The rise in sea levels are primarily caused by melting glaciers and thermal expansion. As temperatures get warmer, winter snowfalls are unable to balance out the melting that occurs over the summer, causing sea level rise; as water heats up it expands, also contributing to an increase in sea levels. The effect of sea level rise on coastal communities can be drastic, causing erosion, flooding, ecological destruction, and more. By 2080, global temperatures are expected to rise by 4°C, causing a 105 centimeter increase in sea levels.[1]
Sea Level Rise at MIT
Much of Boston, Cambridge, and other communities lie at sea level or even below. The map below shows areas (marked in blue) at risk of of being permanently flooded by sea level rise in the next hundred years, and areas (marked in purple) at risk of being permanently flooded in the next 300 years.[2]
Figure 1: Water Level Elevation Map
Source: floodmap.net[3]
However, more land is at risk of being temporarily flooded by storm surge in the nearer future. As sea level increases, the risk of storm surge increases as well, as water levels are higher and storms are more severe due to climate change.[3]
Figure 2: Expert assessment of sea-level rise by AD 2100 and AD 2300
Source: ScienceDirect[4]
Currently, the Charles River is held at a constant water level by the Charles River Dam, which is often below the level of the ocean. The land around the dam is very low lying, at an average of 10 feet above sea level, and a large enough rise in sea level would result is water spilling around the edge of the dam. This would result in a raise of the water level of the river to the level of the sea, return the river to the mercy of oceanic and storm tides, and flood coastal regions like the Esplanade.
Overall these changes will have drastic impacts on many sectors of life in the greater Boston area, including transportation, infrastructure, public health, and energy and resources. Much of the T subway system lies under the level of the river, and spilling into the tunnels during a surge or a risen sea level would flood those tunnels and prevent trains from running properly. Many communities and parks around Boston would flood and a high water level could flood power generation and transmission sites, leaving citizens without necessary conditions for life. Flooded streets and tunnels would prevent emergency services from reaching disaster struck areas in effective time frames.
Solutions Addressing Sea Level Rise at MIT
Efficient Emergency Transportation Plans Emergency Planning Education External Flooding Barriers Green Space Incorporating Drainage MBTA Stations NRL Safety Preparation For Flooding Water Resistant Utilities
Sea Level Rise in Bangladesh
The 105 centimeter rise in global sea levels will induce more extreme flooding and weather patterns in Bangladesh, causing a 30% increase in precipitation during the wet season and a 30% decrease in precipitation during the dry season.[4] The graph below illustrates the future impact zones of storm surges along the coast of Bangladesh, along with the receding shoreline as a result of rising sea levels.[5] Flooding could cause 40% loss of productive land and approximately 18 million people to be displaced.[6] In Bangladesh, rising sea levels yield, and will continue to yield, a wide range of negative effects, including public health, agricultural, economic, ecological, and structural impacts.
Figure 3: Exposure of developing countries to sea-level rise and storm surges
Source: Climatic Change, June 2011[5]
Public Health
In the past 35 years, the salinity of ground and surface water in Bangladesh has increased by 26 percent.[7] This number is continuing to rise, increasing the prevalence of many health problems such as gastrointestinal disease and hypertension. By 2050, child malnutrition in Bangladesh is expected to increase by 31.9%.[8] Next, the coast is encroaching inwards, creating more wetland habitats and therefore also making vector-borne disease more widespread. The World Health Organization approximates that by the year 2070, over 147 million Bangladeshis will be at risk for obtaining malaria, and by 2080 there will be 30 more deaths per 100,000 people each year. Along with the physical health consequences of rising sea levels, there will be many negative psychological impacts. For example, families that are dislocated or at risk for housing destruction will be put under immense mental distress.
Agriculture and Economy
Most people of Bangladesh rely on farming or fishing to support their families. The most common crops to sell are rice, jute, and tea, supporting 15.5% of Bangladesh’s economy.[9] Rising sea levels are detrimental because they decrease the fertility of once-farmable land and create high magnitude floods that destroy these vital crops to the economy. In fact, it is projected that 40% of farmable land will be lost by 2080.[10] Rising sea levels additionally will cause salt fields to shrink, due to the fact that salt fields cannot recede with the shoreline. This will diminish the salt industry in Bangladesh. Finally, rising sea levels will create changes in water availability and housing availability, which will especially affect the poor.[11]
Ecological
Saltwater contamination is a large threat to Bangladesh, as the figure below portrays. It is estimated that rising sea levels will eventually cause the salt-water inundation of 75% of the Sundarbans—a forest of mangroves and streams considered one of the natural wonders of the world.[12] Saltwater contamination could cause the disappearance of the Sundarbans habitat, inducing the extinction of various species such as the Bengal Tiger. Rising sea levels will also drive animals away, creating salt deposits that cannot support ecological habitats and prompting freshwater animals away from rivers. Mangroves may begin to migrate away from the coast causing the canopy to thin.
