Systematic Mapping of Climate Change Impacts on Human Security in Bangladesh

Abstract

There is an increasing consensus that climate change undermines human security by exacerbating existing challenges, acting as a “threat multiplier”. Bangladesh is a climate hot spot due to its geographical location, dense population and vulnerable socio-economic infrastructure. Although there is an increasing number of studies on the impacts of climate change in Bangladesh, aggregated research that combines this evidence and provides a comprehensive overview is lacking. The aim of this research is to thoroughly investigate the characteristics of the academic literature on the complex pathways through which climate variability affects different components of human security in Bangladesh, allowing for determination of the trends and research gaps, as well as whether they lead to conflict or cooperation. We used a systematic mapping methodology to search and screen 1839 publications in Web of Science, including 320 publications for the final synthesis. We found a predominant research focus on rural areas, especially in the southwestern region, with declining crop yield, economic loss, migration, water shortage, food scarcity and health hazards being the highlighted impacts of climate change for Bangladesh. The impacts on food, economic, environmental, health and water security have been well studied, but we found significant research gaps in some human security components, especially energy security. Women and the economically disadvantaged are disproportionately affected, and the causal pathways between conflict or cooperation and the ever-changing climate lack research efforts, implying a dire need to focus on under-researched areas before they become more complex and difficult to address. Policies and interventions should prioritise climate-resilient agricultural practices and infrastructure in high-risk areas, building local capacities and integrating climate risk assessments into urban planning, considering the high influx of environmental migrants. This systematic map provides a foundation for future longitudinal studies, establishes a baseline for this era for future comparisons and serves as a reliable database for relevant stakeholders and policy makers.

1. Introduction

Countries that have contributed the least to human-induced climate change are often at the forefront to face its repercussions [1]. Most of these countries are comparatively less resilient to the impacts of climate change, and their inhabitants are 15 times more likely to die from climate hazards [2]. Bangladesh is one such resourceful country that epitomises vulnerability to the impacts of climate change and is struggling with all of the climate change-related impacts mentioned in the sixth assessment report of the IPCC. This active delta nation, situated in South Asia, possesses a distinctive combination of geographical, socio-economic and demographic attributes that heightens its susceptibility to climate change. Located just above the tropics and north of the Bay of Bengal, Bangladesh is prone to rapid-onset natural hazards such as cyclones, floods, tidal surges and storm surges, as well as slow-onset events including sea level rise and unwanted salinisation [3]. The existing challenges are compounded by its heavy reliance on agriculture, poor infrastructure, increasing population density and limited access to healthcare and education [4]. The rising temperature, erratic rainfall and more frequent and intense extreme events pose severe human security challenges by directly affecting agricultural production, consequently threatening livelihoods [5] and food security [6]. The northwestern part of the country is characterised by frequent droughts, also adversely affecting agriculture and the economy [7]. Moreover, climate change is projected to increase the incidence of vector-borne diseases (e.g., dengue and malaria) and waterborne diseases (e.g., diarrhoea) among vulnerable communities, posing public health risks [8]. In addition to decreasing the area of arable land and contaminating surface water [9], the increasing salinity in the densely populated coastal areas is strongly associated with increased risks of complications during pregnancy [10]. Therefore, it is imperative to understand the ramifications of climate change for human security, which is often referred to as “threat multiplier” or “risk multiplier”, augmenting existing socio-economic challenges in a given region [11]. While examining the implications of climate change on a global level is important, digging deeper into specific climate hot spots with unique features is a critical area of inquiry, as no one size fits all.

Research focused on how Bangladesh is confronting the changing climate is quite extensive, yet fragmented. The related literature is focused on specific topics, indicating a void for aggregated research that holistically encapsulates the entirety of climate change’s effects on the various dimensions of human security. In fact, the elements of human security themselves have intricate interplays in vulnerable countries such as Bangladesh and cannot be fully comprehended through isolated studies. Our study fills this gap through offering a more synthesised approach that offers a comprehensive perspective, which is of utmost importance to understand the complex interrelations.

There is an emerging discourse on how climate change functions as a catalyst for conflicts and, in some cases, also cooperation [12,13]. Exploration of the socio-political repercussions of climate change that could lead (or have already led) to inter-communal conflicts is sparsely mentioned in the context of Bangladesh, indicating a research gap even though this pressing concern can now be seen at the forefront of academic research [12,14]. We aim to fill this gap through extracting direct or indirect indications of such interconnections in the existing academic literature.

Most systematic literature reviews on the impacts of climate change in Bangladesh have focused on either individual aspects of human security (e.g., food security, health, livelihood) [15,16,17,18], adaptation to climate change [19,20] or overall impacts without concentrating on human population only [21]. Rahman et al. [22] concentrated on the overall climate change-related research landscape on Bangladesh in their systematic review, identifying trends, geographical distributions and both what is known and what is yet to be known, regardless of human or non-human vulnerabilities or security concerns. Ahmed and Khan [21] summarised the impacts of climate change in Bangladesh using a systematic review methodology, in which they looked into the different climatic hazards that Bangladesh faces and their impacts across various domains. Prutzer et al. [23], in their systematic study, focused specifically on climate-related smart irrigation in South Asia, where Bangladesh was a case study area. The study by Dastagir [24], although not a systematic review, focused on synthesising extreme weather events based on climate modelling data, not including empirical data. Other narrative reviews have provided evidence related to selected human security concerns; however, these lacked a methodologically robust synthesis of the available evidence [25,26,27,28]. In order to enhance broader understanding on the impacts of climate change on Bangladesh as a whole, our research aims to fill these gaps through providing an organised overview of the heterogeneous literature, based on evidence over a large period and with specific focus on the human population.

With this background, the objective of this study is to systematically map the scope and characteristics of the existing academic literature that (directly or indirectly) discusses the connections between climate change and human security in Bangladesh. We primarily ask the question: how does climate change impact human security in Bangladesh? To examine this overarching question, we further investigate the following sub-questions:

• What is the typology of the peer-reviewed literature?
• In which regions of Bangladesh have the studies been carried out?
• What research methods are applied and what settlement types are researched?
• What climate hazards have been reported to occur in Bangladesh? What are their impacts on the human population? Are there disproportionately affected people?
• How are the components of human security affected by these impacts?
• Is there evidence of climate-related impacts leading to conflict and/or cooperation among individuals or communities?

