When Cyclone Aila hit the coast of Bangladesh in May 2009, water swelled over embankments along the Kholpetua river.
The home Sirajul Islam (pictured) shared with his wife and four children in Kolbari village was flooded, along with the single acre he used to raise shrimp.
They left for Shyamnagar town, 15km away, where for four months he made 300-400 taka a day ($4-5) driving a rented motorbike.
When the floodwater subsided, his field was too salty for shrimp. Village buildings were flattened and there was no fresh water to drink. So in 2011, the family went to seek their fortune in the capital Dhaka.
“The cyclone had broken my economical backbone by destroying everything,” says Islam. “If there had not been such a big cyclone, I would not have moved to Dhaka.”
Bangladesh’s prime minister Sheikh Hasina has told the UN that a one-metre rise in sea level – a plausible scenario this century – would submerge a fifth of the country and turn 30 million people into “climate migrants”.
Islam shows off a set of deer antlers, a trophy from hunting in the Sundarbans, across the river. Most of the household income is from selling fish, crab and honey gathered in the mangroves – supplemented from his eldest daughter’s wages at a garment factory in Chittagong.
If there were to be another cyclone, Islam says “I would fight” to stay. It is not likely to get any easier, though. Sea levels are set to rise, compounding the problem of salt intrusion into groundwater. Tropical cyclones are expected to get more intense and destructive with global warming. In combination, they raise the risk of another devastating storm surge.
Dislocation: Sirajul Islam and his family moved home several times in the five years after Cyclone Aila destroyed his coastal livelihood
Over the past two decades, Bangladesh’s rural population has been pouring into its cities. A 2014 slum census found the number of people living on the margins of cities had doubled to 2.2 million since 1997. Meanwhile, the population in southwestern coastal regions is stagnating.
A smaller, but significant, number of displaced people cross borders, which is where it becomes a matter of at least regional, if not international concern. Up to 20 million Bangladeshis are said to be living illegally in neighbouring India. A militarised fence along 70% of the 4,000 kilometre frontier sends an unwelcoming signal. Still, people find ways to evade the patrols, typically by boat across the rivers.
Zainab Begum (pictured), a 40-year old woman collecting water from Gabura village pond, across the river from Kolbari, has two younger sisters working as waste pickers in Tamil Nadu, a southern Indian state.
With their families, they have crossed the border illegally several times. It is a risky business: one got caught and was badly beaten by Indian border guards, detained for a week before she could bribe her way out.
There was little to keep them in Gabura, one of the worst hit areas by Aila. Not a single house was left standing, says Begum, a fierce note in her voice. The levee that was supposed to keep the river out trapped a layer of sludgy, salty water on the land for three whole years. She lived in a makeshift house on the embankment; others with more resources left permanently.
Eventually, the government helped them rebuild. A three-storey cyclone shelter stands proud at the heart of the village. But land that was previously good for one rice crop a year became too salty: now it is all shrimp.
In this battered economy, Ziaur Rahman is trying to make a living teaching English and maths to private students. With a degree from Khulna University, he shows more awareness than most about the global trends affecting his country. He tells Climate Home in English: “I know about climate change. When climate change in this place, we are not happy.”
The outlook is not all bleak. Just as farmers adapted to fattening shrimp, now some have turned to crab, which can tolerate higher salinity. They do not eat it round here: it is “haram” (forbidden) for the Muslim majority and at 250 taka ($3) apiece in the market, beyond most budgets. But there is strong demand from China and Malaysia. A small plant in Kolbari packs the shellfish for export.
The scale of migration from vulnerable areas will depend on the success of these adaptations, as well as the severity of climate change impacts.
Prime minister Hasina’s forecast of 30 million climate migrants is widely disputed, inside and outside Bangladesh.
Analysis by Climate Central, a US-based science outreach organisation, paints a less dramatic picture. It finds fewer than a million Bangladeshis living within one metre above sea level. Under five metres, the number is still less than 30m.
“It is a troublingly large difference,” says Ben Strauss, a biologist by background who leads Climate Central’s sea level work.
