Adapting to an Uncertain Climate

Our social, cultural and economic sustainability and that of future generations depend on quality decisions and policies that address risks and opportunities. As these decisions and policies are for the most part evidence-based and uncertainties are inherent in that evidence, the quality of those decisions and policies requires effective use of that evidence, including the uncertainties. This chapter provides an introduction to this subject and to the experiences and lessons learnt presented in the publication. It indicates why the authors of the publication believe such a publication is needed and the audience we believe will benefit from such a publication. It also provides a brief description of the content of the ensuing chapters and suggests alternative pathways by which those with specific interests may navigate through the publication. In so doing, the intention has been to invite those interested to learn from others and benefit from those shared experiences.

Although trends in climate change are expected to continue, there is considerable uncertainty about the precise rate of change and its concrete impact. A key element in decision-making on climate adaptation is how to deal with this uncertainty. This chapter provides the background information on dealing with uncertainties: descriptions of uncertainty typology, methods of assessment, as well as a framework for dealing with uncertainty in climate adaptation decision-making. The chapter highlights that the classical elements used in uncertainty assessment (statistics, scenarios and recognised ignorance) can be expanded toward five principal uncertainty dimensions that are crucial for informing/supporting adaptation decision-making: location, level, nature, qualification of knowledge base, and value-ladenness. In practice, to deal with uncertainties, but also because of time and budget constraints, uncertainty assessments may follow a three step approach: (1) identify and characterise sources of uncertainty; (2) weigh, appraise, and prioritise uncertainties; and (3) select and apply methods for dealing with uncertainties in policy. Based on political and societal preferences, adaptation strategies could either use top-down or bottom-up approaches considering adaptation action based on the best prediction, robustness, or resilience. Adaptation policies that focus on enhancing the system’s and society’s capability of dealing with possible future changes, uncertainties and surprises (e.g. through resilience, flexibility, and adaptive capacity) seem most appropriate. For potential climate-related effects for which rough risk estimates are available, ‘robust’ measures are recommended. For potential climate effects with limited societal and/or political relevance, ‘no-regret’ measures are recommended. For highly relevant potential climate-related effects, precautionary measures can be considered. The chapter provides also links to the uncertainty approaches in the case studies described in Chap. 4.

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.

This chapter describes 12 real-life cases showing how policy-makers, decision-makers and researchers from different countries have struggled together to deal with uncertain information in adaptation decision-making. The case studies cover a wide range of sectors and themes, including water management, infrastructure, disaster risk reduction, health, forestry, agriculture, health and nature conservation and development. Each experience highlights the different types of uncertainties addressed, justifies the selected methods that were used to deal with these uncertainties and how it affected the decision taken. The cases discuss both classical types of risk analysis as well as novel approaches such as seeking robust adaptation strategies. They all show the importance of involving stakeholders to deal with uncertainty in adaption decision making.

Adaptation practice is a novel and dynamic field. This is reflected by an as yet limited experience in how climate change uncertainties can be best dealt with in particular situations. This chapter synthesises the theoretical (scientific) and practical aspects of the preceding chapters, draws key lessons and provides guidance for those involved in supporting and ultimately making adaptation decisions.

For this purpose a Common Frame of Reference (i.e. common definitions, principles and understandings) for dealing with uncertainties in climate adaptation decision-making is presented and applied to the analysis of the twelve real-life cases presented in this book. This framework intends to support complex climate adaptation decision-making processes that have to deal with uncertainties and still make informed decisions. Two central questions were addressed and applied to the cases reported: (i) how did the approaches used to deal with climate uncertainty influence the adaptation decision-making process and (ii) have better informed adaptation decisions been made because uncertainties were conscientiously addressed?

The objective of this chapter is not to provide a simple checklist to be followed when facing uncertainties in a climate adaptation process but rather to inform and guide the reader by presenting key lessons and insights from real-life cases where decision-makers and those that support them have already faced and responded to climate adaptation related uncertainty.