Abstract
Drought is increasingly seen as the next “pandemic,” threatening global populations and progress towards achieving zero hunger by 2030. Although drought and food security are well-researched, no studies synthesize the progress and gaps in drought-food insecurity research using the social-ecological systems (SES) approach. Through a systematic review of 186 peer-reviewed studies in Asia and Africa, sourced from Web of Science and Scopus, we identified knowledge gaps and application of an SES approach in the drought-food insecurity nexus. Most studies focused on either social or ecological perspectives; applied quantitative approaches; did not specify drought types; emphasized food availability and access; and did not assess adaptation strategies. The key gap identified was the limited application of a holistic SES approach for achieving the zero-hunger goal. Unlike traditional approaches, our proposed conceptual framework offers a holistic lens for investigating SES components and their complex relationships, and new inquiries in the drought-food insecurity nexus.
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Introduction
The United Nations Sustainable Development Goal (SDG 2) aims to achieve Zero Hunger by 2030 across the globe. However, the global hunger projections show that the world is not on track to achieving this ambitious goal1,2. In 2022, between 691 and 783 million people globally were still hungry despite targeted global, national, and local initiatives3. The developing regions are particularly vulnerable to food insecurity, for example, among the world’s population who experience moderate or severe food insecurity (about 2.37 billion), over half of them (1.2 billion) exist in Asia, followed by Africa (799 million) and Latin America and the Caribbean (267 million)2. Combined, Africa and Asia represent the highest extent of moderate to severe food insecurity (41% and 42.50% population, respectively) compared to other regions of the world4.
Drought – defined as “a period of abnormally dry weather long enough to cause a serious hydrological imbalance”5, is the most complex and recurring hazard that can cause widespread impacts on global sustainable developments6. The United Nations hint that drought could be the next pandemic if immediate actions are not guaranteed6, as its impacts extend beyond a single sector or region7 and are exacerbated by the already warming climate8. The implications are serious, and it has been suggested that several ancient cultures (e.g., The Maya civilization in Central America) disappeared due to the extended droughts6. Globally, droughts affected around 1.5 billion people with economic damages equivalent to $124 billion between 1998 and 20179. While droughts can occur in any region, both Asia and Africa absorb most of the drought impacts due to climate change, geographical contexts, and poor institutional capacity to combat droughts10,11,12. For example, more than 750 million people were affected and $6.57 billion in economic damages were reported due to 48 severe droughts in South Asia between 1990 and 202013. In Africa, drought caused around 680,000 deaths between 1970 and 2012, and the frequency of droughts has increased twofold since 200514.
Reducing the impact of droughts on food insecurity and vice-versa requires an understanding of the interlinkages and interdependencies between droughts and food insecurity15. Here, we define the drought-food insecurity nexus as a concept that characterizes the complex interlinkages (e.g., trade-offs and synergies) between drought and food insecurity from a social-ecological systems (SES) perspective. The drought-food insecurity nexus is a complex phenomenon, which is shaped by both ecological (e.g., lack of rainfall) and social factors (e.g., water demand to increase crop production)16,17. For example, anthropogenic land-use change manifests evapotranspiration, surface runoff, infiltration, and water storage that contribute to the development of subsequent droughts17. The direct effect (Fig. 1) of droughts on food insecurity is through their impacts on crop production due to water stress. This can lead to market shortfalls and higher food prices, reducing food availability and affordability, which in turn exacerbates food insecurity18. As shown in Fig. 1, water is required for food production through crop irrigation, fisheries, and livestock water usage. Hence, drought-induced water shortages could restrict food production through, amongst others, delaying root growth and development, maturation, and yield reduction18. Eventually, reduced food production can increase food insecurity, driving up food demand. This, in turn, may lead to the manifestation of water resources, such as increased water abstraction, and water quality depletion due to intensified use of chemical fertilizers and pesticides. Consequently, these factors can lead to the intensification of drought conditions. These linkages indicate that the drought-food insecurity nexus is required to understand from a social-ecological system (SES) perspective.
The figure was created using Microsoft PowerPoint.