Our aim is to provide a synopsis at a meta-level, as well as to systematically identify knowledge gaps and knowledge clusters in the scientific literature. Finally, we aim to interpret, discuss and analyse our findings and generate a database, which will not only provide information about the state of the art in the related literature regarding past and direct future research trajectories but also assist stakeholders in decision-making and policy formulation.

2. Conceptualising Human Security

Classical definitions of security focus on military concerns as well as political and socio-economic crises from a nation-state perspective [29,30]. Human security, on the other hand, has additional dimensions. Scheffran and Remling [31] have emphasised the shifting emphasis from states to people, from national sovereignty to human welfare and from the threat to the victims. The concept of human security, introduced by the United Nations Development Programme (UNDP) in 1994, has greatly influenced the international discourse on this topic. They considered human security as not only “freedom from fear”, but also “freedom from want”. According to the UNDP, economic crises and pandemics are to be considered security risks just as much as violent conflicts and wars [32]. The UN Commission on Human Security has defined the aim of human security as “to protect the vital core of all human lives in ways that enhance human freedoms and human fulfilment. […] It means using processes that build on people’s strengths and aspirations. It means creating political, social, environmental, economic, military and cultural systems that together give people the building blocks of survival, livelihood and dignity”. Considering the broader meaning, O’Brien and Leichenko [33] referred to human security as “not only to security from physical violence, but also to food security, livelihood security, environmental security, health security and energy security”.

As the UN Commission on Human Security stated, “Human security is to protect the vital core of all human lives in ways that enhance human freedoms and human fulfilment. Human security means protecting fundamental freedoms—freedoms that are the essence of life. It means protecting people from critical (severe) and pervasive (widespread) threats and situations”. The 12th chapter of the IPCC AR5 has adopted a similar approach: “…defines human security, in the context of climate change, as a condition that exists when the vital core of human lives is protected, and when people have the freedom and capacity to live with dignity” [34], which remains the same in the latest assessment report [35]. Scheffran and Remling [31] summarised the diverse discussions and based human security on three pillars:

• “Freedom from fear” addressing the conflict, violence and humanitarian law agenda;
• “Freedom from want” in the context of the human development agenda;
• “Freedom to live in dignity” referring to human rights, rule of law and good governance.

This broad concept of human security is particularly relevant to the context of Bangladesh, as it faces all three challenges as a result of the changing climate. While the recurrence of extreme events poses direct threats to physical safety, widespread poverty and food insecurity impair people’s ability to exercise freedom from want. The unstable economic and political condition is further multiplied by the impacts of climate change, exacerbating vulnerabilities across various dimensions of individual lives and further diminishing people’s ability to live with dignity. However, it is important to break down the broad concept of human security into individual components, in order to thoroughly understand the multifaceted impacts of climate change on human security in Bangladesh and prevent the loss of critical details. Through analysing specific threats to each component, a reliable comprehensive overview where all relevant vulnerabilities are addressed can be generated. To facilitate this, we chose the components of human security mentioned in the report on human development as our basis [32]:

• Economic security;
• Food security;
• Health security;
• Environmental security;
• Personal security;
• Community security;
• Political security.

In the context of Bangladesh, economic and food security is directly threatened by loss of livelihoods and declining agricultural production due to both extreme climate-related events (e.g., cyclone and floods) and slow-onset events (e.g., seasonal change and salinity intrusion) [36]. Health security is affected by disease outbreaks during disasters, high salinity in drinking water and heat-related illnesses [9]. Large-scale ecosystem destruction, land degradation and natural resource depletion affect environmental security [25]. When people are forced to migrate to urban areas in search for livelihood and fail to meet their needs, they may resort to criminal activities which, in turn, impact personal security [37]; furthermore, the competition over scarce resources and social exclusion ultimately undermine community security [38]. The risk-multiplying nature of the overall climate change inevitably influences political security and destabilises fragile governance structures, especially considering Bangladesh’s trend of political instability [39].

Even though the seven elements mentioned in the human development report include the most essential features of human security, we felt the need to update it by adding two missing vital components, namely, energy security and water security. Both these components and their scarcity have been demonstrated to be the key reason for numerous conflicts, wars and social and political instability [40]. It might be compelling to include water security under the umbrella of food or environmental security. Nonetheless, water’s utility for human societies is manifold and encompasses countless other aspects, including agriculture, industry and communication [41]. The impacts of climate change often reach human societies via water in its various forms—for instance, floods, lack of clean drinking water, rainfall variability and so on—with Bangladesh being no exception.

Energy has been an indistinguishable part of human history, development and prosperity, affecting all facets of human life from basic needs to societal stability. It is now unimaginable that human societies all around the world can operate at any level without energy, making it an outright component of human security [42]. The crucial significance of energy security is recognised not only in the context of the two world wars, but also the ongoing war in Ukraine [43]. Climate change poses a significant risk to energy security in Bangladesh by threatening its existing power generation capacity, especially due to its reliance on hydropower, which is susceptible to water availability and extreme weather events [44]. Water and energy security, therefore, need to be seen through separate and independent lenses [45,46]. Thus, we took the concept and components of human security described by the United Nations and the existing literature and expanded them, which served as a foundation and guided our systematic mapping process. This framework not only guided our selection of studies but also the systematic categorisation of information and analysis of research gaps and knowledge clusters, ensuring that our review was built in a bottom-up manner, from detailed findings to an integrated and comprehensive overview.

3. Materials and Methods

3.1. Systematic Mapping as an Instrument

There is no doubt that, in this era of rapid and vast knowledge production and availability, there is a dire need for methodical aggregation of evidence. Such a methodical approach is quite often used in health science [47]; nevertheless, it has also been adapted in the fields of environmental and social sciences fairly recently [48]. We chose systematic mapping over other review methods, such as systematic review, meta-analysis or traditional narrative review, as it is a powerful tool for the aggregation of knowledge on a specific topic and “mapping” of the status quo, which is essentially the aim of our research. It is a transparent, reproducible and robust scientific method used to explore the breadth and complexity of the diverse and heterogeneous literature [49].

