Climate Change and Sundarban Biosphere Reserve | Term Paper | Geography

Here is a term paper on ‘Climate Change and Sundarban Biosphere Reserve’ especially written for school and college students.

Term Paper # 1. Introduction to Climate Change and Sundarban Biosphere Reserve:

Climate change is one of the most important global environmental challenges facing humanity. Is the climate changing irrevocably or is it a naturally recurring phenomenon that has been part of the earth’s deep past for centuries? What is the way ahead for us in a warming world? It has now been established by careful scientific observation that the earth’s climate has warmed by 0.6°C in the last 100 years.

Confirmation of global warming comes from warming of the oceans, rising sea levels, melting glaciers, retreating sea ice in the Arctic and diminishing snow cover in the northern hemisphere. Fragile and delicate ecosystems like coral reefs are extremely sensitive to even the slightest variation in climate.

In the awake of awareness about global climate change, Sundarban biosphere reserve with its 4.1 million strong human population features as one of the most vulnerable areas. Being the world’s largest delta Sundarban receives second highest quantity (1670 million tons) of sediments and is thus, subjected to gradual subsidence.

This is giving rise to additional acceleration to the eustatic rate of sea-level rise in Sundarban. As a result, sea facing islands are vanishing, for which famous Gangasagar Temple had to be shifted northward twice. The salinity of surface and subsurface waters of the estuary is also on the rise. Several endangered mammals, reptiles became extinct during last 100 years.

The accelerated rate of sea level rise has given rise to increased surface water salinity in Sundarban resulting in tiger migration northwards near villages leading to more man-animal confrontation. The freshwater loving gangetic dolphins of Sundarban are being replaced by salt water loving Irrawaddy dolphin. Likewise, the mangrove plant community migrates from outer to mid estuary, sundari trees are stressed.

Nearly half a million inhabitants of Sundarban are facing the hazards of losing land and house to become climate refugees. Fifteen per cent of the embankments of Sundarban are vulnerable to over toppling of tidal inundation within the agricultural areas. Bangladesh coast is subsiding and the sea level rise is at the rate of 10 mm/year at Khulna, which much exceeds the minimum estimate of global sea-level rise i.e. 1.8 to 2 mm/year. In case of Indian Sundarban the rate of sea level rise has been at the rate of 3.14 mm/year at Sagar point and 5 mm/year at Pakhiralay.

Term Paper # 2. Effects of Climate Change on Sundarban Ecosystem:

Sundarban being a subsiding estuary the rate of sea level rise is much faster as well as salinity of surface water is increasing. From a study of last two decades it is revealed that a 20 per cent increase in salinity has taken place along the coast. Coastal salt wedge has now extended upstream. There is a tendency of northerly shift of present mangrove vegetation due to rapid development of shallow marine conditions created due to this accelerated rise of sea-level.

Salinity increased in creek waters. Climax species Sundari (Heritiera fames) does not like shallow marine condition, succumbed to ‘Tip dying’. Outer estuarine Avicennia marina migrated to mid estuary where velocity of water is much higher and developed abnormal stilt roots. Besides, fishing cat (Prionalirus viverrina) and tiger (Panthera tigris) could not cope up with increased salinity and migrated northwards nearer to human habitation leading to more man-animal conflict.

During last 100 years six important animals got extinct (Java rhino, great one horned rhino, swamp deer, barking deer, water buffalo, gharial). From 2000 onwards, Gangetic dolphins (Platinista gangetica) have been largely replaced by salt tolerant Irrawaddy dolphins (Orcella bravirostris). Ghost crabs are replacing the useful Fiddler crabs (hatchlings are food for white pomphrets) due to warming effect.

Another effect is apparent on the subsurface waters salinity. There is salt water incursion into the shallow aquifer of Sundarban. At nearly 35 per cent islands of Sundarban, the shallow aquifer (100 m deep) was useful for the irrigation purposes two decades ago. But now they became saline as observed in Bali Island. The third effect is vanishing islands. The inhabited islands of Lohachara, Supuribhanga have vanished; 85 per cent area of Ghoramara Island has vanished and as a result 7000 families became “climate refugees”.

They have been rehabilitated at the Gangasagar colony, Jimbantala colony, Bankimnagar colony, Mahendragang colony, Hiradenpur colony and Ramghar colony under Sagar Island with only about 2.5 bighas of land for each family. The mangrove covered islands of south facing region also got 20 per cent reduced during last six decades.

Thus, the area of tiger habitat got reduced. The monsoon has been delayed by a month leading to a reduction in crop cultivation time. The intensity of cyclones has increased over last two decades causing more saline flooding of croplands.

Term Paper # 3. Remarks on Reducing Climate Change:

Following steps are to be taken to cope up with these adversities of climate change:

1. Massive mangrove plantation on northern mudflats to make up the loss of tiger habitat.

2. Large scale plantations of sundari (Heritiera fames), dhundul (Xylocarpus granatum) and passur (X. mekongensis), golpata (Nypa fruiticans) along the fresh water canals of reclaimed Sundarban.

3. Increasing the heights of the vulnerable embankments (about 15 per cent) mapped by School of Oceanographic Studies, Jadavpur University.

4. Advance planning for resettlement of the Enviro-refugees. There can be a bilateral arrangements to resettle them even in Andaman and Nicobar Islands where many of them have comfortably settled after several past disasters.

5. Massive rain water harvesting to combat salinisation of ground water by:

i. Digging number of shallow ponds; pond depth in Sundarban cannot exceed 3 m otherwise saline oozing starts from below.

ii. Re-excavation and fresh excavation of the age-old practice of shallow linear channels (for rain water accumulation) in Sundarban can be increased. During monsoon these channels serve as comfortable country boat transport routes.

iii. Recharging the shallow water aquifer in order to dilute the salinity. This has been a very recent effort started by a local NGO with financial support from National Bank for Agricultural and Rural Development (NABARD).

iv. Reintroduction of indigenous saline paddy varieties of Sundarban like Nonabokhra, Talmogra, Matla, Hamilton, Sada Ketu, Kala Ketu, etc. Although productivity of these saline paddy is less (7 md/bigha) but the rice fetch 1.5 times price and with less use of pesticide, the straw of indigenous paddy is 3 times costlier.

In view of above, coping up with the climate adversities in Sundarban became expedient. Massive rainwater harvesting can dilute the shallow aquifer and make it fit for farm irrigation. Large-scale mangrove plantation on new char lands can make up for the drowned mangrove covered south facing Islands.

Height of vulnerable embankments can be raised to prevent inundation of farmlands by saline tidal waters. Advance rehabilitation planning for the possible climate refugees of inhabited vanishing Islands and reintroduction of indigenous saline-paddy varieties are the coping up steps. Thus, the above measures can help the distressed people of Sundarban, Biosphere Reserve sustainably coping up with the adversities of climatic change in Sundarban.