2.3.4 Communicating uncertainty and risk

Communicating risk and uncertainty is a vital part of helping people respond to climate change. However, people often rely on intuitive decision-making processes, or heuristics, in solving complicated problems of judgement and decision-making (Tversky and Kahneman, 1974). In many cases, these heuristics are surprisingly successful in leading to successful decisions under information and time constraints (Gigerenzer, 2000; Muramatsu and Hanich, 2005). In other cases, heuristics can lead to predictable inconsistencies or errors of judgement (Slovic et al., 2004). For example, people consistently overestimate the likelihood of low-probability events (Kahneman and Tversky, 1979; Kammen et al., 1994), resulting in choices that may increase their exposure to harm (Thaler and Johnson, 1990). These deficiencies in human judgement in the face of uncertainty are discussed at length in the TAR (Ahmad et al., 2001).

Participatory approaches establish a dialogue between stakeholders and experts, where the experts can explain the uncertainties and the ways they are likely to be misinterpreted, the stakeholders can explain their decision-making criteria, and the two parties can work together to design a risk-management strategy (Fischoff, 1996; Jacobs, 2002; NRC, 2002). Because stakeholders are often the decision-makers themselves (Kelly and Adger, 2000), the communication of impact, adaptation, and vulnerability assessment has become more important (Jacobs, 2002; Dempsey and Fisher, 2005; Füssel and Klein, 2006). Adaptation decisions also depend on changes occurring outside the climate change arena (Turner et al., 2003b).

If the factors that give rise to the uncertainties are described (Willows and Connell, 2003), stakeholders may view that information as more credible because they can make their own judgements about its quality and accuracy (Funtowicz and Ravetz, 1990). People will remember and use uncertainty assessments when they can mentally link the uncertainty and events in the world with which they are familiar; assessments of climate change uncertainty are more memorable, and hence more influential, when they fit into people’s pre-existing mental maps of experience of climate variability, or when sufficient detail is provided to help people to form new mental models (Hansen, 2004). This can be aided by the development of visual tools that can communicate impacts, adaptation, and vulnerability to stakeholders while representing uncertainty in an appropriate manner (e.g., Discovery Software, 2003; Aggarwal et al., 2006).