The SES is a complex adaptive system in which the intertwined ecological and social systems exert strong influences on each other and the system outcomes19,20. Self-perpetuating feedback loops in SES – an interactive relationship where the output flow of a system is redirected to the origin of the initial input (trigger) for this interaction – could exacerbate food insecurity. For instance, rising temperature increases droughts. This reduces income from agriculture, forcing farmers to extract more groundwater. Excessive groundwater extraction further intensifies drought, ultimately worsening food security21 (Fig. 2).
The figure was created using Stella Professional software.
The application of the SES approach has been growing rapidly across disciplines, and it integrates the complex social and ecological systems as an interconnected system22. As such, an SES approach that captures causality, feedback, non-linearity, spatial-temporal and cross-scale dynamics23,24 might be useful to understand the dynamic interactions between the social and ecological variables in the drought-food insecurity nexus. However, the use of an SES approach integrating social and ecological variables and their dynamic relationships in the drought-food insecurity nexus is lacking.
Therefore, this systematic review addresses the above knowledge gap by examining state-of-the-art of drought-food insecurity nexus research and identifying key research gaps. This review focuses on the drought-food insecurity nexus in Asia and Africa. These regions are most vulnerable to drought and climate change as well as the most food-insecure regions in the world. In addition, we aim to examine the extent to which the SES approach has been considered in global drought-food insecurity nexus research. The specific questions to guide the systematic review were: 1) What are the current trends in drought-food insecurity nexus research? 2) What are the research gaps and opportunities in drought-food insecurity nexus research? 3) To what extent has the SES approach been used in the reviewed studies? and 4) What are the implications of a conceptual SES framework for the drought-food insecurity nexus?
Results
Summary of the published research on the drought-food insecurity nexus
This review considered 184 articles examining the drought-food insecurity nexus within Asia (98) and Africa (86). In Asia, the majority of research was conducted in South Asia (43%), East Asia (38%) and Southeast Asia (9%) (Fig. 3). Interestingly, all of the research on drought-food insecurity within East Asia was concentrated in China (n = 38). However, India (n = 25) and Bangladesh (n = 11) also considerably lead the research on drought-food insecurity after China. In Africa, over 44% of the studies concentrated in Eastern Africa, followed by Southern Africa (30%) and Western Africa (18%). Country-wise, the highest number of research was conducted in Ethiopia (n = 17), South Africa (n = 13), and Kenya (n = 13). Focusing on the spatial scale, the highest number of research (n = 71) were based on local scale. This was followed by regional scale (n = 63) and national scale (n = 33), with only 17 articles based on sub-continental scale. Most of the included papers targeted present status (73.20%) of drought risk and food insecurity, with relatively few research assessing past trends (17.40%) and future scenarios (9.50%) respectively. On the other hand, most of the research assessed the drought-food insecurity using a historical timescale (28.80%), followed by daily timescale (23.37%). A considerable proportion of articles (16.30%) did not specify any time scale (Supplementary Fig. 3).
The figure was created using R software.
The total number of articles on the drought-food insecurity nexus followed an increasing trend between 1986 and 2023 (Fig. 4). However, a rapid increase occurred after 2012 approaching a peak in 2015 and 2017 following the highest peak in 2021. This period coincides with several global events, such as the IPCC Special Report on Extreme Events (SREX) in 2012, United Nation’s Sustainable Development Goals (2015–2030) and the Sendai Framework for Disaster Risk Reduction (SFDRR 2015–2030) in 2015, WFP’s Climate Change Policy in 2017, and the GAR Special Report on Drought (GAR SRD) in 2021. All of these events emphasize the understanding of the nature and risks of extreme disasters, including droughts for global sustainable development. The growth in research during this period may also be attributed to advancements in research methodologies, including the use of environmental and crop models25 and the development in drought monitoring and forecasing sytems18. However, a decline in research after 2021 may be associated with a shift in research focus toward the Covid-19 pandemic compared to non-Covid-19 research26.
Overall research on the drought-food insecurity nexus increased after 2012. IPCC SREX = IPCC Special Report on Extreme Events, UN SDGs = United Nation’s Sustainable Development Goals, SFDRR = Sendai Framework for Disaster Risk Reduction 2015–2030, WFP CCP = WFP’s Climate Change Policy, and GAR SRD = GAR Special Report on Drought 2021. The figure was created using R software.
