resulting change in climate due to global warming. It is indeed alarming to see a regularity of 40 degrees Celsius plus temperatures in the summers across the country, and by late May, heat waves killed about 65 people with highs recorded above 50 Celsius in places like Nawabshah. The impact on Pakistan has been quite severe in this regard and the tragic 2015 heat wave which hit Karachi in July left more than 1200 dead. This was partly due to the “urban heat island” effect and global warming, which is the abnormal rise in temperature due to excess emission of so-called greenhouse gases. Much due to excessive deforestation and built structures, the “urban heat island” effect adds to considerable rise in temperatures to such highly populated areas leading to tragic consequences which will only become harrowing unless steps are taken now.
Granted summers are generally hot, however, it is scientifically known that cities themselves possess unique climates. This is because cities usually have a dense amount of buildings and infrastructure as well as concentrated amount of population, especially cities like Karachi, Lahore and Islamabad. Karachi and other cities suffer through heat waves which were predicted by the Pakistan Meteorological Department in advance, however, while we may know when these heat waves strike, what can we do to stop their severe impacts?
The excessive impacts due to heat are due to the “urban heat island” effect and global warming adds to this effect, which is literally adding fuel to the fire. Much due to excessive deforestation and built structures, the heat island effect adds to considerable rise in temperatures to such highly populated areas leading to tragic consequences which will only become harrowing unless steps are taken now.
The heat island effect is nothing more than built structures retaining more heat, while natural buffers such as forests do exactly the opposite, they absorb extremes of temperature and climate in general. It is well known that temperatures in urban areas are different from suburban and rural areas, due to this effect. The difference can be quite dramatic, in fact, cities are measured to have up to 10 degrees Celsius higher than neighboring rural and sub-urban regions. This effect, caused by excessive infrastructure that is built with concrete, asphalt and other inorganic materials, leading to greater heat reflection and storage. Loss of vegetation and trees also end up creating unnatural conditions, as trees provide efficient heat absorption, shade and moisture that lowers temperatures. Thus, this leads to an overall increase in the temperature of the urban region (see “What is “heat island effect?” for details).
The key reason is the creation of concrete jungle that Karachi has become, with unabashed urbanization, open spaced being encroached upon, and housed being replaced with high rise buildings. Ironically, this is viewed as normal in our cities.
What used to be the ‘City of Gardens’ in the 1920s, has fallen victim to the land and builder mafia. The first casualty of land clearing is urban forestry, that accompanies “development” in almost all forms. Trees and vegetation are considered to lower temperatures locally, and thus unchecked deforestation turns out to be a real killer of cities. In other words, what happens thus is that barren centers of man made creations breed ground for excessive and life-threatening heat waves. Many cities across the world maintain these natural buffers in the form of parks, open spaces, grounds, and city forests. Even if we were to look at financial capitals like London, England, the forest area is 47 percent. In sharp contrast, Karachi’s forest area has shrunk to hardly 7%.
Trees provide a first line defense against temperature extremes. Since they are composed of organic material, provide shade, they can absorb a lot of the reflected heat and hold it. Further, they release moisture in the air, also termed as “evapotranspiration” which again leads to a lessening of ambient temperature in the vicinity.
In this regard, the present state of green cover in Pakistan is lamentable, especially in the urban centers like Karachi and so, is it any wonder that we are experiencing the increased impacts of these heat waves? We are sitting squarely at 2% against a required 25% for a healthy environment. Further, our officials talk a lot about planting a million saplings here or there, without focusing on the cities in terms of addressing this deadly “heat island effect.”
To further compound the situation, the City Government continues to plant Conocarpus, an exotic tree across Karachi, which actually creates more harm than good. The Forest department is all too keen to stay in the forests, while urban planning ministries are making a meal of all this by investing in construction. Highways, apartment buildings, office centers are allowed, while builders are given free rein to create all they can, without understanding both the short-term and long-term effects of this excessive development.
Climate Change: Fuel to the Fire
On a larger scale, climate change is the biggest threat the planet faces today. Its gravity, however, is not translated into policy interventions in Pakistan. Less debated and least bothered, this issue is yet to come out of the scientific quarters in country where climate change has already started taking toll on the lives and livelihood of people.
