The degree to which a system is susceptible to or unable to cope with the adverse effects of climate change, including climate variability and extremes.

Vulnerability is a function of the character, magnitude, and rate of climate variation to which a system is exposed, its sensitivity and its adaptive capacity.

In relation to hazards and disasters, vulnerability is a concept that links the relationship that people have with their environment to social forces and institutions and the cultural values that sustain and contest them. “The concept of vulnerability expresses the multidimensionality of disasters by focusing attention on the totality of relationships in a given social situation which constitute a condition that, in combination with environmental forces, produces a disaster”

Vulnerability research covers a complex, multidisciplinary field including development and poverty studies, public health, climate studies, security studies, engineering, geography, political ecology, and disaster and risk management. This research is of particular importance and interest for organizations trying to reduce vulnerability--especially as related to poverty and other Millennium Development Goals. Many institutions are conducting interdisciplinary research on vulnerability. A forum of that brings many of the current researchers on vulnerability together is the Expert Working Group. Researchers are currently working to refine definitions of “vulnerability”, measurement and assessment methods, and effective communication of research to decision makers.