Publication

Sea level rise (SLR), a slow onset process and an impact of climate change, has two major causes: thermal expansion of the oceans, and the loss of landbased ice due to increased melting. A rise in the local, relative sea level can occur due to sedimentation, especially prominent near river deltas. Bangladesh is at risk of SLR due to its flat terrain in the coastal region, the impacts of which are already manifesting in a variety of ways. While estimates vary, the average estimate of SLR for the year 2100 is 0.62 m.

 

Estimates have shown that as much as 20 percent of the total country and 62 percent of the coastal region may be lost to SLR by the end of the century. This phenomenon may also increase cyclonic storm surge depth. Moreover, SLR reduces the availability of freshwater through salinity intrusion in both water and soil. Projected SLR may increase the extent of salinisation as saline water travels further inland. The reduction of the fresh water zone will have farreaching effects on the ecology of Bangladesh and may threaten species already endangered. SLR is not the only cause of salinisation, however; the salt concentration of water in southern Bangladesh can also be attributed to a decrease in upstream freshwater flow following the construction of the Farakka Dam in India.

 

Rising sea levels also pose a significant threat to infrastructure. In addition, agriculture will be severely affected due to the salinisation of both land and water further north from the coastal region, which will negatively impact those who rely on agriculture for their livelihoods. Aquaculture is also threatened, as SLR will likely cause loss and damage to fisheries, especially shrimp and white fish cultures. Flooding associated with rising tides and storm surges causes the overflowing of shrimp ponds, pushing shrimp into open water. The industry might be harmed in other ways as well, as SLR could affect processing systems. Thus, those whose livelihoods depend on fisheries and fish cultivation will also incur losses from SLR.

 

South-west Bangladesh is home to the Sundarbans, the world’s largest mangrove forest, which has a delicate ecosystem and supports over 1500 species of flora and fauna; this ecosystem’s salinity balance is threatened by SLR. By the year 2050, SLR could inundate 75 percent of the Sundarbans, a process that would lead to significant biodiversity loss and negatively impact the livelihoods of those who are dependent on the forest.

 

Food security and health will both decrease, especially for the poor, with food grain and protein availability per person decreasing, and pathogen and water borne diseases increasing. As many as 52 million Bangladeshis may be affected by SLR by the year 2020, rising to as many as 97 million people by the year 2080. Even using a low emissions scenario (with the base line year 2005), about 44 percent of Bangladeshis will be affected by additional flooding – exacerbated by SLR – by the year 2080.

 

The risk of SLR can be addressed through a broad range of approaches, which include a variety of structural and non-structural measures such as building embankments, tidal river management, and upstream flow augmentation. Regional cooperation for freshwater distribution, such as the Ganges Water Sharing Treaty of 1996, is another method to address the impacts of salinisation. Another method is the development of saline tolerant seed varieties and new cropping patterns and methods, in which there has been some success with jute and tomatoes. However, many will still lose their livelihoods in the coastal region, and as such, alternative income generation will become an increasingly important risk reduction practice. In the worst-case scenario, relocation may be necessary, though permanently relocating vulnerable groups will be difficult for political reasons.

 

At the policy level, the National Adaptation Programme of Action, Bangladesh’s Integrated Coastal Zone Management Plan, and the Bangladesh Climate Change Strategy and Action Plan (BCCSAP) all deal in part with SLR and how to address its impacts. At the institutional level, a dedicated Climate Change Unit has been developed, which works in conjunction with climate change focal points that are being established in each ministry. However, gaps in current policies, institutions, and approaches exist and this paper proposes a set of recommendations to address them. These recommendations are related to establishing a monitoring mechanism as well as capacity building for impact assessment, research on salinity resilient crop development, regional cooperation, and alternative livelihood development. Furthermore, the availability of a global fund and technology transfers are key foundational requirements, both for understanding and addressing the range of approaches related to SLR.