Hazards Beyond Belief: Storylines for the most extreme disasters

Multiple recent weather and climate disasters have shattered assumptions about the nature of regional climate risks. This power of surprise comes not just from the unprecedented severity of the disasters’ component hazards, but from the intricate system interactions that have led to their devastating impacts. The usual tools for risk characterization are particularly challenged by events that, like these, stretch the limits of experience, observation, imagination, and/or modeling capability. Here, we draw from several recent projects to describe the development and application of ‘complex-risk’ storylines that arc from blue-sky discussion of fundamental uncertainties and event conceptualization through to hazard-impact-response cascades and potential state changes in natural and human systems. Such storylines entrain diverse types of knowledge to flexibly envision and strategize for yet-unrealized risks spanning a range of timescales and socioenvironmental conditions. We use our narrative set to identify 12 major emergent themes across physical, social, and institutional domains, and discuss how these themes can contribute crucial guidance for anticipating what the next unprecedented disaster might look like — and thus how to design basic and applied research that speaks to it. The themes also provide a framework that helps highlight historically overlooked geographies, hazard combinations, and event dynamics. We conclude by enumerating several stubborn cross-disciplinary challenges that we see complicating extreme-weather risk calculations, and discuss the potential for this storyline approach, among other techniques, to foster productive insights.