Bangladesh I: Climate Change Impacts, Mitigation and Adaptation in Developing Countries

Bangladesh is a beautiful nation. Sadly, it is facing multiple impacts of global warming. The most prominent issues are increased risks of drought, hurricanes, and cyclones; and salt intrusion due to sea level rise and storm surges. Adaptation is difficult and expensive. The Swedish scientist Svante Arrhenius has already warned that an increase in carbon dioxide concentrations in the atmosphere could lead to worldwide temperature increases. Because of various development activities leading to greenhouse gas emissions, the world climate is changing rapidly. Climate change is found in both developing and developed countries, but many developing countries are more affected by climate change and can do less about it. Many poor tropical countries do not have the means to improve their resilience against the effects of climate change. Many island states in the Pacific present examples of this dilemma. Bangladesh is an example of a large country with a large and dense population and is recognized worldwide as being extremely vulnerable to the impacts of global warming and climate change. It is a large delta area vulnerable to sea level rise. Global climate change has already vastly impacted the climate of Bangladesh, as is described in this book. The climate of Bangladesh is heating up and is also changing rapidly because of developments in the rural and urban landscapes. It is unclear if and when this could lead to massive climate change–related migration because of failed crops and failed governance. The designs of embankments, roads, and drainage schemes have already been altered by the government and various agencies. But are these alterations enough in the light of the developments that have occurred rapidly within the last few years? Should not these adaptations be thoroughly evaluated in the light of these new developments?

Climate change has become a subject of great interest to the scientific community, since it has major impacts on the physical and human environment on the global, regional, and local scales. The climate of Bangladesh is changing, and its vital agricultural sector and groundwater resources will face the greatest impacts. Rising temperatures, high variability in rainfall, and seasonal shortages of rain will affect the local water balance and will be harmful for agriculture, as will the consequences of climate change such as floods, droughts, cyclones, tidal surges, and soil salinity changes. Therefore, country-level information about climate variability and changes, particularly temperature and rainfall changes, is needed. It is widely recognized that policy makers need reliable and well-synthesized information about climate change and its impacts in order to formulate sustainable management policies for resources and the environment.

This chapter illustrates and analyzes the decadal trends and changing patterns of temperature and rainfall in Bangladesh, using the available historical data and geographic information systems (GIS) and maps for the period of 1971–2010. The decadal mean, mean minimum, and mean maximum temperatures, and the decadal average, premonsoon, and postmonsoon rainfall are assessed and analyzed. The short-term (2011–2020) predictions for temperature and rainfall, using an autoregressive integrated moving average (ARIMA) time series analysis model, are also evaluated and analyzed spatially. Moreover, the impacts of temperature and rainfall changes on agriculture and groundwater resources are discussed.

There was an increasing trend in the mean (0.19 °C decade⁻¹), mean minimum (0.17 °C decade⁻¹), and mean maximum (0.21 °C decade⁻¹) temperatures in Bangladesh during 1971–2010, and these temperatures (mean, mean minimum, and mean maximum) predominantly increased over the three decades of 1981–2010. The decade of 2001–2010 was the warmest decade in Bangladesh, and the maximum temperature increased faster than the minimum temperature. The northwest and northeast of the country are more susceptible to a rising minimum temperature, while the southeast and central southern parts are more vulnerable to a rising maximum temperature. It was predicted that warming would continue predominantly in these parts of the country in 2011–2020. The mean temperature of the country would increase by about 0.18 °C, in comparison with 2001–2010, indicating about 0.76 °C warmer temperatures in the decade of 2011–2020 than in 1971–1980.

Though the decadal average rainfall showed an increasing trend at 76 mm decade⁻¹ during 1971–2010, there was a general trend toward decreasing rainfall in the pre- and postmonsoon seasons, in which rainfall declined by 8 and 4 mm decade⁻¹, respectively. The pre- and postmonsoon rainfall in Bangladesh declined sharply during the two decades of 1991–2010. However, the monsoon rainfall increased by 57 mm decade⁻¹. The model-predicted rainfall showed that during 2011–2020, the average and monsoon rainfall would increase by 119 and 21 mm, respectively, in comparison with 1971–1980. Declines in pre- and postmonsoon rainfall of 5 and 9 mm, respectively, were observed during this decade in comparison with 1971–1980. Greater decreases (of 30–252 mm) in premonsoon rainfall were noted in the western, southwestern, southern and, to some extent, northwestern parts of the country, and the decreases (of 100–289 mm) in rainfall would continue in these parts in 2011–2020, indicating areas vulnerable to decreases in premonsoon rainfall. Greater decreases (of 18–75 mm) in postmonsoon rainfall were noted in the southern, southeastern, eastern, and northwestern parts of the country, and it was anticipated that the decline (of 10–111 mm) in the rainfall in these areas would persist in 2011–2020. Moreover, the rainfall projections for 2011–2020 indicated that the monsoon rainfall would also decrease in the southwestern, central, and northwestern parts of the country, and greater decreases (of 200–221 mm) in the monsoon rainfall were projected for Rajshahi, Bogra, Dhaka, Faridpur, and Khulna in comparison with 1971–1980.

