Chapter-5

EFFECTS OF SEA LEVEL RISE (SLR)

The predicted rises in sea level will be experienced through a number

of impacts, including the inundation of coastal areas, increased likelihood of

flooding in storm surge occurrences and substantial increases to the erosion

of coastlines. These impacts will be enough to adversely affect many

ecosystems including beaches, coastal wetlands and coral reefs. In some

areas these ecosystems will be forced to reduce in size and in others they

will be lost completely. These ecosystem losses will in turn impact on

human settlement reducing natural defence against rising sea level in periods

of storm surge. The degree at which the predicted sea level rise is expected

to have on nations varies, with some noticeably more vulnerable to this

environment issue than others. Even conservative sea level rise predictions

will devastate some nations, resulting in the loss of land and displacement of

many people. Coastal regions are some of the most diverse and productive

ecosystems as an active interface between land and water. However they are

currently reeling under immense pressure from a medley of stressors such as

rapid population growth, urbanization and development activities that alter

the structure and function of these ecosystems.

Climate change poses as an additional threat that varies both in the

severity of temporal and spatial impacts. In the coastal regions of West

Bengal current and projected vulnerabilities to the impacts of climate change

in general and sea level rise in particular are being assessed to work out

methods of dealing with them. This will help identifying target areas for

interventions to prepare for such changes.  Uniquely placed in the eastern

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lowland area of the Bay of Bengal, bordering Bangladesh, the state of West

Bengal is vulnerable to any potential rise in the sea levels and thrusts from

cyclonic events and storm surges. Exposure to storm surges, monsoon and

post monsoon storms are comparatively high and make the state vulnerable

to the occurrence of such events. Besides, dense population, rapid

urbanization with high rate of degradation of local environments is

characteristic to most of the region. The Gangetic delta mangroves -the

Sundarbanss, formed at the confluence of the Ganges and the Brahmaputra,

is world's most extensive continuous mangrove forests and covers about

2000 sq Km in the Indian territory. Any impact to the coastal ecosystem has

a direct impact on coastal livelihoods. TERI is studying the effect of climate

related hazards like floods, cyclones and storm surges on the communities

residing in the region. Geographical Information Systems (GIS) is being

used for better identifying pockets vulnerable to hazards such as sea level

rise, floods, cyclones and storm surges. Additionally, vulnerability is being

assessed in terms of the level of socio-economic development of that region.

5.1 Physical (Environmental) Effects5.1.1 Loss of landmass and settlement

Policy changes needed to reduce vulnerability include limitations on

the sitting of new development or infrastructure (including transportation

corridors) in high‐risk areas. Also needed are changes to permit

requirements for setbacks and design elevations and modifications to

building codes for structural elements and corrosion‐resistant

equipment.Long‐term plans for maintenance, retrofits and upgrades should

incorporate opportunities for adapting existing infrastructure to projected

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changes in flood risk through elevation, relocation, increased capacity or

other measures. Emergency management planning must incorporate

increased demand for emergency services and consider sea level rise impacts

on evacuation routes. Use of state resources for repair or construction of

shoreline protective measures–whether natural or engineered, temporary or

long term–should be evaluated to ensure that they are the most cost‐effective, long‐term, site‐specific approaches feasible. Plans for back‐up

measures for critical systems such as energy and drinking water should

include impacts of sea level rise. Determinations of priority for remediation

of hazardous waste sites and brownfields should consider the likelihood of

increased flood risk. Residents of some areas may have to explore

alternative sources for drinking water should their primary sources be

degraded.

Table 5.1 Submerge areas due to see level rise in future.

See Level Rise in(m) Affected Costal Area in Percentage

west centre east

1m 0.1% 14% 21%

3m 4% 29% 38%

6m 32% 47% 59%

9m 49% 78% 94%

source;: Coastal Zone Development Authority

Non‐structural solutions, such as elevation and relocation of

structures, must play a major role in a statewide response, especially in less

urbanized areas where they may be less expensive and more effective at

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reducing long‐term vulnerability (Recommendation 5). Such strategies

include conserving natural systems such as barrier islands, tidal wetlands

and dune systems that currently provide flood protection and community

benefits at no cost. Low‐impact development and green infrastructure could

also help mitigate the effects of sea level rise, including flooding. Low‐impact development emphasizes conservation and use of on‐site natural

features to protect water quality. Green infrastructure refers to the use of

natural or engineered systems that mimic natural processes. It includes rain

gardens, rooftop catchment systems and green roofs, technologies and

practices that allow treated wastewater and storm water to infiltrate back into

groundwater systems rather than piping it into the nearest waterbody, where

it may exacerbate coastal flooding.Non‐structural solutions, such as

elevation and relocation of structures, must play a major role in a statewide

response, especially in less urbanized areas where they may be less

expensive and more effective at reducing long term vulnerability Due to

their escalating capital and maintenance costs and the incentives they create

for new development in high‐risk areas, reliance on structural protection

measures alone, as well as funding such measures, without examining

alternative or complementary solutions, should be significantly reduced over

time. State and federal support for shore defense measures will likely be

reduced and become uncertain in the future as sea level rise effects,

distributed over an expanding geographic area, compete for funding with

other budget priorities. Local governments and private interests compound

their risks by relying on these uncertain external subsidies for high‐risk

development. A more efficient, market‐based approach to decisions on

sitting development or undertaking adaptive measures for existing

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development will be needed to distribute finite resources. A close

association between development decisions and costs for emergency

services, coastal hazard defenses and environmental impacts would facilitate

more realistic analysis of the full costs associated with coastal infrastructure

and development.

5.1.2 Loss of Ecosystem

Climate change affects all aspects of biodiversity; however, the changes

have to be taken into account vis-a-vis the impacts from the past, present,

and future human activities, including increasing atmospheric concentration

of carbon dioxide. For the wide range of IPPC emission scenarios, the

Earth's mean surface temperature has been projected to warm 1.4 to 5.8 C by

the end of the 21st century, with land areas warming more than the oceans

and the high altitudes more than tropics. Then globally, by the year 2080,

about 20% of the coastal wetlands could be lost due to sea level-rise. The

associated sea-level rise is supposed to be 0.09 to 0.88m.So far the impact of

climate change on biodiversity is concerned, it is to affect individual

organisms, populations, species distributions, and ecosystem composition

and function both directly (through increase in temperature and changes in

precipitation and in the case of marine and coastal ecosystems also changes

in sea-level and storm surges) and indirectly (through climate change the

intensity and frequency of disturbances on species assemblage).