Focus of the research articles was primarily either social (32.49%) or ecological perspectives (32.13%). Comparatively little research also focused on economic perspectives (19.86%). The review also identified some research articles that considered multiple perspectives, for instance, social and economic perspectives27, and economic and environmental perspectives28. Figure 5 indicates that the overlap between social and ecological perspectives represents the highest number of research (n = 24), followed by economic and ecological perspectives (n = 12), and social and economic perspectives (n = 7).
The numbers in the Venn diagram indicate the number of research articles. The figure was created using R software.
The Sankey diagram (Fig. 6) represents the relationship between research focus, research approach and methods, drought types and food security dimensions identified in the reviewed articles. The ecological focus shares the highest intersection with quantitative research approach. Whereas social, and social and ecological focus mainly corresponding to quantitative followed by mixed-methods approach. Moreover, methods used within different research approaches reveal the highest intersection between quantitative approach and statistical analysis (29.29%). This was followed by quantitative approach and index-based methods (14.29%), and quantitative approach and crop or hydrological models (5%). Mixed-methods research approaches share maximum intersection with statistical analysis (10.71%). In contrast, qualitative approaches share with qualitative methods (6.07%) such as thematic analysis, and narratives. Considering the link between the frequently used methods and drought types, we find that statistical analysis, qualitative methods and economic models are highly connected to articles that do not specify a particular drought type. In contrast, the index-based methods and hydrological or crop models are linked to agricultural drought assessment. Regarding the drought types and food security dimensions, all the studies share the highest intersection with food availability, followed by food access.
Complying to the research aim, this study categorised both social and economic research focus as social, and ecological and environmental focus as ecological focus. FS dimensions = Food security dimensions. The figure was created using R software.
Current trends in drought-food insecurity nexus research
Examining the research trends in drought-food insecurity nexus within the Asian and African contexts, this review reveals that the research on the topic commenced in the early 1980s. Before 2011, studies were conducted on either social or economic aspects of droughts and food insecurity29. However, the focus shifted after 2011, moving towards more environmental and economic perspectives, particularly after 2015. The reason behind this shift may be attributed to the environmental and economic impacts of the El Niño phenomenon in 2015/201630. Moreover, the call from international organizations (e.g., the UN’s Sendai Framework for Disaster Risk Reduction 2015–2030) to understand the nature of drought attributes and risk may have reinforced this shift31. The use of index-based and modelling approaches gained attention in examining both drought and food insecurity (i.e., crop production) in almost equal depth32,33. During this period, research concentrated more on drought risk assessments and effects on crop production considering either drought indices, e.g., SPEI (Standardized Precipitation Evapotranspiration Index)34 or crop models, e.g., WOFOST (World Food Studies)25 and EPIC (Environmental Policy Integrated Climate)35. However, some of the studies also found statistical models useful for examining drought and food insecurity36.
With regard to the spatial scale, the results reveal that local and regional scale studies primarily assessed the food insecurity situation in the context of droughts37, impacts38 and coping strategies39 of drought. National scale research mainly focused on modelling or framework approaches to examine drought impacts on crop production, food insecurity risk assessment40 and emphasized the causal relationship (a cause-effect relationship) between drought and food insecurity28 and food insecurity policy analysis41.
The major limitations of previous research were data unavailability or weak/missing data, such as data on fresh-water withdrawals for farming42, socio-economic data43. The second major challenge was identified as the modelling complexity, for example, prediction of crop yields by using a crop model could be misleading since other factors (e.g., diseases, insect outbreaks) also influence yield besides droughts32. Other limitations associated with drought-food insecurity research include limited geographical focus28, and cultural barriers for commercial water trading in the context of Afghanistan43.