Since Bangladesh is basically an agrarian country, the expected temperature and rainfall changes would be harmful for its agriculture, because the drought situation would be prolonged and the use of groundwater for irrigation would increase in the country. In particular, because of the increases in the minimum and maximum temperatures and the decreases in seasonal rainfall, the environmental suitability for wheat, boro rice, and other crops grown in the pre- and postmonsoon seasons would be reduced and overextraction of groundwater during the dry season would create geo-environmental problems such as increasing saltwater intrusion and lowering of the water table, thus the country might face worsening of food security in the near future. Hence, agricultural practices, harvesting of surface water, and optimum use of groundwater need to be incorporated into mitigation policies and programs to combat the effects of future climate change.

Aquaculture plays a vital role in the agro-based economy of Bangladesh through its contributions to employment and income generation, and through provision of food and nutrition for the people of the country. In addition to 1.32 million full-time fisherfolk, 14.7 million people are involved in aquaculture in Bangladesh. Though all of Bangladesh is more or less prone to adverse impacts of climate change, the northern and northwestern drought-prone areas and coastal regions are particularly sensitive because of specific hydrometeorological, climatic, and human-induced hazards. Erratic rain, irregular rainfall, and temperature changes affect the readiness of fish for breeding. In 2009–2010, extreme weather caused late maturity of fish for breeding in the Mymensingh region—the largest aquaculture zone in the country. Fish farmers are struggling with higher production costs due to water scarcity, higher and lower temperatures, day–night temperature fluctuations, and lower productivity of ponds. Hatchery production has also declined because of such causes. The Bangladesh Climate Change Strategy and Action Plan have considered the fisheries sector as one of the potentially most threatened areas to be targeted. The fisheries sector differs from mainstream agriculture and has distinct interactions and needs with respect to climate change. Capture fisheries have unique features of natural resource harvesting linked with ecosystem production processes. Aquaculture complements and increasingly adds to the supply and, though it is more similar to agriculture in its interactions, it has important links with capture fisheries. Most indigenous fish are migratory and rely on seasonal flooding for spawning cues and access to larval rearing habitats (floodplains). Habitat destruction also has a significant impact, as does lack of flooding/rain—an obvious impact of climate change in the last few decades. Since the economic impacts of climate change will have to be borne by individuals, communities, and the government, there is a need to evolve a climate-resilient development strategy involving all of the relevant sectors, including aquaculture. Only eco-friendly, improved, and innovative management practices with insights into technological, environmental, and socioeconomic concerns can mitigate the impact of climate change on aquaculture in Bangladesh and ensure sustainable fish diversity and production.

Bangladesh has been considered one of the countries most affected by climatic change impacts. Increases in natural hazards, perceived to be due to climate change, have affected the southwestern coastal environments of Bangladesh and people’s livelihoods in this area. Remarkably, the numbers of human deaths due to floods, cyclones, and tidal surges have decreased, primarily because of mitigation strategies such as safe houses. However, the number of homeless people has increased sharply, contributing to internal migration in Bangladesh, including migration between neighboring cities. This chapter discusses the influence of climate-induced hazards on the decision to move, and the circumstances that prompt migrants to take decisions to migrate. Semistructured questionnaires were used to collect data in the Gabura union in the Shyamnagar thana in the Satkhira district, and qualitative analysis and case studies were conducted to further elaborate the outcomes. The results showed that along with anthropogenic causes—such as government policy implementation to protect the Sundarbans (the largest mangrove forest in the world) and changes of paddy cultivation fields into saltwater fish and shrimp farms—natural hazards such as periodic cyclones and tidal surges have damaged the territory of poor workers and/or day laborers, leading them to move to places where employment is more readily available. In this regard, climatic hazards have played a fundamental and influential role with other factors in the process of migration.

The Chittagong Hill Tracts (CHTs) of Bangladesh are the most disadvantaged and vulnerable regions in the country in terms of geographical settings and almost all major development indicators, such as income, employment, poverty, health, water and sanitation, education, and access to infrastructure. The area is mainly inhabited by indigenous communities, who depend on the hill resources for their livelihoods.