Unlike systematic reviews, systematic maps do not aim to answer a specific narrowed-down question, and they often do not critically appraise the relevant research; rather, they identify and describe the nature and characteristics of the topic of interest, as well as clusters and gaps in academic reporting [50,51]. Meta-analyses are particularly valuable when there is a need to integrate results from studies addressing the same research question and using statistical methods to precisely estimate the effect of an intervention [52]. Furthermore, due to their narrow focus, systematic reviews and meta-analyses are more suitable for synthesising a relatively homogeneous set of studies, whereas the literature on the multifaceted impacts of climate change on various components of human security in Bangladesh is highly heterogeneous. On the other hand, traditional narrative reviews lack the systematic structured approach and, hence, are more prone to human bias, resulting in less objectivity. Therefore, systematic mapping is more suitable to flexibly address our primary research objective of providing an overview of the research focused on the impacts of climate change on human security in Bangladesh. Figure 1 provides a step-by-step overview of the stages of the systematic mapping approach; each step is further described in the following sections, accompanied by Supplementary Materials (S1 and S2 Files).

3.2. Search Strategies

We built on the “Population, Exposure, Outcome” (PEO) framework to define the key components of our research question, search strategy and inclusion criteria (see Table 1 and Table 2). We conducted our search for the academic literature in the Web of Science Core Collection (Clarivate Analytics, Philadelphia, PA, USA) on 16 July 2021, using the “Topic” search feature. Reviewing the academic literature up to July 2021, we provide a comprehensive reflection of the state of knowledge as captured in the recent IPCC 6th assessment report, which can be updated in future systematic maps to track the progress of research and contribute to the upcoming 7th assessment report. We chose Web of Science based on its reputation and rich collection of scientific publications across various disciplines, especially for the environmental sciences. It provides comprehensive coverage of the peer-reviewed literature with high-quality indexing, thereby ensuring a broad and reliable dataset.

Next, we used the reference management software Endnote [53] to remove duplicates. The publications found were then imported into the online platform “Sysrev” to facilitate the screening process [54]. Only the academic literature published in the English language were included. At first, we conducted a few scoping searches and figured out that including words like “security” or “human security” significantly restricted the number of outputs. However, as the impacts of climate change on human security are often mentioned indirectly, we decided to include as many publications (n = 1839) as possible in the first phase, such that we obtained an exhaustive and reliable database at the end. Therefore, we kept the search terms relatively broad and chose words and synonyms in a way that returned most publications. No limitation was applied for the time period, and we used the search string as follows:

Bangladesh* AND (climat* NEAR chang* OR global NEAR warming OR environmenta* NEAR chang* OR hotspot* OR drought* OR disaster* OR flood* OR storm* OR cyclone* OR river NEAR erosion OR climat* NEAR hazard* OR natural NEAR hazard* OR sea-level* NEAR ris* OR salinity NEAR intrusion OR increas* NEAR salinity) AND (human* OR farmer* OR people OR population).

Table 1. Population, Exposure and Outcome (PEO) framework for this study, adapted from the CEE guidelines in Pullin et al. [55] and Hunter et al. [56].

Population (P)	Exposure (E)	Outcome (O)
Human population of Bangladesh	Observed impacts of climate change	Human security component being impacted

Table 1. Population, Exposure and Outcome (PEO) framework for this study, adapted from the CEE guidelines in Pullin et al. [55] and Hunter et al. [56].

Population (P)	Exposure (E)	Outcome (O)
Human population of Bangladesh	Observed impacts of climate change	Human security component being impacted

Table 2. Inclusion and exclusion criteria for this systematic map.

Inclusion Criteria	Exclusion Criteria
→ Region of research is or includes Bangladesh	→ Literature review
→ Research focus on humans	→ No impact or observed impact of climate change
→ Mentions evidence of direct and/or indirect impacts of climate change on humans	→ Projected impacts of climate change without empirical evidence
→ The academic literature: journal articles, book chapters and conference proceedings	→ Climate change is not mentioned as a driver
	→ Ecological impact that does not mention impact on human population → Incomplete (e.g., protocols that do not include results)

Table 2. Inclusion and exclusion criteria for this systematic map.

Inclusion Criteria	Exclusion Criteria
→ Region of research is or includes Bangladesh	→ Literature review
→ Research focus on humans	→ No impact or observed impact of climate change
→ Mentions evidence of direct and/or indirect impacts of climate change on humans	→ Projected impacts of climate change without empirical evidence
→ The academic literature: journal articles, book chapters and conference proceedings	→ Climate change is not mentioned as a driver
	→ Ecological impact that does not mention impact on human population → Incomplete (e.g., protocols that do not include results)

3.3. Article Screening

The publications went through two steps of screening, first at the title and abstract level (n = 1837) and afterwards at the full-text level (n = 716). The first step of screening was carried out by two coders, who both went through all the publications while keeping the inclusion and exclusion criteria in mind. The publications for which the decisions to include or exclude were conflicting were resolved based on discussions between the coders, in order to reduce human bias. Papers that showed any potential connection between climate change and the human system were included, tending towards over-inclusion rather than being exclusionary in the initial screening phase [56]. Another reason for including more papers was that many publications did not clarify their research methods in the abstract (e.g., literature review or empirical research) and, therefore, it could not be determined whether the paper provided empirical evidence. We ensured that irrelevant papers were excluded in the second phase by strictly applying the inclusion and exclusion criteria while extracting data.

In the second stage, three reviewers participated in the coding process. The principal investigator (PI) and the coders had clear knowledge of the inclusion and exclusion criteria and were in agreement before starting the coding process. The PI was involved during the whole process, where papers that were coded by the coders were randomly selected by the PI in order to ensure maximum reduction in human bias and error.

Table 2 elaborates the inclusion and exclusion criteria used in this study. We relied on the authors of the papers’ declaration and framing of climate change-related impacts that have been observed in human populations. Publications focusing on only literature reviews were excluded [57], as the information in that case would be repeated in our systematic map. Publications that focused on modelling, projection, scenario building or analysis not based on empirical data were excluded as well, as one of the primary goals of this study was to include the evidence-based academic literature only. For example, the authors of [58] conducted their research in the southwestern part of Bangladesh, where surveys with farmers were carried out. Although their research focused on adaptation strategies, they still indicated the impacts of climate change to which the farmers were adapting. The journal article, therefore, fulfilled all the inclusion criteria and was included in the database. Another study [59] was conducted in a human population and included empirical evidence on flood-related disasters, but it did not explicitly mention any connection between climatic change and the disasters. Hence, we refrained from including this paper, as it could be misleading. We did not conduct the critical appraisal stage for our study, as our aim was to give an overview of the academic literature and, unlike in systematic reviews, this is not considered a compulsory step for systematic maps in environmental sciences [50].

