Almost every year, Bangladesh experiences environmental disasters, such as tropical cyclones, storm surges, coastal erosion, floods, and droughts, cause heavy loss of life and property. The country is already beset with many problems like high population density (120 million people living in an area of 144 000 square km), shortage of land to accommodate the people, food security, human health, illiteracy, and so forth. In the foreseeable future, Bangladesh is likely to be one of the most vulnerable countries of the world in the event of climate change. Almost every sector of socio-economic life in Bangladesh is likely to be affected by climate change.

Several researchers conducted studies on the impact and vulnerability of climate change in Bangladesh. These are based on past data analysis, model results and expert judgment. Notable among them are those of Mahtab (1989), BCAS (1994), BUP (1994), and Bangladesh Climate Change Country Study Program (1997), Ali (1999). They depicted and framed the climate change adaptation, vulnerability and mitigation approaches in a certain length. But, there is no such research, on the environmental migration induced by climate change.

Climate affects the stability of resources that support human systems. In Bangladesh the climate change impacts are large and sometimes catastrophic. Resources or settlements are destabilized, with little hope for near-term recovery. It shrinks the land and water in the costal areas of Bangladesh. This unequal resource distribution in the region and rapid population growth, are causing widespread landlessness, unemployment, declining wages, income disparities and degradation of human habitat. The affected people, unable to satisfy their needs in an economically less-developed Bangladesh, are increasingly moving to India where the prospect of life appears to be better.

The present paper looks at the climate change induced (environmental) migration from Bangladesh to India. It is not within the scope of this paper to cover all vulnerabilities in Bangladesh and its aftermath. We have selective in analyzing a few vulnerabilities and its consequent effect ‘immigration’. To put the discussions in to perspective, a very brief description of the coastal morphology of Bangladesh is given, followed by the trend of climate change in Bangladesh. The paper focuses on environmental crisis as a reason for the continued migration of people from Bangladesh to India. It examines the climatology of tropical cyclones and storm surges. The paper discusses the impacts of rises in temperature on these climate fonts in Bangladesh and the consequent social tension in India.



1. Costal morphology of Bangladesh:

Bangladesh is situated at the interface of two different environments, with the Bay of Bengal to the south and the Himalayas to the north. The country has a very low and flat topography, except the northeast and southeast regions. About 10% of the country is hardly one meter above the Mean Sea Level (MSL), and one-third is under tidal excursions. The country has three distinct coastal regions—Viz., western, central, and eastern coastal zones (Fig 1, Page 9).


The western part, known as the Ganges tidal plain, comprises the semiactive delta endowed with channels and creeks. The southwestern part of the region is covered with mangrove forest of the world, known as Sundarbans. The mangrove forests act as deterrent to the tropical cyclones and storm surges. In the central continuous accretion and erosion are going on. The Meghna River estuary lies in the region. The combined flow of three major rivers of the region—the Ganges, the Brahmaputra, and the Meghna-discharges under the name of Meghna into the northeastern corner of the Bay of Bengal. This estuarial region has seen the most disastrous effects of tropical cyclones and storm surges in the world and is very vulnerable to such calamities. The eastern region, being covered by hilly areas, is more stable, and it has one of the longest beaches in the world. (Ali, 1999).


2. Cyclone Affected Areas

The southern, southwestern and the coastal areas of Bangladesh remain submerged for long periods every year, especially during the monsoon season. People in these areas have been coping with submerged/flooded conditions for generations. The people of these areas depend on agriculture.  All the cyclonic storms in last thirty years have hit Chittagong, Cox’s Bazar, and Noakhali and sand shoals near Khulna, Barisal, and Patuakhali. All have hit north of Chittagong,  Jessore, Kushtia, Faridpur and coastal islands of Barisal and Khulna.