Climate change impact on plants, animals and humans is enormous in

volume and it is more or less everywhere of the world. But the impacts of

climate change on sea-level-rise and its consequent effects on coastal

ecosystems are exceptionally significant. These impacts are equally

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devastating to the biodiversity and to the people in the different areas of the

ecosystem. A coastal ecosystem provides high species assemblage and at the

same time human need-resources. Human need-resources are available in the

coastal ecosystems from different dimensions and different formations.

Coastal ecosystems are affected by both anthropogenic activities and climate

change variability. Coastal developments, tourism management, land

clearance, pollution, exploitation of species, habitat degradation, and

depletion of coral reefs, mangroves, sea grasses, coastal wetlands and loss of

beaches are due to anthropogenic activities. Climate change impacts affect

physical, biological, and biochemical characteristics of the ocean and coastal

ecosystems at different time and space scales. These modify their ecological

structure and functions. As it is told that,when sea surface temperatures will

increase by more than 1C, coral reefs will be impacted upon detrimentally. It

is already reported that many coral reefs occur at or close to temperature

tolerance thresholds. Over the past several decades, increasing sea-surface

temperatures have been recorded in much of the tropical oceans. Coral reefs

have been adversely affected by rising sea surface temperatures. Many coral

reefs have undergone major, although often partially reversible, bleaching

episodes when sea surface temperatures have raised 1C above the mean

seasonal sea-surface temperatures in any one season, and extensive mortality

has occurred in a 3C rise. The coral bleaching events of 1997-1998 were the

most geographically widespread with coral reefs throughout the world being

affected leading to death of some corals.

If sea-surface temperatures increase by 3C in short term, and if this

increase is sustained over several months, it will cause extensive mortality of

corals. In addition, an increase in atmospheric CO2 concentration and hence

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oceanic CO2 affects the ability of the reef plants and animals to make

limestone skeletons (reef calcification); a doubling of atmospheric CO2

concentration could reduce reef calcification and reduce the ability of the

coral to grow vertically and keep pace with rising sea level. The overall

impact of sea-surface temperature increase and elevated CO2 concentration

could result in reduced species diversity in coral reefs and more frequent

outbreaks of pests and diseases in the reef system. The effects of reducing

productivity of reef ecosystems on mollusks, echinoderms, crabs, birds and

marine mammals are expected to be substantial.

It is anticipated that globally about 20% of coastal wetlands could be lost by

the year 2028 due to sea-level rise, with significant regional variations. Such

losses would reinforce other adverse trends of wetland loss resulting

primarily from other human activities.

Climate change has negative impacts on the abundance and

distribution of marine biota as a whole. The impact of climate change will

affect dynamics of fish and shell fishes. Climate change impacts on the

ocean system include sea-surface temperature-induced shifts in the

geographic distribution of marine biota and compositional changes in

biodiversity, particularly at high latitudes. The degree of the impact is likely

to vary within a wide range, depending on the species and community

characteristics and the region-specific conditions.

Sea-level rise with many other factors could affect a range of fresh

water wetlands in low-lying regions. In tropical regions, low-lying

floodplains and associated swamps could be displaced by saltwater habitats

due to the combined actions of sea-level rise, more intense monsoonal rains,

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and larger tidal or storm surges. Saltwater intrusion into freshwater aquifers

is also potentially a major problem. Scientists are concerned with a fact that,

everybody anticipates sea-level-rise impact and associated climate change

impact on Bangladesh coastal areas. It is already reported that about 18% of

Bangladesh's land will be submerged if the sea-level rises by one meter.

We must remember that impact of climatic change anywhere in an

ecosystem (especially in the tropics and subtropics) is first and most

sensitively received by plant phenology and by the life stages of animals

(especially of phytophagous animals). Plant-animal relation in an ecosystem

is biotic-biotic interaction. Sequence and or occurrence of biotic-biotic

relation is the key factor for species assemblage/ species richness in an

ecosystem. This species richness is the healthiness of biodiversity in a region

of the biosphere. Healthiness of biodiversity is the sustenance of integration

of biotic-biotic and abiotic-biotic interactions. This sustenance of integration

never stands in proper 'functioning' condition when phenological stages of

the plant and life stages (especially developmental stages) of animals are

affected by climatic changes or any other anthropogenic activities.

sunderbans is a natural laboratory and the place of highest species

assemblage as well as species richness in the world, especially the

southwestern coastal areas of the country. This area functions both as

terrestrial and aquatic ecosystems ensemble. This situation is presented by

mangrove vegetation as the aquatico-terrestrial condition and estuarine

ecosystem as the highest productive area of marine and riverine ecosystem.

Here is the secret of containing highest integration of biotic-biotic and

biotic-abiotic interactions; and then for the maintenance of the highest

species assemblage in the world. 

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5.1.3 Salinity intrusion

In addition to inundation, SLR will cause saltwater intrusion into

coastal aquifers, particularly in regions of high groundwater withdrawal. For

the populations of small islands, reduction or disappearance of potable water

may be the greatest impact on their survival, rivaling in importance both

coastal erosion and lowland flooding. Entire island nations are already being

affected by saltwater intrusion (Tuvalu, Marshall Islands, etc; Roy and

Connell 1991, Nunn and Mimura 1997) and this hazard should be

considered together with surface flooding associated with rising sea level.

One dramatic and immediate effect of SLR is the inundation of low-lying

coastal areas around the world (Bird 1993). In addition to increased coastal

erosion caused by SLR, flooding of deltaic regions, saltwater incursion into

coastal urban centers, and disruption of transportation are of great concern in

many countries (Leatherman 1997, Titus 2002).

