Bangladesh faces unprecedented threat as rising seas could submerge 18% of coastal areas by 2100
Bangladesh, one of the world’s most climate-vulnerable countries, is facing an unprecedented threat from rising sea levels, with projections suggesting that up to 18% of its coastal areas may be permanently submerged by the end of the century, according to a new report.
The report, “The Future Climate of Bangladesh,” was jointly developed by the Bangladesh Meteorological Department (BMD) and the Norwegian Meteorological Institute, with technical support from Save the Children. It warns that Bangladesh is already confronting converging climate hazards including rising temperatures, heavier monsoon rains, sinking coastlines, stronger storm surges, and widening disease burdens.
Coastal regions are currently experiencing sea level rise of 3.8–5.8 mm per year, nearly double the global average.
Sea level rise and vertical land motion
The relative sea level along Bangladesh’s coast is influenced not only by ocean rise but also by vertical land motion (VLM). While natural geological processes play a role, human activities such as groundwater extraction, wetland loss and urban expansion have accelerated subsidence, particularly in Dhaka and the south-western coast.
“Subsidence is highly localised, but when combined with rising seas, it significantly increases the risk of flooding for millions,” BMD officials said.
In some tidal delta zones, natural sedimentation offsets subsidence, but this buffer has weakened due to upstream dam construction and riverbank stabilisation.
Under a high-emission scenario (SSP5-8.5), global mean sea level could rise 0.63–1.01 metres by 2100, with the Bay of Bengal potentially seeing around 0.77 metres. Even moderate sea level rise is expected to dramatically amplify storm-surge impacts. Analyses show that regions including the Sundarbans, Bhola Island and northern Barishal could see more than double the current inundation during extreme events.
Although China is now the largest annual carbon emitter, industrialised Western nations—including the US, EU member states, Russia, Japan, Canada and Australia—remain most responsible historically, accounting for over 70% of global carbon emissions, said Prof Dr Ahmad Kamruzzaman Majumder, Founder and Director of CAPS.
“If global temperatures rise 4.5°C by 2100, Bangladesh’s southern coastal districts like Khulna, Bagerhat, Patuakhali, Barguna, Bhola and Satkhira will face the highest risk from sea level rise, salinity, cyclones, storm surges and riverbank erosion,” he warned.
Storm surges and inundation risks
Bangladesh’s low-lying delta makes it extremely susceptible to storm surges caused by tropical cyclones. Historical disasters such as Cyclone Sidr (2007) and Cyclone Amphan (2020) show the scale of devastation. In 2020 alone, storm surges displaced 500,000 families, pushing seawater up to 15 km inland.
By 2100, similar cyclones could increase the number of affected people by 50–80%, unless global warming is limited to 2°C. Chronic inundation would destroy homes, croplands, and freshwater sources while heightening salinity intrusion.
Health impacts and vulnerable populations
Heatwaves are projected to become longer and more intense, sharply increasing risks of heat-related illnesses and chronic cardiovascular, respiratory and kidney diseases. Children, the elderly, and people with limited access to clean water and shelter remain most vulnerable. Even small increases in extreme heat days significantly raise childhood stunting rates, particularly in the first two years of life.
Vector-borne diseases like dengue and malaria are expected to spread further as temperature and humidity favour mosquito breeding. Waterborne diseases such as cholera may move inland as heatwaves and flooding compromise drinking water sources, particularly in densely populated Dhaka.
Agriculture, food security and fisheries at risk
Agriculture, which employs more than one-third of the population, faces escalating risks from heat stress, salinity and flooding. Crop yields are expected to decline, livestock face heat-related health threats, and fisheries may suffer from saline intrusion and lost mangrove habitats. By 2100, rising salinity alone could affect 27% more coastal farmland, jeopardising food security.
Ecosystems under pressure
The Sundarbans, the world’s largest mangrove forest, are highly vulnerable. Up to 23% of its area could be flooded under high-emission scenarios, undermining biodiversity, local livelihoods and the region’s natural cyclone shield. Forests in hilly regions, vital in preventing landslides and soil erosion, are also threatened by erratic rainfall.
Adaptation and resilience measures
Despite these threats, Bangladesh is recognised globally for its climate-adaptation leadership. The Cyclone Preparedness Programme (CPP) has reduced cyclone fatalities from six-digit levels to just over 4,500 in recent decades. Coastal polders, embankments, floating agriculture and saline-tolerant crops continue to enhance community resilience. The government allocates 6–7% of its annual budget to climate adaptation.
Experts, however, emphasize that national efforts alone cannot counter global emissions.
“Bangladesh can implement the most advanced adaptation measures, but without strong international action to reduce emissions, millions will remain at risk of flooding, displacement and disaster,” the International Centre for Climate Change and Development (ICCCAD) said.
A narrowing window for action
The convergence of sea level rise, storm surges, land subsidence and extreme heat paints a stark future for Bangladesh. By 2100, vast swathes of the coastal delta—including major agricultural zones and millions of homes—could be permanently lost.
“The choices made today, both globally and nationally, will determine whether much of this country survives above water or becomes a tale of lost land and livelihoods,” the report warned.
