What is the evidence that scarcity and shocks in freshwater resources can cause conflict instead of promoting collaboration in arid to subhumid hydroclimates? (systematic map)


Anthropogenic activities such as the combustion of fossil fuels, land-use change and intensive agriculture are increasingly influencing the Earth‘s climate and exerting pressure on ecosystems. These changes have amplified the risk of scarcity and shocks (discrete and sudden events) in natural renewable resource (henceforth, NRR) scarcity across the spectrum of spatial scales. The interplay between freshwater scarcity and conflict/collaboration is the most prominent and referenced of the environment-conflict issues in the Third and Fourth Assessment Reports of the IPCC. Discussions with the review user-group, confirmed that a systematic mapping of the literature in this particular field was a priority.


To identify and systematically map all published and unpublished research to address the following primary question, ‗What is the evidence that scarcity and shocks in freshwater resources cause conflict instead of promoting collaboration?‘

The secondary objectives are to: Provide an overview of research activity in the area for different users of research such as practitioners, academics, policymakers, students and the public; Inform decisions on what future research might usefully address by identifying gaps in the literature; Improve access to knowledge by supporting identification of high quality study design; Provide a resource for future systematic reviews in the field.


A search strategy was employed to identify both academic and grey literature using general purpose electronic databases (e.g. Web of Knowledge), web searches, hand searching of key academic journals and consultation with content experts. Our survey of previous reviews was used to test the efficacy of the search strategy. To be considered for inclusion in this study, a primary study had to match key concepts in the review question.

Relevant subject(s): human populations in arid, semiarid and dry subhumid hydroclimates. nations outside these climatic zones will be excluded. Global studies were also included. Types of exposure: Any study where a measure of sudden (shocks) or long-term scarcity of freshwater resources is used as the explanatory variable. Studies that only consider freshwater quality were excluded. Both physical and social scarcity of freshwater resources were considered. Types of outcome: Studies where a measure of human conflict or collaboration as the dependent variable at the micro level (within communities), micro-micro level (between communities), micro-macro (between communities and private/state institutions), and macro-macro (between states). Types of study: To be included, a study had to be empirical and quantitative in nature, such as an observational, quantitative study analysing freshwater scarcity as an independent variable. Language: Studies should be published in English. Date: Studies should be published after 1990. All reports that meet the inclusion criteria that were available were then coded using EPPI Reviewer 4. The coding was based on generic, methodological and review specific keywords. Studies were ranked using an assessment framework developed from discussions with experts in the field, and based on their suggestions of the ideal study design for addressing the research question.

Main results

From a set of 589 studies identified after the first round of screening, we identified just 47 relevant studies. Of the 47 studies, 19 explored interstate interactions. Just one examined interstate conflict in relation to freshwater scarcity, while the remaining 18 were specifically related to transboundary river basins. At the intrastate level, 15 studies examined the relationship at the national level, while the remaining 13 explored interactions at the sub-national level. The systematic map suggests research into the impact of freshwater scarcity and conflict/ collaboration is growing. This is true at all spatial scales examined, apart from state-state interactions that were not specifically related to transboundary river basins. However, there is little consensus on the impact of scarcity on social interactions at multiple spatial scales and this is true across the three scales examined (interstate, national-level, micro-level). This is because the research in this field is still at the formative stage, and is limited by data availability.

There is significant heterogeneity between studies. We find that divergent definitions of conflict/collaboration, scarcity, theoretical frameworks and additional explanatory variables are key reasons for variations between study outcomes. As such, we do not attempt to draw any conclusions regarding the direction of the relationship. The systematic map identifies seven theoretical frameworks that define the literature. The neo-liberal, neo-Malthusian and common property management theoretical frameworks are most commonly used. But, it is only the neo-Malthusian theoretical framework has been adopted across all spatial scales. Neo-liberal and common property management are used at the interstate (transboundary river basins) and intracommunity levels respectively. Despite the popularity of the neo-Malthusian theoretical framework, the causal pathway posited by this theory not widely supported by the literature identified in this review.