Methodological approaches in drought-food insecurity nexus research
The review of the methodological approaches (Supplementary Fig. 4) used in drought-food insecurity research reveals that 73.40% of the included papers applied a quantitative, 16.30% applied a mixed-methods, and 8.20% applied a qualitative approach (Supplementary Fig. 5). Most of the quantitative research applied statistical analysis (35.79%), index-based methods (18.95%), and participatory methods (10.53%). On the contrary, most of the qualitative research used narratives (4.74%) to explain drought impacts on food insecurity and livelihoods. The review further identifies that about half of the included papers (49.46%) used secondary data to assess the relationship between drought and food insecurity. Considerably few research papers (31.52%) used primary data (e.g., questionnaire survey data), and only 19.02% of the research considered both primary and secondary data for analyses (Supplementary Fig. 5).
Assessment of droughts and food insecurity
The majority of the published research (52.17%) did not specify drought types when researching the drought-food insecurity nexus. These research primarily focussed on socio-economic and food insecurity impacts of drought exposure, without assessing the biophysical characteriestics of droughts44. Moreover, a few of the research articles (6.52%) considered multiple droughts, e.g., meteorological and agricultural droughts45, or meteorological, agricultural, and hydrological droughts42. Examining the dimensions of food insecurity (Supplementary Table 3), nearly half of the articles (44.57%) considered food availability. Some 29.35% of research considered more than one food insecurity dimension, such as food availability, access, and utilization27. Some research articles considered the food access (19.57%) and food utilization (5.98%) dimensions, whereas only 0.54% articles assessed the food stability dimension exclusively.
Figure 7 represents the relative frequency of drought types and food insecurity dimensions. The number of the articles that measured food availability without specifying any drought type are the highest (n = 60). However, some research on food availability also considered either agricultural drought (n = 26) or meteorological drought (n = 26) when linking with drought and food insecurity. Other dimensions of food insecurity, such as food access and utilization were measured in most studies but without specifying any drought type (n = 56 and 20, respectively).
All the articles (n = 184) were coded multiple times, as one study could consider more than one food insecurity dimension. Multiple droughts indicate research that considers more than one drought type. The figure was created using R software.
The analysis identified that 69.02% of the published research examined a direct link between droughts and food insecurity, whereas the rest of the published research (30.98%) did not examine a direct link between them. Regression models (23.62%), correlation analysis (20.47%) or perceptions (18.11%) were commonly used in the published research to link drought and food insecurity (Fig. 8).
The figure was created using R software.
Adaptation options for drought-food insecurity nexus
The adaptation options proposed in the published research on the drought-food insecurity nexus (Supplementary Table 5) have also been assessed. Most of the research articles (n = 107) did not recommend any adaptation options to reduce drought risk and food insecurity outcomes. The rest of the articles (n = 77) proposed some adaptation measures which have been grouped into either structural (e.g., technology-based) or non-structural (individual-level, community-level, institution-level, and nature-based) adaptation measures46. The majority of the articles (87.39%) primarily focused on non-structural adaptation options, while only 12.61% addressed structural adaptations. Among the structural adaptations, the most frequently recommended strategies included the development of water storage and control infrastructure (n = 7), irrigation system development (n = 5), and agricultural water management techniques (n = 4). Within the non-structural adaptations, emphasis was placed on either individual-level adaptation (35.29%), nature-based adaptation (33.61%), and institution-level adaptation (15.13%). In contrast, community-level adaptation was rarely considered, with only 3.36% of articles mentioning strategies such as community investment in irrigation. At the individual level, common adaptation strategies included migration (n = 15), income diversification (n = 12), reduced intake of food quantity and quality (n = 12), and asset selling (n = 12). At the institutional level, frequently recommended measures included crop insurance schemes (n = 3), drought relief programs (n = 2), and employment opportunities (n = 2). As for nature-based adaptations, the most commonly suggested strategies were changes in farming practices (n = 24), water management practices (n = 8), irrigation practices (n = 7), and soil conservation techniques (n = 6).
Use of social-ecological systems (SES) approach in drought-food insecurity research
From Stage 1 of the systematic review, this paper confirms that the use of the SES approach in the drought-food insecurity nexus is still unexplored. None of the articles used the SES approach to understand the complex interactions and feedback between drought and food insecurity. Only three articles35,47,48 highlighted the importance of coupled ecological and social systems for drought-food insecurity nexus research. These studies recommended that future drought processes need to incorporate ecological (e.g., crop moisture index) and social (e.g., human role) variables to identify droughts and consequent impacts on crop production.
