Browsing by Author "Walker, Brian H."
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Working Paper Aligning Key Concepts for Global Change Policy: Robustness, Resilience, and Sustainability(2012) Anderies, John M.; Folke, Carl; Ostrom, Elinor; Walker, Brian H."Globalization, the process by which local social-ecological systems (SESs) are becoming linked in a global network, presents policy scientists and practitioners with unique and dicult challenges. Although local SESs can be extremely complex, when they become more tightly linked in the global system, complexity spirals as multi-scale and multi-level processes become more important. Here, we argue that addressing these multi-scale and multilevel challenges requires a collection of theories and models. We suggest that the conceptual domains sustainability, resilience, and robustness provide a suciently rich collection of theories and models but overlapping denitions and confusion about how these conceptual domains articulate with one another reduces their utility. Here we attempt to eliminate this confusion and illustrate how sustainability, resilience and robustness can be used in tandem to address the multi-level and multi-scale challenges associated with global change."Journal Article Building Resilient Pathways to Transformation when 'No One is in Charge': Insights from Australia's Murray-Darling Basin(2016) Abel, Nick; Wise, Russell M.; Colloff, Matthew J.; Walker, Brian H."Climate change and its interactions with complex socioeconomic dynamics dictate the need for decision makers to move from incremental adaptation toward transformation as societies try to cope with unprecedented and uncertain change. Developing pathways toward transformation is especially difficult in regions with multiple contested resource uses and rights, with diverse decision makers and rules, and where high uncertainty is generated by differences in stakeholders’ values, understanding of climate change, and ways of adapting. Such a region is the Murray-Darling Basin, Australia, from which we provide insights for developing a process to address these constraints. We present criteria for sequencing actions along adaptation pathways: feasibility of the action within the current decision context, its facilitation of other actions, its role in averting exceedance of a critical threshold, its robustness and resilience under diverse and unexpected shocks, its effect on future options, its lead time, and its effects on equity and social cohesion. These criteria could potentially enable development of multiple stakeholder-specific adaptation pathways through a regional collective action process. The actual implementation of these multiple adaptation pathways will be highly uncertain and politically difficult because of fixity of resource-use rights, unequal distribution of power, value conflicts, and the likely redistribution of benefits and costs. We propose that the approach we outline for building resilient pathways to transformation is a flexible and credible way of negotiating these challenges."Journal Article Drivers, 'Slow' Variables, 'Fast' Variables, Shocks, and Resilience(2012) Walker, Brian H.; Carpenter, Stephen; Rockström, Johan; Crépin, Anne-Sophie; Peterson, Garry D."Different uses of the terms 'drivers,' 'variables,' and 'shocks' cause confusion in the literature and in discussions on the dynamics of ecosystems and social–ecological systems. Three main sources of confusion are unclear definition of the system, unclear definition of the role of people, and confusion between variables and drivers. As a contribution to resolving some of the confusion, we offer one interpretation of how the terms might be used."Journal Article Fifteen Weddings and a Funeral: Case Studies and Resilience- based Management(2006) Anderies, John M.; Walker, Brian H.; Kinzig, Ann P."'Resilience theory' is a systematic methodology for understanding the dynamics of coupled social-ecological systems (SESs). Its ongoing development requires that resilience theory be confronted with case studies to assess its capacity to help understand and develop policy for SESs. This paper synthesizes the findings from several papers in the special feature 'Exploring Resilience in Social-Ecological Systems' that do just this. It then highlights key challenges facing resilience as a theory for understanding SESs and provides some avenues for future research."Journal Article Handful of Heuristics and Some Propositions for Understanding Resilience in Social-Ecological Systems(2006) Walker, Brian H.; Gunderson, Lance; Kinzig, Ann P.; Folke, Carl; Carpenter, Stephen; Schultz, Lisen"This paper is a work-in-progress account of ideas and propositions about resilience in socialecological systems. It articulates our understanding of how these complex systems change and what determines their ability to absorb disturbances in either their ecological or their social domains. We call them 'propositions' because, although they are useful in helping us understand and compare different social-ecological systems, they are not sufficiently well defined to be considered formal hypotheses. These propositions were developed in two workshops, in 2003 and 2004, in which participants compared the dynamics of 15 case studies in a wide range of regions around the world. The propositions raise many questions, and we present a list of some that could help define the next phase of resilience-related research."Journal Article Impacts of Grazing on Semiarid Rangelands(2002) Walker, Brian H."Gary Jones criticizes the model of rangeland dynamics on the grounds that it assumes a negative impact of livestock on grasses and