3.4. Coding and Data Extraction

We used the online platform “Sysrev” [54] to extract data and code, which we then exported to MS Excel for analysis and visualisation. To develop the codes, we primarily relied on our research questions, which were the main categories based on which data were extracted. The PI took the first 50 papers where the research clearly focused on the impacts of climate change on human populations in Bangladesh and developed the individual codes, such as “decreasing crop yield”, “lack of food”, “decreasing arable land” and so on under the umbrella category “impacts of climate change”. A similar method was applied to develop codes for other categories, which formed the basis for data extraction from the retrieved publications by all coders (see S2 File). However, there were options to extract new data under “other” for each category—for example, methodology (other)—if they did not fit the existing coding scheme as the coding process progressed. Most of those were assigned as codes if they were found repeatedly in the publications, and the rest remained in the “other” category (see S1 File). Alongside the main categories, we also extracted metadata (year of publication, DOI, publication type).

In order to systematically record the geographical location of the research, we divided the whole country into six regions—namely, north central, northeast, northwest, south central, southeast and southwest—mostly based on the official administrative boundaries of the “divisions” of Bangladesh [60]. The divisions comprise 64 districts; however, a few of the districts of Bangladesh were appointed to a region keeping the capital city Dhaka at the centre and their direction from Dhaka (see S1 File). The exact location, up to sub-district level, was additionally recorded if this information was available in the paper.

The climate hazards were extracted based on the papers explicitly mentioning a hazard as a consequence of climate change. The same applied to the impacts of climate change on human populations, where the researcher had mentioned a direct or indirect impact because of climate change. The components of human security were assigned based on the impacts mentioned in respective publications guided by the criteria detailed in

Table 3. Examples of threats to human security, modified from the UNDP report on Human Development [32] and UN trust fund for human security report [61].

Human Security Component	Criteria and Examples of Threats
Economic security	Impacts that cause economic distress at individual, community or national level (e.g., economic loss, unemployment, loss of income, poverty)
Food security	Impacts affecting food chain (e.g., crop loss, hunger, famine, rising food prices)
Health security	Spread of diseases, malnutrition, lack of access to basic health care, epidemics, poor sanitation
Environmental security	Impacts that cause environmental degradation, resource depletion and so on
Personal security	Physical abuse or violence (e.g., terrorism, domestic violence, assault)
Community security	Inter-ethnic, gender, religion and other identity-based tensions; lack of social capital; social exclusion
Political security	Political repression, human rights abuses, lack of rule of law
Water security	Impacts that cause water-related scarcity or suffering (e.g., high salinity in drinking water, waterlogging)
Energy security	Impacts that cause distress in access to energy resources (e.g., lack of fuel wood for cooking)

. The complete list of codes, their descriptions and labels can be found in S2 File.

3.5. Critical Reflection

The main limitation of this study is that it looked into the academic literature in one database only, whereas, in many instances, the grey literature can contain novel and significant information. Acknowledging that the Web of Science covers only a subset of the academic literature and does not cover the grey literature, we focused on its database as it represents the most important research outlets and current state of research in the context of our research topic.

Although methodologies for the synthesis of systematic evidence in the environmental sciences are relatively flexible—for example, compared to similar approaches used in the medical sciences—the recommendation is to run each publication by at least two reviewers [55]. Two reviewers carried out the title and abstract-level screening, where a common consensus had to be obtained for the conflicting literature. Due to resource constraints, the full-text-screening phase of this study was conducted by one reviewer at a time. However, the reviewers were well trained with respect to the coding scheme and the PI periodically controlled the quality of coding, ensuring minimisation of the inevitable human bias and errors.

4. Results

We obtained 1839 publications after searching in the database and removed any duplicates (n = 2). A total of 1837 publications went through title and abstract-level screening, of which 716 were selected for full-text screening. We finally included 320 publications in the evidence map database (see S1 File). Figure 2 provides the counts of papers in each step using the ROSES (RepOrting standards for Systematic Evidence Syntheses) protocol [62], and we report counts of results in parentheses (n) throughout the paper.

The majority of the publications (298) were journal articles, where most (292 out of 320) were published from 2013 onward, with 20 to 41 publications per year (Figure 3). This year marked the beginning of a decade that saw a significant surge in scholarly interest within this field of study.

Figure 4 reflects scholarly interest across the whole of Bangladesh, where the southwest part received the most attention (173), followed by 106 publications in the northwest region while the least research focused on the northeast (71). There was a notable concentration of research efforts in the coastal zone of Bangladesh (212 out of 320 publications), and 45 publications adopted a nationwide approach instead of a regional one (see S1 File).

Our analysis of the methodologies (Figure 5) adopted by the studies suggested a strong preference for human-centric approaches, with surveys (60%) and interviews (participant, 35%; key informant/expert, 25%) as the prevalent choices. They were often complemented with focus group discussions (38%) and statistical analysis (27%), indicating the application of mixed-method approaches. It is difficult to find or produce freely available remote sensing data for research focusing on human populations, which could explain the low number in this category (11%). We observed a similar tendency regarding economic methods, with only a few (20) publications.

Climate change adaptation (33%) and impacts (34%) were the most predominant focus of the studies (see S1 File), both constituting approximately one-third of the included publications. Around 35 to 60 publications focused their research on agriculture, health, migration, vulnerability and risk assessment and perception of climate change, which were often co-addressed with impact- and adaptation-focused research. Almost one-third of the publications either did not specify their target research population or did not conduct targeted group-based research. Among the rest, nearly one-third (30%) conducted research on farmers and people residing in the coastal areas (22%). Interestingly, only nine papers focused on the indigenous community, while Bangladesh hosts almost 1.65 million people belonging to ethnic communities and are underprivileged [63].

One of the noteworthy findings of this systematic map is the distinct focus of studies in the rural areas in Bangladesh (Figure 6). More than half (accounting for 64% of the total) of the studies focused on rural communities, whereas only 30 papers (approximately 9% of the total corpus) dealt with urban contexts. Only a small fraction of the studies (2%) focused on both urban and rural areas.