When groundwater is pumped from aquifers that are in hydraulic

connection with the sea, the gradients that are set up may induce a flow of

salt water from the sea toward the well. The migration of salt water into

freshwater aquifers under the influence of groundwater development is

known as seawater intrusion. There is a tendency to indicate occurrence of

any saline or brackish water along the coastal formations to sea water

intrusion. The salinity can be due to several reasons and mostly it can be due

to the leaching out of the salts from the aquifer material. In order to avoid

mistaken diagnoses of seawater intrusion as evidenced by temporary

increases of total dissolved salts, Revelle recommended Chloride-

Bicarbonate ratio as a criterion to evaluate intrusion. In India, sea water

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intrusion is observed along the coastal areas of West Bengal. One potential

impact of a global warming and rise in sea level would be an increase in the

salinity of coastal zones, which would potentially threaten drinking water

and aquatic ecosystems. There is a need to be better prepared to respond and

adapt to these changes. This report examines the potential impacts of

accelerated sea level rise on salinity in the South West region of Bangladesh.

The study aims at determining the sensitivity of river salinity to upstream

discharge and downstream sea level. To do that, the minimum upstream

flow will be determined to protect the salinity intrusion from sea level rise.

A one dimensional river salinity transport model has been developed and

coupled with an existing surface and river flow model. The model has been

proved to be robust with calibration and verification against observed data.

The model outputs indicate a significant change of river salinity in the

coastal zone.

The results also indicate that a considerable advance in seawater

intrusion can be expected in the coastal aquifer if current rates of sea level

rise continue. The topography of the area is flat and gently sloping towards

the Bay of Bengal. The consequences of salinity intrusion in the coastal area

especially in the South West region of Bangladesh would be significant on

many sectors like land fertility, agriculture, availability of fresh water,

existence of the Sundarbanss forest etc. Pond culture in the coastal area will

be affected by intrusion of salt water into ponds, unless embankments are

made around them. Shrimp culture in the coastal area is a lucrative business.

The main impacts of sea level rise on water resources are fresh water

availability reduction by salinity intrusion. Both water and soil salinity along

the coast will be increased with the rise in sea level, destroying normal

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characteristics of coastal soil and water. Salt-water intrusion is the invasion

of seawater into fresh water and brackish areas. The salt-water intrusion that

occurs as a result of sea-level rise will have important ecological effects. In

estuaries the gradual flow of fresh water toward the oceans is the only factor

preventing the estuary from having the same salinity as the ocean,” and it is

this decreased and fluctuating salinity that helps induce estuaries’ high levels

of biodiversity. Sea-level rise thus has the potential to interfere with coastal

ecosystems and, in particular, to greatly reduce or destroy estuarine

biodiversity.

However, from a public health perspective, it is the effects on public

water supply that are the most important consequences of salt-water

intrusion. The coastal communities most vulnerable to sea-level rise often

depend on local sources of fresh water. These water supplies can come from

either surface source, such as lakes and rivers, or from underground aquifers,

accessed through wells. Both sources of coastal fresh water are vulnerable to

salt-water intrusion as the seas rise were actually inundated, particularly

those that rely on unconfined aquifers just above sea level.” In such aquifers,

generally, a freshwater “lens” floats on top of heavier salt water, and “if the

top of the aquifer is one meter above sea level the interface between fresh

and salt water is forty meters below sea level.”If fresh water is plentiful, the

unconfined aquifer will simply rise with the rising sea level. However, if

drought or wells deplete the fresh water in the aquifer, then existing wells

will be too deep and will draw brackish or salt water instead of fresh water.

Fresh water management authorities currently deal with the threat of salt-

water intrusion by storing fresh water in reservoirs and then releasing it

Chapter-5

during droughts, preventing saline water from creeping upstream. However,

as sea level rises, this solution may become impracticable, both because of

rising salinity tables and the potential for decreased water supply, reducing

areas’ ability to store excess water in reservoirs. Instead, water managers in

coastal states should begin to evaluate seriously the potential impact on fresh

water supplies of a range of sea-level rise scenarios, taking into account the

region’s population dynamics as well. In addition, water managers should

identify and, where fiscally and politically possible, secure alternative

sources of water supply. Finally, managers and the relevant government

should begin to identify and plan for potential water supply infrastructure

needs (e.g., transportation, desalination, water treatment) for a range of sea-

level rise scenarios.

5.1.4 Tropical cyclones and storm surges

West Bengal is already vulnerable to extreme climate events such as

cyclones, storm surges and The CCSLR will add fuel to the fire. The Bay of

Bengal is a favorable breeding ground of tropical cyclones and study area is

the worst suffer of all cyclonic casualties in the world. About 5.5% cyclonic

storms (wind speed greater than or equal to 62 km/hr) form in the Bay of

Bengal and about 1% cyclonic storm of the global total hit this area (Ali,

1996, 1999a, 1999b). On the other hand, if the tropical cyclone disasters due

to each of which the minimum death tolls were 5,000 are considered, then it

is found that a death toll of about 53% of the global total occurred (Ali,

1999a). Thus it is seen that with 1% cyclones hitting, it is the worst sufferer

in terms human casualty. If, on the top of that,the CCSLR affects cyclone

activity. Two major aspects of cyclones that are most likely to be affected by

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climate change are cyclone frequency and cyclone intensity, as well as the

storm surges accompanying a cyclone. Ali (1996, 1999a, 1999b) has made a

somewhat in-depth study on the impacts of climate change and SLR on

cyclones and storm surges in the Bay of Bengal Coastal region.

An analysis of all the cyclones that formed in the Bay of Bengal

during the period 1877-1997 showed no corresponding increase in cyclone

frequency in the Bay of Bengal, rather an oscillation of about 40 years. A

recent study by Singh and Khan (1999) shows that the annual frequency of

tropical cyclones over the north Indian Ocean (the Bay of Bengal and the

Arabian sea) has shown a decreasing trend of one cyclone per hundred years.

