Task overview

Potential impact projection does not include adaptation of actors in projecting impacts.

Impact projection methods analyse the possible impact of climate change and other potential drivers on a study unit. The fundamental theoretical assumption of impact analysis is that it is possible to analytically distinguish between a study unit and its (natural and socio-institutional) environment in the sense that the environment influences the study unit but whatever happens "inside" the study unit does not feed back on its environment. This separation allows for the representation of the evolution of the environment in form of a set of scenarios that are independent from the model used to represent the study unit. If changes in the study unit would influence the environment, than an integrated (assessment) model would need to be used for representing both the study unit and its environment together.

We follow the IPCC in distinguishing methods that analyse potential impacts, which are those that "may occur without considering adaptation" (Parry et al. 2007: 876), in opposition to methods that assess residual impacts, which include adaptation.

One problematic aspect about potential impact assessments is that the theoretical assumption made that people don't adapt is often empirically rather unlikely to be met. The potential impact that "many millions more people are projected to be flooded every year due to sea-level rise by the 2080s", reported in the AR4 WG2-SPM (IPCC 2007), for example, is rather unrealistic because this would assume that people continue to live in the coastal zone even though they experience frequent flooding or even permanent inundation (Hinkel 2011b).