SSP-Consistent Pathways and Circular Economy Interventions for Global Cement of the 21st Century

Global cement production grew 250% between 1990 and 2019 and today accounts for 5-8% of annual CO₂ emissions. Chinese demand, which represents half of global production, has likely peaked, but growth in regions like Sub-Saharan Africa and India is expected to continue. Cement is “hard-to-abate”: most emissions arise from limestone calcination, and kilns require temperatures above 1,300 °C. If alternative chemistries remain niche, carbon capture and storage (CCS) may be the only route to near-zero emissions, though technology, cost, and storage remain uncertain. Demand reduction - through sufficient living, efficient design, or material substitution - offers complementary mitigation pathways as part of Circular Economy (CE).

Quantifying CE impacts on cement demand is challenging. Global material flow analysis (MFA) models often rely on stock-saturation assumptions, limiting their ability to capture levers such as material intensity or sufficiency, and complicating alignment with end-use models like for buildings. Service-based MFA models exist but are usually regional or sector-specific; a global framework covering all cement-using sectors is lacking.

We propose an integrated MFA framework combining detailed bottom-up service-demand modelling with comprehensive top-down estimates. Residential and commercial building stocks are modelled bottom-up but harmonized with top-down totals, while industrial building and civil engineering demand is inferred top-down. The harmonization is achieved by a novel semi-analytical reconciliation algorithm that adjusts parameters according to their uncertainty, following maximum likelihood estimation (MLE) principles. This approach enables the comprehensive coverage required for integrated assessment models (IAMs) while retaining sufficient detail for CE assessment. We construct scenarios of CE penetration, focusing on material efficiency, sufficiency, and beyond, producing regional projections for clinker, cement, and concrete/mortar demand. As part of the “REMIND Materials” effort, this development improves industry representation in the REMIND IAM, forming the foundation for comprehensive future assessments of both supply- and demand-side mitigation options for basic materials.