change rcp settings for NDC-LTS scenarios

[RahelMA]

Purpose of this PR

Change the rcp settings for SSP2-NDC-LTS-my and SSP2-NDC-LTS-pf from rcp37 to rcp26.

This harmonizes the assumption with the MAgPIE settings SSP2|NDC|AR-natveg|nocc_hist|rcp2p6 for both scenarios.

This change solves the convergence issues in these scenarios in REMIND stand alone.

In REMIND stand alone runs this change reduced required carbon prices the default is rcp37

with small changes in the non land use emissions

Type of change

Indicate the items relevant for your PR by replacing ◻️ with ☑️.
Do not delete any lines. This makes it easier to understand which areas are affected by your changes and which are not.

Parts concerned

• ◻️ GAMS Code
• ◻️ R-scripts
• ◻️ Documentation (GAMS incode documentation, comments, tutorials)
• ◻️ Input data / CES parameters
• ◻️ Tests, CI/CD (continuous integration/deployment)
• ☑️ Configuration (switches in main.gms, default.cfg, and scenario_config*.csv files)
• ◻️ Other (please give a description)

Impact

• ☑️ Bug fix
• ◻️ Refactoring
• ◻️ New feature
• ◻️ Change of parameter values or input data (including CES parameters)
• ◻️ Minor change (default scenarios show only small differences)
• ◻️ Fundamental change of results of default scenarios

Checklist

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In the end all checkboxes must be ticked before you can merge.

• I executed the automated model tests (make test) after my final commit and all tests pass (FAIL 0)
• I adjusted the reporting in remind2 if and where it was needed
• I adjusted the madrat packages (mrremind and other packages involved) for input data generation if and where it was needed
• My code follows the coding etiquette
• I explained my changes within the PR, particularly in hard-to-understand areas
• I checked that the in-code documentation is up-to-date
• I adjusted forbiddenColumnNames in readCheckScenarioConfig.R in case the PR leads to deprecated switches
• I updated the CHANGELOG.md correctly (added, changed, fixed, removed, input data/calibration)

Further information (optional)

• Runs with these changes are here:

• Comparison of results (what changes by this PR?): /p/tmp/leaha/REMIND_2026_09_21/remind
compScen-NDC-LTS-pf-standalone-2026-09-24_09.20.58-H12.pdf
  and
  compScen-NDC-LTS-my-2026-09-24_09.27.57-H12.pdf

[dklein-pik]

I will be out of office this afternoon, so cannot engage in this discussion. If you are fine with the scenario design, I am, too. One question, however, why is the NDC combined with rcp26 in the MAgPIE config? Does this make sense? Wouldn't rcp37 or even rcp45 be closer than rcp26? And does the rcp switch have any effect in MAgPIE if nocc_hist is active at the same time, @mishkos ?

[mishkos]

I will be out of office this afternoon, so cannot engage in this discussion. If you are fine with the scenario design, I am, too. One question, however, why is the NDC combined with rcp26 in the MAgPIE config? Does this make sense? Wouldn't rcp37 or even rcp45 be closer than rcp26? And does the rcp switch have any effect in MAgPIE if nocc_hist is active at the same time, @mishkos ?

My understanding is that this is NDC-LTS scenario were net-zero targets are reached and the budget at the end of the century is closer to rcp26.
To you second point, changes rcps when we have nocc or nocc_hist doesn't have any effect. But it's good to have the right mapping for scenarios and rcps.

[RahelMA]

I will be out of office this afternoon, so cannot engage in this discussion. If you are fine with the scenario design, I am, too. One question, however, why is the NDC combined with rcp26 in the MAgPIE config? Does this make sense? Wouldn't rcp37 or even rcp45 be closer than rcp26? And does the rcp switch have any effect in MAgPIE if nocc_hist is active at the same time, @mishkos ?

My understanding is that this is NDC-LTS scenario were net-zero targets are reached and the budget at the end of the century is closer to rcp26. To you second point, changes rcps when we have nocc or nocc_hist doesn't have any effect. But it's good to have the right mapping for scenarios and rcps.

In these policy scenarios, there are no budgets only the policy targets. For This release, I believe it's closer to rcp26 as we also have carbon prices in the coupled version from 2030 that price land-use emissions. For the next release we should discuss if we prefer a way in-between!