Exploring decarbonisation strategies in the Southern-European region of Catalonia through a multi-scenario assessment

This study evaluates decarbonisation pathways for the southern European region of Catalonia, addressing the critical gap of downscaling biophysical system-dynamics models to regional contexts. We explore variations in economic growth, energy efficiency, and renewable energy deployment. Using pymedeas2 , a system dynamics-based integrated assessment model, we assess the implications of these pathways for climate change mitigation, land use, and energy demand. Scenarios that combine post-growth strategies with strong renewable expansion and efficiency gains achieve superior outcomes across these dimensions. In the reference scenario, GDP per capita stabilises by 2040 while ambitious renewable and efficiency targets are met. The most sustainable pathway reduces cumulative CO 2 emissions by 21.0% and renewable land use by 15.4% relative to the reference, remaining within Catalonia’s fair-share carbon budget of 495 MtCO 2 . In contrast, under a high-growth scenario with delayed efficiency gains, this limit is exceeded, reaching 793 MtCO 2 in cumulative emissions and increasing land-use requirements by 1.8%. These findings show that combining post-growth strategies with energy system decarbonisation can enable Catalonia to meet climate targets while reducing spatial and ecological pressures. The analysis highlights the urgency of a paradigm shift from purely supply-side technological fixes towards demand-side sufficiency policies. The pymedeas2 framework provides a transferable approach for evaluating context-specific transition pathways under ecological constraints which could be applied to other regions. • Multi-scenario analysis reveals critical land-use and emissions trade-offs in regional decarbonisation. • Post-growth transition strategies achieve highest sustainability, reducing cumulative emissions by 21.0% and land use by 15.4%. • Growth-oriented scenarios exceed Catalonia’s proportional carbon budget of 495 MtCO 2 and increase land requirements. • The enhanced pymedeas2 model provides a transferable framework for regional energy transition analysis. • Energy efficiency improvements alone are insufficient without complementary demand-reduction measures.