3. Climate change trends in Bangladesh:


Anthropogenic changes in the global climate and associated sea level rise are widely accepted with policy makers and scientists. The fourth Assessment Report of IPCC has stated that since 1961 the average temperature of the global ocean has increased to depths of at least 3000 m and that the ocean has been absorbing more than 80 per cent of the heat added to climate system. Such warming causes seawater to expand, contributing to sea level rise. Global average sea level rose at an average rate of 1.8 (1.3-2.3) mm per year over 1961 to 2003. Bay of Bengal and North Indian Sea is also no exception in this. It is broadly recognized that Bangladesh is very vulnerable to these changes. Indeed, it has internationally been argued that Bangladesh, as a country, may suffer the most severe impacts from climate change.


The geographical location and geo-morphology of Bangladesh have made the country more vulnerable to climate change. About 80 tropical storms (tropical cyclones with wind speeds greater than or equal to 17 m s–1) are being formed in the world’s waters every year (McBride 1995). Of these, about 6.5% form in the North Indian Ocean (Bay of Bengal and Arabian Sea) (Neumann 1993). Since the frequency of cyclones in the Bay of Bengal is about 5 to 6 times the frequency in the Arabian Sea (IMD 1979), the Bay of Bengal share comes out to be about 5.5%. Bangladesh is hit by about 0.93% (~1%) of the world’s total tropical storms, India by 3.34%, Myanmar by 0.51%, Sri Lanka by 0.22%, and 0.50% die in the Bay without hitting any country. These numbers were arrived at by considering the tropical storms that formed in the Bay of Bengal during the period 1877 to 1995 (Ali,1999). It is to be noted that major cyclone disasters are still continuing in Bangladesh (Cyclones of 1985, 1988, and 1991 causing deaths of 11 069, 5708, and 138 000, respectively).


The increasing trend of Sea Surface Temperature (SST) has also been causing significant numbers of cyclone in Bangladesh. Researchers like Miller (1958), Wendland (1977), Gray (1979), Emanuel (1987, 1988), and Saunders & Harris (1997) found it that any rise in sea surface temperature (SST) due to climate change is likely to be accompanied by an increase in cyclone frequency. Using SST data for the Bay of Bengal for the period 1951 to 1987, Joseph (unpubl.) has shown that SST has been increasing since 1951 and till now it kills displaces a sizeable number of population from the costal areas. Besides, storm surge and Back Water Effect (BWE) is very pronounced in Bangladesh. It also caused threat to the country. A few examples of storm surge for cyclones affecting Bangladesh since 1960 is given in table -1 (Page 8). Each of which caused at least 1000 human deaths. Back Water Effect (BWE), particularly in the Meghna River estuary, through which about 90% of the river water in the country discharges into the Bay of Bengal, is also important during flood seasons. Because of this effect, floodwater inside the country continues to accumulate, bringing more areas under inundation and increasing the length and depth of inundation in areas already inundated, thus further aggravating the flood situation that already exists.



4. Environmental crisis and migration:

Floods and cyclones continue to plague Bangladesh. It is recorded that climate change in the costal and southern part of the Bangladesh, has displaced and killed a huge population. In 1970, 300,000 people died in a cyclone and in 1988, 700 people are known to have died, according to the data of United Nations Office for the Co-ordination of Humanitarian Affairs.  Just three years after the 1988 cyclone – another struck, killing an estimated 140,000 people.  In this cyclone about 85 % of homes were flattened. The 1998 flood in Bangladesh ravaged approximately 60% of the land and affected over 30 million people. The number of death is more in all these incidents, because of the thick population density in the costal areas of the country. Large number of people are always affected by climate hazards with lesser resilience due to poverty aggravates the situation. (Bangladesh is the most densely populated country of the world with a density of 2,200 people per square mile). Moreover, because of the landlessness and chronic poverty (per capita income less than a dollar per day) of the people, they do not have any option to mitigate with it. This vulnerability rather, forces them to take survival decisions day by day.


