Bizarrely 'erratic behaviour' of the weather for the global climate change is impacting Bangladesh's agriculture adversely as the country begins to reap low crop yields from costlier farming.
Other climatic fallouts include risks to ensuring national food security and achieving the UN-set sustainable development goals, experts say.
As observed by meteorologists and greens, rise in temperatures, untimely or prolonged floods, heavy downpours or droughts, short-lived winter etc., form new phenomena in Bangladesh -- a country ranked 6th most vulnerable to climate change in the world.
The August report of the IPCC (Intergovernmental Panel for Climate Change) says the prospect of world temperatures rising by 1.5C from pre-industrial levels by 2040 signifies such behaviour will be more frequent in coming days. For 1.5°C global warming, there will be increasing heat waves, longer warm seasons and shorter colds.
Some 36 districts had faced severe heat waves with temperatures crossing 35 degrees Celsius for two consecutive days in April last, blighting crops on more than 70,000 hectares of paddies worth over Tk 3.0 billion.
Other crops -- maize, peanuts and bananas -- also were affected adversely in the scorching heat, Department of Agriculture Extension (DAE) said.
The average maximum temperature for April usually in Bangladesh is about 33 degrees Celsius, meteorological department said.
The main cause of such hot weather is often human action, such as emitting greenhouse gases, over-farming and excessive irrigation, which erodes soil and drains aquifers, according to experts.
"The recent erratic behaviour of weather is adversely impacting agriculture and it threatens the future food security of Bangladesh," says Dr Fazle Rabbi Sadeque Ahmed, Director (environment and climate change) at the Palli Karma-Sahayak Foundation (PKSF), the apex body of micro-financiers.
He terms this type of behaviour a short-term one.
Dr Ahmed says under such an unfavourable weather, not only grain growth is impacted but pest attacks on the plants also become severe.
The country is losing agricultural land by approximately 80,000 hectare annually, on average, due to urbanisation, the building of new infrastructures such as roads and implementation of other development projects.
The agricultural sector plays a vital role in the economy of Bangladesh in terms of its contribution to the GDP, employment generation, livelihoods and poverty alleviation.
It has approximately 12-per cent share in the country's over Tk 30- trillion economy, though its full potential has yet to be tapped through modernization mechanisation. It employs nearly 50 per cent of the workforce.
Experts believe heat-waves affect all types of agriculture. During flowering stage, fluctuation in temperature affects the output.
"Even one-hour high temperatures, like above 35 degrees, affect paddy adversely. It causes grain sterility," said Dr Jiban Krishna Biwas, executive director at Krishi Goveshona Foundation, an agricultural research outfit.
Abu Wali Raghib Hassan, a former project director at the climate-and disaster-resilient project of the DAE said, such behaviour of weather is a new growing problem in Bangladesh that calls for attention urgently, failing which it will emerge as major threat to attaining the sustainable development goals or SDGs by 2030.
"The heat-wave that swept during April last gave the farmers a grim lesson on the dangers of climate change," he said.
In 2020, he adds, Bangladesh had faced floods five times, which is also a gloomy sign for erratic behaviour of the weather, let alone short winter that hit some key vegetables
However, some experts are worried about long-term impact of the existing erratic behaviour of the weather that includes 'desertification' or loss of productivity of the land.
Desertification means land degradation in arid, semi-arid and dry sub-humid areas, resulting from various factors, including climatic variations and human activities leading to reduction in or loss of the biological or economic productivity and complexity of rain-fed cropland, irrigated croplands, or ranges, pastures, forests and woodlands.
Dr Fazle Rabbi Sadeque Ahmed said that the desertification process is there. "Climate change is gradual process, and the desertification of the country's land is going on…slowly."
An often-irreversible process, desertification is a growing problem in Bangladesh.
Salinity due to rise in sea level is also a growing threat in coastal areas that affects agricultural production.
Shameem Hassan Bhuyan, a meteorologist and World Bank consultant, says the recent rise in thundershowers or lightening is part of an erratic weather pattern.