Hence, the current research extended the review search to Stage 2 to ascertain the use of the SES approach in drought-food insecurity nexus research worldwide (Supplementary Fig. 2). Just two articles were identified that met the search criteria (Supplementary Table 2). These articles, however, rarely investigated the drought-food insecurity nexus using a conceptual SES framework including both social and ecological components and variables with them. For example, Sanga et al.49 explored the barriers to achieving food security and climate change adaptation (including excessive rainfall, droughts, and high temperatures) using causal loop diagrams. Murungweni et al.50 investigated variables and drivers of rural livelihoods (i.e., cattle-based, crop-cattle-based, & non-farm-based livelihoods) and their vulnerability to external hazards, such as droughts using the Fuzzy Cognitive Map (FCM).
Conceptual SES framework for drought-food insecurity nexus
This section presents the conceptual SES framework linking drought and food insecurity based on the reviewed literature and authors’ discussion. In the proposed SES framework, the system components are social, ecological, and the interactions and outcomes (social-ecological) between social and ecological systems. Figure 9 shows that the ecological and social system components interact with the central panel (interactions & outcomes) and produce system outcomes (food insecurity and well-being). The framework also provides some example variables under the key system components.
The direction of arrows indicates a potential interaction (either positive or negative) between key variables. The framework was inspired by the Ostrom’s original SES framework19. The figure was created using Microsoft PowerPoint.
Weather and climate directly interact with water resources and food production (Fig. 9). However, rainfall deficit and high temperature over an extended period can initiate droughts (e.g., meteorological drought), which in turn, interact with food production (water stress) and water resources that could result in other forms of drought (e.g., hydrological drought)51 as well as human well-being (access to drinking water)52. Human interventions (e.g., water resources management) could play a significant role for drought propagation. For example, extensive groundwater abstraction during droughts could manifest hydrological cycle (water resources), and this, coupled with climate change, can lead to severe droughts53. Soil resources, another ecological key variable, interact with crop production, and are influenced by weather and climate, droughts and crop production. A possible interaction between weather and climate and soil resources is soil degradation due to surface runoff of precipitation. Inadequate soil water due to drought can also deteriorate soil quality, e.g., soil organic carbon, which is important for soil health and fertility54. Excessive use of chemical fertilizer and pesticide for crop production can also degrade soil and water quality55. Key variables in social system includes governance and policy, population, economy, and global political instability. Governance and policy and demand for food and water (population) interact with crop production and water resources management. Furthermore, global political instability, for example, trade restrictions on agricultural inputs (e.g., fertilizer, energy) could also influence crop production, food insecurity (e.g., higher food price) and overall economy56. Crop production directly interacts with food insecurity and economy; therefore, drought-induced yield loss could result in food insecurity, income loss, and other well-being (e.g., child mortality). Conversely, the prevalence of food insecurity requires more crop production, which again manifests water resources and droughts. However, the severity of food insecurity also depends on how government plans for drought management and food preservation, food demand (population), economy and global political instability57. For instance, insufficient food import due to trade restrictions could lead to higher market price that could restrict access to sufficient food.
The proposed framework also considers potential feedback loops (Fig. 10) between the social and ecological variables that govern the dynamics of the drought-food insecurity nexus. Figure 10 conceptualizes the complex interactions (i.e., feedback) between the social-ecological variables within the system components presented in Fig. 9. Both positive (R) and negative (B) feedback loops play a crucial role in the sustainability of the drought-food insecurity nexus. For example, droughts reduce water availability reducing food production and availability, increasing food insecurity and food demand, which increases food production through abstracting more water for food production, reducing water availability and increasing droughts (R4). On the contrary, droughts reduce water availability reducing food production, which also reduces income, enhancing demands for governance & policy for increasing adaptation measures, which eventually increase water availability and reduce droughts (B1). Overall, the framework represented the system components, social-ecological variables and complex interactions between the variables in the drought-food insecurity nexus. One limitation is that the spatial-temporal scales over which the system elements would operate are not considered. Future research can overcome this limitation by defining clear a system boundary (e.g., local, regional) and appropriate timescales (e.g., monthly, seasonal, annual), and integrating multiple methods, such as combining system dynamics modelling with GIS. Nevertheless, the framework would benefit in developing an operational framework for drought-food insecurity nexus considering the key variables under social, ecological, and social-ecological components. However, the key challenge would be identifying interactions between the system components and data availability across multiple levels and contexts need to be considered in operationalizing the framework. To address this limitation, researchers can employ a range of methods, including the use of established equations from existing models, participatory model-building approaches (e.g., co-design), and the integration of survey data with secondary data sources across different scales. Overall, this systematic review reveals persistent knowledge and methodological gaps that future research can address to advance the achievement of sustainable development goals (SDG 2, 3, 6, and 13).
