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.
Ainun Nishat*, Nandan Mukherjee**, Anna Hasemann, and Erin Roberts
* Vice-Chancellor, BRAC University
** Assistant Professor of BRAC University and Program Manager of Centre for Climate Change and Environmental Research (C3ER)