Bangladesh is losing sunshine hours across all seasons, steadily and substantially, as air pollution has kept worsening, compounding the impacts of climate change in one of the world鈥檚 most climate-vulnerable countries.
In the pre-monsoon season stretching between March and May, 0.76 hours of sunshine were lost every decade since 1980, representing the second largest loss of sunlight after the winter season - December to February, when in every decade the loss of sunshine hour was 0.83 hours, according to a recent study released by the Bangladesh Meteorological Department.
The monsoon and post-monsoon seasons also saw a significant decrease in sunshine hours.
Illegal brick kilns, unfit vehicles, mega-infrastructural projects, construction activities, and the increased use of fossil fuels, especially for power generation, have become an eternal source of airborne particles, including dust, dirt, soot, and smoke.
Under favourable conditions, these airborne particles give rise to thick layers of fog, blocking sunlight for long hours, according to weather and environmental scientists.
Trans-boundary pollutants travelling from India, Pakistan, and Afghanistan over Bangladesh have further worsened the situation, particularly over five months a year, though the presence of dense fog blocking sunlight is observed all over the year by the BMD.
Sunlight, the source of life, going away is sure to have serious consequences, environmental experts and agriculturists said, explaining its negative impacts on public health and nature, potentially leading to catastrophic consequences.
The impacts of disappearing sunlight stay across all seasons, the experts said, intensifying cold feelings in short-lived winters, indirectly facilitating global warming, exposing public health to various hazards, and decimating crop production.
鈥榃atching sunlight hours diminish is like seeing life slip through your fingers,鈥� said Ahmad Kamruzzaman Majumder, who teaches environmental science at Stamford University Bangladesh.
The BMD, in its report titled 鈥楥hanging Climate of Bangladesh,鈥� revealed that winter days lost more sunlight than days in any other season.
In each of the four decades since 1980, the report said, the winter season lost 0.83 hours of sunlight, implying that by 2020, the winter season received 3.32 hours less sunlight each day than it did four decades ago.
The pre-monsoon months lost a cumulative 3 hours of sunlight in the four decades since 1980, the report said.
Monsoon season - June to August - has lost 0.32 hours of sunlight every decade since 1980, with a cumulative loss of 1.28 hours of sunlight per day by 2020.
The post-monsoon season 鈥� September to November - has lost 0.29 hours of sunlight every decade since 1980 with a cumulative loss of one hour of sunlight per day over four decades.
The BMD report noted that Dhaka, Bogura, and Jashore recorded the most significant decrease in sunlight hours.
鈥楶ollution is mainly responsible for the loss. Airborne pollutants work as a platform for fog to form,鈥� senior meteorologist Muhammad Abul Kalam Mallik told 抖阴精品.
He said that foggy conditions had become more frequent than ever, especially during the winter.
Dense fog can still be seen in the morning hours in rural Bangladesh in the middle of summer.
Bangladesh鈥檚 air contains one of the world鈥檚 highest concentrations of airborne particles and is often ranked as the worst air in the world.
Bangladesh鈥檚 power consumption has tripled over the last one and a half decades. The power is produced mainly using fossil fuels, resulting in the release of various pollutants. Haphazardly implemented mega-infrastructural development projects, releasing enormous volumes of dust day and night, keeping the sky grey.
Air pollution peaks between November and March when trans-boundary pollutants gather over Bangladesh, with the wind blowing from the west carrying pollutants from India, Pakistan, and Afghanistan, experts said.
About 60 per cent of pollution in Bangladesh occurs during this period.
Meteorologists pointed out that another essential component of fog 鈥� moisture 鈥� has also been in good supply over a prolonged period between the winter and pre-monsoon seasons because of a change in wind direction influenced by unusually high pressure formed over the Bay of Bengal.
鈥楾here is a shift in wind patterns supplying more moisture during winter and beyond preventing flushing out airborne pollutants into the ocean,鈥� said Abdul Mannan, the climate adaptation coordinator at the Bangladesh Agricultural Research Council.
鈥楾he shift in wind patterns is linked to climate change,鈥� he said.
The absence of sunlight has serious impacts on agriculture, Mannan said, explaining the role sunlight plays in carrying out the biological process in plants known as photosynthesis.
Disrupted photosynthesis means slowed plant growth and lower yields, he said.
Lack of sunlight could also result in vitamin D deficiency in humans, said Kamruzzaman.
Lack of vitamin D means lower levels of immunity.
Professor Tofazzal Islam, director of the Institute of Biotechnology and Genetic Engineering at Bangabandhu Sheikh Mujibur Rahman Agricultural University, said that the entire biodiversity was in danger due to the increasing loss of sunlight, which is essential for creating energy from carbon dioxide in the environment.
鈥楳any organisms cannot even survive without certain hours of sunlight,鈥� he said.
Tofazzal found the loss of sunlight over four decades to be rather rapid, which no organism can adapt to through genetic mutations.
Every plant has a light sensor playing a profound role in flowering, he said, adding that diminishing sunshine could cause early flowering, resulting in almost no yield in many plants.
The decay of plants means the accumulation of carbon dioxide in the environment.
Long foggy hours have given rise to another strange development, turning a short-lived winter intense, meteorologists said.
The feeling of cold becomes intense and unbearable for the human body when the difference between day and night temperatures stands at less than 10C.
Prolonged foggy spells also prevent maximum temperatures from rising during winter, often leading to conditions in which maximum and minimum temperatures become almost the same, giving rise to an intense cold feeling.
Bangladesh witnessed such a situation in January in Dhaka and elsewhere.
On January 12, the difference between day and night temperatures dropped to just 2.8C in Rangpur, followed by a 2.6C difference between the temperatures in Tarash the same day. The same day, the difference between the temperatures in Nikli in Kishoreganj, Dhaka, dropped to 6.6C.
A review of data from the BMD showed that Bangladesh has seen its maximum temperature drop to 15C or below frequently since 1998.
In the decade between 1981 and 1990, the maximum temperature never dropped below 15C, but in the decade after that 鈥� 1991-2000 鈥� the maximum temperature dropped to 15C or lower for 30 days.
In 2001鈥�2010, there were 89 days when the maximum temperature dropped to 15C or below.
In the decade between 2011 and 2020, 44 days saw the maximum temperature drop to 15C or lower.
鈥楾he problem is that we are not aware of the impacts declining sunshine hours are having on lives,鈥� said meteorologist Bazlur Rashid, also one of the authors of the BMD study.