The figure draws on example variables, based on the framework developed in Fig. 9, to highlight the interlinked social-ecological dynamics shaping the nexus. Positive sign (+) indicates changes in the same direction; Negative sign (−) indicates changes in the opposite direction; R indicates a positive feedback loop; and B indicates a negative feedback loop. The figure was created using Stella Professional software.
Discussion
This review reveals multiple knowledge and methodological gaps in drought-food insecurity nexus research. First, in general, insights into how droughts have affected socio-economic systems and feedback on drought aggravation due to poor governance have been largely overlooked. A typical example of poor governance includes the Syrian case, where persistent droughts were aggravated due to the government’s agricultural and energy subsidy policy to abstract more groundwater for food production and other usages58 that eventually led to long-term food insecurity, migration, and conflicts. In contrast, the California model exemplifies good governance, where coordinated, decentralized policies across local, state, and federal levels helped mitigate the impacts of multi-year droughts (2011–2016) on food security59. In addition, food insecurity is not only a function of yield loss, rather a cumulative effect of a multitude of factors including non-farm income, market access, food reserve, and global political issues. This signifies the inclusion of social systems (e.g., governance) in the drought-food insecurity nexus research. Thus, future endeavours need to drought-food insecurity nexus as a complex SES that captures cross-scale dynamics and complex interaction (e.g., feedback, non-linearity) between social and biophysical variables. Robust research is needed to quantify how social systems (e.g., socio-economic, governance and political factors) affect drought and food insecurity at different spatial-temporal scales. This will require improvement of both methodological tools (e.g., how to integrate and downscale/upscale data from various sources) and data availability (particularly socio-economic and governance data) at different spatial-temporal scales.
Second, most of the reviewed articles (52.17%)) did not specify the type of droughts. Although varied across different contexts, the impacts of drought on food production and insecurity depend on the extent, severity, and duration of droughts18. For instance, meteorological droughts are less likely to cause water scarcity across humid, tropical, continental, and temperate regions but are more likely to affect water system in arid or semi-arid regions where evaporative demand is high60. Therefore, methodological advancements, aiming to identify the correct stage of droughts and corresponding impacts would be necessary for tracking the assessments and outcomes of the drought-food insecurity nexus.
Third, most of the published research examined the effect of droughts on crop production (51% in Asia and 65% in Africa) as an indicator of food availability (Supplementary Fig. 6). However, other indicators pertaining to food access (e.g., income, food expenditure), utilization (e.g., dietary diversity, macro- and micro-nutrients consumption) and stability (e.g., how droughts effects on long-term stability with corresponding effects to other food security dimensions) could provide a holistic picture of food insecurity attributable to drought risk.
Fourth, recommendations across articles both in Asia and Africa emphasize quantitative assessments of the drought risks and food insecurity for evidence-based policy design. Therefore, preparing robust datasets and making it available at different spatial-temporal scales is crucial for the drought risk quantification, decision-making and management plan18. This paper reveals that unavailability or missing data at different levels (e.g., local, regional, national, or global) is a major challenge in drought-food insecurity nexus research. High quality data can also be used to develop data-driven drought monitoring and early warning systems to support management strategies and overall resilience in the long term.
Fifth, monitoring and predicting drought risk and food insecurity over time considering scenario analysis can be useful for sustainable policy implications46. Findings show that most of the published research (73.15%) has provided a snapshot of the current situation of drought risk and food insecurity. Learning of plausible future outcomes, based on past and present dynamics, are of great importance for leveraging alternative policy options well ahead for system resilience. This unveils further knowledge gap that only 13.59% of research performed a scenario analysis (Supplementary Fig. 7).
