This repository contains the integrated assessment model setups used to develop the scenarios informing the study Decarbonization Pathways and Equity Implications of Pakistan's Climate Ambition.

NEST-Pakistan (Nexus of Energy, Systems and Transitions) is a multi-sector modelling framework for Pakistan that examines the interlinkages between Energy, Water, and Agriculture in the context of climate change and sustainable development.

Repository structure

NEST-Pakistan/
├── MESSAGEix-Pakistan/
│   ├── data/
│   │   ├── MESSAGEix-Pakistan-CurrentMeasures-SSP2.xlsx   # CM scenario input
│   │   ├── MESSAGEix-Pakistan-NDC-U-SSP2.xlsx             # NDC-U scenario input
│   │   ├── MESSAGEix-Pakistan-NDC-C_NZ-SSP2.xlsx          # shared input for NDC-C and NZ
│   │   ├── emissionAllocation.xlsx                        # emission trajectories for the NDC scenarios
│   │   └── legacy/                                        # inherited ENGAGE_SSP2_v417 run configuration and default tables for reporting
│   ├── notebooks/
│   │   ├── current_measures.ipynb                         # build → solve → report — one notebook per scenario
│   │   ├── ndc-u.ipynb
│   │   ├── ndc-c.ipynb
│   │   └── net-zero.ipynb
│   ├── scripts/
│   │   ├── calibrate_t_d.py                               # historical-activity calibration for transmission/distribution technologies
│   │   ├── reserve_margin.py                              # reserve-margin (res_marg) constraint on elec_t_d
│   │   ├── emissions.py                                   # emission-bounds for NDC-U, NDC-C and Net Zero
│   │   └── utilities/                                     # shared helper functions used across scripts
│   ├── report/
│   │   ├── __init__.py
│   │   └── legacy/                                        # inherited MESSAGEix-GLOBIOM ENGAGE reporting code (IAMC output)
│   └── output/                                            # generated IAMC report files (timestamped)
├── docs/
│   ├── energy/                                            # MESSAGEix-Pakistan documentation
│   ├── water/                                             # Water pillar (planned)
│   └── agriculture/                                       # Agriculture pillar (planned)
└── requirements.txt

MESSAGEix-Pakistan

MESSAGEix-Pakistan directory contains the input excel workbooks, the scenario notebooks, and the reporting files. The data/legacy/ and report/legacy/ directories are inherited from the MESSAGEix-GLOBIOM ENGAGE reporting routines and adapted for the Pakistan node. Reporting is invoked from report/legacy/iamc_report_hackathon.py. Four scenarios are developed: Current Measures (CM), NDC-Unconditional (NDC-U), NDC-Conditional (NDC-C), and Net Zero (NZ). Each is solved through GAMS, and reported in an IAMC format by a dedicated notebook.

Prerequisites

This is not a self-contained Python package; reproducing requires the full MESSAGEix toolchain:

• GAMS with a valid academic licence. The scenario.solve() step calls the GAMS backend. We used version 40.
• message_ix and ixmp version 3.9.0 were used.
• Python version 3.12.7 was used.

GAMS must be installed separately. Please consult https://docs.messageix.org/en/latest/install.html for the complete MESSAGEix installation guide. The Python dependencies are listed in requirements.txt.

Scenarios

Scenario	Notebook	Scenario name (ixmp)	Input workbook	Emission treatment
Current Measures	current_measures.ipynb	current-measures	MESSAGEix-Pakistan-CurrentMeasures-SSP2.xlsx	none (baseline)
NDC-Unconditional	ndc-u.ipynb	ndc-u	MESSAGEix-Pakistan-NDC-U-SSP2.xlsx	emission bounds from emissionAllocation.xlsx
NDC-Conditional	ndc-c.ipynb	ndc-c	MESSAGEix-Pakistan-NDC-C_NZ-SSP2.xlsx	emission bounds from emissionAllocation.xlsx
Net Zero	net-zero.ipynb	net-zero	MESSAGEix-Pakistan-NDC-C_NZ-SSP2.xlsx	emission bounds from net_zero_emissions()

Provenance and attribution

MESSAGEix-Pakistan is built on the message_ix and ixmp framework developed by IIASA. Please cite message_ix (Huppmann et al., 2019, Environmental Modelling & Software) and acknowledge GAMS alongside any use of this repository.

Documentation

Full documentation lives under docs/ and is organized by sector pillar:

Pillar	Status
Energy	Active
Water	Planned
Agriculture	Planned