It may be mentioned here that during the period 1877-1997, about 366

cyclones did not strike any country and they died in the Bay. If it is assumed

that any increase in the sea surface temperature (SST) would have activated

them and made them landfall, then the percentage increase of striking

cyclones would be about 32. That is, in the event of climate change, the

number of land-falling cyclones would increase by about 32% in the Bay of

Bengal, bringing in more disastrous situations for the littoral countries.

There does not seem to be any study on the increase of cyclone intensity in

the Bay of Bengal. But theoretical considerations show that a 10C rise in

SST will increase the cyclone intensity by 4%, 20C rises by 10% and 40C

rises by 22% (Emanuel, 1987). Most of the cyclonic casualties are caused by

storm surges. Surge heights as high as 10 m (occasionally even more) are

not uncommon in sunderbans. An increase in cyclone intensity will cause an

increase in storm surge heights and the horizontal extent of flooding. A

model analysis by Ali (1996) shows that storm surge heights will increase by

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21% and 47% for a corresponding rise in SST by 20C and 40C respectively

for a particular location along the eastern coast of west Bengal

5.2 Economic Effects5.2.1 Fisheries and Aquaculture

Sea level rise would change the location of the river estuary, causing a

great change in fish habitat and breeding ground. Penaid prawns breed and

develop in brackish water, where salt water and fresh water mix. Sea level

rise would turn this interface backward, changing habitat of prawn. There

are 60 shrimp hatcheries and 124 shrimp processing plants in the coastal

zone (Haque, 2003). The hatcheries are located at digha, sankarpur and

tejput of Midinipure district. Favourable environmental condition and brood

stock availability are the main reason to set up hatcheries in the area. Some

hatcheries have also started test production in north 24 pargana and South 24

pargana coast.

It is to be mentioned that all the above districts are located in the

coastal zone. As the zone is vulnerable to sea level rise, shrimp hatcheries

and shrimp fields are also vulnerable to the phenomena. However, sea level

rise is helping shrimp farming by introducing salinity in the coastal area, but

it is also harmful. If we consider another sea level rise phenomena, for

instance flooding; it is doing massive harm to the sector by overflowing

shrimp pond and let the shrimps to set free in open water. A flood, which

ravaged the southwestern part of West Bengal in 2000 caused damage or

losses of at least US$500 million to crops, fish farms, property and

infrastructure. The shrimp sector was the most affected sector, losing shrimp

fields of equivalent US$230 million (CNN, 2000). After the flood,

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representative of West Bengal Frozen Foods Exporters Association

expressed that flood hits the shrimp sectors seriously (Basher, 2000). A

shrimp farmer expressed "I have lost up to 400 million taka (US$7.4

million) invested in 40 shrimp projects, maybe I will never be well-off

again” (Asaduzzaman, 2000). In addition, high projected magnitude of sea

level rise will inundate the present shrimp ponds and will destroy this

prospective foreign exchange earning sector of West Bengal.

There are 21 government fisheries service centre’s in the coastal zone.

These centres facilitate the fishery sector with fuel supplies, landing, whole

sale, icing, inland transportation and other activities with an aim to improve

the yield of the sector. These service centre’s are much closed to coastline or

estuaries and are potential to be inundated by sea level rise. There are some

areas in the coastal zone that are far from city or fisheries service centre and

have no icing facilities. Fishermen of such areas dry fishes in open sunlight

to avoid spoilage. Locally these dry fishes are known as ‘Shutki’. Dry fishes

are rich in nutrient value and a popular dish among the coastal people,

especially in the southeastern coastal zone. The dry fish industry will also be

affected by anticipated sea level rise.

If we search the cause-impact relationships of sea level rise and

coastal fisheries of West Bengal, as described in the following causal loop

diagram or CLD (Figure; for more about CLD, please see Haraldsson,

2004), we see that coastal fisheries are affected by sea level rise in three

ways; by salinity, by flooding and by increasing cyclone frequency and

damage. These three factors collectively decrease the coastal fisheries.

Fisheries are the main protein source for the coastal people of West Bengal.

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About 60- 80 per cent of animal protein intake of the people of West Bengal

comes from fish consumption (Alam & Thomson, 2001; World Bank 2000,

p.61). So, decreased coastal fisheries would cause protein scarcity among the

coastal populace that ultimately causes health hazards. Poor health status

will gear up poverty in the coastal area. At the same time poverty will boost

up health hazards because of lacking sufficient medicine, health care and

nutrition. If the coastal fisheries decrease, it will hinder West Bengal from

earning foreign exchange, as because the frozen food industry, the second

largest foreign exchange earner sector of West Bengal, is dependent on

coastal fisheries. Insufficient earnings will also increase poverty. Increased

poverty will cause West Bengal to seek national and international aid.

5.2.2 AgricultureSalinity intrusion due to sea level rise will decrease agricultural production

by unavailability of fresh water and soil degradation. Salinity also decreases

the terminative energy and germination rate of some plants (Rashid et al.,

2004; Ashraf et al., 2002). Ali (2005) investigated the loss of rice production

in a village of midinipure district and found that rice production in 2003 was

1,151 metric tons less than the year 1985, corresponding to a loss of 69 per

cent. Out of the total decreased production, 77 per cent was due to

conversion of rice field into shrimp pond and 23 per cent was because of

yield loss. Practicing shrimp cultivation in saline water has a drawback, and

that is a decrease in rice production due to degraded soil quality. The

decrease rate is very high and the scene is common for almost all rice fields

in north 24 pargana, south 24 pargana and midinipure districts.