Certain climatic hazards were mentioned repeatedly, with flood being dominant, cited in 194 publications and representing a significant 61% of the total research corpus (Figure 7). Cyclones and storm surges were similarly recognised as key hazards in almost half of the included publications (153). There is a general consensus regarding the increasing frequency and severity of such extreme events. Other significant hazards include salinity intrusion, temperature increases, changing precipitation patterns, rising sea levels, droughts and riverbank erosion (24% to 40%). A few catastrophic extreme weather events appeared frequently (see S1 File), namely Cyclone Sidr in 2007 (23); Aila in 2009 (30); Mahasen in 2013 (4); Ronau in 2016 (1); Amphan in 2020 (1); and disastrous floods in 1970 (1), 1991, 2004 (4), 2007 (3), 2012 (1) and 2017 (2).

We extracted detailed information regarding the impacts of climate change (

Table 4. Impacts of climate change reported in the included articles.

Overarching Theme	Impact of Climate Change	Number of Publications
Agriculture	Decreasing crop yield	125
	Lack of food	86
	Decreasing arable land	47
	Decrease in fish stock	37
	Livestock loss	31
	Deteriorating soil fertility	30
	Increasing crop diseases and pests	18
Economic	Economic loss	109
	Loss of shelter	59
	Infrastructure damage	44
	Land erosion	43
	Change in occupation	30
	Reduced mobility	24
	Insecure housing	14
Health	Health hazard	71
	Disease outbreak	47
	Casualty	41
	Psychological distress	30
	Lack of hygienic sanitation	20
	Reduced access to healthcare	16
Water	Lack of clean water	67
	Water shortage	55
	High salinity in drinking water	42
	Waterlogging	38
	Salinity intrusion in groundwater	11
Environmental	Biodiversity loss	22
	Land use change	14
Others	Migration	92
	Sexual harassments (women)	6
	Scarcity of fuel and energy sources	5
	Violence	5

), which we broadly categorised under overarching themes, keeping in mind that many of those are strongly interrelated. Our systematic map reveals significant impacts of climate change on agriculture and economy in Bangladesh. Crop loss or decreasing yield (125) ranks highest on the spectrum of influences on agriculture, followed by lack of food (86) and decreasing arable land (47). The momentous socio-economic implications of climate change are reflected by high numbers of papers mentioning income loss (109) and various other factors, including loss of shelter (59) and occupation change (30), which are directly connected to economic loss. Both internal and external migration is another critical area of concern, being featured in 92 publications.

A significant number of publications mentioned that the changing climate poses various health risks (71), such as disease outbreaks (47) and psychological distress (30), to individuals as well as communities. Critical impacts on water security are reflected in people’s lack of access to clean water (67) or water shortages (55), as well as salinity intrusion in both drinking water (42) and groundwater (11).

There were fewer publications mentioning environmental issues, as we did not focus on extracting evidence that does not mention effects on humans. However, 22 publications mentioned biodiversity being negatively impacted by the changing climate concerning further implications for human population. Controversial topics such as sexual harassment (6) or violence (5) that can be traced back to the changing climate are seen in a negligible amount of publications, closely echoed by lack of energy sources (5).

The differential impacts of climate change on underprivileged demographic groups in Bangladesh are portrayed in Figure 8. While more than half (182) of the publications did not report on any particular group of people who were disproportionately affected by climate change, 81 of the rest mentioned that people with low income are more negatively affected and 46 publications mentioned that women are more vulnerable to the impacts of climate change compared to men. As a considerable amount of the studies focused on the impacts on agriculture, farmers were next in line. Interestingly, we found that relatively less attention has been paid to research on indigenous communities, even though Bangladesh hosts around 1.59 million indigenous people, according to the official consensus, while some sources claim the number to be closer to 5 million.

Although this systematic map did not solely focus on finding clear or subtle evidence for conflict or cooperation affected by climate change in Bangladesh, the reviewers keenly attempted to extract the slightest hint of this information. It is an expressively under-explored theme in the research landscape, with 90% of articles not reporting relevant data. However, 25 publications mentioned conflict, constituting 8% of the included studies. Even fewer publications (five) acknowledged cooperation, even if vaguely or indirectly.

In addition to violent conflict, we recorded mentions of tensions amongst individuals or groups, such as disputes amongst local elites and people dependent on them for economic and social reasons, distribution of scarce resources especially freshwater, land ownership, secure housing, social crimes and injustices. The vast majority of these publications mentioned such disputes in the context of shrimp farming in southwestern Bangladesh, where salinity intrusion is a key concern related to environmental change.

Figure 9 illustrates the percentage of publications showing direct or indirect evidence for the impacts of climate change on the nine components of human security considered in our study. It can be clearly seen that economic security is mostly negatively affected, which appears in 242 papers, representing nearly two-thirds of the total corpus. The second most commonly present component, discussed in 59% of the literature, was food security (202 papers). Environmental, health and water elements encompassed almost one-third of the coded literature each. On the other hand, the comparatively less-examined aspects of human security start with personal security, receiving only 21% of the attention. Community (8%), political (2%) and energy (1%) security appear closest to the inner circle, representing the least-examined themes in the academic literature, with each accounting for less than 10% of the publications.

5. Discussion

The impacts of climate change in Bangladesh, their perception and related adaptations have been significantly investigated over the past decade, as mirrored by the increasing number of academic publications. The aim of this study is to provide an overview of the existing literature focused on the impacts of climate change on human populations in Bangladesh, as well as eliciting their primary characteristics and scope, with a specific focus on human security. For this purpose, we extracted relevant information to present the associated trends and gaps, as well as to reveal how the academic literature connects the impacts of climate change to different components of human livelihoods and security in our study region.

5.1. General Trends and Gaps

Bangladesh is a riverine country, located just above the Bay of Bengal; rivers and canals are spread throughout the country like a net. These geographic features emphasise Bangladesh’s heightened vulnerability to floods and cyclones. This is well reflected in the scientific literature, as they appear to be the most commonly considered climate change-related events. Two devastating cyclones in the recent history of Bangladesh—cyclones Sidr in 2007 and Aila in 2009—were consistently cited throughout the publications. These natural hazards have been part of the adaptions made by Bangladeshi people for centuries. Added challenges emerge when climate change intensifies these natural phenomena in terms of severity and frequency. The rate at which it is increasing often surpasses the adaptive capacity of local communities [64]. We found that scholars in our systematic map repeatedly mentioned that the difference between old Bangladesh and new Bangladesh is the increased frequency and severity of natural hazards. This applies to floods, cyclones, temperature and rainfall extremes, droughts and so on. Sea level rise and ensuing salinity intrusion in the southern part of the country was the next most-prominent climatic hazard. There were a small number of studies that attempted to determine the correlation between climate variability and landslides, which are heavily affected by anthropogenic factors such as cutting hills to collect soil for brick-manufacturing purposes. Nevertheless, the lack of research efforts in this regard indicates a research gap, as landslides are increasing due to heavier and erratic rainfall patterns induced by climate change, thereby exacerbating the existing situation, especially for indigenous populations [65,66].