Besides, climate change affects the vulnerable low income populations of the country. IPCC in its assessment report also marked that areas are at risk from several climate impacts relevant to health (for example, stress on food and water supplies, and risk of coastal flooding). It would increase the risks of infectious disease epidemics.

In Bangladesh, incidence of diarrhea just after flood and cyclones, followed by other epidemic diseases like malaria etc. are also the impact climate change. Kunii (2002) found in a study that after 1998 flood, 98.3% developed health problems or found that existing health problems were exacerbated. The most prevalent condition was fever (63.6%), followed by respiratory problems (46.8%), diarrhoea (44.3%), and skin problems (41.0%). Similar kind of epidemic was also recorded in 1970 and 1998. Further, people of Bangladesh are also pressed with the low income generation, low Gross Domestic Product –GDP (only 5.7%), loss of crop land (total cultivable area: 17.77 million acres) and low crop yield (1 million metric tones), which is lowest in Asia (as per the Govt of Bangladesh information).

These attributes of the country are displacing people in two ways- ‘in-migration of people from southern costal region to east and northern region’ (Which is relatively in higher altitude) and ‘migration to the neighboring county India’.  Indeed, the later shows a higher degree of human flow. Now, it is in the psychology of Bangladeshi People that to get rid of the problem of ‘living space’, population movement can be a suitable strategy[1].

As per the government of India record (Home Ministry, GOI, 1997) there are 10 million illegal migrants residing in India. As per the Home Ministry/Intelligence Bureau source, the 10 August 1998 issue of India, today by State wise in India – there are 5.4 millions migrants in West Bengal, 4 millions in Assam, 8 millions in Tripura.

Bangladesh census records indicate a reduction of 39 lakhs population between 1971 and 1981 and another 36 lakhs between 1981 and 1989. These 75 lakhs (39+36) population have migrated to India. Perhaps most of this population has come into Assam, (Singh, 1998).  Recent enumeration of electors list in Assam by the Election Commission shows more than 30% increase in 17 Assembly constituencies and more than 20% increase in 40 constituencies between 1994 and 1997. Whereas the All India average growth for a three year period intervening the two intensive revisions in 1994 and 1997, is 7 %, the growth in Assam for this period is 16.4%. Table-2 (Page 8)



Migration: The Future

It is broadly understood that migration in Bangladesh is taking place basically because of the flooding (due to storm surges), land loss due to accelerated sea-level rise. These conditions are also further correlated with the population growth in the costal region.


The present geographical area of Bangladesh is 144,000 Sq Km and total land area is 133,910 sq km with 10,090 sq Km area under water. Interestingly, total coastal line in Bangladesh is 580 km. Because of this geographical nature, southern areas of Bangladesh like Mongla, Khulna, Barisal, Cox’s Bazar, Chittagong and Comilla are inundated with water most of months of the year (Figure 2, Page 10).


This impacts of climate change on coastal areas could be severe and in some areas catastrophic. Nicholls et al. (1999) estimate that (assuming no adaptation and no change in existing population) a 1-m rise in sea level could displace nearly 15 million, 7 million, and at least 2 million people from their homes in Bangladesh, India, and Indonesia, respectively. Further, a 1-m rise in sea level could lead 30,000 km2 land loss in Bangladesh.


Recent geological studies suggest that the magnitude of tectonic subsidence in the Ganges-Brahmaputra delta of Bangladesh is greater than has been taken into account in some earlier projections; this subsidence is expected to result in higher estimates of relative sea-level rise. Around the city of Dhaka, average subsidence is about 0.62 mm/yr; elsewhere, it can exceed 20 mm/yr (Alam, 1996).By considering this subsidence rate it can be visualized that the degree of submergence in Bangladesh is going to increase in manifold by 2020. The incidence of flood will be more profuse with the combined effects of subsidence and sea-level rise. It could cause serious drainage and sedimentation problems, in addition to coastal erosion and land loss. These impacts clearly would have immense socioeconomic costs.


