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Uncertainty guidance topic 3

When informing on adaptation decisions it is important that the implications of uncertainties are also communicated. Decision and policy makers make decisions with uncertain information every day (for example, making investments, buying products, taking up new opportunities, making investments, using weather forecasts) but they may not describe it as such. Communicating the implications for decision-makers of the uncertainty associated with climate information is a key undertaking. There will be other sources of uncertainty relevant to adaptation decisions (for example, demographics, economic activity, legislation) and decision-makers should be made aware that they will have to identify and consider these too.

It will be important to reassure those responsible for implementing adaptation decisions that appropriate choices have been made. A decision can still be robust if it is based on the best available evidence, even though that evidence may be incomplete or uncertain. Understanding the uncertainties, supported by effective communication, should permit better and more flexible responses. This guidance refers only to communicating uncertainty in climate information.

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What are lessons in communicating uncertainty?

Understanding the audience is critical, as is being clear about the nature of the decision they are making. Some decisions will require little, if any, information about uncertainty. For example, "summers will generally be warmer" or "the trend indicates more autumn rainfall" may be sufficient for some audiences and decisions. Other decisions may require more detailed information, relating to particular regions, timescales or variables. In these cases, understanding sources of uncertainty is likely to be more important.

The representation of climate change in popular media provides the context in which climate adaptation takes place. The quality and extent of reporting on climate change varies, and it is important to be mindful of this when developing communication strategies and information for adaptation. Mainstream media can be a helpful resource through which to generate support for adaptation strategies and options. However, it can also be a difficult medium through which to portray accurately the nature of uncertainties. Approach with caution!

It is important to be open about the consequences of uncertainty for adaptation planning and to frame these in familiar and understandable terms. This requires effective and honest communication between providers and users of climate information where the nature of the decisions and the strengths (and weaknesses) of the climate information are transparent and understood by all.

There is no single simple recipe for communications. Climate science has always taken a long-term approach. The communication of that science must be just as strategic in its analysis, design, implementation and evaluation. Communication about uncertainties must be such that it is understandable to those needing the information; otherwise it can impede the pickup of the information and taking of decisions. In addition, those needing to take action can get an exaggerated sense of the uncertainty (or certainty).

Over the past 40 years, social and decision science research has addressed these challenges across a broad front. This body of research has identified basic processes guiding risk perceptions and has applied that knowledge to facilitating informed choices involving complex, uncertain and contested science. Like climate systems, human systems involve the complex, uncertain interaction of many processes. As a result, even the best-designed communications, based on the strongest social and decision science, require rigorous implementation and empirical evaluation to determine how effective they are.

Some key lessons are below:

  • Understand the audience and the information they need.
  • People deal with uncertainty all the time (economic growth, technological change) and uncertainty around future climate change is extensively described.
  • Avoid complex or obscure language. Explain the meaning of descriptions or phrases where they have a particular application, especially if they have alternative or everyday interpretations.
  • Make scenarios locally relevant – stories, examples and case studies bring adaptation planning to life.
  • People have different ways of learning new information. Explore new tools such as visualizations to provide a range of opportunities for audiences.
  • Support people in their adaptation journey: provision of data alone will not stimulate action.

There are many resources for creating climate change communications (including adaptation) available online. A few are listed here.

Resources for further reading:

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How can uncertainty be presented?

Uncertainties can be presented in different ways. Clear and careful use of language is important, but it is helpful to provide information in a variety of ways, that will take account of individuals' preferences for absorbing new information, as well as the application of that information in decision-making.

Scenarios and storylines, diagrams and images can all be used to offer a rich source of information for decision-makers, but would need to be scrutinised to ensure that they remain technically robust.

One of the tasks for communicators is to help audiences understand what is known with a high degree of confidence and what is relatively poorly understood. Climate scientists working within the IPCC have adopted a lexicon to communicate confidence in their findings, and this is widely used in the climate change community (see also). For example, "very high confidence" is used to refer statements where there is a good deal of agreement and plenty of evidence. Other such terms included "high," "medium," "low," and "very low" confidence. "Very low confidence" refers to findings were there is less agreement and limited evidence. This language is now more widely used in describing climate change, but it still poses communication challenges. It is important for communicators to ensure that their audience understands and applies the meanings formally associated with these descriptions. Using everyday language to describe uncertainty makes the concept more accessible, but there is a risk of misunderstanding, as people may have personal and differing interpretations of terms like ‘high confidence'. 

Resources for further reading:

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How are uncertainties communicated in European national portals?

There is some experience from around the European Union of describing and working with uncertainties, and links are shown below.

Name Uncertainty guidance provided
Austrian Database on adaptation Contains a page on uncertainties. Lists uncertainties as one of the guiding principles (Leitprinzipen) for adaptation. Advocates stepwise planning, implementation and improvement of adaptation measures. Highlights sustaining / building resilience for sectors with a long planning horizon
Danish Portal for Adaptation to Climate Change No specific guidance. Reference is given to various external documents
Finland's Climate Portal Work in progress. Attractive scenario tool in development
KomPass Provides uncertainty guidance (in German) in various part of "Klimalotse" tool (1, 2, 3, 4)
National Climate Research, The Netherlands Work in progress as part of research project. Provides background document with terminology
Norwegian Climate Change Adaptation Programme No specific (English) guidance. Refers to background study and courses
UKCIP Uncertainty guidance accompanying the UKCP09 scenarios. Uncertainty page and background report.


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