The conceptual framework developed around vulnerability to climate change is rather vast and includes the concepts as for example, time horizon, hazards, risk, impact and other.
The researchers of vulnerability argue that there should be the object of vulnerability, the specified system. A system is vulnerable to a specific hazard or range of hazards (Brooks, 2003, Fussel, 2007) or specific sets of stressors (Luers et al. 2003). United Nations (2004) defines a “hazard” broadly as a “potentially damaging physical event, phenomenon or human activity that may cause the loss of life or injury, property damage, social and economic disruption of environmental degradation”. So a hazard Hence, a hazard is understood as some influence that may adversely affect a valued attribute of a system. A hazard is generally but not always external to the system under consideration. Hazards are often distinguished into discrete hazards, denoted as perturbations, and continuous hazards, denoted as perturbations, and continuous hazards, denoted as stress or stressor. (Turner II et al., 2003)
The system of concern here could be a coupled human-environment system, a population group, an economic sector, a geographical region, or a natural system. Some researchers restrict the concept of vulnerability to social systems (Downing and Patwardhan, 2004) or coupled human-environment systems (Turner II et al., 2003). McCarthy et al use the concept to describe any system that is potentially threatened by hazard (McCarthy et al, 2001) Luers et al also argue that vulnerability research should focus on vulnerable variables in a system (Luers et al., 2003)
Multiple authors stress the importance of temporal dimension of vulnerability: one should distinguish between current and future vulnerability, as it changes through time (Brooks, 2003, Wisner et al, 2003, Füssel, 2007).
Downing and Patwardhan’s nomenclature of vulnerability of social systems includes the following concepts: the threat, the region, the sector, the population group, the consequence, and the time period.
Thus, one can only speak meaningfully about a system, located on a specific territory, or variables of a system, which are vulnerable to a specific hazard – a heat wave in this case – with specific impacts or consequences, during a specific time period.