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A World Bank (2000) study suggests that increased salinity alone

from a 3 metre sea level rise will cause a net reduction of 0.5 million metric

tons of rice production. Sea level rise affects coastal agriculture, especially

rice production in two ways. Salinity intrusion degrades soil quality that

decrease or inhibit rice production. When the rice fields are converted into

shrimp ponds, total rice production decreases because of decreased rice field

areas. In the fiscal year (FY) 1997-1998, rice production area was decreased

by one per cent compared to the FY 1993-1994, whereas the total rice

production was decreased by 26 per cent during the same period (Islam,

2004, p.190). Farmers couldn’t produce two rice crops2 during the year, as

one vegetation cycle was used for shrimp cultivation instead. For that

reason, the decrease in production is seemingly too high compared to the

decrease in area. Figure represents the crop-wise agricultural production in

the coastal zone. It shows that rice production (16%) in the coastal area is

lower comparative to production area (24%). The coastal zone is very

important for pulses, oil seeds and vegetables production, which will fall

gradually similarly to rice, with increase in salinity in the zone. It may be

questioned why the coastal zone is still producing high volume of pulses and

oil seeds. The answer is because these crops are produced in comparatively

inner or landward part of the zone, where salinity is still very low. Sea level

rise with adding more salinity to the water and soil of the area will decrease

production of the mentioned and other crops.

Table 5.2 Impact of Sea Level rise on Agriculture in West Bengal Coast

See level rise( in m) Loss of agriculture land in %

1m 2%

2 8%

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4 23%

6 60%

Source: West Bengal Agriculture Department.

Rice is the staple food of the people of West Bengal. It was estimated

earlier that farmers of the country have 10,000 rice varieties in their

collection (Brammer et al., 1993). These varieties include Aus, Aman, Boro

and IRRI group. Most of the varieties are in the Aman group. Sea level rise

will increase flood frequency and flooding duration, affecting Aman

production. Due to sea level rise, salinity of water and soil will increase, and

this will damage Aman cultivable land. Because of the shortage of fresh

water, Boro rice production will be decreased. IRRI and wheat production

will also be affected by salinity increase. A study by BARC (1999; cited in

Islam, 2004) concluded that salinization will cause a reduction of wheat

production equivalent to US$ 586.75 million. Miller (2004) stated that high

projected rise in sea level of about 88 cm (35 inches) would flood

agricultural lowlands and deltas in parts of West Bengal. Agricultural lands

in the coastal area will be affected by salinity; soil quality will be degraded

and flooding event will loss the agricultural production of the coastal land of

West Bengal. As West Bengal is a dense populated state, there is no specific

grazing field for cattle. Farmers get grass from their rice field. Hey is

another source of fodder. Decreased rise production is decreasing fodder

production resulting in fodder shortage. Ali (2005) noticed that fodder

shortage is the cause for a declining livestock population from 630 in 1985

to 168 in 2003 in a small village in midinipure district.

Table 5.3 Impact on Crops of Sea Level Rise (Two Crops areas) in Study Area

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Sea Level Rise (in m) Jute Paddy

1 4% 11%

2 18% 23%

4 29% 41%

6 48% 70%

Source;: West Bengal Agriculture Department.

If we try to find out the big picture of sea level rise impacts on

agriculture of West Bengal, it shows almost similar behavior as in the case

of coastal fisheries. Sea level rise affects agriculture in three ways, i.e. by

salinity intrusion, by flooding and by increasing cyclone frequency and its

depth of damage. Combined effects of these three factors decrease

agriculture production in the coastal zone. Decreased agriculture will cause

decreased GDP. If agricultural production is decreased, food and cash crop

production will be decreased too. Decreased food production will cause food

shortage leading to health hazards or even famine. The ultimate result of

reduced agricultural production is high poverty that will force West Bengal

to seek much aid from central government. When the rice fields are

converted into shrimp ponds, total rice production decreases because of

decreased rice field areas. It was estimated earlier that farmers of the country

have 10,000 rice varieties in their collection (Brammer et al., 1993). These

varieties include Aus, Aman, Boro and IRRI group. Most of the varieties are

in the Aman group. Sea level rise will increase flood frequency and flooding

duration, affecting Aman production. A study by BARC (1999; cited in

Islam, 2004) concluded that salinization will cause a reduction of wheat

production equivalent to US$ 586.75 million. Miller (2004) stated that high

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projected rise in sea level of about 88 cm would flood agricultural lowlands

and deltas in parts of West Bengal. Agricultural lands in the coastal area will

be affected by salinity; soil quality will be degraded and flooding event will

loss the agricultural production of the coastal land of West Bengal. Thus sea

level rise will have an impact on agricultural production, especially on food

production, leading West Bengal to fail, obtaining food security.

5.2.3 Tourism A significant part of West Bengal coast is sandy beaches that attract

tourists. Digha is West Bengal's most popular sea resort. It is located 187

KM south west of Kolkata. Digha has a low gradient with a shallow sand

beach extending upto 7KM in length and has gentle rolling waves. The

scenic beauty of this place is charming and alluring. The beach is girdled

with Casuarina plantations along the coast enhancing its beauty. These trees

apart from beautifying also aid in reducing erosion of the dunes. Recent sea-

level rise has mostly been attributed to global warming and this process is

expected to continue for centuries. The extent of the impact of sea level rise

on tourism in Ghana is unknown though there are predictions that some

prominent tourism facilities are at risk. This paper assessed the potential

impact of enhanced sea level rise (ESLR) for different IPCC scenarios on

tourism facilities along the coast of Accra. Shorelines for 1974 and 2005

were extracted from orthophotos and topographic maps, and vulnerability

for tourism facilities estimated. Mean sea level measurements indicated an

average rise of 3.3 mm/year, while the shoreline eroded by as much as

0.86 m/year. Predictions for Ghana showed 10 cm, 23.4 cm and 36.4 cm sea

level rise for 2020, 2060 and 2100 respectively with 1990 as base year.

Modelled predictions for the years 2020, 2060 and 2100 based on A2

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(enhanced regional economic growth) and B2 (more environmentally

focused) IPCC scenarios indicated that 13 tourism facilities are at risk to sea

level rise. Out of the total number of tourism facilities at risk, 31 % cannot

physically withstand the event of sea level rise hazard. In terms of socio-

economic vulnerability, accommodation facilities are the most susceptible.

Salinization and sanitation problems along the coast will adversely affect

tourism.

Table 5.3 Trends of Coastal Tourism in West Bengal Coastal Region

Year Tourist in million (approx) Economic Profits (Rs in crore approx)

1981-1991 13 4430

1991-2001 16 6220

2001-2011 19 9240

2011-2012 2.3 101

Source: Tourism Industry of West Bengal

Digha beach in midinipure district, Sagar beach in south 24 pargana

district and bakhhali beach are attractive tourist areas of the country.

