Vulnerability to climate change

There are three major approaches or mental models on vulnerability to climate change (Füssel and Klein, 2006).   

Risk hazard approach
The risk hazard approach, which is often used by spatial planners, engineers and the natural hazard community, frames vulnerability as the risk that a certain event will occur. Risk is thus defined as the product of probability and consequence (e.g. Brooks, 2003, Füssel and Klein, 2006). This approach mainly relates to sensitivity, that is how significantly climate change will impact society and nature. 

Social constructivist approach
The social constructivist approach has its origins in human geography and political economy (adger, 1999). Here, vulnerability is seen as a condition of a household or a local community that is assumed before the real analysis starts. This condition is determined by socio-economic and political factors (adger and Kelly, 1999). thus underlining the non-climatic drivers of change that affect social systems. 

Integrated approach
The third approach frames vulnerability as an integrated measure and is prominent in studies of global change. The IPCC in its third assessment report defined vulnerability in an integrated manner as “the degree to which a system is susceptible to, and unable to cope with, adverse effects of climate change”, and it is seen as a function of “the character, magnitude, and rate of climate change and variation to which a system is exposed and the sensitivity and adaptive capacity of that system” (McCarthy et. al. 2001). Accordingly, vulnerability contains an external dimension, that is the exposure to environmental and economic change determined outside the local community, and an internal dimension capturing the sensitivity and adaptive capacity of the local community to these mainly externally determined stressors. It is not only the existence of adaptation measures that limits climate vulnerability, but also and more importantly, the capacity of social organisations — households, businesses, public agencies — to put these measures into practice. It is this implementation deficit that needs to be recognized, discussed and, hopefully, overcome.

According to IPCC definition the vulnerability is related to three inter-related elements: exposure, sensitivity, and adaptive capacity. Exposure and sensitivity are hard to separate in a system. Exposure represents what risks the local community is facing and how much a system is stressed, while sensitivity addresses how much these stressors actually modify or affect the studied system. Adaptive capacity depicts the ability of a system to adjust to climate change in order to moderate potential damages, take advantage of opportunities, or cope with the consequences McCarthy et. al. 2001).