Back in 2009, when a team of researchers and scientists were collecting data for a study in the southern coastal districts of Bangladesh, they hit upon something quite bizarre. Local fishermen said a large number of their colleagues were languishing in Indian prisons.
When the researchers checked the facts, they found that no less than 20,000 Bangladeshi fishermen were indeed incarcerated in the South Indian state of Andhra Pradesh. Most of the fishermen had landed there in the last three-four years.
How did they end up on foreign shores?
The answer is unequivocal: their fishing boats sank in rough waves at sea.
"This was it: the waves – huge, strong and unexpected – were the culprits. The fishermen were facing a turbulent sea," said Ahsan Uddin Ahmed, a scientist who was part of the research team. "We double-checked the data and found a very strange thing unfolding: the sea, hitherto familiar to the experienced fishermen, was behaving quite differently. More and more fishing boats were sinking in turbulent waters while fishing in the deep sea. The lucky ones landed on unknown shores."
The trend has not changed since. Mohammad Akbar Hossen Rubel, a fisherman in Cox's Bazar, said fishermen often get caught unawares in turbulent waters and their boats sink. Most of them do not have any gadgets that can alert them of impending storms.
Another trend that has caught the attention of Ahsan Uddin's team is that there has been a sharp increase in the number of loan-defaulter fishermen who had taken "dadon" (a special system of taking bonded loans) because they are being forced to shorten their fishing sorties drastically and come back empty handed. Again, a clear outcome of the sea getting rough.
So, what is behind these changes in the manners of the sea?
"All the available data was dragging us to an obvious conclusion: the surface of the sea was getting hotter day by day, creating more depressions and inviting giant waves, if not cyclonic storms," said Ahsan Uddin.
Back then linking the fate of some unlucky fishermen with something as remote as the rise of ocean surface temperature sounded a tall tale.
A decade later, when I set foot in Shyamnagar, an area in the south-western corner of the country, I came across another group of people who faced a different kind of ordeal from the sea – tropical cyclones. In the second week of
November this year, a mighty storm named Bulbul with wind speeds up to 150 kilometres per hour, was heading towards the coastal belt that is shielded by porous embankments already damaged by the onslaughts of several deadly cyclones one after another.
"If we are hit by another cyclone, even a moderate one, we are doomed," said Anil Roy, a farmer of erstwhile Zaliakhali, a village beside the sea in a remote part of southern Khulna, near the Sundarbans. He was standing on an embankment that was still under construction. The embankment was destroyed 10 years ago by a huge tidal surge brought along by Aila, a tropical cyclone.
Researchers say as the surface temperature of the sea is rising constantly, the coastal belt of the country, with 19 districts, is becoming prone to cyclones with increasing intensity.
"Regular cyclones are turning into super cyclones," said Ahsan Uddin Ahmed, who is a co-author of a number of Inter-Governmental Panel on Climate Change (IPCC) reports.
But cyclones and mighty waves are not the only perils that people on the coast are facing. There are the problems of growing salinity and the shifting patterns of monsoon rainfall that are weighing down heavily on the livelihood of a population of 38.52 million, which outnumbers that of many countries of Europe.
Experts say the rise in sea surface temperature is an outcome of a bigger phenomenon that is called global warming, the driving force behind climate change. It is inviting a range of interrelated climatic events that are bringing about changes on an unprecedented scale, shifting the mode of cultivation and the pattern of crops in 48 upazilas of 12 southern districts that are specially marked as being "exposed to the sea".
The village that doesn't exist
When I asked Anil Roy, a farmer of Zaliakhali, where his home was, he waved towards a point in the middle of a mighty river named Bhadra. In fact, the whole village of Zaliakhali does not exist anymore as it went under water 10 years ago when Aila, a deadly tropical cyclone, destroyed the embankment inundating the whole island housing two unions of Kamarkhola and Sutarkhali. The island in Dakop, a southern upazila in Khulna, is surrounded by four rivers that cut it off from the mainland. It is one of the areas that was hit very badly by the onslaught of the storm.
Most of the 80 families that lived in Zaliakhali village have migrated further north, some have even crossed the border.