At the intrastate level, no study considered the impact of scarcity on collaborative interactions. At the transboundary and micro-levels, however, the distribution between collaborative and conflictive interactions was much more balanced. However, studies at all spatial scales considered rarely examined multiple outcomes in the same analyses. Instead, binary variables such as treaty/no treaty or conflict/ no conflict are most commonly employed. It is only at the micro-level (i.e. intercommunity, intracommunity interactions) that multiple dimensions of the collaboration-conflict spectrum are explored. Here, multiple indicators of collaboration are observed and analysed such as sharing, participation in local institutions or compliance with local institutional rules.


Implications for policy

There are a number of reasons why, despite the increase in studies in recent years, there is, as yet, no clear sign of consensus on the expected societal responses to freshwater scarcity. The heterogeneity of study design is one key reason. This review has shown that studies vary significantly in research question, theoretical frameworks employed, definitions of conflict or collaboration and scarcity, and spatial scale. Furthermore, freshwater scarcity is rarely considered to be the sole driver of conflictive or collaborative interactions between two or more parties. Instead it is regarded as one of many factors that influence social dynamics. While the quantitative research included in this review may appear to be at odds with the dire predictions cited in early empirical case studies, we caution such conclusions from being drawn from the evidence presented here; particularly when policy makers and researchers seek to identify the implications of this review. The small number studies identified and theheterogeneity between them means we are not in a position to confirm or refute this position. Furthermore, few studies identified were considered weighted as ‗very high‘ (n=7) or ‗high‘ (n=6) in our assessment of methodological approach and reporting. Observed and predicted trends in global environmental change, and particularly climate change, means there is an urgent need to develop understanding of the multiple conditions of possibility under which conflict and cooperation emerge when societies are exposed to environmental stress. The huge economic and social costs of violent conflict, means a systematic and coordinated research programme in this field would be worth the investment.

Implications for research

Understanding how and why conflict or collaboration emerge under conditions of scarcity are a critical research questions. However, this review suggests that the field is still formative. This review has identified a number of gaps in the literature and future research priorities. These include: A coordinated research strategy of both small-N and large-N studies Theory building: the development of new or refined theories. Monitoring and datasets, dependent variables: The continuum from harmony to conflict is multidimensional, and therefore requires a broader monitoring and systematic reporting of different forms of social interactions Monitoring and datasets, independent variables: More widespread, comprehensive and geo-referenced data for control and interactive terms may make a significant contribution to the robustness of future studies. Consideration of groundwater aquifers: one study reported a growth in claims over groundwater aquifers; however, we did not identify any study that specifically addressed groundwater aquifers and conflict or collaboration. This highlights a significant gap in the research Continued research into the differentiation between progressive and acute scarcity. Additional exploratory variables: There is a need for more research into additional social, economic, political, geographical and historical explanatory variables. Continued focus on methodologies that use spatially disaggregated and geo-referenced data: The state-centric approach has the potential to overestimate the risk of conflict. An increase in micro-level research: research at this level offers the opportunity to examine the importance of the cultural and historical context. Geographical diversity: The review has demonstrated there is a strong geographical bias in the literature. The majority of studies identified at the national level or below were conducted in African states, and in particular SSA Interdisciplinary approaches: Future research could benefit from working closely with researchers from other disciplines. Future systematic reviews: Systematic reviews are evolving processes. As such we welcome continuation of this work that draw on non-English language studies. Building on this review, further mapping of studies that explore other NRRs is recommended.


Anthropogenic activities such as the combustion of fossil fuels, land-use change and intensive agriculture are increasingly influencing the Earth‟s climate and exerting pressure on ecosystems (Rockström et al., 2009; Solomon et al., 2007). These changes have amplified the risk of scarcity and shocks (discrete and sudden events) in natural renewable resource (henceforth, NRR) scarcity across the spectrum of spatial scales (MEA, 2005; Parry et al., 2007).

The relationship between shocks and longer-term scarcity in NRR and the direct or indirect impacts of climate change and human conflict or collaboration (see section 3.2 for working definitions) has become the subject of increasing scrutiny by researchers, policy makers and opinion formers. This is due to the often high human, social and economic costs of conflict (Wolf, 2007). The capacity to monitor, predict, pre-empt or resolve conflicts is, therefore, central to promoting human and environmental security. This has generated a renewed interest in the environmental conflict literature (Floyd, 2008).

