More than two million Bangladeshis may face displacement from their homes by 2100 because of rising sea levels.
That is the key finding of a new study examining the effect of sea level rise on Bangladesh’s population, migration, and food security, published today in Environmental Research Letters.
The study, which included Paolo D'odorico, a professor in the Department of Environmental Science, Policy and Management, used human mobility modelling combined with population, geographic, and climatic data to predict the sources, destinations, and flux of potential migrants caused by sea level rise.
Lead author Kyle Davis, from Columbia University, explained: “More than 40 percent of Bangladesh’s population is especially vulnerable to future sea level rise, as they live in low-lying areas that are often exposed to extreme natural events. However, sea level rise is a very different type of migration driver from short-lived natural hazards, in that it will make areas permanently uninhabitable.”
The team’s results using Representative Concentration Pathway (RCP) scenarios showed that mean sea level rise will cause population displacements in 33 percent of Bangladesh’s districts, and 53 percent under more intensive conditions. By mid-century, they estimated nearly 900,000 people are likely to migrate because of direct inundation from mean sea level rise alone.
Under the most extreme scenario—up to six feet rise in mean sea levels—the number of migrants driven by direct inundation could rise to as many as 2.1 million people by the year 2100.
Their analysis considered mean sea level rise without normal high tides, so the results—both in terms of inundated area and displaced population—are conservative.
The researchers also estimated the extra jobs, housing, and food needed to accommodate these migrants at their destinations. They found that to cope with the numbers likely to be displaced by 2050, 600,000 additional jobs, 200,000 residences and 784 billion food calories will be needed.
These results have clear implications for the places that are likely to receive incoming migrants.
“SLR migrants are unlikely to search far for an attractive place to move to, and the destination will generally be a trade-off between employment opportunities, its distance from the migrants’ origin, and how vulnerable it is to SLR itself,” said Davis. “We found that the city of Dhaka was consistently favoured, coming out as the top destination in all scenarios. This means the city will need to prepare for the largest number of migrants, which may compound the area’s already rapid urban growth.”
The study also identified other risks from sea level rise, most notably on livelihoods and food security.
“Inundation by the sea, and the out-migration it causes, will have significant effects on agriculture and aquaculture. For instance, 1,000km2 of Bangladesh’s cultivated land could be underwater by the end of the century, with an even larger area made unusable by saltwater intrusion. Given that 48 per cent of the labour force works in agriculture, the impact of this would be keenly felt in terms of jobs and food security,” Davis explained. “We hope that the modelling tool we have developed can be used by planners to accurately predict the relocation of climate-induced migrants, and to enable the development of political and economic strategies to face the challenge.”
Read the full story on Environmental Research Letters.