Long droughts, extended heat waves, delayed monsoon rains and floods are what Pakistanis observe every year. The frequent power outages in scorching summer heat make the situation worse. People do discuss the changing weather patterns but except for few, all are clueless as to why the nature has started behaving oddly.
In 2001, scientists declared that overwhelming odds pointed to global average temperatures rising 4 to 7 degrees over the coming century. As early as 2030 the planet would likely heat up 1 to 2 degrees. By comparison, a one-degree temperature rise was observed over the past century. In 2007, a United Nations panel of 2500 scientists from 130 countries concluded that temperatures are likely to rise 5.4 degrees (3 degrees Celsius) by the year 2100.
In some parts of world, extraordinary drier weather is predicted in coming decades while in some regions, much more rain is anticipated as the ice caps melt. Agricultural patterns worldwide are being affected. Rising sea levels mean future storms could cause much more severe flooding than anticipated otherwise, in low-lying coastal areas. This situation is to hit severely the life and livelihood of humanity besides posing serious threats to other species of life.
Pakistan is not heavily industrialized, but alarmingly its ratio of emitting harmful gases is much higher. There are some ineffective laws, while their enforcement is still to see the light of day. No industry has ever been seriously punished for not taking care of measures necessary to control harmful emissions.
The climate change issue is directly linked with the lives of people; but sadly, the debate on the issue is still to come out of political spheres in Pakistan. The relationship of global warming with the health and livelihood of the people is well established scientifically, but little to no efforts are made to involve people in counter strategies or to disseminate the information in some comprehendible format.
To address the rising amount of heat waves in the cities, the situation becomes doubly worse. It is not just that greenhouse emissions be curbed, however and more importantly, the heat island effect needs to be considered especially in the case of Pakistan, one of the fastest urbanizing nations in the world. This requires proper landscaping, increased vegetation through afforestation strategies as well as stopping deforestation. Building buildings, concrete highways and infrastructure endlessly will escalate the already dire situation that is wreaking havoc across the nation and can ultimately drown our cities forever.
What is Global Warming?
Global warming is the increase in the average temperature of the Earth’s near-surface air and oceans since the mid-20th century and its projected continuation. The Intergovernmental Panel on Climate Change (IPCC) concludes that increasing greenhouse gas concentrations resulting from human activity such as fossil fuel burning and deforestation are responsible for most of the observed temperature increase since the middle of the 20th century.
Climate model projections summarized in the latest IPCC report indicate that the global surface temperature will probably rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century. Increasing global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts. The continuing retreat of glaciers, permafrost and sea ice is expected, with the Arctic region being particularly affected. Other likely effects include shrinkage of the Amazon rainforest and Boreal forests, increases in the intensity of extreme weather events, species extinctions, and changes in agricultural yields.
What is the Heat Island Effect?
An urban heat island (UHI) is a metropolitan area, which is significantly warmer than its surrounding rural areas. The temperature difference usually is larger at night than during the day and larger in winter than in summer, and is most apparent when winds are weak. The main cause of the urban heat island is modification of the land surface by urban development; waste heat generated by energy usage is a secondary contributor. As population centers grow, they tend to modify a greater and greater area of land and have a corresponding increase in average temperature. The UHI decreases air quality by allowing pollutants such as ozone to form, and decreases water quality as warmer waters flow into area streams, which stresses their ecosystems. The energy and health costs of the urban dwellers also increase due to UHI.
How a tree contributes to betterment of environment?
Besides their main role of absorbing carbon dioxide in photosynthesis process and producing oxygen for us, research has shown that plant leaves also act as biological filters, removing large quantities of particles from the urban atmosphere. Stomata are microscopic pores on the underside (abaxial) of the leaf. These allow air into and out of the leaf through which the plant takes in carbon dioxide and lets out oxygen, and allows water vapor out in the process of transpiration. As air passes through the stomata, most of the airborne particles will not pass through the stomata but will rather eliminated on the leaf’s outer surface due to available moisture. In this release of moisture, the tree also reduces the temperature, thus reducing the dangerous effects of “urban heat island effect” considerably.
Writer: Prof. Farrukh Chishtie