Figure 4: An assessment of impacts from shrimp aquaculture in Bangladesh and prospects for improvement
Source: Food and Agriculture Organization of the United Nations[13]
Solutions Addressing Sea Level Rise in Bangladesh:
Adapting Polders Atmospheric Water Generation Community-Based Adaptation Crop Selection and Genetic Engineering Fishing Protecting and Expanding Existing Mangroves Rainwater Collection and Solar Distillation Sustainable Land Management Urine Diverting Dry Toilets Waste Management Water Security
By Christian Schillinger and Lauren Cooper
References
1. World Bank. 2013. Turn Down the Heat: Climate Extremes, Regional Impacts, and the Case for Resilience. A report for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics. Washington, DC:World Bank. License: Creative Commons Attribution—NonCommercial–NoDerivatives3.0 Unported license (CC BY-NC-ND 3.0). Retrieved from, http://www.worldbank.org/en/topic/climatechange/publication/turn-down-the-heat-climate-extremes-regional-impacts-resilience
2. Climate Change Vulnerability Assessment . (2017, February). Retrieved from, https://www.cambridgema.gov/CDD/Projects/Climate/~/media/F93208C3B12D4A ACBD3E0F3A712F68C7.ashx
3. Swapma, S. (n.d.). Flood Map: Water Level Elevation Map. Retrieved from, http://floodmap.net/
4. Horton, B. P., Rahmstorf, S., Englehart, S. E., & Kemp, A. C. (2013, November 23). Expert assessment of sea-level rise by AD 2100 and AD 2300. Retrieved from, http://www.sciencedirect.com/science/article/pii/S0277379113004381
5. Dasgupta, S., et al. (2011). Exposure of developing countries to sea-level rise and storm surges. Climatic Change, 106, 567-579. doi:10.1007/s10584-010-9959-6. Retrieved from, https://link.springer.com/article/10.1007/s10584-010-9959-6
6. Harris, G. (2014, March 28). Borrowed Time on Disappearing Land: Facing Rising Seas, Bangladesh Confronts the Consequences of Climate Change. The New York Times. Retrieved from, https://www.nytimes.com/2014/03/29/world/asia/facing-rising-seas-bangladesh-confronts-the-consequences-of-climate-change.html
7. Bagri, N. (2017, April 25). Bangladesh’s water crisis: A story of gender. Al Jazeera. Retrieved from, http://www.aljazeera.com/indepth/features/2017/04/bangladesh-water-crisis-story-gender-170416104845643.html
8. Climate and Health Country Profile–2015 (pp. 1-8, Rep.). (2015). Geneva, Switzerland: World Health Organization. Retrieved from, http://www.searo.who.int/entity/water_sanitation/ban_c_h_profile.pdf?ua=1
9. Bangladesh GDP and Economic Data (Rep.). (2107). New York, NY: Global Finance. Retrieved from, https://www.gfmag.com/global-data/country-data/bangladesh-gdp-country-report
10. Warming Climate to Hit Bangladesh Hard with Sea Level Rise, More Floods and Cyclones, World Bank Report Says. (Rep.). (2013). The World Bank. Retrieved from, http://www.worldbank.org/en/news/press-release/2013/06/19/warming-climate-to-hit-bangladesh-hard-with-sea-level-rise-more-floods-and-cyclones-world-bank-report-says
11. Impacts – X – Sea Level Rise 5 – Bangladesh [Web log post]. (2017, May 4). Retrieved from, https://scienceofdoom.com/2017/05/04/impacts-x-sea-level-rise-5-bangladesh/
12. Payo, A. et al. (2016). Projected changes in area of the Sundarban mangrove forest in Bangladesh due to SLR by 2100. Climatic Change, 139(2), 279-291. Retrieved from, https://link.springer.com/article/10.1007/s10584-016-1769-z
13. An assessment of impacts from shrimp aquaculture in Bangladesh and prospects for improvement – Scientific Figure on Research Gate. Retrieved from, https://www.researchgate.net/publication/321125753_An_assessment_of_impacts_from_shrimp_aquaculture_in_Bangladesh_and_prospects_for_improvement