The current condition of the feature It is important to try to capture the status of the feature if known whether it is in good or bad condition and the trajectory of improvement or decline to date. In addition to considering the impact of climate change to date, this information factors in the impact of non-climate related stressors and to what extent they have influenced the feature. A feature in poor current condition is more likely to be vulnerable to future climate change.
The sensitivity of the feature to climate change The sensitivity of a feature is a measure of the degree to which it will respond to climate changes. For example, a biological feature such as an animal may be directly sensitive to a change in temperature – unable to survive beyond a certain threshold. In addition, features can be indirectly sensitive to climate change through a wide range of other mechanisms. For example, a living or a non-living feature may respond to human behaviour change that occurs because of climate change. Features with higher sensitivity are more likely to be vulnerable to future climate change.
The exposure of the feature to climate change Exposure reflects the degree, and way, in which a feature is exposed to climate change. Exposure is independent from sensitivity. For example, a feature found all year round in the PDNP might be very sensitive to a rise in sea level if it was located near to the sea, but in practice, it will not be exposed directly to this change. The location in which features occur within the PDNP could also affect the exposure experienced. For example, a plant found at high altitude on north-facing slopes may be exposed to a smaller temperature rise than one occurring on low altitude south-facing slopes. Again, exposure encompasses not only direct changes, but also indirect changes occurring because of climate change. A feature that is exposed to a high level of change is more likely to be vulnerable to future climate change. The categories of exposure used in this assessment are temperature change, precipitation change, extreme events, sea level change and atmospheric pollution. While the last category of atmospheric pollution is not necessarily a result of climate change, increasing CO2 and nitrogen, for example are closely tied in with predicted changes.
The adaptive capacity of the feature Finally, the capacity that a feature has to adapt to changes also affects its overall vulnerability. The higher the adaptive capacity rating, the less vulnerable to change a feature is likely to be. In this assessment, this capacity relates both to the inherent properties of a feature, and the potential for human adaptation to take place. Examples of inherent adaptive capacity could be the plasticity of animal behaviour – is an animal capable of adapting its behaviour to meet new conditions? Human adaptation potential includes factors such as the availability of economic resources, the existence of institutions and the management practices they could put into place.
The exposure and sensitivity when viewed together create a picture of the potential impacts of climate change upon a given feature. These potential impacts are theoretical scenarios that do not take into account the adaptive capacity, and so should be viewed as distinct from overall vulnerability ratings. When considered together, these four components can be used to produce an overall estimation of vulnerability.