In contrast with SoE reports that typically assess past and current trends and dynamics, IEAs combine retrospective integrated analyses with future outlook. Defining the temporal scale—how far do you look back and ahead—is important for conceptual clarity. There are also important methodological and technical implications.
Setting the retrospective boundary is relevant in Module 5, while the future outlook matters for the scenario analysis discussed in Module 6.
When considering the temporal scale, the key questions you may want to ask and answer include:
- Is the time scale on which you need to report explicitly defined in the mandate for the IEA? If this is the case, there is little room for flexibility.
- In which time scale do the environmental issues you want to assess show significant or detectable change?
- Do you need to use one time scale for all of your issues, or can you choose time scales as required by the dynamics of any given environmental issue?
- How far back do you expect to have reliable data?
- How far into the future do you need to or can you project environmental trends?
An additional question to consider is whether the time horizon chosen could or should be linked to a landmark event say, the publication of a key report, a political declaration or some other milestone that can serve as a point of comparison both from the policy and progress point of view. The key point is that besides technical feasibility and scientific rationale, a time should be chosen that also helps maximize the impact of the assessment.