IPCC_Managing Risks of Extreme Events.pdf - Climate Access

Chapter 2Determinants of Risk: Exposure and Vulnerability2.1. Introduction and ScopeMany climate change adaptation efforts aim to address the implicationsof potential changes in the frequency, intensity, and duration of weatherand climate events that affect the risk of extreme impacts on humansociety. That risk is determined not only by the climate and weatherevents (the hazards) but also by the exposure and vulnerability to thesehazards. Therefore, effective adaptation and disaster risk managementstrategies and practices also depend on a rigorous understanding of thedimensions of exposure and vulnerability, as well as a proper assessmentof changes in those dimensions. This chapter aims to provide thatunderstanding and assessment, by further detailing the determinants ofrisk as presented in Chapter 1.The first sections of this chapter elucidate the concepts that are neededto define and understand risk, and show that risk originates from acombination of social processes and their interaction with the environment(Sections 2.2 and 2.3), and highlight the role of coping and adaptivecapacities (Section 2.4). The following section (2.5) describes the differentdimensions of vulnerability and exposure as well as trends therein.Given that exposure and vulnerability are highly context-specific, thissection is by definition limited to a general overview (a more quantitativeperspective on trends is provided in Chapter 4). A methodologicaldiscussion (Section 2.6) of approaches to identify and assess risk providesindications of how the dimensions of exposure and vulnerability can beexplored in specific contexts, such as adaptation planning, and thecentral role of risk perception and risk communication. The chapterconcludes with a cross-cutting discussion of risk accumulation and thenature of disasters (Section 2.7).2.2. Defining Determinants of Risk:Hazard, Exposure, and Vulnerability2.2.1. Disaster Risk and DisasterDisaster risk signifies the possibility of adverse effects in the future. Itderives from the interaction of social and environmental processes, fromthe combination of physical hazards and the vulnerabilities of exposedelements (see Chapter 1). The hazard event is not the sole driver of risk,and there is high confidence that the levels of adverse effects are ingood part determined by the vulnerability and exposure of societies andsocial-ecological systems (UNDRO, 1980; Cuny, 1984; Cardona, 1986,1993, 2011; Davis and Wall, 1992; UNISDR, 2004, 2009b; Birkmann,2006a,b; van Aalst 2006a).Disaster risk is not fixed but is a continuum in constant evolution. Adisaster is one of its many ‘moments’ (ICSU-LAC, 2010a,b), signifyingunmanaged risks that often serve to highlight skewed developmentproblems (Westgate and O’Keefe, 1976; Wijkman and Timberlake, 1984).Disasters may also be seen as the materialization of risk and signify ‘abecoming real’ of this latent condition that is in itself a social construction(see below; Renn, 1992; Adam and Van Loon, 2000; Beck, 2000, 2008).Disaster risk is associated with differing levels and types of adverseeffects. The effects may assume catastrophic levels or levels commensuratewith small disasters. Some have limited financial costs but very highhuman costs in terms of loss of life and numbers of people affected;others have very high financial costs but relatively limited human costs.Furthermore, there is high confidence that the cumulative effects ofsmall disasters can affect capacities of communities, societies, or socialecologicalsystems to deal with future disasters at sub-national or locallevels (Alexander, 1993, 2000; Quarantelli, 1998; Birkmann, 2006b;Marulanda et al., 2008b, 2010, 2011; UNISDR, 2009a).2.2.2. The Factors of RiskAs detailed in Section 1.1, hazard refers to the possible, future occurrenceof natural or human-induced physical events that may have adverseeffects on vulnerable and exposed elements (White, 1973; UNDRO,1980; Cardona, 1990; UNDHA, 1992; Birkmann, 2006b). Although, attimes, hazard has been ascribed the same meaning as risk, currently itis widely accepted that it is a component of risk and not risk itself.The intensity or recurrence of hazard events can be partly determinedby environmental degradation and human intervention in naturalecosystems. Landslides or flooding regimes associated with humaninducedenvironmental alteration and new climate change-relatedhazards are examples of such socio-natural hazards (Lavell, 1996,1999a).Exposure refers to the inventory of elements in an area in which hazardevents may occur (Cardona, 1990; UNISDR, 2004, 2009b). Hence, ifpopulation and economic resources were not located in (exposed to)potentially dangerous settings, no problem of disaster risk would exist.While the literature and common usage often mistakenly conflateexposure and vulnerability, they are distinct. Exposure is a necessary,but not sufficient, determinant of risk. It is possible to be exposedbut not vulnerable (for example by living in a floodplain but havingsufficient means to modify building structure and behavior to mitigatepotential loss). However, to be vulnerable to an extreme event, it isnecessary to also be exposed.Land use and territorial planning are key factors in risk reduction. Theenvironment offers resources for human development at the sametime as it represents exposure to intrinsic and fluctuating hazardousconditions. Population dynamics, diverse demands for location, andthe gradual decrease in the availability of safer lands mean it isalmost inevitable that humans and human endeavor will be located inpotentially dangerous places (Lavell, 2003). Where exposure to events isimpossible to avoid, land use planning and location decisions can beaccompanied by other structural or non-structural methods for preventingor mitigating risk (UNISDR, 2009a; ICSU-LAC, 2010a,b).Vulnerability refers to the propensity of exposed elements such ashuman beings, their livelihoods, and assets to suffer adverse effectswhen impacted by hazard events (UNDRO, 1980; Cardona, 1986, 1990,69