1.1 The environmental-conflict literature

The literature examining the interplay between direct or indirect impacts of climate change and/or NRR scarcity and shocks and human conflict/ collaboration is substantial and growing (Mason et al., 2008; UNEP, 2004). Primary studies are spread across the academic and grey literature (Mason et al, 2008). These studies are diverse and vary in terms of theoretical arguments, scale, study design (e.g. case studies, case control studies, multivariate statistical analyses, econometric modelling), definition and goal (Dabelko et al, 2000; Mason et al, 2008; Bernauer et al., 2010).

A number of scholars have argued that perspectives contending climate change and/or shocks and scarcity in NRR lead to conditions where violent/armed conflict may arise, dominate political circles and the media (Bernauer et al., 2010; Barnett, 2009; Hartmann, 1998; 2010; Leach and Mears, 1996; McDonald, 1999; Nordås and Gleditsch, 2009). Despite this apparent dominant view, reviews of the literature consistently argue there is little consensus on the direct correlation between climate change, scarcity or shocks in natural renewable resources and conflict (Bernauer et al., 2010; Wolf, 2007).

The lack of consensus is primarily due to complex interactions between different variables that may lead to the outbreak conflict or the emergence of collaboration. For example, Bohorquez et al., (2009: 911) argue that, „Possible political, ideological, cultural, historical and geographical influences make conflict arguably one of the ‘messiest’ of all human activities to analyse.‟ Furthermore, there may be no clear relationship because of theoretical (viz. understanding of causal pathways) and methodological limitations (e.g. diverse indicators of climate change and natural resource scarcity, data quality and coverage, different sample sizes, time periods and challenges of attribution) (Bernauer et al., 2010).

Furthermore, the quality of the literature is varied. For example, Nordås and Gleditsch (2009: 23) note that much of the climate-conflict literature ‘tends to move from sophisticated climate models to flimsy evidence and (at best) case studies of unknown representativity’.

The environment-conflict nexus is a longstanding, diverse and wide-ranging body of work. For example, one body of thought identifies the modern way of life as endangering the stability and functioning of the world’s ecosystems (Pirages et al, 2004). Another strand is concerned with how humans, especially the poor, are rendered insecure by environmental change (Dalby, 2002; Barnett, 2001; Matthew, 1999). Much of the environment-conflict thesis, in turn, is concerned with the threat posed by environmental-conflict to national or state security (Homer-Dixon, 2001; 1999; 1994). A large part of the emerging „climate security‟ literature focuses on the impacts of climate change onNRR, in particular scarcity, and the subsequent influence on conflict.

The environment-conflict literature has been shaped by two contrasting arguments, referred to as the ‘greed versus grievance’ debate (Berdal and Malone, 2000). First, ‘grievance’ arguments suggest that environmental degradation and scarcity in renewable resources leads to conflict (Homer-Dixon, 1999). Second, ‘greed’ arguments suggest that localized abundance of non-renewable natural resources and competition to gain control over these resources leads to conflict (de Soysa, 2002). Transgressing the ‘greed versus grievance’ debate, a third body of literature has emerged to argue that resource scarcity does not necessarily lead to violent conflict, but can instead lead to collaboration. This argument has emerged from three key areas of scholarship; examination of the emergence of multi-lateral riparian agreements (e.g. Yoffee et al., 2003; Wolf et al., 2007), transboundary management practices such as „Peace Parks‟ (e.g Ali, 2007) and community-based natural resource management (CBNRM) (e.g. Buckles, 1999; Walker et al., 2002). This review is primarily interested in the first and third bodies of literature.

1.2 Evolution of the literature – NRR scarcity and conflict

Research on resource scarcity and conflict has evolved in several stages. In the 1990s, the argument that scarcity of natural renewable resources can contribute to violent conflicts emerged (Floyd 2010). Theoretical arguments were made and supported with empirical case studies that the interaction of environmental pressures and social effects (e.g. reduced agricultural production, economic decline, population displacement, disruption of social relations) can lead to disputes within countries, to civil strife, and ultimately to violent conflict (Homer-Dixon, 1991; 1998; 1999). To support theoretical work, Homer-Dixon carried out a range of empirical studies, including case studies in Mexico, the Philippines and South Africa (Homer-Dixon, 1999; 1994). At the same time, researchers at the Environment and Conflicts Project in Switzerland arrived at similar conclusions on the basis of a different set of empirical case studies (Baechler and Spillman, 1996).