In general, the research attention spans more towards southern Bangladesh, compared to the northern part of the country, considering salinity intrusion as a significant impact of climate change. The southwest part of Bangladesh suffers severely from this incrementally increasing challenge due to its coastal geographical position. This area is also often in the frontline, receiving the destructive energy of cyclones more frequently [67]. Saltwater intrusion has reduced the fertility of soil and arability of lands, forcing people to change their occupations, even though farming is the primary livelihood skill that they have possessed for generations [68]. Similar trends have been observed in the Mekong delta in Vietnam, where salinity intrusion into freshwater systems is compromising agriculture and domestic water supply [69,70]. Being an agriculture-focused country, the relatively high concentration of studies conducted in this part of the country underscores the critical socio-economic implications of salinity intrusion and academic efforts to find scientific solutions.

The northwest region is characterised by recurrent river flooding, seasonal water scarcity issues and droughts [71], and it has received a fair amount of scholarly attention. On the other hand, despite being at the forefront of sea level rise-related challenges and cyclonic activities, the southeast coastal area reported few studies, raising the question of whether this mirrors the varying intensity of climate change impacts or, instead, represents an uneven scholarly focus. Similarly, even though the northeast region has attracted less research attention, it is not immune to the consequences of climate change, especially as seasonal flooding is a characteristic phenomenon here due to its location within the Meghna river basin [72,73]. This region accommodates the biodiversity-rich freshwater wetland ecosystem, named “Haor”, which remains flooded during monsoons for almost seven to eight months and dries up in the post-monsoon period [74]. People live here in harmony with nature—that is, on shaky homes heightened and supported by bamboo—and heavily rely on agriculture and fishing. Due to climate change, seasonal flooding has become more unpredictable and severe [75], disrupting the human security of the localities through undermining food and economic security, thereby increasing their vulnerability. The contrast of research efforts between the southwest and northeast regions indicates a potential gap in the research landscape which may lead to uneven policy responses, thereby exacerbating the lack of adaptation measures.

The research focus on rural areas could be attributed to the socio-economic vulnerabilities and heightened exposure of the people living in rural areas, as well as their reliance on climate-sensitive sectors such as agriculture and fishing. This significant research gap is directly linked to our finding that only 9% of studies addressed urban contexts. However, as rapid urbanisation is attracting more people to cities and most of the environmentally displaced people can be expected to look for a safer home there, this crucial under-representation cannot be ignored. According to a census report in 2022, 31.5% of the total population live in urban areas and the urban population has increased almost two-fold over the last decade [63]. With this rate of urbanisation, it is predicted that more than 50% of the population will be living in urban areas [76]. Zhou et al. [77] reported a similar trend in South Africa in their review, where the research and policy recommendations are tailored more towards rural areas, although urban areas are also being exposed to the impacts of climate change. This relative research void limits our overall understanding of climate change impacts and effective adaptation measures within urban contexts. Furthermore, it indicates the lack of comparative studies between rural and urban populations; for example, the nuanced differences and potential commonalities in their perception of the changing climate, as well as their coping mechanisms and capacities.

Having an agrarian economy, Bangladesh suffers from impacts of climate change predominantly through agriculture, which was reflected in the high numbers of publications reporting the impacts of climate change on various aspects of agriculture. However, other momentous issues, such as the interconnections between climate change and energy security or gendered issues, also require attention. Women and children are not considered as target groups in research very often, whereas they have been mentioned as being disproportionately affected by climate change-related impacts. The correlation between increasing temperature and health hazards is becoming more prominent, yet it seems to have been less scrutinised by the scholarly community, indicating a research gap. Mental health discussions are somewhat of a taboo in Bangladeshi society [18]. Nevertheless, quite a number of publications have mentioned it in connection with climate change-induced events, indicating a greater need to explore this branch of knowledge.

People-centric methodological tools such surveys and interviews were predominantly employed to conduct research, which are instrumental for the collection of tangible evidence on the impacts of climate change. However, valuable empirical data can also be captured using methods such as field measurements and remote sensing, which were less prevalent, signifying potential for expanding the methodological repertoire in this line.

As expected, Ahmed and Khan [21], and Rahman et al. [22], as well as our study, revealed an exponentially increasing amount of publications, therefore emphasising the need for systematic syntheses. Ahmed and Khan [21] have provided a spatial overview of all dimensions of the impacts of climate change on Bangladesh in their systematic review. Complementing this review, as well as that by Rahman et al. [22] on overall climate change-related research focused on Bangladesh, our review provides a comprehensive human-dimensions-focused, yet inclusive, synopsis of the academic literature. A novelty of our study is the sole inclusion of empirical evidence, identifying regional and sectoral patterns and, most importantly, framing climate impacts through our identified nine components of human security, as discussed further in the following section. In order to provide an even more comprehensive picture of the impacts of human security “on the ground”, future reviews could also include the grey literature and local databases and repositories, which was beyond the scope of this systematic map.

5.2. Human Security

Our study revealed that impacts of climate change on the agriculture and the economy of Bangladesh are well-researched themes. Bangladesh is highly dependent on climate-sensitive sectors, such as agriculture and fisheries, which face intensive challenges including unpredictable weather patterns or seasonal shifts. A significant amount of studies have reported (Table 4) crop loss (125), income loss (109), food (86) and clean water shortages (67) which, along with other impacts in these categories, are reflected in the high ranks of food, economic and water security factors (Figure 9). To the contrary, only 2% of studies addressed the impacts of climate change on political security and 8% on community security (Figure 9), indicating a less direct causal pathway leading to a significant research gap on this topic. Nevertheless, it is questionable whether this lack of research represents the actual volume of such impacts. Limited data regarding the effects of climate-induced migration on political dynamics and community cohesion suggest a need for research attention. Furthermore, policies should focus on enhancing the adaptive capacities of the whole agricultural system through emphasising climate-resilient agricultural practices, such as drought- and salinity-resistant crop varieties, sustainable irrigation methods, diversified livelihoods supported by access to early warning systems and financial subsidies and assistance.