Mandarmoni sea beach is one of the world’s largest unbroken sandy beach

having a length of 145 km (Hossain and Lin, 2001), attracting the tourists of

home and abroad. Out of 24 tourist areas identified by West Bengal tourism,

five spots namely Digha, sankarpur, mandarmani, tejpur and the

Sundarbanss are located in the coastal zone (West Bengal online, 2005).

Numerous tourism related infrastructures are situated in the coastal zone.

Besides government establishments, private owned hotel, motel, guest house

or other mode of tourist accommodations would be around 500 in the same

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areas. All the tourist facilities in the coastal zone will be affected by sea

level rise directly or indirectly. Tourism sector of Digha will suffer the most

because all the facilities are very close to the coastline and the area is more

vulnerable comparative to sakarpur and tejpur. However, all the mentioned

areas are highly vulnerable in terms of sea level rise related natural disaster,

e.g. flood, storm surge, etc.

5.2.4 Salt Industry West Bengal coastal region is one of the most salt producing coastal

region of india.When investigating the salt trade and coastal salt production,

it has become evident that coastal flooding and at other times lowering of the

sea level, made the filling of solar evaporation pans very difficult. This

seems to have been due to erratic changes of sea levels particularly in the

midinipure, where salt production had been relatively easy because of a very

small and predictable tide level, during certain periods, and impossible at

other times. The evidence that has accumulated has indicated flooding of salt

fields on coasts according to a curve at the end of the last ice age,

approximately 8000 BP, it is estimated, and the sea level rose by more than

60 m. The eustatic changes of the oceans in prehistoric and historic times are

recognized as erratic and steep. A hypothesis is proposed to explain these

erratic changes with Albedo changes of the West Bengal Coastr ice caps,

caused in turn by erratic volcanic and terrestrial dust fall-out. Ash layers in

the Antarctic ice cores are connected with historic dislocations of salt

production on ocean coasts and of maritime civilizations. All the activities

(sea water collection, storing in reservoir, condensing and crystallizing) of

salt production that are handled by salt farmers are performed in the close

area of the coastline. Moreover, salt mills are also located very close to the

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coastline. A one metre sea level rise will inundate all the salt fields and will

ruin the sectors. Salt farmers can’t move upwards land for the purpose

because, physical properties of the soil of the present salt field will not move

backwards with sea level rise. About 20 million people are directly or

indirectly related in salt production (Hossain and Lin, 2001) and/or trading

in Bangladesh. Sea level rise, by inundating salt fields will force this huge

number of people to be unemployed

5.3 Socio-cultural effects5.3.1 Health

In early April 2008, the World Health Organization (WHO)

reported that “climate change is one of the factors causing an increase in the

incidence of 2010 diseases like malaria and dengue fever.” As one of the

effects of climate change, sea-level rise will contribute to the spread of these

and other diseases and health problems in several ways. In combination with

higher temperatures in many coastal areas, sea-level rise will contribute to

the expected resurgence of certain mosquito-borne diseases such as malaria

and the introduction of new mosquito-borne diseases, such as dengue fever,

in the United States. As James Titus has noted, “by deepening shallow

bodies of water, a sea level rise could cause them to stagnate.”Warm,

stagnant bodies of brackish water are perfect breeding grounds for disease-

bearing mosquitoes. Worldwide, malaria and dengue fever are spreading,

both by emerging into new areas and by returning to areas where the

diseases had been under control. For example, WHO reported in April 2008

that “malaria kills at least 100,000 people each year” worldwide, and it

noted that malaria-carrying mosquitoes are now found in areas where

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malaria has never existed before. Moreover, malaria has returned to

countries like Peru, largely as a result of climate change and deforestation.

In Peru, malaria was almost eradicated 40 years ago, but this year 64,000

cases have been registered in the country, half in the Amazon region. It is

thought there are many more unregistered cases deep within the massive and

humid rainforest, where health authorities find it almost impossible to gain

access. Malaria is also endemic in the United States, if currently essentially

eradicated; thus, the resurgence of the disease in Peru provides a cautionary

note for Americans. “WHO also estimates that there may be 50 million cases

of dengue infection around the world every year, of which half a million will

require hospitalization. About 12,500 of the cases will be fatal.”Dengue

fever epidemics are currently spreading through South America, and the

disease has spread up both coasts of Mexico to the United States border,

with a small number of noted cases in South Texas. Indeed, the Centers for

Disease Control and Prevention (CDC) have already warned health officials

in Texas 532 Widener Law Review to look for the disease’s emergence

there. Sea level rise in the Gulf of Mexico could thus help to provide the

breeding grounds that will introduce dengue fever to the United States.

The sea itself is a reservoir of disease bacteria and viruses, and rising sea

levels could expose new and more extensive populations to these diseases.

For example, cholera outbreaks are “associated with drinking or bathing in

unpurified river or brackish water” but also appear to be linked to climate

and temperature. Moreover, the cholera bacterium (Vibrio cholera) has a sea

stage, during which copepods (a type of tiny animal, or zooplankton) act as

host organisms. According to researchers investigating the link between

climate change and cholera, “climate, seasonal weather changes and

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seasonal changes in ocean currents affect the growth of copepods.”Thus,

researchers hope that by measuring ocean parameters such as temperature

and plankton blooms, they will be able to provide “an early warning system

for cholera, enabling an effective deployment of resources to minimize or

prevent cholera epidemics. Cholera-carrying copepods “live in salt or

brackish waters, including rivers and ponds, and travel with currents and

tides. Copepods harbor dormant, nutrient-deprived and culturable Vibrio.

The bacteria can survive as an inactive spore like form dormant but still

infectious in the gut and on the surfaces of copepods in between

epidemics.”Moreover, ships transport a very large number of copepods and

other disease organisms in ballast water.