Critics, however, highlight the difficulties of identifying a causal link between environmental change / resource scarcity and violence using the methods employed by Homer-Dixon (1991; 1994; 1999) and Baechler and Spillman (1996). It is argued that the case studies involved long causal changes with many intervening social variables. It is, therefore, difficult to establish a direct link between environmental change/ resource scarcity and conflict as no allowance was made for variation in either independent or dependent variables. Concerns have also been raised about case- selection bias. At this time, most research failed to take into consideration other conflict generating factors such as existing ethnic tensions, socio-economic inequalities, state instability and geography.

Some of the more recent academic studies that seek to remedy these shortfalls have included further empirical analysis supporting the environment-conflict nexus using a wide range of methods. These include, empirical case studies (Klare, 2001), large quantitative studies (Hauge and Ellingsen, 1998) and an ‘intensive qualitative approach that explicitly analyzes the conditions under which each distinctive type of causal pattern occurs rather than attempting to address the frequency to which each outcome or causal pattern occurs.‟ (Kahl, 2006: 60, emphasis in original).

Nevertheless, the environment-conflict thesis continues to be the focus of extensive criticism on methodological, theoretical and policy grounds (Barnett, 2003; Dalby 2002; Peluso et al., 2001; Hartmann, 1998). Especially in the context of climate conflict, some researchers have subjected the resource scarcity – conflict nexus to rigorous analytical scrutiny (Hendrix and Glaser, 2007; Meier et al., 2007). Based on quantitative analysis, these studies suggest that links between climate change, natural renewable resource scarcity and conflict are few and weak (Salehyan, 2008).

1.3 NRR scarcity and collaboration

A growing body of literature focuses of the potential of resource scarcity for engendering collaboration rather than conflict. For example, there is a large body of evidence that implies water management has played a role in forestalling violence and promoting collaboration in regions around the world (Wolf et al., 2005; Wolf, 2007).

Alongside the literature on water management there is an emerging literature on so- called „Peace Parks‟ (Ali et al, 2007). Peace parks can be broadly defined as: „conservation areas that cross one or more international borders, and they are intended to have common management practices, often to conserve a single transnational ecosystem‟ (Duffy, 2007). Here, empirical case studies suggest that in areas with high levels of environmental stress, joint resource and conservation management plans can forestall and even end environmental conflict. While this body of research focuses primarily on the interstate level, a second body of research examines the potential of CBNRM to forestall conflict at the intrastate level.

While there is no single definition of CBNRM, these programmes seek to, ‘encourage better resource management outcomes with the full participation of communities and resource users in decision-making activities, and the incorporation of local institutions, customary practices, and knowledge systems in management, regulatory and enforcement processes‟ (Armitage, 2005). However, different advocates imagine CBNRM differently. As such, there is no consensus on the design, definition or goal of CBNRM (ibid.). Case studies are increasingly well documented and involve natural renewable resources, such as, forests, water resources, wildlife, fisheries, coastal areas, and protected areas.

1.4. Previous reviews

Reviews examining the linkages between NRR shocks/scarcity and climate change and conflict/ cooperation are emerging (Buhaug et al., 2008; Carius, 2006; Dabelko et al, 2000; Gleditsch, 1998; Parry et al. 2007; Khagram and Ali, 2006; Mason et al, 2008; Nordås and Gleditsch, 2007; Salehyan, 2008). These reviews are limited, however, as they are not systematic.

Whether or not, or under what circumstances the direct or indirect impact of climate change on natural renewable resources or scarcity and shocks in natural renewable resources lead to conflict or collaboration, a systematic review in this field is both important for scientific reasons and has significant policy implications.

Due to the volume of the literature, the limited time frame for this review, and the challenges of directly attributing discrete events and long-term changes to NRR to climate change (Stott et al., 2010) this review will focus specifically on shocks and scarcity in freshwater resources.

The interplay between freshwater scarcity and conflict/collaboration is the most prominent and referenced environment-conflict issues in the Third and Fourth Assessment Reports of the IPCC (Nordås and Gleditsch, 2009). For example, climate change is likely to affect the volume and timing of river flows and groundwater recharge (Arnell, 2004). Discussions with the review user-group, confirmed that a systematic mapping of the literature in this particular field was a priority.