Attributing proportionality to climatic impact-drivers of systemic risk
Abstract
Systemic risk in cities arises from interactions between climate hazards and urban systems as well as how we respond to them. While we have made progress in understanding the diversity of climate-related drivers and nature of interactions that affect systemic risk at different scales, we lack clarity on the relative weight of these drivers. To address this gap, the paper proposes a practical framework for attributing the proportional influence of hazards, exposure, vulnerability, and response actions on systemic risk. The method combines impact-chain mapping, counterfactual storylines, and sensitivity analysis to produce a proportional ‘risk budget’ to identify interaction effects. Using Cape Town’s Day Zero drought as a detailed case, this paper shows that proportionality is critical for the allocation of adaptation resources to drivers that matter the most for risk. The example shows how delayed responses at the utility level and uneven business and household-level responses to the drought shaped the systemic risk concerns of the crisis beyond the severity of the drought (hazard) itself. Through extension of attribution to responses, decision-makers are better able to reallocate attention and investment in proportion to multivariate risk drivers and potentially avoid maladaptive responses. The framework supports more strategic, equitable, and adaptive forms of urban risk governance as climate and socio-economic conditions evolve.