Last month, the effect of global warming were acutely felt by the residents of Karachi and Sindh, when a mercury hit a blistering 45 degrees Celsius – the more so heavily built-up areas were the ‘Heat Island Effect’ kicked in. The consequent death of thousand people is a dire warning of how extreme climate changes are expected to affect Pakistan in the years to come if immediate action is not taken.
The Heat Island Effect is used to describe metropolitan areas that become significantly hotter than their surroundings as a result of human activities. Karachi became an urban heat island because the sun’s intense heat was soaked up and then and radiated back out from concrete and glass structure and billboard which have replaced trees and other green spaces across the city.
Although provincial governments have an important role to play in creating and maintaining green spaces, you too can help mitigate the impact of future heat waves by initiating tree planting drives at your workplace, home, rooftop or the ‘wastelands’ in your neighbourhoods, vacant plots surrounding schools and other institutions and parking lots.
It takes time (depending on the species) dorm trees to grow big enough yo provide shade (something that Pakistani cities severely lack), and visibly reduce temperatures, through evaporative cooling (plants absorb atmospheric heat as water turns to vapor and evaporates from the tree/plant surface). So the sooner you start planting the better.
Tree species suitable for Karachi include coconut, date palms, guava , gulmohar, mango, neem, peepal and tamarind (imli). Young trees are ideal for planting and they are not very expensive with prices ranging between 500 and 1,800 rupees. Remember to purchase trees that are pot , bag or sack-grown from your local nursery , and not those that are bare-rooted or dug up straight from the earth as the latter are only suitable for winter planting. Plant them in carefully prepared planting holes and keep them watered- every evening initially and then every other evening once they take root.
By B Khan