One of our significant findings is the small number (1%) of publications mentioning connections between the impacts of climate change and energy security based on empirical data (Figure 9). In Bangladesh, where basic sustenance is not always guaranteed, access to sufficient energy may be regarded as a luxurious commodity, making it the probable reason for such low attention in the literature. Many agricultural processes (e.g., cow-pulled ploughs) and day-to-day transportation of goods or commuting (e.g., human-pulled rickshaws) are still carried out by human labour or domestic animals, indicating the scarcity of energy resources as well as economic impoverishment. Nevertheless, as Bangladesh’s economy is rapidly developing [78] along with an ever-increasing population density, so is its need for energy. With rising temperatures and more frequent extreme events (e.g., droughts or heatwaves), as evidenced in our results (Figure 7), there is a rising energy demand for cooling and machine-operated agricultural practices. Bangladesh has been struggling with energy shortages and the energy landscape is heavily reliant on non-renewable sources [79], and increasingly frequent severe extreme events may further disrupt the energy supply through damaging infrastructure [80,81]. The Middle East and North Africa (MENA) region is encountering comparable complications, where increasing summer temperatures and decreasing precipitation are intensifying already-existing water and energy security-related issues [82]. It is crucial to bridge this gap and explore the connections between the impacts of climate change and energy security based on empirical data. Necessary attention to energy security within national climate adaptation strategies is imperative, that is, through ensuring the resilience of energy infrastructure against foreseeable climatic impacts and a transition to renewable sources such as wind and solar energy.

We found that health security has been reported to be primarily associated with high salinity in drinking water, leading to widespread health issues in Bangladesh (Table 4). Residents in the southern coastal zones are often compelled to consume saline water and use it for household purposes. Consequently, they suffer from health issues related to salt intake exceeding the allowed thresholds, such as hypertension, skin diseases and both pre-eclampsia and eclampsia in pregnant women [10,83,84]. Some publications have indicated outbreaks of water- and food-borne diseases following extreme weather events (Table 4). In Bangladesh, mosquitoes are carriers of deadly diseases such as malaria and dengue, which are a yearly public health concern [85]. A few publications cited that mosquito larvae can survive longer and thrive better at higher temperatures, and so the increasing temperature due to global warming is exacerbating this health threat [86]. Increased heat-related mortality and morbidity, associated with factors such as heat strokes, heat exhaustion and psycho-social effects, were also referenced as an impact of climate change on health security, especially in urban areas, as Bangladesh is getting warmer every year and heatwave incidents are occurring more often and continuing for longer [15]. In order to strengthen health security, policies should put emphasis on improving health, water and sanitation infrastructure, using water purification technologies at the household level, expanding heat action plans and investing in research on climate-related health impacts.

Community security includes identity-based vulnerability as well, and our study revealed a disproportionate impact on women (46 publications, Figure 8). Due to climate change, clean water has become scarcer in Bangladesh. Women often need to travel long distances to collect clean water, and some publications have reported that they face sexual, physical and psychological harassment on their way (Table 4). Many migrant women confront similar challenges when they take up jobs (i.e., as housemaids) in the receiving area. They have reported feeling that it is unsafe to go to cyclone shelters due to the fear of potential abuse and lack of privacy, prompting many to choose to remain at home even in the face of impending cyclones or floods [87]. As a result, the rate of casualty and mortality—and, therefore, overall vulnerability—is higher among women when compared to that of men [88]. Yadav and Lal [89] have elucidated the similar disproportionate vulnerability of women in South Asia, particularly in India, where women encounter gender-specific challenges for water and fuel collection, as well as greater health hazards, poor social well-being and even mortality under the influence of climate change.

Furthermore, we found that around 2% of publications reported disproportionate impacts on indigenous communities (Figure 8), which is again represented in the low impact on community security (Figure 9) but may not accurately reflect reality. According to the 2023 government census report, there are 1.59 million indigenous people [63], whereas organisations such as the Bangladesh Indigenous People Forum (BIPF) have estimated the actual number to be around 5 million [90]. The indigenous people are systemically neglected and under-represented by both government and academic institutions, compounded by their geographic marginalisation, with many communities living in remote areas [90]. They live close to nature, which makes them even more vulnerable to climate change impacts; hence, the comparatively low number of publications is indicative of the limited inclusion of indigenous populations in mainstream climate studies in Bangladesh. Gender and indigenous-identity-sensitive adaptation approaches are therefore vital in every step of policy formulation. Most importantly, a holistic and multi-sectoral policy approach, such as coordinated efforts between the ministries of health, environment, energy and disaster management, is necessary to address the inter-related impacts of climate change on human security and multiple aspects of vulnerability simultaneously.

5.3. Conflict and Cooperation

Bangladesh could be regarded as a conflict-ridden country if compared to regions with comparatively peaceful conditions, but not when compared to regions involved in active violence (i.e., war). Although the evidence sometimes indicates relatively clear interconnections with climatic variability, this debate remains controversial within the scientific community [91,92]. We found that many of the publications retained a rather conservative approach when tracing the reasons for conflicts back to the impacts of climate change, as reflected in the relatively low number (8%) of studies. It is essential to consider that the impacts of climate change have the potential to ignite unrest and conflict, especially in settings with limited resources [34]. We found that the researchers did not seem confident in mentioning the causal pathways between climate change and violent conflicts. Undoubtedly, unlike other regions such as Africa [93,94,95], this is a direction that has not been extensively researched in the context of Bangladesh. Most of the conflicts that appear in the scholarly literature are stated to be due to political or economic reasons, such as the ethnic cleansing in Myanmar, which resulted in millions of the Rohingya minority community to take refuge in already-struggling Bangladesh. However, Ahmed et al. [96] have shown that the protracted Rohingya refugee crisis has led to considerable deforestation, natural resource depletion and, consequently, conflicts with local populations in the hosting southeastern region which is already strongly impacted by extreme rainfall, cyclones and landslides, exemplifying how climate change can act as a threat multiplier [96].