Sixth, the emerging scholarships of drought as both natural and anthropogenic event unveil the complexity of propagation and distribution of drought risks and impacts across scales. Thus, assessments of drought risk and impacts as well as mitigation strategies will require a concerted effort from stakeholders at different levels59 which is recommended across articles both in the Asian and African contexts. Future research needs to focus on identifying those actors who are the primary victims as well as catalysts of drought; institutions that are responsible for policy development and implementation; spatial-temporal scales of drought risks and impacts (e.g., local, regional, national, and global); and sectors (e.g., agriculture, ecosystems).
In conclusion, remarkable progress has been made to assess and manage drought and food insecurity at the scientific, community, and organizational levels. Despite these, the systematic review presented here identifies some persistent knowledge gaps that need to be addressed in future research. In general, although the drought–food insecurity nexus is driven by complex interactions between ecological and social systems, existing studies have largely overlooked the potential of adopting an SES approach to fully capture these dynamics. Findings further reveal that social or ecological focus was mostly considered to explore drought-food insecurity, and a shift from social and economic to environmental and economic focus was triggered after 2011. While regional scale research was dominant, informing the current snapshots of the drought-food insecurity nexus was emphasized. The findings further inform that quantitative research approaches corresponded with statistical analysis were mainly used, with limited applications of other methods such as index and crop or hydrological models. We suggest that a conceptual SES framework for drought-food insecurity nexus that would serve as a guide in defining social and ecological components and selecting appropriate indicators in different contexts. Future research could operationalize the conceptual SES framework (e.g., Roy et al.61) and examine the dynamic system behaviour (i.e., interactions and feedback). However, the need for a range of available data across different levels could be a challenge for future endeavours. Our findings may contribute to tackling global sustainability challenges, as addressing the drought-food insecurity nexus through the lens of an SES approach support the progress towards achieving the zero hunger goal (SDG 2) by 2030 and beyond. Moreover, the findings align with other interconnected SDGs related to poverty (SDG 1), health (SDG 3), clean water (SDG 6), and climate action (SDG 13).
Methods
This systematic review followed the guidelines of the Reporting Standards for Systematic Evidence Synthesis (ROSES) (Supplementary Figs. 1 and 2), which has been developed particularly for conservation and environmental management research62. The framework offers appropriate and detailed information in each stage of the systematic review (e.g., reasons for excluding documents)63. The use of ROSES framework is gaining prominence in conservation and environmental management research, such as climate change adaptation or mitigation64, climate and health65, and biodiversity loss66.
Information source and search strategies
The systematic review was performed in two stages. Stage 1 focused on the research progress made on the drought-food insecurity nexus within Asia and Africa, and Stage 2 focused on the use of the SES approach in drought-food insecurity research worldwide. Initial screening of the articles confirmed that an SES approach has not been considered in drought-food insecurity nexus research in Asia and Africa. Therefore, the study was extended to a global context (Stage 2) to comply with the research questions regarding the prospect of using an SES approach in drought-food insecurity nexus. The literature searches were conducted using the Web of Science Core Collections and Scopus database between February and March 2023, without restricting the search to any specific time period. These two databases were considered because they are the major sources of bibliometric data67,68 with wider coverage of research across disciplines69. However, the scope the review could be broadened by incorporating studies from other sources, such as Google Scholar, and this is recommended for future research. We considered only the peer-reviewed research articles to ensure transparency, reproducibility, and quality of the systematic review46. Analyzing gray literature – such as reports and publications from governments and international organizations (e.g., IPCC, FAO) – could enhance the comprehensiveness of the review. These sources may offer valuable insights, data, and policy responses relevant to drought and food security. Search terms used in this study are presented in supplementary information (Supplementary Table 1).
