The main concept of this guidance is to support an analyst in choosing approaches that are salient for addressing a given adaptation challenge. By salient we mean adequate from a problem-oriented perspective (Cash et al., 2003). From a pure research perspective, many approaches may be adequate, as long as they reveal new insights. Here, however, we are interested in approaches that have the potential to advance adaptation practise on the ground.
Following this line of thought, approaches are only considered salient if they avoid maladaptation. While this guidance does not explicitly address maladaptation, the literature on maladaptation has informed its development, as it raises the important point that actions that are effective in the short term may not be in the long term (Barnett and O'Neill, 2010).
An adaptation challenge is conceptualized as a particular problem an actor in a socialecological system (Berkes and Folke, 1998) exposed to climate change is facing (Hinkel and Bisaro, 2013b). This involves climatic stimuli affecting coupled ecological (or natural) and social (or human) systems, where actors expect, perceive or experience climate impacts and adapt, thereby interacting with each other at various levels of decision making. The actors' interactions are shaped by the characteristics of the biophysical and institutional setting in which the interaction takes place. An adaptation challenge faced by alpine ski resort owners, for example, may be described as follows: Alpine ski resorts owners are faced with declining profitability, part of which is caused by less snowfall. The resort owners know that there are technical solutions (artificial snowmaking) but they come with environmental costs and may not be sufficient under further temperature increases.
Choosing approaches or methods that are salient for addressing a given challenge depends on a number of criteria. The main set of criteria relevant for choosing salient approaches are empirical criteria, that is criteria that describe the given adaptation challenge in terms of conditions that must be met by the adaptation challenge in order to meaningfully apply an approach or method. For example, an institution analysis approach may be applicable in order to support a policy maker that is trying to identify policy measures for influencing the adaptation of others. On the contrary, a decision analysis approach such as cost-benefit analysis may be more applicable for the adaptation challenge in which a private investor is deciding upon future infrastructure to be build. There might also be challenges to which both of these methods are applicable. We discuss these empirical criteria in more detail in the next subsection.
Empirical criteria are not the only set of criteria that may play an important role for choosing an approach. A second set of criteria are theoretical criteria. For some tasks, the empirical setting will not uniquely determine which method should be applied. Available approaches differ with respect to their underlying theoretical assumptions, which are independent from the empirical characteristics of an AS. These assumptions may be based on, for instance, the assumptions underlying a scientific discipline or school of thought or particular computational model at hand. For example, certain methods that analyse and predict the consequences of individual behaviour are based on socio-psychological theory, which links cognitive variables to the behaviour of an adapting actor. This cause-effect relationship between variables and outcomes is a theoretical assumption determined by the analyst. Alternative methods employing assumptions of utility maximisation could be applied to the same task. A further example would be an analyst's choice between applying an impact model in which adaptation occurs, as opposed to one in which no adaptation occurs. The criteria for selecting between these alternatives is not based on the adaptation situation. For example, selecting an impact assessment method often involves the theoretical choice about how to represent autonomous adaptation, e.g. "no adaptation", "clairvoyant adaptation", etc. (Füssel and Klein, 2006).
A third set of criteria is normative criteria. In both research and decision making, selecting approaches is strongly influenced by many normative criteria. The challenge of drawing boundaries around a system of interest is ever present, and often cannot be resolved empirically or theoretically. Selecting, for example, which options to consider in a decision is often a normative choice depending on the needs or framing of the decision maker. This guidance cannot hope to provide a panacea solution for issues of this kind. Rather, the guidance can assist to make explicit some of the criteria that should be considered in VIA, and outline the fact that normative choices must be made by readers selecting and applying the methods contained in this guidance.
A fourth and final set of criteria is pragmatic criteria associated with the analyst carrying out the work. Many of the methods require expert knowledge and the skills or expertise of the analyst is thus relevant for choosing appropriate methods. Furthermore, the resources available are relevant in that they also constrain the application of methods. In particular some of the computational and empirical methods require substantial resources to be committed. This might be a relevant in terms of considering the costs of generating new information, versus the disadvantages of acting on incomplete information. As this is a fundamental decision making problem, we cannot aim to provide definite prescriptions on these kind of choices. Finally, the scope of the assessment or the terms of references often constrain the approaches considered to be relevant. This fourth set of criteria has not been used in building the decision trees in order to provide guidance based on the best available knowledge from VIA research and adaptation practice.
