Update docs for 2025/SSP 3.0/ScenarioMIP-CMIP7

[khaeru]

The ‘conceptual’ documentation contains, in its own words…

…a thorough methodological description of the particular, central, global-scope instance of MESSAGEix-GLOBIOM developed by the IIASA ECE Program, from which most other instances derive.

Put another way, the pages describe, in a generally non-technical way, how the model is designed and operated in order to provide a valid representation of real-world phenomena. “Non-technical” means with minimal mention of particular MESSAGE parameter or set names, set elements, orthe code used to manipulate these.

In 2023–2025, work on the SSP "3.0" updates and preparation of scenarios for ScenarioMIP-CMIP7 has involved many changes to these methods: both the structural representation of different parts of the energy system, and the data sources, particular values, and input data processing used to parametrize this structure.

The docs therefore need a corresponding update.

• These docs will serve multiple purposes:
  • As an introductory or “non-/less-technical” description of the ‘main’ global model instance.
  • As a source for material that will be referenced or reproduced elsewhere, e.g. in the IAMC wiki or the Supplementary Information of publications about this model instance or work that builds on it.
• These docs may in turn include references and links into more-technical documentation of code and data; thus these latter may also be updated to match.
• The work of updating the docs will be divided among many colleagues, but will also require integrative editing.

Things you can do:

• Comment below.
• Create sub-issues, or independent issues, linked to this one.
• Create PRs into the doc/2025-update branch / Update docs for 2025/SSP 3.x/ScenarioMIP-CMIP7 #425.

[khaeru]

@glatterf42 identified this comment on iiasa/message_data#431 by @gidden in 2023.

Note that the comment predates #99 and many other costs-related PRs here, which I'd guess have at least partly addressed the issue by consolidating and updating the info that Matt was referring to.

Whomever works on the section(s)/page(s) on costs for the current issue could double-check and, for instance, add links to any older material that is not yet linked.