does not assume that livestock damages woody plants. He cites the writings of Voisin (unreferenced) and others as evidence that grazing stimulates grass growth. Experimental evidence on the stimulation of grasses by grazing is not common, although we acknowledge that it exists. Some of the best hard evidence for compensatory growth by grasses following defoliation comes from the work of McNaughton and colleagues in the Serengeti. Although some work was reported on the effects of herbivore saliva as a stimulant for grass growth, research on this effect has not been replicated and has largely fallen by the wayside."Journal Article Navigating Trade-Offs: Working for Conservation and Development Outcomes(2010) Campbell, Bruce; Sayer, Jeffrey A.; Walker, Brian H."In this introductory essay, we synthesize some lessons from integrated conservation-development initiatives in developing countries, drawing particularly on the case study material in this special issue. There is an emerging consensus that at the heart of achieving positive outcomes are a core of institutional issues involving landscape governance, trust building, empowerment, and good communication, all implying long-term commitment by, and flexibility of, external actors. Fundamental to success is the recognition of the significant trade- offs that occur between conservation and development goals."Journal Article An Overview of the Implications of Global Change for Natural and Managed Terrestrial Ecosystems(1997) Walker, Brian H.; Steffen, Will"Global change is the net effect of individual and interactive effects of changes in land use, atmospheric composition, biological diversity, and climate. A synthesis of the past six years' activities of the Global Change and Terrestrial Ecosystems project of the IGBP (International Geosphere-Biosphere Programme) deals with global change effects as ecosystem responses and living with global change. Ecosystem responses are considered in terms of changes in function and vegetation composition/structure. Field experiments of elevated CO2 effects on aboveground biomass show, on average, a positive effect on biomass, ranging from -20% to +80%. Some early predictions of CO2 effects (C3 vs. C4 plants, N-fixers, C:N in litter) are not generally supported, and it is necessary to consider the interactive effects of changes in CO2, temperature, and nitrogen. Dynamic global vegetation models involving transient changes show that biomes will not shift as intact entities. Significant changes in vegetation, especially in high latitudes, are likely over the next century, and changes in disturbance regimes will be most important. Based on forecast changes in land use, vegetation structure, and ecosystem physiology, the terrestrial biosphere will probably become a source rather than a sink for carbon over the next century. "Because of land use change, the terrestrial biosphere of the 21st century will probably be further impoverished in species richness and substantially reorganized. More natural ecosystems will be in an early successional state or converted to production systems. The biosphere will be generally weedier and structurally simpler, with fewer areas in an ecologically complex old-growth state. "Temperate crop production will probably increase slightly because of CO2 increases (5-7% for wheat for average field conditions), but crop production in the tropics may decline in some areas. Land use change will have the greatest effect on pastures and rangelands; due to a required >2% annual increase in crop production to meet the expanding human population, there will be increased incursion of cropland into rangelands."Journal Article Perspectives on Resilience to Disasters across Sectors and Cultures(2011) Walker, Brian H.; Westley, Frances"We present some insights on the use and interpretation of resilience ideas that arose in a conference on 'Societys Resilience in Withstanding Disaster.' Three points in particular have relevance for those interested in resilience in social-ecological systems: (1) Time as a threshold vs. avoiding quick fixes; (2) Trading risks: specified vs. general resilience; (3) Response origination: building local general resilience, and general resilience in central agencies. In the latter the need is to allow improvisation, and failure, during times of crisis."Journal Article Planetary Boundaries: Exploring the Safe Operating Space for Humanity(2009) Rockström, Johan; Steffen, Will; Noone, Kevin; Persson, Åsa; Chapin, F. Stuart; Lambin, Eric; Lenton, Timothy M.; Scheffer, Marten; Folke, Carl; Schellnhuber, Hans Joachim; Nykvist, Björn; de Wit, Cynthia A.; Hughes, Terry; van der Leeuw, Sander; Rodhe, Henning; Sörlin, Sverker; Snyder, Peter K.; Costanza, Robert; Svedin, Uno; Falkenmark, Malin; Karlberg, Louise; Corell, Robert W.; Fabry, Victoria J.; Hansen, James; Walker, Brian H.; Liverman, Diana; Richardson, Katherine; Crutzen, Paul; Foley, Jonathan"Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely. Transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental- to planetary-scale systems. We have identified nine planetary boundaries and, drawing upon current scientific understanding, we propose quantifications for seven of them. These seven are climate change (CO2 concentration in the atmosphere <350 ppm and/or a maximum change of +1 W m-2 in radiative forcing); ocean acidification (mean surface seawater saturation state with respect to aragonite ³ 80% of pre-industrial levels); stratospheric ozone (<5% reduction in O3 concentration from pre-industrial level of 290 Dobson Units); biogeochemical nitrogen (N) cycle (limit industrial and agricultural fixation of N2 to 35 Tg N