Preparing for the worst

In recent years, heatwaves are getting more intense and prolonged. Usually, heatwaves are experienced during the months of March, April and May in Bangladesh. People experienced hot to very hot summers also in the past. But the use of the term heatwave is rather recent in this part of the world. Heatwaves are a period of abnormally hot weather. But depending on the usual climatic condition of the area concerned, the definition of heatwave may vary. Bangladesh has a subtropical monsoon climate. And summertime air in Bangladesh is marked by a high level of humidity. And the mixture of heatwave and high level of humidity is very toxic as it is the main cause of heatstroke. So, heatwaves are also a serious public health issue in Bangladesh. 

Nowadays, many would like to explain heatwaves as a fallout from   climate change which causes global warming. In fact, we are having fewer cold days during the winter. And this is happening not just in Bangladesh and other South Asian countries. Of late, the traditionally cold countries of Europe and North America are also experiencing fewer cold days. Extremely hot summers with long spells of heatwaves are now common in those countries.

In July 2023, for example, the world broke its record for the hottest days on record, four days in a row. Recent scientific studies done in the USA project that, annually, the number of days with a heat index over 100 degrees Fahrenheit or 37.77 degrees Celsius will double and those with heat index above 105 degrees Fahrenheit (40.55 degrees Celsius) will triple in that country, when compared to the end of 20th century. Though such studies have not been done in Bangladesh, the trend says it all. The recent years, especially 2014, 2016, 2019, 2002 and 223 saw extreme heatwaves. But 2023, as elsewhere in the world, experienced the longest spell of heatwave in April for two weeks at a stretch. And, according to the Met office, in 2023, the heatwave continued for 20 to 23 days in a row.

What about 2024? Going by the Met office, there is no good news so far as the mercury level for the current month of April is concerned. Bangladesh Meteorology Department (BMD) fears that heatwaves this year may continue for longer periods than in the past years.

The district of Chuadanga on Sunday (April 6) experienced the hottest spell at 40.2 degrees Celsius. On the same day, other districts including Pabna, Barishal, Patuakhali, Rangamati experienced strong heatwaves, though Rajshahi, Rangpur, Khulna and Dhaka experienced mild to moderate heatwave. The Met office has already issued 'heat alert' .In Bangladesh. Heat alert is issued when the temperature of a place rises over 36 degrees Celsius. Meanwhile, a number of heat alerts have been issued by the Met office following heatwaves sweeping across different districts, especially Chuadanga and the Ishwardi mupazila of Pabna district. Currently, the phenomena of extreme temperatures are being observed in the north-western districts of the country. The proximity of those Bangladeshi districts to the states of West Bengal, Bihar and Uttar Pradesh of neighbouring India has made those areas susceptible to higher temperatures. Notably, in this time of the year, the temperatures in those Indian states range between 42 and 48 degrees Celsius. Last year, the temperature rose to as high as 52 degrees Celsius in some areas of those Indian states.  And the hot air generated there flows across the border into the districts of Jashore, Kushtia and Rajshahi in Bangladesh raising temperatures of those and other adjacent districts.

The phenomena of extreme temperatures and related heatwaves are now a global reality, which is being attributed to climate change. A study was done in South Pole, the coldest region of this planet, at a research centre located in its eastern plateau. Recorded on March 18 of 2022, the result shocked scientists. The temperature recorded was 38.5 degrees Celsius above the average seasonal temperature of that region.

So, we will have to brace ourselves for the worst to come in the days ahead.

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