Migration is the most obvious fallout of climate disasters. When Cyclone Sidr hit the coastal districts in 2007, nearly 36,000 people are estimated to have migrated from Bagherhat, Pirojpur, Patuakhali, Barguna and Bhola. And two years later, another 4 lakh immediately migrated from Dakop, Koira, Paikgachha, Ashashuni and Shyamnagar when Cyclone Aila hit.
The exodus has not stopped since
"Koira, a southern upazila in Khulna, for a long time looked something like an area hit by an atom bomb," said Hassan Mehedi, chief executive of the Coastal Livelihood and Environmental Action Network (CLEAN), an NGO that works in coastal areas.
The island in Dakop, where Anil's village had been, was protected by 60 kilometres of embankment. The embankment was destroyed by the tidal surge that accompanied Aila. In the last 10 years, two-thirds of the embankment have been rebuilt, but construction is still going on leaving the island vulnerable to another storm. Cyclone Bulbul, in the second week of November this year, was a very close call. The islanders heaved a sigh of relief because the storm hit during ebb tide.
In Gabura, another island union in Shyamnagar upazila, people live in constant fear of cyclones as the newly restored embankment looks feeble in the face of mighty storms.
"We doubt it can withstand a storm as big as Aila or Sidr," said Abdur Rashid, a school teacher in Gabura.
"The embankments have been weakened by holes made for pipes that are used to bring saline water in and out for shrimp cultivation," said Hassan Mehedi.
Depressions, cyclones and super cyclones
Studies show that in the last five decades, the sea temperature in the Bay of Bengal has increased by up to 0.54 degrees Celsius. This has resulted in a steady rise in the sea level.
According to Maminul Haque Khan, advisor of the Centre for Environmental and Geographic Information Services (CEGIS), measuring sea level rise at a regional level is a very complicated process. There are numerous local factors that alter the sea level almost every hour. There are the effects of rainfall, fluctuation in the level of salinity, the wind etc.
However, a survey by the Department of the Environment published in 2016 titled "Assessment of Sea Level Rise on Bangladesh Coast Through Trend Analysis", says during the last 30 years, the overall sea level adjacent to the coastal zone has risen at the rate of 6-21mm per year.
Another study carried out by Southampton University has put the rate of sea level rise in the coastal zone up to 50mm per year.
Furthermore, according to a study by the CEGIS, the Sundarbans area is sinking at a rate of 1-2.5mm per year. So, the coast of the Sundarbans experiences the sea level rise more intensely.
"There is a direct link between the increase of sea temperature and the intensity of cyclonic storms," said Dr Saleemul Huq, co-author of the third assessment report of the Inter-Governmental Panel on Climate Change (IPCC).
He said whether there is indeed a rise in the frequency of tropical cyclones due to global warming is a subject of debate. Researchers have not yet been able to establish any direct link between the two, but experts do agree that the Bay of Bengal is experiencing mightier storms than before.
"We call them super cyclonic storms," said Ahsan Uddin Ahmed. He explained that according to the Safgir-Simpson scale, for the North Indian Ocean, the official name for the Bay of Bengal, any storm that has a wind speed of 221km/hr or more is considered a super cyclone. We will continue to experience more and more of these super cyclones that otherwise would have remained moderate. Bulbul, the last cyclone that hit the coast, has been in the category of "very severe cyclonic storm".
Anwar Ali, a renowned cyclone expert, has predicted that sometime in the 2050s or 2060s, when the mean temperature becomes 4 degrees Celsius higher than that during the pre-industrial age, as predicted by scientists, there will be frequent super storms as intense as that of 1991, and tidal surges 10.7 metres high hitting coastal belts. Our embankments, which now are no higher than 7.5 metres, will easily give in.
Depressions on the rise
Environment researcher Ahsan Uddin Ahmed has taken a different approach in observing the fallout of global warming. In order to explain the spike in the number of fishing-boats sinking in the Bay, and the disruption of fishing patterns affecting the fishermen badly, he and his team analysed the frequency of distant cautionary signal number 3, hoisted by the Met department.
"This particular signal expresses the primary formation of depressions, which are the seeds of cyclonic storms," he explained.
ata from 1991 to 2007 show that in the first decade there were four distant cautionary signals per year on average, which grew to an average of 7 in the last decade of the time frame. And the primary data indicates that after 2007 the frequency of distant signals has kept growing.
