Uncertainty

The definitions below refer to Adaptation to Climate Change.

Definitions

European Definitions

CLIMATE-ADAPT

Uncertainty is an expression of the degree to which a value (e.g. the future state of the climate system) is unknown.

Uncertainty can result from lack of information or from disagreement about what is known or even knowable. It may have many types of sources, from quantifiable errors in the data to ambiguously defined concepts or terminology, or uncertain projections of human behaviour. Uncertainty can therefore be represented by quantitative measures, for example, a range of values calculated by various models, or by qualitative statements, for example, reflecting the judgement of a team of experts.

RESIN project

The RESIN project gives the following definition:

A state of incomplete knowledge that can result from a lack of information or from disagreement about what is known or even knowable.

National Definitions

Germany

Unsicherheit: Ein Ausdruck für das Ausmaß, in dem ein Wert ungewiss ist (z. B. der zukünftige Zustand des Klimasystems).

Unsicherheit entsteht durch einen Mangel an Information oder durch Meinungsverschiedenheiten darüber, was bekannt ist oder überhaupt bekannt sein kann. Unsicherheit kann viele Quellen haben, von bezifferbaren Fehlern in Daten bis hin zu mehrdeutig formulierten Konzepten und Terminologien oder unsicheren Projektionen über menschliches Verhalten. Unsicherheit kann deshalb entweder quantitativ angegeben werden, z. B. durch eine Auswahl von berechneten Werten aus verschiedenen Modellen, oder durch qualitative Aussagen, die das Urteil eines Expertenteams wiedergeben.

Uncertainty can result from lack of information or from divergent opinions about what is or can be known.

There may be many causes of uncertainty: faulty data, ambiguous concepts and terminology, or uncertainty about how people will behave. Uncertainty may be expressed in figures – for example where different climate models arrive at different forecasts about the rise in temperature. however, uncertainty may also be a qualitative statement by a team of experts.

Norway

Usikkerheten knyttet til analyseresultatene uttrykkes gjennom en vurdering av kunnskapsgrunnlaget de bygger på og resultatenes følsomhet for endringer i scenarioets forutsetninger og sentrale antagelser i analysene.

Uncertainty related to the analysis results is expressed through an assessment of the knowledge base they are built upon, and the sensitivity of the results to changes in the prerequisites for the scenario and key assumptions in the analyses.

Sweden

Uncertainty in the context of National Risk Assessment refers to the type of knowledge that exists about a particular event and how reliable this knowledge is as a basis for assessing the likelihood that the event will occur, as well as its impacts, should the event actually occur. Uncertainty may thus refer to the assessment of likelihood and/or the assessment of impacts.

United Kingdom (UK)

Uncertainty ia situation where the current state of knowledge is such that (1) the order or nature of things is unknown, (2) the consequences, extent, or magnitude of circumstances, conditions, or events is unpredictable, and (3) credible probabilities to possible outcomes cannot be assigned.

United States

DHS

Uncertainty is the degree to which a calculated, estimated, or observed value may deviate from the true value.