2.2.1 Frameworks for CCIAV assessment
Although the following approaches and methods were all described in the TAR (Ahmad et al., 2001), their range of application in assessments has since been significantly expanded. Factors that distinguish a particular approach include the purpose of an assessment, its focus, the methods available, and how uncertainty is managed. A major aim of CCIAV assessment approaches is to manage, rather than overcome, uncertainty (Schneider and Kuntz-Duriseti, 2002), and each approach has its strengths and weaknesses in that regard. Another important trend has been the move from research-driven agendas to assessments tailored towards decision-making, where decision-makers and stakeholders either participate in or drive the assessment (Wilby et al., 2004a; UNDP, 2005).
The standard approach to assessment has been the climate scenario-driven 'impact approach', developed from the seven-step assessment framework of IPCC (1994).2 This approach, which dominated the CCIAV literature described in previous IPCC reports, aims to evaluate the likely impacts of climate change under a given scenario and to assess the need for adaptation and/or mitigation to reduce any resulting vulnerability to climate risks. A large number of assessments in this report also follow that structure.
The other approaches discussed are adaptation- and vulnerability-based approaches, integrated assessment, and risk management. All are well represented in conventional environmental research, but they are increasingly being incorporated into mainstream approaches to decision-making, requiring a wider range of methods to fulfil objectives such as (SBI, 2001; COP, 2005):
• assessing current vulnerabilities and experience in adaptation,
• stakeholder involvement in dealing with extreme events,
• capacity-building needs for future vulnerability and adaptation assessments,
• potential adaptation measures,
• prioritisation and costing of adaptation measures,
• interrelationships between vulnerability and adaptation assessments,
• national development priorities and actions to integrate adaptation options into existing or future sustainable development plans. The adaptation-based approach focuses on risk management by examining the adaptive capacity and adaptation measures required to improve the resilience or robustness of a system exposed to climate change (Smit and Wandel, 2006). In contrast, the vulnerability-based approach focuses on the risks themselves by concentrating on the propensity to be harmed, then seeking to maximise potential benefits and minimise or reverse potential losses (Adger, 2006). However, these approaches are interrelated, especially with regard to adaptive capacity (O'Brien et al., 2006). Integrated approaches include integrated assessment modelling and other procedures for investigating CCIAV across disciplines, sectors and scales, and representing key interactions and feedbacks (e.g., Toth et al., 2003a, b). Risk-management approaches focus directly on decision-making and offer a useful framework for considering the different research approaches and methods described in this chapter as well as confronting, head on, the treatment of uncertainty, which is pervasive in CCIAV assessment. Risk-management and integrated assessment approaches can also be linked directly to mitigation analysis (Nakicenovic et al., 2007) and to the joint assessment of adaptation and mitigation (see Chapter 18).
Two common terms used to describe assessment types are 'top-down' and 'bottom-up', which can variously describe the approach to scale, to subject matter (e.g., from stress to impact to response; from physical to socio-economic disciplines) and to policy (e.g., national versus local); sometimes mixing two or more of these (Dessai et al., 2004; see also Table 2.1). The standard impact approach is often described as top-down because it combines scenarios downscaled from global climate models to the local scale (see Section 2.4.6) with a sequence of analytical steps that begin with the climate system and move through biophysical impacts towards socio-economic assessment. Bottom-up approaches are those that commence at the local scale by addressing socio-economic responses to climate, which tend to be location-specific (Dessai and Hulme, 2004). Adaptation assessment and vulnerability assessment are usually categorised as bottom-up approaches. However, assessments have become increasingly complex, often combining elements of top-down and bottom-up approaches (e.g., Dessai et al., 2005a) and decisionmaking will utilise both (Kates and Wilbanks, 2003; McKenzie Hedger et al., 2006). The United Nations Development Programme's Adaptation Policy Framework (UNDP APF: see UNDP, 2005) has also identified a policy-based approach, which assesses current policy and plans for their effectiveness under climate change within a risk-management framework.
Application of the standard IPCC impact approach has expanded significantly since the TAR. The importance of providing a socio-economic and technological context for characterising future climate conditions has been emphasised,
2 The seven steps are: 1. Define problem, 2. Select method, 3. Test method/sensitivity, 4. Select scenarios, 5. Assess biophysical/socio-economic impacts, 6. Assess autonomous adjustments, 7. Evaluate adaptation strategies.
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