WITCH_Circular v1.0 dataset

Data archive accompanying the manuscript: Magalar, L., Drouet, L., Szklo, A., Verdolini, E. (2026). The conditional role of circular economy in low-carbon transitions: a stock-flow integrated assessment with WITCH-Circular. Journal of Cleaner Production (under review). Overview This repository archives the input data and post-processed outputs of WITCH-Circular v1.0, an extension of the WITCH v5.0 integrated assessment model that embeds dynamic stock-flow material accounting and a circular economy (CE) policy portfolio. The framework tracks in-use material stocks, inflows, and outflows for steel, aluminium, copper, and cement across 20 world regions from 2005 to 2100, and operationalises three CE strategy families: Narrow (material efficiency, vehicle downsizing, lightweighting, and mobility demand reduction), Slow (lifetime extension and component reuse), and Close (recycling and secondary use). Results cover 15 scenarios combining three climate pathways (SSP2 current policies, SSP2–2°C, SSP2–1.5°C) with five CE configurations (No-CE baseline, Narrow, Slow, Close, All-CE). Repository contents The archive contains 16 data files grouped into three categories: Pre-processing inputs — harmonised material intensity coefficients for electricity generation, grid infrastructure, and light-duty vehicles; time-varying market shares for technology subtypes (solar PV, wind drivetrain, battery chemistry); vehicle lightweighting and downsizing parameters; and circular economy policy parameters covering recycling and reuse rate trajectories. LCA emission factors — Premise-generated, scenario-specific emission factors (kgCO2e/kg) for primary and secondary production of all four materials, across the three climate scenarios. Generated with Premise v2.0 applied to the Ecoinvent v3.10.1 database. Post-processed results — consolidated model outputs underlying every figure and table in the paper, provided as a complete database (gzip-compressed CSV, ~2 million rows) and three aggregated summary tables (annual global flows, cumulative material totals, and cumulative emissions reductions). Full provenance and primary literature sources for each individual data file are documented in DATA_SOURCES.md, which also lists every reference used to compile the input coefficients. Headline numbers (cumulative 2020–2100, SSP2 current-policies pathway) Under the combined All-CE configuration, cumulative steel demand falls by 42.7% (8.86 Gt avoided), copper by 28.9% (0.47 Gt avoided), and cement by 9.3% (3.88 Gt avoided). Aluminium demand increases slightly due to substitution dynamics in transport that increase aluminium content while reducing steel content per vehicle. The full distribution across the 15 scenarios is available in witch_circular_cumulative_summary.csv. Scope of the archive The WITCH v5.0 model source code is proprietary to CMCC and is not included in this archive. The R post-processing scripts that produce the consolidated database from WITCH GDX outputs are also not redistributed publicly. Both are available on request from the corresponding author and from the CMCC team (https://www.witchmodel.org/). The aggregated result files provided here allow all paper figures and tables to be regenerated directly, without GAMS or a WITCH license. License Creative Commons Attribution 4.0 International (CC BY 4.0). Third-party data redistributed in aggregated or transformed form retain their original sources, which are credited individually in DATA_SOURCES.md.