Moreover, by considering the IPCC TAR-2001 data (Table: 3), it can be assumed that due to sea level rise in Bangladesh, the current potential land loss – 20.7% (29,846 km2) will become more acute in 2020 with three fold increase. Besides, more than 50% population will be exposed to this effect. Indeed, this is an assumption based on annual extrapolation of the present figure of the land loss and population affected. In a very conservative estimate, it can be further added, that the present population growth in Bangladesh will also give an impetus to this problem. If the rate of population growth in Bangladesh will continue in the same pace like the present (2.09%), then by 2020 the situation will be more worse, leading to a  serious lack of ‘living space’ in the country. Consequently, it will accelerate the outward migration from Bangladesh. And, in fact, because of the geographical proximity and other socio-economic reasons, this migration is very likely take place to India only.  With the current rate of migration of Bangladesh to India, it can be assumed that by 2020 at least 5 Cores (36% of the present population) people will migrate to India. Because of this migration, the probable social tension in India can be easily understood.


Other causes for migration:

In fact, besides, climate change, a few others factors are also accelerating the immigration process. Researchers like Datta (2004), Upadhaya (2005), Singh (1998) etc. identified these factors as push and pull factors. Out of these, economic push factors that motivate people to leave Bangladesh are instability and economic depression, poverty, lack of employment opportunity, struggle for livelihood, forced grabbing of landed property from minority group etc. on the other hand, factors like linguistics and cultural similarities, same food habit, homo-ethnic climate, belief of getting shelter, geographic proximity of Bangladesh and India worked as pull factors for migrants to India. However, it is understood from the previous discussion of this paper that other push and pull factors are the consequent of the climate change. Keeping asides, the political and social dimensions, it can be visualized that economic displacement and loss of livelihood in Bangladesh is basically taking place due to the climate hazards and vulnerability to climate change. Besides, the porous international borders are also playing a decisive role in the situation.   

Consequences in India:

Immigration of Bangladeshis has become a serious problem for India. It is the biggest issues for the last two decades in North East India. The problem has taken many shapes under political patronage (starting from Students’ Movement, Illegal Migrants (Determination by Tribunals) Act, 1983, militancy etc.). Till now, Assam experienced two major riots, one in 1972 and another in the year 1981-82. Both of these riots were originated from the class-conflict and xenophobia of the indigenous people of India. The anti-foreigner uprising in Assam from 1979 to 1985 was led by the All Assam Student’s Union (AASU) was perhaps among independent India’s largest mass uprisings. The central issue raised by the AASU was of ‘foreigners’ swamping Assam. The goal of this agitation were the three ‘Ds’: detection, deletion and deportation of the immigrants.

Contrary to this, migrants from Bangladesh (especially the Muslim migrants) are trying to be united for strategically resisting the pressure of various local bodies of India. Its initiatives have opened up to radicalism and to a network of fundamentalist campaigns, in the region, which have access to arms and easy connections to sanctuaries across a porous international border.  Islamic fundamentalist organisations in North East India are a recent phenomenon with most of them having come into existence in the early 1990’s. It is believed that the continuous agitations in the region over the issue of infiltration of population from across the borders and the resulting communal and ethnic clashes in which migrant Muslims were the prime victims was the primary reason for the formation of such groups

Similar kind of social unrest can not be denied, if the immigration from Bangladesh will continue to India. This can be further aggravated with the increase in population density and shortage in employment opportunities for the people of India. Indians will be reduced to a minority in their home country. And it can also jeopardize the national development. It may lead to violent tribal insurgencies in many part of the region with guerrilla groups targeting migrant settlers often seeing them as land grabbers[2].




The paper advocates that environmental hazards and climate change have a direct link with migration.  It is broadly understood that migration in Bangladesh is taking place basically because of the flooding (due to storm surges). These conditions are also further correlated with the population growth in the costal region and the huge land loss in Bangladesh because of the geo-morphological traits of the country.