Evidence indicates that “cholera outbreaks occur shortly after sea-

surface temperature and sea-surface height are at their zenith.”Thus, sea-

level rise, in connection with changes in currents and sea temperatures,

could promote the spread of cholera. Moreover, cholera spreads through

drinking water and, as has already been discussed, one consequence of sea-

level rise is contamination of drinking water supplies. Perhaps not

coincidentally, therefore, in this decade that is, within the same time-frame

that climate change has begun to affect ocean temperatures and ocean

currents cholera has re-emerged in epidemic form in the coastal areas of

Southeast Asia, Central America, and South America.

A related species, Vibrio vulnificus, is another sea-dwelling bacterium

that can cause disease in humans. These bacteria, found in most ocean

waters around the United States, “colonize filter feeding animals such as

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oysters, crabs and mussels, but can also be found free-living in seawater.”

While “most people become infected with V. vulnificus through eating raw

shellfish,” the bacterium “can also cause wound infections where an open

wound is exposed to seawater.”In addition to unpleasant but less serious

effects, septicemia leading to amputation or death is one potential outcome

from either route of infection.

The disease potential of Vibriovulnificus appears to be linked to sea

temperature, and through the 20th century most identified infections

occurred along the very warm Gulf of Mexico, especially in Florida.

However, the emergence of Vibriovulnificus disease in other parts of the

world, notably Israel, has been linked to climate change and increasing

temperatures Similarly, in the United States in the early 21century, there has

been an increase in the number of Vibriovulnificus infections along the

Atlantic coast, stretching as far north as Delaware, New Jersey, and Rhode

Island, linked to increasing sea temperatures. Sea level rise, in concert with

this temperature increase, will expose new populations of humans to the

Vibrio vulnificus bacterium, potentially increasing the disease’s incidence

throughout the United States.

Contaminated sea water is already the source of increasingly frequent

toxic algae blooms. A variety of factors spur marine algae blooms, including

temperature, nutrients from agricultural run-off, and other oceanic

properties. Some of these algae produce toxic chemicals, and when the algae

are present in high concentrations, these toxins can affect humans and other

animals. Certain marine algae produce domoic acid. As with Vibrio

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vulnificus disease, sea-level rise will take these public health threats inland

to new populations.

Even melting ice could potentially expose people to long-forgotten

diseases. In 2006, Dr. Scott Rogers, a Bowling Green State University

biologist, reported “the potential for long-dormant strains of influenza,

packed in ice in remote global outposts, to be unleashed by melting and

migratory birds.”As a result, melting ice could expose human populations to

strains of flu, such as the virus that caused the 1918 flu pandemic, against

which human immunity has died out. Dr. Scott contends this “information

could be used to help develop inoculation strategies for the future.”

The connection between sea-level rise and disease suggests another set of

adaptation strategies that coastal states and local governments might pursue:

public health preparedness. The medical profession in the United States is

generally unaccustomed to dealing with malaria, dengue fever, and cholera,

especially in epidemic proportions, and Vibriovulnificus and algae blooms

are already presenting new medical challenges to many coastal communities.

Therefore, training medical personnel in these communities to recognize and

treat these diseases and other sea-related health issues would seem to be an

appropriate adaptation strategy. Such training, moreover, will help to ensure

that coastal medical communities recognize these diseases if and when they

emerge, allowing public health officials to implement control measures and

to engage in larger-scale public health preparation in case of epidemics.

5.3.2 Security

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The Ganges delta which encompasses nearly 33,707 square miles

(87,300 square kilometers) in Bangladesh and West Bengal, India—is Asia's

largest delta. It is also the world's most populated delta, home to some 111

million people. The residents of this region are particularly at risk from

accelerated global sea-level rise linked to climate change. Sea level rise is

projected to increase the salinity of the water and soil of this now-fertile

region, endangering crops and food security. During the twentieth century,

global mean sea level rose at an average of 0.07 inches (1.8 millimeters) per

year. But from 1993 to 2003, that rate increased to 0.12 inches (3.1

millimeters) per year. Scientists attribute rising sea levels to expansion of the

oceans as they warm, as well as to the melting of mountain glaciers and the

Greenland and Antarctic ice sheets.

West Bengal is one of the world's most populous area, is highly

vulnerable to the effects of sea-level rise including more Salinization of both

ground and surface waters. The deltaic plains of the Ganges, and their

tributaries compose most of the state's land area and the vast majority of the

coastal zone is at an elevation of less than 32 feet (10 meters)

Local sea-level rise of as much as 1 inch (25 millimeters) per year has

been recorded in sections of the sunderban Delta. Most deltas experience

natural sinking and settling of land (subsidence), which can increase relative,

or local, sea-level rise. Human interventions such as extraction of

groundwater can speed up subsidence, as has been the case on the coast.

Local sinking and groundwater extraction can allow seawater to creep

inland, displacing coastal plant and animal communities that depend on

brackish or freshwater. Encroaching seawater and salty groundwater may

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also increase soil salinity, which can hinder growth of crops. For example,

increased salinity inhibits rice growth and can lower rice yield. What the

Future holds by mid-century, more than 3 million people stand to be

directly affected by sea-level rise in this Delta. In a worst-case scenario,

west Bengal could lose nearly 12 percent of its 1989 land area by around

2100. Climate change is projected to cause further sea-level rise during this

century and beyond. If we do nothing to reduce our heat-trapping emissions,

global sea level is projected to increase some 23 inches (59 centimeters)

over recent average levels by the end of this century.

However, if we make significant efforts to reduce emissions, sea-level

rise could be limited to about 15 inches (38 centimeters) by the end of this

century. Recent evidence of higher rates of global sea-level rise suggests that

these projections may be low. And regional variations in sea-level rise are

expected to continue. In West Bengal coast, the impact of sea-level rise may

be worsened by other effects of global warming, such as variable

precipitation, more frequent droughts and floods, and shrinking of the

glaciers that supply water to the rivers of the delta. Reduced rainfall during

the dry season, for example, can increase the salinity of rivers through

encroaching seawater that moves upstream during periods of low flow.