yr-1) and phosphorus (P) cycle (annual P inflow to oceans not to exceed 10 times the natural background weathering of P); global freshwater use (<4000 km3 yr-1 of consumptive use of runoff resources); land system change (<15% of the ice-free land surface under cropland); and the rate at which biological diversity is lost (annual rate of <10 extinctions per million species). The two additional planetary boundaries for which we have not yet been able to determine a boundary level are chemical pollution and atmospheric aerosol loading. We estimate that humanity has already transgressed three planetary boundaries: for climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. Planetary boundaries are interdependent, because transgressing one may both shift the position of other boundaries or cause them to be transgressed. The social impacts of transgressing boundaries will be a function of the social–ecological resilience of the affected societies. Our proposed boundaries are rough, first estimates only, surrounded by large uncertainties and knowledge gaps. Filling these gaps will require major advancements in Earth System and resilience science. The proposed concept of 'planetary boundaries' lays the groundwork for shifting our approach to governance and management, away from the essentially sectoral analyses of limits to growth aimed at minimizing negative externalities, toward the estimation of the safe space for human development. Planetary boundaries define, as it were, the boundaries of the 'planetary playing field' for humanity if we want to be sure of avoiding major human-induced environmental change on a global scale."Journal Article Resilience and Regime Shifts: Assessing Cascading Effect(2006) Kinzig, Ann P.; Ryan, Paul; Etienne, Michel; Allison, Helen; Elmqvist, Thomas; Walker, Brian H."Most accounts of thresholds between alternate regimes involve a single, dominant shift defined by one, often slowly changing variable in an ecosystem. This paper expands the focus to include similar dynamics in social and economic systems, in which multiple variables may act together in ways that produce interacting regime shifts in social-ecological systems. We use four different regions in the world, each of which contains multiple thresholds, to develop a proposed 'general model' of threshold interactions in social-ecological systems. The model identifies patch-scale ecological thresholds, farm- or landscape-scale economic thresholds, and regional-scale sociocultural thresholds. 'Cascading thresholds,' i.e., the tendency of the crossing of one threshold to induce the crossing of other thresholds, often lead to very resilient, although often less desirable, alternative states."Journal Article Resilience Management in Social-Ecological Systems: A Working Hypothesis for a Participatory Approach(2002) Walker, Brian H.; Carpenter, Stephen; Anderies, John M.; Abel, Nick; Cumming, Graeme S.; Janssen, Marco A.; Lebel, Louis; Norberg, Jon; Peterson, Garry D.; Pritchard, Rusty"Approaches to natural resource management are often based on a presumed ability to predict probabilistic responses to management and external drivers such as climate. They also tend to assume that the manager is outside the system being managed. However, where the objectives include long-term sustainability, linked social-ecological systems (SESs) behave as complex adaptive systems, with the managers as integral components of the system. Moreover, uncertainties are large and it may be difficult to reduce them as fast as the system changes. Sustainability involves maintaining the functionality of a system when it is perturbed, or maintaining the elements needed to renew or reorganize if a large perturbation radically alters structure and function. The ability to do this is termed 'resilience.' This paper presents an evolving approach to analyzing resilience in SESs, as a basis for managing resilience. We propose a framework with four steps, involving close involvement of SES stakeholders. It begins with a stakeholder-led development of a conceptual model of the system, including its historical profile (how it got to be what it is) and preliminary assessments of the drivers of the supply of key ecosystem goods and services. Step 2 deals with identifying the range of unpredictable and uncontrollable drivers, stakeholder visions for the future, and contrasting possible future policies, weaving these three factors into a limited set of future scenarios. Step 3 uses the outputs from steps 1 and 2 to explore the SES for resilience in an iterative way. It generally includes the development of simple models of the system's dynamics for exploring attributes that affect resilience. Step 4 is a stakeholder evaluation of the process and outcomes in terms of policy and management implications. This approach to resilience analysis is illustrated using two stylized examples."Journal Article Resilience Thinking: Integrating Resilience, Adaptability and Transformability(2010) Folke, Carl; Carpenter, Stephen; Walker, Brian H.; Scheffer, Marten; Chapin, Terry; Rockström, Johan"Resilience thinking addresses the dynamics and development of complex social–ecological systems (SES). Three aspects are central: resilience, adaptability and transformability. These aspects interrelate across multiple scales. Resilience in this context is the capacity of a SES to continually change and adapt yet remain within critical thresholds. Adaptability is part of resilience. It represents the capacity to adjust responses to changing external drivers and internal processes and thereby allow for development along the current trajectory (stability domain). Transformability is