It is also discussed that due to sea level rise in Bangladesh, the current potential land loss – 20.7% (29,846 km2) will become more acute in 2020 with three fold increase. Besides, more than 50% population will be exposed to this effect. In a very conservative estimate, it can be further added, that the present population growth in Bangladesh will also give an impetus to this problem. If the rate of population growth in Bangladesh will continue in the same pace like the present (2.09%), then by 2020 the situation will be more worse, leading to a  serious lack of ‘living space’ in the country. Consequently, it will accelerate the outward migration from Bangladesh. And, in fact, because of the geographical proximity and other socio-economic reasons, this migration is very likely take place to India.  With the current rate of migration of Bangladesh to India, it can be assumed that by 2020 at least 5 Cores (36% of the present population) people will migrate to India. Because of this migration, the social tensions such as militancy, unemployment, identity crisis, ethnic uprisings etc. will be more acute in India.


The migration projection of this paper has been undertaken on the basis of existing literature and best judgment. But still there are lot of uncertainties in the assessment which is understandable in the light of the non-availability of long period data, limitation of models and lack of full understanding of the climatic parameters and their variation etc. The assessment results need to be updated continuously and hence more in-depth research efforts should be put into this.


Bangladesh is no way responsible for the projected consequences of climate change. Considering this alarming situation seriously, Bangladesh need to take initiatives to rehabilitate the inhabitants in likely affected areas.  This effort will be sole mitigation option to minimize the risk of damages to potential affectees.




Storm surge scenarios for cyclones affecting Bangladesh since 1960, each of which casued at least 1000 human deaths. Business as usual: no climate change: 2 and 4 degree Celcius: lower and upper bounds of the rise in temperature by 2010, as given by the IPCC:


Cyclones date


Business as usual

Sotrm surge height (m) at 2 degree Celcius

4 degree Celcius

Oct 9, 1960





Oct 30, 1960





May 9, 1961





May 28, 1963





May 11, 1965





Nov 12, 1970





May 25, 1985





Nov 29, 1988





Apr 29, 1991






Source: IPCC-TAR 2001



Relative decadal percentage growth of population of Assam, All India and Bangladesh



All India


(i) 1901-1911




(ii) 1911-1921




(iii) 1921-1931




(iv) 1931-1941




(v) 1941-1951




(vi) 1951-1961




(vii) 1971-1981




(viii) 1981-1991




Explanatory Notes

  1. There was no census in Assam in 1981. The figures indicated have been worked out on the basis of 1971-91 growth rate.
  2. There was no census in Bangladesh in 1971. It was carried out in 1974. The population grew by 40.4% between 1961-74 and another 21.9% during 1974-81.
  3. The much higher percentage of growth rate in Assam from 1911 to 1971 over the All India and Bangladesh figures indicate migration into Assam. The All India growth rate for 1921 should be treated as an aberration but even in that decade Assam’s growth rate was higher than neighbouring Bengal districts which now constitute Bangladesh.



Table 3

 Potential land loss and population exposed in Asian countries for selected magnitudes of sea-level rise, assuming no adaptation:


Sea-Level Rise

Potential Land Loss

Population Exposed
























.Source: IPCC:TAR-2001

  Figure 1

Map of Bangladesh showing coastal area and the major river system

















Figure 2

Potential areas of Bangladesh, from where migration to India is possible



              Most venerable areas to climate change


                 Possible way of migration



Migration sink


Migration sink



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[1] Bangladeshi diplomat Mr. Sadeq Khan wrote in the Holiday of October 18, 1991, that “All projections, however, clearly indicate that by the next decade, that is to say by the first decade of the 21st century, Bangladesh will face a serious crisis of living space (Holiday of October 18, 1991). 


[2] Recently, militant outfit of Assam, ULFA (United Liberation Front of Assam) had assassinated immigrants and also targeting inter-state migrants from India also.  



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