Not all the formations of depressions necessarily end up becoming tropical cyclonic storms. But it definitely brings about a turbulent sea with giant waves, forcing fishing boats to shorten their sorties.
In meteorological terms, in the North Indian Ocean, 26.9 degrees Celsius is the threshold temperature that generates a depression. The mean sea surface temperature is clearly heading towards that threshold temperature, rising above 23 degrees Celsius most of the time, which will result in frequent depressions and more turbulent seas.
Exposed to salinity
"Getting drinking water from deep tube-wells has become hard these days," said Shamsher Ali, a farmer living in Munshiganj union of Shyamnagar, Satkhira. He said, "When you dig only 7-8 feet in the ground, you find saline water seeping out. This was not the case a decade ago. People are moving out of these areas only because of the acute drinking water problem."
The main sources of drinking water in the southern coastal areas are open ponds. People collect water from these water bodies during winter. In the rainy season, preserving rain water in large community tanks is becoming popular.
"More and more ponds holding fresh drinking water are getting spoilt as saline water takes over new areas," said Mohon Kumar Mandal, executive director of LEDARS, a voluntary organisation that works for the livelihood of coastal people.
According to Mohon, as tidal surges are getting higher day by day, new areas are becoming more saline.
The country has had three nationwide surveys on salinity of soil so far. The last two surveys, conducted in 2000 and 2009, clearly show how more and more areas were becoming saline. In 2000, there was 10.2 lakh hectares of land with a varied range of salinity. This grew to 10.56 lakh hectares in 2009.
Amerendranath Biswas, the senior scientific officer of the Salinity Management and Research Centre at Bagerhat, said during winter, salinity in Shyamnagar, Koira and Paikgachha has been monitored at 15-20 decisiemens per metre (dS/m), much higher than the tolerable level for any crop to grow.
Most of these areas are still reeling under the after-effects of Sidr and Aila, the twin cyclones that ravaged 19 coastal districts around a decade ago. Saline water stagnated on the land for two or three years, making it hard to cultivate anything there.
Changes in the cultivation pattern
In the second week of November this year, a farmer named Animesh Dey was standing motionless before his ruined papaya field. Cyclone Bulbul had ravaged his field a day before. It was only a week before he would have gone for the harvest. He said he was ruined.
"I only recently shifted to cultivating fruits because rice yields had been adversely affected by the disruption in the pattern of rainfall. But cyclones are becoming a new hazard," said Animesh who took loans for cultivating papayas.
The local agriculture officer, Mosaddek Hossen, explained that the area had a rainfall of only 32ml in June this year, compared to 75ml in the same month the previous year. The rainfall pattern is shifting. This has resulted in the adoption of late varieties of rice, like BR-23, which yield a smaller harvest.
According to Mosaddek Hossen, shifting towards a late variety is pushing the farmers hard.
A few miles away, Ramkrishna Mallik, a farmer, complained that attacks by insects in his cabbage field has increased in recent times, making it hard to get a proper yield. He did not have any idea whom to blame for this new situation, but the agriculture officer was unequivocal about blaming the rise of mean temperature during winter.
Elsewhere, in Gabura, almost the whole union has given up rice cultivation after the fallout of Aila, which caused saline water to stagnate in the fields for up to three years at a stretch.
"We could not grow anything because of the salinity," said Habibullah, a farmer. He had to shift to shrimp farming because that was the only option left.
Almost the whole island of Gabura now has sprawling shrimp farms. The green fields have disappeared and the area has turned white.
This was also the case in Shyamnagar and in Koira, said Amerendranath Biswas, senior scientific officer of the Salinity Management and Research Centre. The average salinity in some parts of the land is too high for regular crop cultivation.
Gawher Nayeem Wahra, a disaster expert, said there are ways we can mitigate the inevitable fallout of climate change. Most of the impacts are avoidable if prudent steps are taken by the authorities.
Wahra said the Water Development Board, the agency responsible for building and maintaining embankments, should consult local people before building any structures. The local community should be given the responsibility of looking after and maintaining the dykes. Local knowledge should be valued. People can invent their own technology. The government only has to play the role of a facilitator.