Eligibility criteria and documents selection
A total of 612 research articles in stage 1, and 43 research articles in stage 2 in full text were selected guided by a set of eligibility criteria (Supplementary Table 2). Peer-reviewed articles conducted in Asia and Africa and examined both droughts and at least one dimension of food insecurity (e.g., availability, access, stability, and utilization), and published in English language were considered for full text screening in Stage 1. Similar criteria were applied in Stage 2, except for the articles that represented the global context and considered an SES approach. Finally, 180 articles in Stage 1, and 2 articles in Stage 2 were included for the final review. In addition, 4 pre-screened articles from other sources (e.g., Google Scholar) were included in the review as they met the inclusion criteria. These articles were identified during the initial scoping phase of the review but were not found through the original search. Following rigorous screening, a total of 184 articles in Stage 1 and 2 articles in Stage 2 were identified for synthesis and analysis. First and second reviewers independently reviewed full texts of the potential articles for suitability and cross-checked by all four reviewers for any disagreement. Similarly, first and second reviewers independently extracted data using a standard form and cross-checked by all four reviewers to minimize measurement bias70. The ROSES flow diagram summarises the process of document selection and indicates the number of documents excluded at each phase of screening is presented in supplementary information (Supplementary Figs. 1 and 2). A list of the reviewed articles is included as supplementary information with a full bibliography.
Data extraction and analysis
Two data extraction forms (i.e., Excel spreadsheets) were prepared for Stage 1 and Stage 2. After critical appraisal – a process of examining research articles for their credibility and relevance of findings71, final articles were classified according to a comprehensive list of themes (e.g., methodological focus, social-ecological variables, food insecurity dimensions). Data were coded and analysed using R software (https://www.r-project.org/). Broadly, the coding and analysis were structured around four metadata: i) basic research information (e.g., publication year, geographical location, spatial and temporal scale, and research focus); ii) methodological focus, including research approach (e.g., quantitative, qualitative, or mixed), general methods used in drought-food insecurity research (e.g., crop model), methods linking drought with food insecurity (e.g., regression model), and data type (e.g., primary, secondary, or both); iii) type of droughts, dimensions and variables of food insecurity, and social and ecological variables; and iv) inter-relational intensity among research focus, research approach and methods, drought type, and food insecurity dimensions. Details of the methodology including data analysis are provided in supplementary information.
In this study, we also developed a conceptual framework (Fig. 9) grounded in the reviewed literature and SES approach considering the relationships between ecological and social systems that influence the drought-food insecurity nexus. First, we identified social and ecological variables related to drought and food insecurity as reported across the reviewed articles. Second, we organized the variables into thematic components (e.g., climate, water resources, economy, food security), and subsequently classified into social and ecological systems (Supplementary Table 4). Third, Ostrom’s original SES framework19 served as a guiding tool for conceptualizing social and ecological subsystems, and interactions between them. Finally, the connections between system components (e.g., interactions between water resource and crop production) were identified based on evidence from the literature and informed by discussions among the authors. Based on the conceptual framework, we also developed a causal loop diagram72 to illustrate complex interactions of social-ecological variables across system components within the drought-food insecurity nexus (Fig. 10). We began by selecting example social-ecological variables within the system components presented in Fig. 9. Next, we defined the causal relationships between these variables drawing on the reviewed literature and asssumptions. However, the development and operationalization of the causal loop diagramme in future research will require careful consideration of the variables and their relationships, taking into account the specific context of the study.
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Code availability
The code created for data analysis and visualizations is available on request.
References
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Acknowledgements
D.R. is grateful to the University of Glasgow, UK for supporting the research by providing the College of Social Sciences (CoSS) PhD Scholarship.
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D.R.: Conceptualization, Methodology, Analysis-articles reviewed, Visualization, Writing-Original draft preparation. Y.C.K.: Analysis-articles reviewed (African studies), Review-editing. S.A.G.: Conceptualization, Methodology, Writing–review-editing and co-supervision. M.S.H.: Conceptualization, Methodology, Writing–review-editing and supervision. All authors have read and approved the final manuscript.
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Roy, D., Korir, Y.C., Gillespie, S.A. et al. Social-ecological systems approach in drought-food insecurity nexus research. npj Sustain. Agric. 3, 26 (2025). https://doi.org/10.1038/s44264-025-00070-4
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DOI: https://doi.org/10.1038/s44264-025-00070-4
