Climate change impacts on Bangladesh

Bangladesh is vulnerable to climate changes. Indeed, it has internationally been established that Bangladesh, as a country, may suffer the most severe impacts from climate change. The country is one of the most densely populated on earth having more people than geographically huge Russia. It faces most of the impacts of climate change due to its geophysical location, hydrological influence from monsoon rains and regional water flow patterns.
The country is trapped between the Himalayas in the north and the encroaching Bay of Bengal to the south. It is most vulnerable to natural disasters due to the frequency of extreme climate events and its high population density. Floods are frequent and cause the greatest economic and human losses to the country. The flooding problems are exacerbated by sediment transported by three major rivers the Ganges, the Brahmaputra and the Meghna.
Five sectors have been identified as most relevant to Bangladesh in relation to climate change impacts: (i) coastal resources, (ii) fresh water resources, (iii) agriculture, (iv) ecosystems and biodiversity, and (v) human health. Of these sectors, coastal resources are most impacted by climate change, whereas ecosystems may be most endangered. The country faces too much water during the monsoon and too little water in the dry season. This situation will be aggravated by a warmer climate, resulting in more severe droughts and increased flooding. Further adding to the problem is sea level rise in the south and enhanced Himalayan snow and glacial melt from the north, which will inundate additional large parts of Bangladesh over today's flood affected areas.
The impacts result not only from gradual changes in temperature and sea level but also, in particular, from increased climate variability and extreme events. These changes are already having major impacts on the economic performance of Bangladesh and on the lives and livelihoods of millions of poor people. Its national economy immensely depends on agriculture and natural resources that are sensitive to climate change and sea level rise.  
Projections indicate that sea level rise will inundate large parts of the coastal regions of Bangladesh. Sea level rise of 45 centimetre is predicted to result in the inundation of about 10 per cent of the country. In case of sea-level rise of 1 metre, 21 per cent of the country will go under saltwater (IPCC, 2005). Such a rise is likely to inundate coastal wetlands and lowlands, accentuate coastal erosion, increase frequent and severe floods and create drainage and irrigation problems.
Agriculture, mangroves, including the Sunderbans, and coastal ecosystems have already been affected. Additionally, problems with salinity, which is caused by low flow of fresh water from the Ganges and ingress of salt water from the Bay of Bengal, have already increased in the coastal zones. Poor and marginal groups will be critically affected by further sea level rise and salinity intrusion in Bangladesh coastal zones. This will dislocate millions of people from their homes, occupations and livelihoods.
It is widely accepted that the gravest effect of climate change may be on human migration. Climate change impacts are already adding significant stress to our physical and environmental resources, our human ability, and economic activities. A major concern for Bangladesh is that climate change victims are increasing in number every year and must seek refuge in urban centres due to loss of their homes and lands to river erosion, coastal erosion, and permanent inundation. As the stress increases, they are more likely to migrate to major cities, such as Dhaka and Chittagong. As the problem intensifies there will be pressure for people to migrate to the industrialised countries.
Climate change will adversely impact human, social and natural systems and sub-systems in different degrees. Due to its poor socio-economic development and lack of capacity to address impacts, developing and poor Bangladesh will be the most vulnerable to the adversities of climate change. A recent example is cyclone SIDR, which hit the coast of Bangladesh on 15 November 2007, not only killing over 10,000 people but also devastating the lives of over 30 million, reconfirming the IPCC assertion. The other one AILA hit the south western part of Bangladesh (Khulna Division) and West Bengal in India on 25 May 2009, affecting more than 3 million people and killing approximately 190 in Bangladesh.
Bangladesh is projected to be 0.5 to 0.20 Celsius warmer than today by the year 2030. The 30 years' mean summer temperature in Bangladesh is 27.50 Celsius and it is relatively higher during the monsoon than during summer. Winter is the driest season. The 30 years' mean winter rainfall amounts to about 64 millimetre with a variability of around 53 per cent.
By 2030, the estimated projection is for monsoon rainfall to increase by 10 to 15 per cent and winter rainfall by 5 to 10 per cent. In several geographical areas, multiple impacts will reinforce the overlapping impacts and the consequences will be compounded.   
Bangladesh's agricultural growth is especially effective in reducing poverty. Agriculture is a key economic driver in Bangladesh, accounting for nearly 20 per cent of the Gross Domestic Product (GDP) and 65 per cent of the labour force. Estimates show that overall GDP growth originating in agriculture is, on average, at least twice as effective in benefiting the poorest half of a country's population as growth generated in non-agricultural sectors. Moreover, much of the rural population, especially the poor, is reliant on agriculture as a critical source of livelihoods and employment.
Climate change and its associated events will negatively affect both natural and common property resources such as fisheries, mangroves and forests, which provide livelihood support for common people and the poor. Furthermore, Bangladesh's major crop rice is vulnerable to increased temperature. At the high ranges of temperature, yield of rice crops drops. In some areas, particularly in the northwest, crop yields are likely to be reduced up to 30 per cent. Replacement of rice by wheat or maize will require a change in farmers' perceptions and practices, which is a long term phenomenon. These effects will contribute to increased poverty. The impacts of higher temperatures, more variable precipitation, more extreme weather events, and sea level rise are already felt in Bangladesh and will continue to intensify.
It is being observed that Bangladesh is already experiencing the adverse impacts of global warming and climate change. Summers are becoming hotter, monsoon irregular, untimely rainfall, heavy rainfall over short period causing water logging and landslides, very little rainfall in dry period, increased river flow and inundation during monsoon, increased frequency, intensity and recurrence of floods, crop damage due to flash floods and monsoon floods, crop failure due to drought, prolonged cold spell, salinity intrusion along the coast leading to scarcity of potable water and redundancy of prevailing crop practices, coastal erosion, riverbank erosion, deaths due to extreme heat and extreme cold, increasing mortality, morbidity, prevalence and outbreak of dengue, malaria, cholera and diarrhea, etc.   
Climate change will also affect the sectoral as well as regional developments and current disaster preparedness, and its impacts may affect successful achievement of the Millennium Development Goals (MDG), particularly goal number one i.e., eradicating poverty and hunger, because climate change is likely to directly impact the poor's livelihoods in many ways, their assets and resources base including their employment and income, and their access to water and natural resources and health.
Bangladesh has already achieved one of the key MDG - gender parity in primary and secondary schooling. The country is on track to achieve most of the MDG goals, even the difficult ones like infant and maternal mortality by 2015. However, the predicted adverse impacts due to global warming could reverse the recent economic and social gains. A 1 Celsius rise in temperature (temperatures have already risen by 0.7 Celsius globally since the end of the 19th century) is associated with 10 percent productivity loss in farming. For Bangladesh, it means losing about 4 million tones of food grain, amounting to about $2.5 billion i.e. about 2 percent of Bangladesh GDP.
Adding up the damages to property and other losses, Bangladesh is faced with a total loss of about 3-4 percent of GDP. Without these losses, Bangladesh could have easily secured much higher growth. These changes are threatening the significant achievements Bangladesh has made over the last 20 years in increasing incomes, reducing poverty and in achieving self-sufficiency in the production of rice, the country's staple food crop. The progress towards achieving the MDG, such as eradicating poverty, combating communicable diseases and ensuring environmental sustainability could be in jeopardy.
The writer is a retired Professor              of Economics, BCS                        General Education Cadre.                    [email protected]