IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

18.1.1 Background and rationale

Traditionally the primary focus of international climate policy has been on the use and production of energy. This policy focus was reflected in the Second Assessment Report (SAR), which, in discussing mitigation, paid relatively little attention to greenhouse gases other than CO2 and to the potential for enhancing carbon sinks. Likewise, it paid little heed to adaptation. Since the publication of the SAR, the international climate policy community has become aware that energy policy alone will not suffice in the quest to control climate change and limit its impacts. Climate policy is being expanded to consider a wide range of options aimed at sequestering carbon in vegetation, oceans and geological formations, at reducing the emissions of non-CO2 greenhouse gases, and at reducing the vulnerability of sectors and communities to the impacts of climate change by means of adaptation. Consequently, the Third Assessment Report (TAR) provided a more balanced treatment of adaptation and mitigation.

The TAR demonstrated that the level of climate-change impacts, and whether or not this level is dangerous (see Article 2 of the UNFCCC), is determined by both adaptation and mitigation efforts (Smith et al., 2001). Adaptation can be seen as direct damage prevention, while mitigation would be indirect damage prevention (Verheyen, 2005). However, only recently have policy-makers expressed an interest in exploring inter-relationships between adaptation and mitigation. Recognising the dual need for adaptation and mitigation, as well as the need to explore trade-offs and synergies between the two responses, they are faced with an array of questions (GAIM Task Force, 2002; Clark et al., 2004; see also Figure 18.1). How much adaptation and mitigation would be optimal, when, and in which combination? Who would decide, and based on what criteria? Are adaptation and mitigation substitutes or are they complementary to one another? When and where is it best to invest in adaptation, and when and where in mitigation? What is the potential for creating synergies between the two responses? How do their costs and effectiveness vary over time? How do the two responses affect, and how are they affected by, development pathways? These are some of the questions that have led the IPCC to include this chapter on inter-relationships between adaptation and mitigation in its Fourth Assessment Report (AR4).

Figure 18.1

Figure 18.1. A schematic overview of inter-relationships between adaptation, mitigation and impacts, based on Holdridge’s life-zone classification scheme (Holdridge, 1947, 1967; M.L. Parry, personal communication).

The relevant literature to date does not provide clear answers to the above questions. Research on adaptation and mitigation has been rather unconnected to date, involving largely different communities of scholars who take different approaches to analyse the two responses. The mitigation research community has focused strongly, though not exclusively, on technological and economic issues, and has traditionally relied on ‘top-down’ aggregate modelling for studying trade-offs inherent in mitigation (see the WGIII AR4 (IPCC, 2007)). After a period of conceptual introspection, the adaptation research community has put its emphasis on local and place-based analysis: a research approach it shares with scholars in development studies and disaster risk reduction (Adger et al., 2003; Pelling, 2003; Smith et al., 2003; see also Chapter 17). In addition, adaptation is studied at the sectoral level (see Chapters 3 to 8).

One important research effort that does consider both adaptation and mitigation is integrated assessment modelling. Integrated assessment models (IAMs) typically combine energy models and sectoral impact models with climate, land-use and socio-economic scenarios to analyse and compare the costs and benefits of climate change and climate policy to society (see also Chapter 2). However, climate policy in IAMs to date is dominated by mitigation; adaptation, when considered, is either represented as a choice between a number of technological options or else it follows from assumptions in the model about social and economic development (Schneider, 1997; Corfee-Morlot and Agrawala, 2004; Fisher et al., 2007).

New research on inter-relationships between adaptation and mitigation includes conceptual and policy analysis, as well as ‘bottom-up’ studies that analyse specific inter-relationships and their implications for sectors and communities. The latter studies often place the implementation of adaptation and mitigation within the context of broader development objectives (e.g., Tompkins and Adger, 2005; Robinson et al., 2006; Chapters 17 and 20). They complement integrated assessment modelling by studying the factors and processes that determine if and when adaptation and mitigation can be synergistic in climate policy. Owing to it being a new research field, the amount of literature is still small, although it is growing fast. At the same time, the literature is very diverse: there is no consensus as to whether or not exploiting inter-relationships between adaptation and mitigation is possible, much less desirable. Some analysts (e.g., Venema and Cisse, 2004; Goklany, 2007) see potential for creating synergies between adaptation and mitigation, while others (e.g., Klein et al., 2005) are more sceptical about the benefits of considering adaptation and mitigation in tandem.

The differences in approaches between adaptation and mitigation research, and between integrated assessment modelling and ‘bottom-up’ studies, can create confusion when findings published in the literature appear to be inconsistent with one another. In assessing the literature on inter-relationships between adaptation and mitigation, this chapter does not hide any differences and inconsistencies that may exist between relevant publications. As artefacts of the research approaches that have emerged as described above, these differences and inconsistencies reflect the current state of knowledge. To provide as much clarity as possible from the outset definitions of important concepts are provided in Box 18.1. Next, Section 18.1.2 summarises important differences, similarities and complementarities between adaptation and mitigation.

Box 18.1. Definitions of terms

This box presents chapter-specific definitions of a number of (often related) terms relevant to the assessment of inter-relationships between adaptation and mitigation. Unless indicated otherwise, the definitions are specialisations of standard definitions found in reputable online dictionaries (e.g., http://www.m-w.com/, http://www.thefreedictionary.com/).

Trade-off: A balancing of adaptation and mitigation when it is not possible to carry out both activities fully at the same time (e.g., due to financial or other constraints).

Synergy: The interaction of adaptation and mitigation so that their combined effect is greater than the sum of their effects if implemented separately.

Substitutability: The extent to which an agent can replace adaptation by mitigation or vice versa to produce an outcome of equal value.

Complementarity: The inter-relationship of adaptation and mitigation whereby the outcome of one supplements or depends on the outcome of the other.

Optimality: The condition of being the most desirable that is possible under an expressed or implied restriction.

Portfolio: A set of actions to achieve a particular goal. A climate policy portfolio may include adaptation, mitigation, research and technology development, as well as other actions aimed at reducing vulnerability to climate change.

Mainstreaming: The integration of policies and measures to address climate change in ongoing sectoral and development planning and decision-making, aimed at ensuring the sustainability of investments and at reducing the sensitivity of development activities to current and future climatic conditions (Klein et al., 2005).