The RICE50+ model

Version 1.5.0 This is RICE50+, a multi-regional Integrated Assessment Model, described in the paper Gazzotti et al. (2021): 'Persistent inequality in economically optimal climate policies', Nature Communications, 12, Article number: 3421, https://www.nature.com/articles/s41467-021-23613-y

A calibrated multi-regional Integrated Assessment Model with 50+ regions, calibrated abatement cost curves, a modular and phase structure of the code, and additional optional modules.

Requirements

1. Installation: Install GAMS, Github Desktop, (and optionally VSCode as advanced editor)

• GAMS from https://www.gams.com/download/ (Run the installer in advanced mode and mark the check-box Add GAMS directory to PATH environment variable).
• GitHub Desktop from https://desktop.github.com/ and log-in with your personal GitHub Account.
• VisualStudio Code from https://code.visualstudio.com/ (optional)

2. GAMS license

• In order to run the model, you need a GAMS license and CONOPT license. You can request a temporary license from gams https://www.gams.com/download/ but for serious model runs you will need a full license, academic and non-for-profit versions might be available. Once you obtain the license as gamslice.txt file, copy this file to your GAMS folder.

Create the data folder, run the model, and analyze results

3. Get the source code of the RICE50x model: Either cloning it in Github desktop (preferred), download it from https://github.com/witch-team/RICE50xmodel, or using git at the command line.

4. Download and unzip calibrated input data from https://github.com/witch-team/RICE50xmodel/releases/download/v1.5.0/data_ed57.zip and into the same folder.

5. Run the model in gamsIDE (creaing a project file in the RICE50x folder) or on the command line:

gams run_rice50x.gms

6. [OPTIONAL] Analyze and visualize model output, using the produced results_*.gdx files in the RICE50x folder. This can be done in GAMS itself, or exporting to Excel, or using your sofwrate of choice with a gdx importing possibility. You can also get the "witch-plot" repository from github (https://github.com/witch-team/witch-plot) download it to the same root folder as RICE50x, and after running the model, launch teh interactive visualization tool:

Rscript plotgdx_rice50x.R

Main setting flags for the RICE50x to be set in run_rice50x.gms

What follows is a summary of main model settings. Bold elements are model default values.

flag	values	description
policy	bau bau_impact cba cbudget ctax	BAU without damages BAU with damages cost-benefit analysis carbon budget carbon tax
baseline	ssp1 ssp2 ssp3 ssp4 ssp5	Shared Socio-Economic Pathway for TFP, population, and carbon intensity baseline
cooperation	coop noncoop coalitions
impact	off dice burke dell kalkuhl howard
climate	dice2016 witchco2 cbsimple	dice 2016 dice with coeffs. corrected as in witch Simple transient concentration response
savings	fixed flexible	Fixed saving rates (converging to DICE optimal in 2150) Free saving rates