IPCC_Managing Risks of Extreme Events.pdf - Climate Access

Chapter 6National Systems for Managing the Risks from Climate Extremes and Disasterswhen the lifespan of a decision, policy, or measure has implications formultiple decades or the decision is irreversible and sensitive to climate,the performance of adaptation and risk reduction options across arange of climate change scenarios becomes critical (Auld, 2008b;Kwadijk et al., 2010; Wilby and Dessai, 2010).Vulnerability thresholds-based approaches start at the level of thedecisionmaker, identify desired system objectives and constraints,consider how resilient or robust a system or sector is to changes in climate,assess adaptive capacity and critical ‘tipping points’ or threshold points,then identify the viable adaptation strategies that would be required toimprove resilience and robustness under future climate scenarios(Auld, 2008b; Urwin and Jordan, 2008; Hallegatte, 2009; Kwadijk et al.,2010; Mastrandrea et al., 2010; Wilby and Dessai, 2010). Vulnerabilitythresholdsapproaches can be independent of any specific future climatecondition.Options that are known as ‘no regrets’ and ‘low regrets’ provide benefitsunder any range of climate change scenarios, although they may notbe optimal for every future scenario, and are recommended whenuncertainties over future climate change directions and impacts arehigh (Dessai and Hulme, 2007; Auld, 2008b; Hallegatte, 2009; Kwadijket al., 2010). These ‘low regrets’ adaptation options typically includeimprovements to coping strategies or reductions in exposure to knownthreats (Auld, 2008b; Kwadijk et al., 2010; Wilby and Dessai, 2010), suchas better forecasting and warning systems, use of climate informationto better manage agriculture in drought-prone regions, flood-proofingof homesteads, or interventions to ensure up-to-date climatic designinformation for engineering projects. The vulnerability-thresholds-firstapproaches are particularly useful for identifying priority areas foraction now, assessing the effectiveness of specific interventions whencurrent climate-related risks are not satisfactorily controlled, whenclimatic stress factors are closely intertwined with non-climatic factors,planning horizons are short, resources are very limited (i.e., expertise,data, time, and money), or uncertainties about future climate impactsare very large (Agrawala and van Aalst, 2008; Hallegatte, 2009;Prabhakar et al., 2009; Wilby and Dessai, 2010).Vulnerability-thresholds-first approaches have sometimes been critiquedfor the time required to complete a vulnerability assessment, for theirreliance on experts, and for their largely qualitative results and limitedcomparability across regions (Patt et al., 2005; Kwadijk et al., 2010).Vulnerability-thresholds approaches can sometimes prove less suitedfor guiding future adaptation decisions if coping thresholds change, orif climate change risks emerge that are outside the range of recentexperiences (e.g., successive drought years could progressively reducecoping thresholds of the rural poor by increasing indebtedness)(McGray et al., 2007; Agrawala and van Aalst, 2008; Auld, 2008b;Hallegatte, 2009; Prabhakar et al., 2009; Wilby and Dessai, 2010).The scenarios-impact-first approaches typically start with several climatechange modeling scenarios and socioeconomic scenarios, evaluate theexpected impacts of climate change, and subsequently identify adaptationand risk reduction options to reduce projected risks (Kwadijk et al.,2010; Mastrandrea et al., 2010; Wilby and Dessai, 2010). The scenariosimpacts-firstapproaches are most useful to raise awareness of theproblem, to explore possible adaptation strategies, and to identifyresearch priorities, especially when current climate and disaster riskscan be effectively controlled, when sufficient data and resources areavailable to produce state-of-the-art climate scenarios at the spatialresolutions relevant for adaptation, and when future climate impactscan be projected reliably (Kwadijk et al., 2010; Wilby and Dessai, 2010).Scenarios-impacts approaches depend strongly on the chosen climatechange scenarios and downscaling techniques, as well as the assumptionsabout scientific and socioeconomic uncertainties (OECD, 2009; Kwadijket al., 2010). Pure scenarios-impacts approaches may not be available atthe spatial scales relevant to the decisionmaker, may not be applicablefor the purpose of the decisionmaker, and usually give less considerationto current risks from natural climate variability, to non-climatic stressors,and to key uncertainties along with their implications for robustadaptation policies (Füssel, 2007; Wilby and Dessai, 2010). In practice,there are very limited examples of actual adaptation policies beingdeveloped and planned adaptation decisions being implemented basedon scenarios-impacts approaches only (Füssel, 2007; Biesbroek et al.,2010; Wilby and Dessai, 2010).Increasingly, studies are recognizing that the scenarios-impacts andvulnerability-thresholds approaches are complementary and need to beintegrated and that both can benefit from the addition of stakeholderand scientific input to determine critical thresholds for climate changevulnerabilities (Auld, 2008b; Haasnoot et al., 2009; Kwadijk et al., 2010;Mastrandrea et al., 2010; Wilby and Dessai, 2010). Critical thresholds (oradaptation tipping points) help in answering the basic adaptationquestions of decision- and policymakers – namely, what are the firstpriority issues that need to be addressed as a result of increasing disasterrisks under climate change and when might these critical thresholds bereached (Auld, 2008b; Haasnoot et al., 2009; Kwadijk et al., 2010;Mastrandrea et al., 2010). The integration of scenarios-impacts andvulnerability-thresholds approaches provides guidance on the sensitivityof sectors and durability of options under different climate changescenarios (Haasnoot et al., 2009; Kwadijk et al., 2010; Mastrandrea etal., 2010). Integrated approaches that link changes in climate variables todecisions and policies and express uncertainties in terms of timeframesover which a policy or plan may be effective (i.e., roughly when will thecritical threshold be reached) also provide valuable information forplans and policies and their implementation (Haasnoot et al., 2009;Kwadijk et al., 2010; Mastrandrea et al., 2010).Regardless of the approaches used, it is important that uncertainty overfuture climate change risks not become a barrier to climate change riskreduction actions (Auld, 2008b; Hallegatte, 2009; Krysanova et al., 2010;Wilby and Dessai, 2010). In cases where climate change uncertaintiesremain high, countries may choose to increase or build on their capacityto cope with uncertainty, rather than risk maladaptation from use ofambiguous impact studies or no action (McGray et al., 2007; Hallegatte,2009; Wilby and Dessai, 2010). In order to reduce the risk of maladaptation351