Small update in 44_biodiversity

[flohump]

🐦 Purpose of this PR 🐦

• Improvment and simplification for setting a lower bound for the BII

🔧 Checklist for PR creator 🔧

• Labeling pull request correctly from the label list.

• Low risk : Simple bugfixes (missing files, updated documentation, typos) or Start/output scripts
• Medium risk : New realization / Changes to existing realization / Other changes which don't modify default.cfg
• High risk : New input files (if cfg$input is changed in default.cfg) / Modification to core model (eg. changes in equations, calculations, introduction of new sets etc.) / Other changes in default.cfg

• Providing additional information based on PR label

• Low risk : No new model run needed.
• Medium risk : Default run based on the current version of the fork from which PR is made
• High risk
  • Default run from the current develop branch: MAgPIE PR399_SSP2−Ref_updated3
  • Default run based on the current version of the fork from which PR is made: MAgPIE PR400_2_SSP2−BII0−Mode1

• 📉 Performance loss/gain from current default behavior 📈
  • run time of the default of this PR is very simliar to the current develop.

Results of the default are unchanged:

Results for different lower bounds for the BII
cfg$gms$c44_bii_decrease <- 1: decrease of lower bound for BII is allowed in case the BII in the start year is above the provided lower bound.

cfg$gms$c44_bii_decrease <- 0: stricter implementation. No decrease of BII below the lower bound is allowed after the start year.

• Added changes to CHANGELOG.md
• Compilation check (model starts without compilation errors - use gams main.gms action=c in model folder for testing).
• No hard coded numbers and cluster/country/region names.
• The new code doesn't contain declared but unused parameters or variables.
• Where relevant, In-code comments added including documentation comments.
• Made sure that documentation created with goxygen is okay (use goxygen::goxygen() for testing).
• Changes to magpie4 R library for post processing of model output (ideally backward compatible).
• Self-review of my own code.
• For high risk runs: validation of major model indicators - Land-use, emissions, food prices, Tau. %Delete this line in case it is not a high risk run%

⚠️ Additional notes or warnings ⚠️

NA

🚨 Checklist for RSE reviewer 🚨

• PR is labeled correctly.
• CHANGELOG is updated correctly
• No hard coded numbers and cluster/country/region names.
• No unnecessary increase in module interfaces
• All required updates in interfaces (if any) have been properly adressed in the module contracts
• In-code comments and documentation comments are satisfactory.
• model behavior/performance is satisfactory.
• Requested changes (if any) were applied correctly

🚨 Checklist for MAgPIE reviewer 🚨

• PR is labeled correctly.
• CHANGELOG is updated correctly
• No hard coded numbers and cluster/country/region names.
• Changes to the model are scientifically sound
• In-code comments and documentation comments are satisfactory.
• model behavior/performance is satisfactory.
• Requested changes (if any) were applied correctly

[tscheypidi]

looks good

[pvjeetze]

One thing also caught my attenttion: Should the BII continue to decrease even with cfg$gms$s44_bii_lower_bound <- 0 and cfg$gms$c44_bii_decrease <- 0 as is the case right now?

[flohump]

Good point. I changed the implemenation such that the combination of
cfg$gms$s44_bii_lower_bound <- 0
and
cfg$gms$c44_bii_decrease <- 0
produceds a no decrease sceanrio.