3. How Is Uncertainty Addressed in the Knowledge Base for National Adaptation Planning?

Adaptation actors are generally encouraged to develop adaptation strategies that are robust in the presence of unavoidable uncertainties. However, where can they obtain information on key uncertainties relevant to their decisions? In response to this question, we review the consideration of key uncertainties in the knowledge base for adaptation planning in 14 European countries. In this context, the adaptation knowledge base is understood as information that is directly relevant for adaptation planning and which is provided by or on behalf of public authorities (e.g. through reports and web portals). It includes in particular national climate projections, relevant non-climatic scenarios and climate change impact, vulnerability and risk assessments.

We find substantial differences across countries and jurisdictions. Some key findings are as follows. Almost all national-level climate change projections consider uncertainties related to emission scenarios, global climate models and downscaling methods. Many countries have established web portals that provide access to climate projections; their functionality and the presentation of uncertainty vary widely across them. Only a few countries have developed non-climatic (e.g. socio-economic, demographic and environmental) scenarios for use in climate change impact, vulnerability and risk assessments. All countries have conducted climate impact, vulnerability or risk assessments. The consideration of uncertainty within these varies widely, from a generic qualitative discussion to a probabilistic assessment based on a comprehensive modelling exercise. Most countries have developed guidance material for decision-makers concerned with adaptation. Such guidelines generally explain key sources of uncertainty in climate and climate impact projections but only few guidelines provide practical guidance on adaptation decision-making under uncertainty.

We conclude that substantial efforts are needed to improve the appreciation of uncertainties in climate and climate impact projections by decision-makers and the public at large. Dynamic interactive tools in web portals can be an important part of the tool box for those who are confronted with adapting to climate change. In addition, targeted guidance is needed that explains the relevance of key uncertainties and how they can be addressed by appropriate adaptation strategies in a specific adaptation context.