The publications frequently portray conflict among social groups over competition for scarce resources, for instance, for clean water or land ownership. The land use pattern in the southern salinity-ridden part of Bangladesh has drastically changed over the last few decades. Due to the increasing salinity in soil, surface and groundwater, there is a growing trend towards converting agricultural lands into shrimp farms. Many publications hold sea level rise induced by climate change responsible for this phenomenon, even though there are plenty of anthropogenic factors that are often not taken into account when establishing the causal relationship. Ensuing disputes arise between the local elites or commercial shrimp farm owners and ordinary farmers or anglers over occupation of land (e.g., illegal land-grabbing) [97,98,99]. However, Sovacool (2018) has mentioned that such disputes occur as a result of adaptation efforts intended to originally mitigate the impacts of climate change [39]. In many cases, the benefits of large-scale infrastructure projects, such as embankments or resettlement programs, which often disrupt existing land use patterns and displace marginalised populations, are captured by local elites, leading to conflicts over land rights and access to resources. Therefore, it is crucial for policymakers to actively involve local communities equally in the decision-making process, therefore preventing the fuelling of local power dynamics and the exacerbation of social conflicts.

A further manifestation of social friction is illegal or criminal activities carried out by migrants in the receiving area. We found migration to be a prevalent phenomenon in Bangladesh, reported in 92 publications (Table 4), where people often migrate to larger overcrowded urban areas after extreme weather events in search of better opportunities and safer living conditions [100]. These migrants subsequently have to compete for resources, employment and housing with locals [101]. A few publications mentioned instances where such individuals become involved with illegal drug-related offences and other social crimes driven by poverty [37,101]. These dynamics create a vicious cycle where environmental stress and social conflict feed into each other. Therefore, urban planning policies should provide equitable access to essential services, as well as decentralisation of the economy to reduce the migration pressure in urban areas.

In comparison to conflict, even fewer (ca. 1.5%) publications mentioned cooperation driven by the impacts of climate change. Cooperation takes place primarily when communities are adapting, which could be the reason behind the low percentage, as our study focused on impacts rather than adaptation. Cooperation is reflected as social capital in the receiving areas in the migration context, playing the role of a major pull factor [99]. Further examples include collective actions to address water scarcity, such as rainwater harvesting, pond water conservation and cooperative adaptation strategies to adopt salt-tolerant crop varieties, where government agencies and NGOs have enhanced these efforts through providing the necessary resources and technical expertise [102]. In peri-urban areas of Khulna suffering from high salinity, local grassroots communities, with the help of NGOs and local government bodies, have collectively organised resistance to the intrusion of saline water into freshwater systems, which has often been manipulated by local elites for economic benefits resulting from shrimp farming [103]. Cooperation amongst communities, governing bodies and the non-profit sector is therefore crucial to mitigate conflicts over resource use, and thus inclusive adaptation strategies should be emphasised when formulating policy.

6. Conclusions

This systematic map painted a vivid meta-level picture of the academic literature on the extensive and multifaceted impacts of climate change on human security in Bangladesh, describing their characteristics and synthesising research trends and gaps. We found a significant research focus on rural areas, especially in the southwestern region, and less scholarly attention to urban areas and the northeast. Climate change is impacting Bangladesh primarily through agricultural production loss and water shortages which, in turn, are leading to economic losses and food insecurity. Additionally, while health hazards and migration-related consequences have been well documented, the impacts on political, community, personal and energy security remain under-explored, especially the pathways leading to conflict or fostering cooperation. Moreover, we found that certain underprivileged groups (i.e., women, low-income and indigenous communities) suffer from the burdens of climate change disproportionately.

The research gaps identified in this study could serve as a guide to inspect significant yet unasked questions for future research and potentially open doors for several specific follow-up systematic reviews on individual human security components, providing enhanced findings through extracting information from multiple reliable sources including the grey literature. Causal relationships between specific categories based on relatively homogeneous primary or secondary data could be analysed using elaborate statistical methods, such as meta-analyses. Additionally, future research should focus on diverse methodologies based on economics, remote sensing or Geographic Information Systems and projections of climate futures based on empirical data.

Cities are centres for economic development and educational progress in Bangladesh, and a significant percentage of the population is already living in or is migrating to the urban areas, as seen in the recent past. Given the health hazards stemming from the impacts of climate change, future research could investigate how increasing and extreme temperatures exacerbate health issues and vector-borne diseases in dense urban areas. Furthermore, the impact of environmental migrant influxes on housing, employment and access to resources in cities, as well as their inclusion in improved urban planning, should be emphasised in both research and policy. Furthermore, research should investigate how climate change exacerbates existing gender inequalities, the impacts on mental health and how cultural and social norms influence the ability to respond to climate-related challenges. Considering the imbalanced impact on indigenous communities and the value of indigenous knowledge, ethnographic studies that document traditional knowledge and practices related to climate adaptation could provide valuable insights. Therefore, policies should ensure equitable access to resources, such as financial support, training and healthcare, in keeping with the unique needs of these groups and including women and indigenous communities in decision-making processes regarding climate adaptation.

Acknowledging the lack of research investigating conflict or cooperation influenced by the impacts of climate change, research should focus on its role as risk multiplier for tension over scarce resources and land use rights in the salinity-ridden southwestern region among different social groups. A similar approach could be applied to migrants and host communities, in order to determine the root cause of tensions, potentially tracing back to specific climate change-related impacts. Conflict-sensitive adaptation policies and enforcing legal frameworks that protect the rights of vulnerable groups, such as those regarding land ownership, are crucial for the prevention of maladaptation. Furthermore, the importance of capacity building, income diversification and community-based adaption measures are crucial for mitigating the impacts of climate change in Bangladesh.

In conclusion, this research offers valuable insights that extend beyond the country’s borders, and the robust and reproducible methodology can be utilised in regions facing similar challenges, especially in low-lying coastal areas with weak socio-economic infrastructures. Climate change knows no boundaries, and in this era of globalisation, impacts in one region have the potential to trigger cascading effects with global consequences. Therefore, it is imperative to understand the broader implications of climate change on human security for developing nations, where our research can serve as a microcosmic analysis. Comparison with other developed nations can highlight disparities and opportunities for knowledge exchange. Understanding how high carbon emissions in developed nations disproportionately affect low-income and low-emission countries can emphasise the urgent need for global emission reductions and targeted funding to mitigate the damage already inflicted on industrially under-developed regions. In summary, our evidence is expected to provide valuable insight into anthropogenic climate change impacts for this era, serving as a reliable database for researchers, stakeholders and policy makers and a robust example that can be applied to any region in the world.