The government estimate has been in currency for at least seven years, its source apparently lost along the way. An official in the environment department could not say exactly where it came from, suggesting it was a rough assumption based on the population of 19 coastal districts.
Climate Central’s “Surging Seas” model is more transparent and there are identifiable reasons why it might err on the conservative side.
Firstly, Strauss explains, they use land elevation data from NASA’s Shuttle Radar Topography Mission (SRTM). It is the best publicly available dataset for Bangladesh, but it has limitations. The satellites cannot tell the difference between the tops of buildings or trees and the soil. In places where there is more precise light detection data to compare with, SRTM has been found to overstate the height of the land on average by more than 2 metres.
Secondly, it represents a narrow definition of those affected by sea level rise. Surging Seas maps out homes that will fall below the high tide mark or be exposed to annual flooding. But a household does not have to be under water for its members to feel the impacts of the creeping tide.
All along the coast, saltwater intrusion is hitting crop yields, contaminating drinking water and eroding infrastructure. Other things being equal – and the amount of freshwater India draws from upriver plays a major role – sea level rise will push salinity further inland.
(It is worth mentioning that rising seas are not the only climate change impact Bangladesh faces, just the most predictable. Earlier this year, abnormally heavy pre-monsoon rainfall wiped out 2m tonnes worth of rice crops in the northeast. Flooding, drought and ocean acidification are rising threats.)
The flipside is that Surging Seas does not account for the thousands of kilometres of embankments that surround coastal settlements. Indeed, the ability and willingness to defend these homes may be more pertinent than the technical accuracy of measuring equipment.
Veteran Bangladeshi climate researcher Ahsan Uddin Ahmed is sceptical of mass migration predictions. Accepting that salinity is going to push northwards and some crops will become unviable, he nonetheless places great faith in the capacity of Bangladeshis to adapt.
“Salinity is no longer a hopeless scenario,” he tells Climate Home from the office in his Dhaka apartment, expounding knowledgeably on mango orchards, pond sand filters and capillary action. “Through innovation and research, the tide has been diverted in a different direction.”
The government is adding 30cm to the height of embankments, he says: “There is no reason we would not be able to match up with the gradually rising sea level. Our economy will allow further protection.”
The experience of communities like Kolbari and Gabura shows the fragility of such gains. For all their ingenuity adopting shrimp cultivation, a tropical storm dealt a huge setback. At category one, Aila was not even an exceptionally strong cyclone.
And traditional defences may be counterproductive. The levee that was supposed to protect Gabura became a liability when the floodwater got in and could not get out again.
A 2015 study concluded that embankments do more harm than good, causing the land to subside.
Recovering from such crises is putting a drag on Bangladesh’s economic growth, with the Asian Development Bank forecasting annual climate losses by 2050 will amount to 2% of GDP.
But none of these vulnerabilities, real as they are, lead inevitably to migration.
Alex Randall, migration expert at UK-based NGO Climate Outreach, argues it is futile to try and quantify climate migration. “Large numbers of people are already moving from rural areas in Bangladesh into cities. It makes more sense to see climate change as a force that adds to this existing trend, rather than trying to pick out a number of people who will move because of climate change,” he says.
In some cases, climate impacts may even prevent people moving, he adds, as they become too poor to make the leap. “The ways in which climate change will re-shape patterns of rural to urban migration in Bangladesh are not straightforward.”
But if the medium-term prognosis is not as clear-cut as official rhetoric implies, the ultimate destination of human-caused global warming is sobering.
Surging Seas’ “seeing choices” interactive shows that 2C temperature rise – the upper limit countries have agreed to try and stay below – is consistent with 4.7m of sea level rise. That turns most of southwestern Bangladesh – and the city of Chittagong in the east – blue on the map. Unchecked pollution locks in sea level rise that ultimately swamps half the country, including its three biggest cities: Dhaka, Chittagong and Khulna. The timescale for this could be anywhere from 200 to 2,000 years.
“It is very plausible that the amount of carbon we put in the atmosphere between today and 2050 will determine whether Bangladesh can even exist in the far future,” says Strauss.
“Our emissions pathway does not make a big difference for mid-century sea level rise. It makes a consequential difference by the end of the century and it makes an existential difference after that for Bangladesh.”
