Scenario

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Scenario is a set of assessment-specific deliberate deviations from the results of one or more variables in the assessment. It is noteworthy that the result of a variable is the current best estimate of the truth; therefore, scenarios are deliberate deviations from the truth because they serve the functionality of learning what would happen if this was the situation (compared with a baseline, business-as-usual, or other scenarios). There are also alternative definitions that are slightly different from the one used in the Intarese framework or in open assessment:

1. Archetypal descriptions of alternative images of the future, created from mental maps or models that reflect different perspectives on past, present and future developments.
2. A coherent, internally consistent and plausible description of a possible future state of the world.
3. Variation in the assumptions used to create models.
4. A synthetic description of an event or series of actions and events. <section end=glossary />

Question

What are scenarios and how should they be used in open assessment?

Answer

Definition

A scenario is a set of assessment-specific deliberate deviations from the results of one or more variables in the assessment.

There are two main ways of using scenarios in open assessment: 1) as decision options and 2) for excluding unwanted parts of results of variables.

Scenarios as decision options

Scenarios can describe possible worlds were a set of decision options are selected over some other options. Using several scenarios, it is possible to perform an assessment where all interesting combinations of decisions are explicitly evaluated against each other. For more details, see Decision, and for an example, see Climate change policies in Kuopio.

Scenarios for excluding unwanted parts of variables

The world is very rich and diverse, and often this richness would make assessments very complex or computationally large if everything that is related would be included. In some cases, it is useful to limit the assessment by either excluding whole variables, some locations of selected indices, or some values from the probability distribution of the result. Excluding such parts of an assessment may increase the usability and acceptability of the resulting simpler assessment although the assessment may not be as calibrated description of the truth as the full assessment would be.

This makes it possible for the assessor to choose a belief system that deviates from the belief system of the open community without violating the rules of open assessment. However, all deviations become explicit in this way, which makes it possible for others to evaluate the results of the assessment against their own belief systems. This is one answer to the very common "Who decides" question asked by almost all audiences not familiar with the concepts of open assessment: the assessor may decide what is included in his or her particular assessment, but he or she may not decide what descriptions are used in general or in other assessments.

See also

• 2052-A Global Forecast for the Next Forty Years, written by Jorgen Randers
• MATCH geoportal (Metadata Access Tool for Climate and Health)
• MM5 Community Model The PSU/NCAR mesoscale model (known as MM5) is a limited-area, nonhydrostatic, terrain-following sigma-coordinate model designed to simulate or predict mesoscale atmospheric circulation.
• RCPs from IIASA (Representative Concentration Pathways (RCPs))
  • Database v. 2
• University Corporation for Atmospheric Resarch