Clarifying vulnerability definitions and assessments using formalisation

The purpose of this paper is to present a formal framework of vulnerability to climate change, to address the conceptual confusion around vulnerability and related concepts. The framework was developed using the method of formalisation – making structure explicit. While mathematics as a precise and general language revealed common structures in a large number of vulnerability definitions and assessments, the framework is here presented by diagrams for a non‐mathematical audience. Vulnerability, in ordinary language, is a measure of possible future harm. Scientific vulnerability definitions from the fields of climate change, poverty, and natural hazards share and refine this structure. While theoretical definitions remain vague, operational definitions, that is, methodologies for assessing vulnerability, occur in three distinct types: evaluate harm for projected future evolutions, evaluate the current capacity to reduce harm, or combine the two. The framework identifies a lack of systematic relationship between theoretical and operational definitions. While much conceptual literature tries to clarify vulnerability, formalisation is a new method in this interdisciplinary field. The resulting framework is an analytical tool which supports clear communication: it helps when making assumptions explicit. The mismatch between theoretical and operational definitions is not made explicit in previous work.