19.1.2.2 Scientific assessment and value judgements

The assessment of key vulnerabilities involves substantial scientific uncertainties as well as value judgements. It requires consideration of the response of biophysical and socio-economic systems to changes in climatic and non-climatic conditions over time (e.g., changes in population, economy or technology), important non-climatic developments that affect adaptive capacity, the potential for effective adaptation across regions, sectors and social groupings, value judgements about the acceptability of potential risks, and potential adaptation and mitigation measures. To achieve transparency in such complex assessments, scientists and analysts need to provide a ‘traceable account’ of all relevant assumptions (Moss and Schneider, 2000).

Scientific analysis can inform policy processes but choices about which vulnerabilities are ‘key’, and preferences for policies appropriate for addressing them, necessarily involve value judgements. “Natural, technical and social sciences can provide essential information and evidence needed for decision-making on what constitutes ‘dangerous anthropogenic interference with the climate system’. At the same time, such decisions are value judgments determined through socio-political processes, taking into account considerations such as development, equity and sustainability, as well as uncertainties and risk” (IPCC, 2001b).