Probability, Uncertainty and Risk in the Natural Environment

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Natural hazards pose serious problems to society and to the global economy. Recent examples in the UK include the cold winters of 2009 and 2010 and the eruptions of the Grimsvotn and Eyjafjallajökull volcanoes with the consequent disruption to air travel. Moving further afield, the first half of 2011 saw major disasters in Australia (flood), New Zealand (earthquake), Japan (earthquake and tsunami) and the US (hurricanes).It would be nice if scientists could provide precise information to help with the management of such events. This is unrealistic, however, for several reasons: data are usually incomplete (e.g. not available at all required locations) and measured with error; predictions are made using computer models that can at best approximate reality; and our understanding of some phenomena is limited by lack of experience (for example, the historical tsunami record is relatively limited). Therefore, natural hazard scientists must acknowledge the uncertainty in the information they provide, and must communicate this uncertainty effectively to users of the science. However, neither of these tasks is easy. Moreover, scientists do not always understand what users want and need; and users themselves often are uncomfortable with uncertainty. Despite these problems, modern statistical methods are available for handling uncertainty in complex systems using probability theory. In parallel, social science researchers are interested in understanding how people react to and understand uncertainty. By bringing these two developments together, and linking with scientists from several hazard areas along with a variety of users, we aim (a) to demonstrate a generic framework for handling uncertainty across hazards; and (b) to develop improved tools for communicating uncertain information. The generic framework considered here has three core components. The first is the treatment of uncertainties arising from our imperfect models and imperfect understanding of any complex system. The second is the combination of information from various sources that are all judged to be relevant: this is particularly important in event management situations where decision-makers must take rapid action based on multiple strands of evidence that might be apparently contradictory. The third is the treatment of uncertainties that are deemed to be "unquantifiable" or too hard to handle:an example from the insurance industry involves how much money to set aside to cover the cost of an event that is known to be possible but for which no historical loss data are available (such as an Atlantic tsunami caused by the collapse of the Cumbre Vieja volcano in La Palma). Five case studies will be used to illustrate the framework: (1) flood risk management in the UK; (2) earthquake hazard in the UK (relevant to the nuclear power industry) and in Italy; (3) tsunami hazard and risk assessment, including the development of methods to improve real-time warning systems; (4) the interpretation of days-ahead weather forecasts (focusing on wind speeds and cold weather); (5) volcanic ash dispersal, again including real-time warning systems. A final, and critical, component of the proposed research relates to the communication and use of the uncertainty information derived from the three previous components. Working with industrial partners, we will demonstrate how an improved understanding of uncertainty in the hazard itself can be translated through into risk assessments (which focus on the consequence of the hazard, for example the economic loss or damage to infrastructure). We will also carry out research to understand better how people perceive and use risk information. The results will be used to inform the development of novel methods for communicating natural hazard risk information to specialist and non-specialist users; and also (in collaboration with the PURE Network) to produce a handbook of risk communication for natural hazards.