the capacity to cross thresholds into new development trajectories. Transformational change at smaller scales enables resilience at larger scales. The capacity to transform at smaller scales draws on resilience from multiple scales, making use of crises as windows of opportunity for novelty and innovation, and recombining sources of experience and knowledge to navigate social–ecological transitions. Society must seriously consider ways to foster resilience of smaller more manageable SESs that contribute to Earth System resilience and to explore options for deliberate transformation of SESs that threaten Earth System resilience."Journal Article Resilience, Adaptability and Transformability in Social-Ecological Systems(2004) Walker, Brian H.; Holling, C.S.; Carpenter, Stephen; Kinzig, Ann P."The concept of resilience has evolved considerably since Holling's (1973) seminal paper. Different interpretations of what is meant by resilience, however, cause confusion. Resilience of a system needs to be considered in terms of the attributes that govern the system's dynamics. Three related attributes of social-ecological systems (SESs) determine their future trajectories: resilience, adaptability, and transformability. Resilience(the capacity of a system to absorb disturbance and reorganize while undergoing change so as to still retain essentially the same function, structure, identity, and feedbacks) has four components-latitude, resistance, precariousness, and panarchy-most readily portrayed using the metaphor of a stability landscape. Adaptability is the capacity of actors in the system to influence resilience (in a SES, essentially to manage it). There are four general ways in which this can be done, corresponding to the four aspects of resilience. Transformability is the capacity to create a fundamentally new system when ecological, economic, or social structures make the existing system untenable. "The implications of this interpretation of SES dynamics for sustainability science include changing the focus from seeking optimal states and the determinants of maximum sustainable yield (the MSY paradigm), to resilience analysis, adaptive resource management, and adaptive governance."Journal Article Resilience, Adaptability, and Transformability in the Goulburn-Broken Catchment, Australia(2009) Walker, Brian H.; Abel, Nick; Anderies, John M.; Ryan, Paul"We present a resilience-based approach for assessing sustainability in a sub-catchment of the Murray-Darling Basin in southeast Australia. We define the regional system and identify the main issues, drivers, and potential shocks, then assess both specified and general resilience. The current state of the system is a consequence of changes in resource use. We identify ten known or possible biophysical, economic, and social thresholds operating at different scales, with possible knock-on effects between them. Crossing those thresholds may result in irreversible changes in goods and services generated by the region. Changes in resilience, in general, reflect a pattern of past losses with some signs of recent improvements. Interventions in the system for managing resilience are constrained by current governance, and attention needs to be paid to the roles and capacities of the various institutions. An overview of the current state of the system and likely future trends suggests that transformational change in the region be seriously considered."Journal Article Sustainability, Stability, and Resilience(1997) Ludwig, Donald; Walker, Brian H.; Holling, C.S."The purpose of this essay is to define and refine the concepts of stability and resilience and to demonstrate their value in understanding the behavior of exploited systems. Some ecological systems display several possible stable states. They may also show a hysteresis effect in which, even after a long time, the state of the system may be partly determined by its history. The concept of resilience depends upon our objectives, the types of disturbances that we anticipate, control measures that are available, and the time scale of interest."Journal Article Thresholds in Ecological and Social-Ecological Systems: A Developing Database(2004) Walker, Brian H.; Meyers, Jacqueline A."Increasing interest in regime shifts in ecological and linked social-ecological systems (SESs) has placed a strong focus on the thresholds of change. However, research into this topic has been hampered by a lack of empirical data. This paper describes a developing database established to address this need. The database is freely available and comprises a set of summarized published examples and a searchable bibliographic database of publications on the topic. Thresholds in the database are characterized in terms of a standardized set of 24 descriptors, including the variables along which they occur, the variables that change, and the factors that have driven the change. Readers are encouraged to contribute new examples. Examples range from conceptual models to empirical evidence. The former predominate in the literature and, although they make valuable contributions and will continue to be included, the intention is build up the number of examples based on data. Examples are presented in terms of whether the threshold occurs in the ecological system, the social system, or both, and the direction of interactions between systems. The paper concludes with some initial observations on thresholds based on the examples included so far, and poses some questions for future research. Research on a typology of thresholds is a priority topic in the emerging area of "sustainability science" and it requires a rich database of empirical data."