Climate change is one of the greatest threats to human security and sustainability. This chapter illustrates five key areas of its effects in relation to climate change in Bangladesh. These are (i) changes in temperature; (ii) intensity of tropical cyclones; (iii) storm surge heights; (iv) sea level rise; and (v) social vulnerability. In 2008, the Ministry of Environment and Forests revealed that Bangladesh and its adjoining areas had warmed by 0.5 °C over the preceding 100 years. The rise in temperature is generally observed in the monsoon season (June–August). An analysis of the relationship between tropical cyclones and sea surface temperatures (SSTs) for the period between 1901 and 1998 showed that despite increases in SSTs, the frequency of tropical cyclones had decreased since 1981 in the Bay of Bengal. Under the Intergovernmental Panel on Climate Change (IPCC) scenario, it is projected that tropical cyclone activity in the future is likely to decrease in the Bay of Bengal. It is predicted that rises in the mean sea level (MSL) and increases in the tropical cyclone wind speed will increase the depth of inundation along the Bangladeshi coast by more than 3 m and increase exposed areas by 69% in size. Increases in SST of up to 2 °C will increase the height of storm surges by 23% and increase areas of inundation by up to 1.26 times the present levels of inundation. Analyzing 22 years of data (1977–1988), the South Asian Meteorological Research Council (2003) showed that the relative sea levels in the Bay of Bengal have risen by 4.0 mm/year and 7.8-mm/year along the western and eastern coasts, respectively. Climate change and its associated impacts may include, but are not limited to, declines in livelihood diversity, migration, and disease. The government of Bangladesh and local residents have adopted various strategies in response to extreme events related to climate change. This review identifies further areas of research in relation to understanding of the distinctive impacts of climate change and developing synergy between institution- and community-led adaptation strategies.

Bangladesh is a small country, but it has different land types in different areas. According to the Bangladesh Agricultural Research Council, in 2014 about 80% of people in Bangladesh were directly or indirectly involved with agriculture. Climatic variation is the most pressing issue for agriculture now all over the world. Weather is the day-to-day condition of the atmosphere at a specific place and includes changes taking place over a matter of seconds, minutes, or hours, and their effects upon life and human activities. Climate change may refer to a change in average weather conditions, or a time variation in longer-term (30- to 40-year) average weather conditions. Generally, the impacts of climate change are progressively familiar as a substantial aspect disturbing life. Several studies have indicated that the climate in Bangladesh is changing and becoming more unpredictable every year. The climate is changing rapidly, resulting in a rise in the earth’s average temperature. Global climate change and its consequences are having a bad impact on developing countries, which face natural calamities and poverty. Climatic variation impacts include temperature rise; erratic rainfall; greenhouse and CO₂ gas emissions; salinity intrusion; increases in floods, cyclones, storm surges, and drought; and melting of ice sheets. These impacts will seriously affect agriculture and livelihood, especially for the poor. Bangladesh, because of its geographical location, is likely to be one of the most seriously affected countries.

Climate change can influence agricultural land use patterns and cause farmers to fall into poverty. The study described in this chapter shows that climatic variation and its impact, especially variability in temperature and rainfall, are highly responsible for changes in agricultural land use patterns in the Madhupur Tract agro ecological zone (AEZ) of Bangladesh. An AEZ is an area of nearly the same ecological and soil characteristics for agricultural crop production, so cropping patterns in a definite AEZ are mostly the same. The homogeneity of an AEZ is more prominent in a sub region and most prominent at a unit level. The AEZs of Bangladesh have been determined on the basis of some definite characteristics of physiography, hydrology, cropping patterns, seasons, soil types, and tidal activity. In fact, an AEZ indicates an area characterized by homogeneous agricultural and ecological characteristics. Bangladesh has tentatively been divided into 30 AEZs. These 30 zones have been subdivided into 88 agro ecological sub regions, which have been further subdivided into 535 agro ecological units.

Bangladesh possesses enormous areas of wetlands including rivers and streams, fresh water lakes and marshes, haors, baors, beels, water storage reservoirs, fishponds, flooded cultivated fields, and estuarine systems with extensive mangrove swamps. The haors, baors, beels, and jheels are of fluvial origin and are commonly identified as freshwater wetlands. Wetlands are subject to periodic inundation, changing from shallow to deep water during the wet monsoon. Most of the wetlands are inland wetlands located in the northeastern part of Bangladesh. The total area of the wetlands in this country has been estimated at 7–8 million ha, or about 50% of the total land surface. The wetlands provide habitats for many special plants, birds, mammals, reptiles, amphibians, fish, and invertebrate species. The wetlands are critically important in Bangladesh for human settlements, biodiversity, fisheries, agricultural diversity, irrigation, navigation, communication, and ecotourism. Wetlands help to reduce the impacts of flooding, maintain good water quality in rivers, recharge groundwater, store carbon, stabilize climatic conditions, and control pests. Wetlands also improve water quality by trapping sediments, filtering out pollutants, and absorbing nutrients that would otherwise result in poor water quality for downstream users.