Human activities such as shrimp farming and damming of rivers are

also expected to intensify the effects of sea-level rise. Dams can retain

sediment that would otherwise replenish eroded or subsided land in the river

delta. More dams are planned in Asia, which are likely to increase erosion as

well as relative sea-level rise, and might worsen water shortages and extend

the area affected by salinity during the dry months. With the added pressure

of rising air temperatures, rice production in this region could drop by 8

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percent and wheat production by 32 percent, by the middle of this century.

Unless we act now to cut our heat-trapping emissions, and take steps to

prepare for the warming already projected to occur in the coming decades,

the food and freshwater supply of millions of people in the coastal region is

likely to be in danger.

5.4 Demographical effects Contrary to a common assertion according to which "it is estimated

that 50-70% of the global human population lives in the coastal zone" (IPCC

1996b, p. 294), the population is rather land-bound, as illustrated in Table 1

below. The densities given are approximate in that they are based on an

assumed total length of the coastline of 100,000 km and on "large, round"

continents. Global population density is about 39 persons/km2.In spite of the

gross approximations involved in the last. It is clear that population densities

are far higher along the coasts than inland. Small (personal communication)

indicates the percentages to be 37% within 100 km, and 66% within 400 km.

There are, of course, large local differences. For instance, Sestini (1992;

quoted by Zwick 1997), writes that: "the importance of the Mediterranean

seafront in relation to the rest of the country varies; as an example, it is

relatively less so in Spain, France and Turkey than in Italy, Greece, Albania,

Algeria, Israel. In Greece as much as 90% of the population lives within 50

km of the coast and all major industrial centres’ are coast-related as well as

much of agriculture. In Egypt, the Nile delta north of Cairo represents 2.3%

of the area of the country, but contains 46% of its total cultivated surface and

50% of its population; the [altitude] belt 0-3 m harbors about 20 % of the

population (with Alexandria 3.5 mill., and Port Said 450.000 inhabitants),

40% of industry, 80% of port facilities, 60% of fish production." As a whole,

world population, now at 5,880 million, is expected to begin levelling off

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around 2050 at about 9,300 to 9400 million people (middle estimates of UN

1996a and 1996b), although in some continents, notably Africa, population

will probably continue growing at a more sustained pace well into the 21st

century. The urbanized population should exceed 60% of the total in 2030,

from current values of around 50%. It is also well known that most of the

current largest urban concentrations [3] are on the seacoasts (Engelman

1997). The population in the world's 15 biggest cities is projected to be 223

million in the year 2000. It appears that overall urban population trends are

not so obvious. While most coastal megacities do grow in size, their share of

the total population often remains stable (1%, from 1950 to 2015 in Calcutta

and Shanghai), and sometimes decreases (from 7% to 6% in New York in

the same period. Also, the percentage of the urban population living in the

megacities often decreases (New York: 12% to 7% between 1950 and 2015;

Cairo: 35% to 32%; Rio de Janeiro: 14% to 6%; Calcutta: 7% to 4%;

Beijing: 6% to 2%; Jakarta: 15% to 10%, etc.), which points to the growth of

other urban areas.

Figure 5.1. Recent and future population and urbanization trends

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Source: Based on data from UN 1996a, 1996b and 1997

Also noteworthy is the fact that many cities suffer land subsidence due to

groundwater withdrawal (Nicholls and Leatherman, 1995). This, of course,

may be compounded by sea-level rise, the more so since current rates of

subsidence may exceed the rate of sea-level rise between now and 2100.

Table 2 below indicates how some socio-economic and physiographic

indicators vary among land-locked countries, those with coastlines and the

smallest islands, which are members of the Alliance of Small Island States

(AOSIS). It is striking that the average Gross Domestic Product (GDP) per

capita in landlocked countries is just above that of AOSIS members, and

well below the global average. It is also worth noting that the population

densities of the small island states are currently intermediate between

landlocked and "other" countries, while they should reach a value

comparable to "other" countries in 2050. It is unlikely that this will be

accompanied by a marked increase in GDP per capita

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In order to examine with more detail the relation between some of the

indicators in Table 2 and the "insularity" of the respective countries, we

define an "Insularity Index" as the ratio between the length of the coastline

(km) and the total land area (km2) that it encloses: The definition of The

"Insularity Index" is, of course, fraught with problems [4] linked with the

actual shape of countries, the fractal nature of coasts, and the scale at which

it is determined, and the distribution and extent of low-lying areas within

each country. It is admittedly a crude index, but meaningful if a consistent

method is used to estimate the length of the coastlines. Some interesting

links with other variables can be found at the global level. Table 6 lists some

typical values of The Insularity Index. It is obvious; to start with, that

Europe and Africa - which represent 50% of all countries and territories - are

far less "insular" than the other continents. It is also apparent that the insular

character has a strong positive skew and covers 5 to 6 orders of magnitude,

to the extent that it can be represented only on a logarithmic scale. The

positive skew is clearly visible in Table 3, in which the large difference

between median and average is due to the occurrence of a limited number of

very high values.

The two figures below clearly show the association between the

insular character of countries and population density: less insular countries

are generally relatively less populated, which is linked to the fact that

landlocked countries are mostly at higher elevations and latitudes (Eurasia)

or in semi-arid areas (Africa) where productivity and population supporting

capacities tend to be low.In a similar way, and as a consequence of the

situation described previously, GDP tends to decrease with insularity,

mostly so above a "threshold" of 0.01.while CZMS (1990) indicates 3,280

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for the length of the coast "as the crow flies" with a step of 50 to 100 km.

The same source applies a multiplier of 10 to obtain 32,440 km of "length of

low coast", i.e. the actual length of coast that should be protected, taking into

consideration its "micro" structure. For Vietnam, the figures are 3,260,

3,444, 512 and 6,095 (respectively CGER, Fact book, CZMS with and

without multiplier). For Japan, the figures 29,751, 34,390, 530 and 3,870 are

obtained by the same sources. Regarding the total length of all coasts

(excluding Antarctica), we found 642,770 based on a 1:25M map, while the

data from the Fact book (1997) add up to 715,917. Annex D2 of CZMS

(1990) finds 46,185 km using 50 to 100 km "steps" and 339,185 km of "low

coast".