Where will they go?
Travelling inland from the salt-soaked coast, the trees get taller, the cows wandering across the road fatter, the crops more diverse: jute, banana, bitter gourd. Every field and pond is in use; there is seasonal work to be found, but no permanent home for the dispossessed.
Nazzma Begum came from Bhola, on the coast, as an 18-month-old baby. Now 32 and a widow, Dhaka is her only home: her parents lost everything to river erosion. She shares a single room with her two children in the generically named “boat ghat” slum and makes a living cooking and cleaning for wealthier families.
City life has its upsides: Begum loves the cinema, naming her elder son after film star Shakib Khan. An electric light and ceiling fan is included in the 1,800 taka ($22) monthly rent. But her flimsy shack lets mosquitoes in and she is suffering from the chikungunya virus – a disease that causes severe joint pain.
Her neighbour Mohamed Miraz, also from Bhola, came to Dhaka after one too many fishing nets came up empty. If he can save enough, he will go back and buy land. A single acre costs as much as he earns in a thousand days pulling a rickshaw. The struggle to escape poverty is relentless.
The population of Dhaka has roughly doubled in 20 years to 19 million, its rapid growth not matched by its planners. Ponds and canals have been concreted over with no regard for the natural drainage they provided. Monsoon rainbursts frequently submerge streets in knee-high water.
Climate change will only intensify the pressures that drive people to the capital.
If the slums are claustrophobic, the alternative – leaving the country – is daunting. India is welcoming enough to middle class Bangladeshis doing their Eid shopping, but an armed border patrol is there to deter unskilled labourers. Catching a plane to a wealthier nation is an outrageously expensive gamble. For every success story, there are cautionary tales of exploitation.
The UN Population Division estimates the Bangladeshi diaspora at 7.2 million, which is almost certainly an understatement. India alone claims to have 20 million Bangladeshis living within its borders, most of them illegally, although that could equally be an exaggeration.
Awareness of climate migration is well established at an international level. “As regions become unliveable, more and more people will be forced to move from degraded lands to cities and to other nations,” said UN secretary-general Antonio Guterres in a speech on climate change.
Millions of Bangladeshis are living in India, Pakistan, Malaysia and the Middle East. The precise number is hard to count because many travelled illegally. Data is from various sources and may not be comprehensive.
Plans to deal with it are embryonic, however. A task force on displacement under the auspices of UN climate talks had its first meeting in May. Its work plan grapples with patchy data and institutional clashes.
There is no ready source of financial support directed at climate migrants, nor do they have any protected status under international law if they cross borders.
In most cases, climate migrants are not easy to distinguish from economic migrants: they arrive looking for work. The welcome they receive hinges more on the value of their labour than any duty of care to the climate-afflicted.
In Khulna, the third largest city in Bangladesh and regional capital of the southwest, technical education was as important as buildings in accommodating the people who arrived after Cyclone Aila and myriad smaller crises.
A pilot offering vocational training – phone repair, welding, sewing – to new arrivals recently marked its first 25 graduates. Eight of the city’s 278 slums are in line for infrastructure upgrades, funded by German development banks.
“It is not enough,” admits city mayor Moniruzzaman Moni, holding court at his “club” one evening.
At between 2 and 4 metres above sea level, enmeshed in the Ganges-Brahmaputra river delta, Khulna is only marginally safer than the coastal villages. When heavy rainfall coincides with the high tide, water washes through the streets.
“Khulna is one of the most vulnerable cities in Asia,” says Moni. “This is because of climate change. Fifty years ago, the situation was not like this but now it is changed.”
As though to demonstrate, during the half-hour audience rain lashes down and a large puddle forms outside the door. Bricks are laid out to step across to dry road.
Moni hopes that his grandchild will be able to stay in Khulna, where his family has lived for generations. But it will require “major projects” to keep the rising sea at bay. Meanwhile, he cannot deny the trend for outward migration.
“A large number of people, they are moving to Malaysia, India, Pakistan and the Middle East. These are climate-affected people. Officially, we have the number, but unofficially more and more people are going.”
The story was first appeared at Climate Home