There is a strong relationship between climate change and the early monsoon that has led to flash-floods across the border in India and major portions of Sylhet division in Bangladesh, leaving millions of people stranded and creating a humanitarian disaster, said experts.
Climate scientists and water-management experts at home and abroad see a significant influence of climate change behind this erratic behaviour of rainfall, leading to record-level flooding in the area.
In the light of the extreme weather events across South Asia - happening over the last decade or so, it can be said that there is a strong connection between climate change and early monsoon coupled with excessive flash-floods, said Prof A K M Saiful Islam from the Institute of Water and Flood Management (IWFM) of Bangladesh University of Engineering and Technology (BUET).
"The nature of flooding has also changed over the years. Earlier this year, we witnessed early flooding before the monsoon in May. Now we are witnessing another catastrophic flooding in north Bangladesh."
"In short succession, we have huge flooding right at the beginning of the monsoon, which was not the case a few decades ago. Not only that, the total volume has increased over the years, and there is rainfall almost six to seven times in one month. We must prepare for this unpredictable flooding," he added.
At least 12 north-eastern and northern districts in Bangladesh are currently experiencing a devastating flood, with major rivers such as the Brahmaputra, Jamuna, Surma, and the Kushiyara flowing above their danger marks at 18 points.
Floodwaters inundated fresh areas in Jamalpur, Sherpur, Habiganj, Kishoreganj, Moulvibazar, Nilphamari, Lalmonirhat, Gaibandha, Bogura, Sirajganj, Tangail, Rajbari and Feni following heavy rainfall and rise in water level in different rivers.
About 6.0 million people are now stranded in these districts, and suffering from shortage of food, sanitation and water.
Studies have shown that the Himalayan region's rainfall patterns have been changing, leading to an unpredictable weather situation. For instance, India witnessed two waves of flash-floods, with dozens killed in extreme rain-induced landslides and floods, said Dr Anjal Prakash, Lead Author on IPCC AR5 and IPCC Oceans and Cryosphere and Research Director, Adjunct Professor from Indian School of Business.
He also said, "Due to climate change, a wetter climate has been predicted for this region. However, the rainfall variability means that the seasons' rainfall may happen in 2-3 high rainfall events, while the rest of the days would be a dry spell."
"There has been a climatic shift in monsoon patterns over South Asia since the 1950s," said Dr Roxy Mathew Koll, Lead Author of IPCC Oceans and Cryosphere, who wrote the chapter on Indian Ocean Warming in the climate assessment report.
The author pointed out that the most significant change is that the monsoon season is now fragmented into long dry periods, broken by spells of heavy rain.
Experts warned that this shift in seasonal characteristics would significantly impact people's lives, livelihoods, irrigation, food and water security, and industries.
Prof Ainun Nishat at the Centre for Climate Change and Environmental Research, BRAC University, warned that the agricultural sector would bear the brunt of these disasters - ranging from crop losses to fish farms washed away - while small and medium industries would also suffer substantially because of increased disasters.
Dr. Saleemul Huq, Director of the International Centre for Climate Change and Development (ICCCAD), stated, "The potential damage to crops and economy of Bangladesh from these severe floods in the country's north-eastern part is likely to be very severe indeed."
To minimise the losses, the experts emphasised dredging rivers, joint river basin management, especially between India and Bangladesh, and improving drainage infrastructure and early warning mechanisms - fed by information such as water discharge in rivers upstream shared between the countries.
"Furthermore, Bangladesh must have a rapid response system in place to address post-flood concerns, such as water-borne diseases, food, and clean water availability, as well as the loss of wealth and livelihood assets of flood-affected people," said Arfan Uzzaman, Climate Change Expert, the Food and Agriculture Organisation (FAO) of United Nations.
While urging the government to remove infrastructure from river basins and promote nature-based solutions, the experts called for introducing weather insurance for farmers and ensuring their access to credit with soft loans to tackle these disasters in the future.
They also called for increased investment in research for developing short-duration and stress-tolerant crop varieties, as future farming would be far more complicated if the globe was warmed by 2-3 degrees Celsius.
Dr. Saleemul Huq mentioned, "The losses will almost certainly increase unequally, as the poorest people will be worst affected. Moreover, as these floods are occurring in Bangladesh as well as India, the cross-border impacts will be severe."
"The IPCC 6th Assessment Report makes it clear that global GDP losses due to adverse impacts of human-induced climate change will be very severe."
As one of the most vulnerable developing countries, Bangladesh will bear an unequal burden of such adverse impacts, which will cause significant losses and damages to the country's economy, he added.
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