As sea breeze resumes, Karachi gets some respite — for now

Karachi breathed a sigh of relief on Thursday, as the temperature in the city dropped to a maximum of 37 degrees Celsius, providing a much needed respite after a five-day heatwave.

“The temperature in Karachi dropped by six degrees from yesterday [Wednesday] due to resumption of sea breeze,” said Met Office city chief Abdur Rashid. “The weather is expected to remain pleasant for a few days.”

Met officials said they were not expecting the weather to turn pleasant before Friday, but conditions have been changing rapidly in the Arabian Sea, and under their influence there is an extreme variation in the wind direction in the city. But Pakistan Meteorological Department chief Dr Ghulam Rasool warned of another heatwave that is expected in the city by the end of this month or by the start of the next due to rapidly changing conditions and temperature in the Arabian Sea.

The UHI effect

The urban heat island (UHI) effect is another cause for concern for meteorologists. In the absence of sea breeze for several days the city’s temperature remained hot even during the night, as trillions of tons of concrete traps heat during the day and starts radiating it in the night.

It is because of the UHI effect that hundreds of people had died in Karachi in 2015, when the metropolis was deprived of sea breeze and warm wind was trapped in the city for several days, keeping the temperature as high as 46°C but feeling like 52 to 55°C due to high humidity.

“There is an urgent need to stop constructions in Karachi and to bring an end to the city’s vertical and horizontal expansion,” said environmentalist Nasar Usmani. “Now this city needs more trees, not more buildings and concrete structures.”  

Heatwaves

No one was officially reported dead during the five-day heatwave in Karachi, most probably due to a lack of humidity and the growing awareness among people.

In the 2015 spell, however, thousands of people had died after a deadly heatwave triggered by a well-marked depression in the Arabian Sea had deprived the city of sea breeze for four to five days.

The metropolis has witnessed three heatwaves so far this year since March. Weather pundits say chances of a few more heatwaves are very likely, one of which can strike within a few days.

“For the past few years, the temperature of the Arabian Sea has been on the rise, and the frequency of the forming of low pressure areas has increased in summers,” said Dr Rasool. “These low pressure areas cut off sea breeze towards the coast, especially towards Karachi, and under the influence of warm and dry winds the city’s temperature starts shooting.”

He said that although no one died due to the hot and dry weather conditions in the city during this year’s heatwaves, as humidity levels remained very low and reduced the chances of heatstroke, it cannot be predicted if the next spell will be as benign.

He requested that people and state organisations remain on high alert for the next couple of months, advised everyone to adopt precautionary measures to prevent heatstroke and stressed that it would be wise to adapt to the changing climatic and weather conditions.