Human body that is sensitive to rising temperatures also suffers from an outbreak of a number of diseases, including skin cancer and some other skin-related diseases.
About a quarter of the nation's over 160-million-strong population is already considered food-insecure, meaning people in this group have inadequate or uncertain access to nutritious and safe food, according to the United Nations World Food Programme (WFP).
In the meantime, the cost of irrigation is on the rise in many major crop-growing areas following less-than-expected rain coupled with droughts.
Rajshahi-based Barind Multipurpose Development Authority (BMDA) conducted a small survey on irrigation cost in two districts---in Godagari of Rajshahi district and in Sadar upazila of Thakurgaon. It shows 40-per cent irrigation-cost spike in Thakurgaon in 2021 to Tk 862 per bigha over 2020 in cultivating boro rice.
On the other hand, for Aman it swelled to Tk 255 per bigha, up by 14 per cent over the 2020 cost. The aus irrigation cost surged to Tk 324, up by 37 per cent over 2020.
In Rajshahi the boro-irrigation cost swelled to Tk 305 from Tk 260 or 17 per cent spike from the level a year before. The cost of aman and aus paddy cropping in Godagari is, however, inverse or reduced, remaining the same respectively.
Shamsul Huda, chief engineer at BMDA, says the irrigation cost in Godagari dropped to some extent, due also to a peculiar character of rainfall in 2021.
"This is also new character or part of erratic behaviour of the weather. It may reverse again next year."
Barind is a region spanning greater Rajshahi, Dinajpur, Rangpur and Bogura districts of Bangladesh and the Indian territorial Maldah District in West Bengal. This region is geographically identified as Barind Tract with largely arid land. The hard red soil of these areas is very significant in comparison to that of other parts of the country.
Saleemul Huq, a Bangladeshi scientist based in London, said it is important for Bangladesh to pay more attention to extreme temperatures particularly in terms of effects on agriculture where some crops may be adversely affected each year.
"The government should pay more attention to heat-wave," said Saleemul Huq, also director of the International Centre for Climate Change and Development.
The IPCC estimates that, by 2050, rice production in Bangladesh could decline by 8.0 per cent and wheat by 32 per cent. A number of studies show that a rise of 1 to 20 C in combination with lower solar radiation causes sterility in rice spikelet.
Dr Md Golam Rabbani, head of Climate Bridge Fund Secretariat, says the 1.0 degree Celsius helps raise the temperature by 2-3 degrees higher as an effect of urban heat islands.
Urban heat islands occur when cities replace natural land cover with dense concentration of pavements, buildings and other surfaces that absorb and retain heat.
Criticism of the climate fund:
Dr Rabbani noted that each year the government allocates resources for the mitigation and adaptation strategies. "There is lacking in proper selection of projects."
The government has allocated on average 1.0 million dollars worth of resources through its budget mechanism since 2010.
He thinks the adaptation strategies should be right-directed. "To my mind, the technical committee involved with the process has large responsibilities [in choosing right projects]."
Wheat is the worst victim:
By 2050, up to 32 per cent of Bangladesh's total wheat production may be lost, primarily due to heat stress, according to the IPCC.
Potato yields are expected to suffer increasingly from moisture stress due to untimely raining.
Director-General of Wheat Research Institute Md Aminujjaman found yield falling due to short-span winter. "Besides, there are many pest attacks on the wheat plants as a result of the short winter," he said.
NDC [nationally determined contributions]
Bangladesh submitted an NDC account in August to the UN, showing up its strategies on how to combat the challenges relating to erratic behaviour and climate change as per the Paris agreement.
It has an ambitious greenhouse gas-reduction target of 15 per cent from a Business as Usual (BAU) level by 2030, if global fund for the green climate is available. Of this, 5.0 per cent reduction was targeted as unconditional.
The interim NDC aims to further strengthen mitigation actions that Bangladesh may take to tackle its growing emissions and to play its role in global efforts to limit temperature rise to 2 degrees, or preferably 1.5 degrees, Celsius above pre-industrial levels.