Modeling sustainable development pathways

Sustainable development demands balancing ecological protection with socioeconomic prosperity; however, quantitative tools for assessing integrated policy strategies that achieve this balance are still limited. We developed the first modeling framework using the Sustainable Development Pathway Index (SDPI) as outcome to assess the impact of policy interventions on the sustainability of development pathways over time. Our framework models development as movement through two-dimensional space, where ecological infrastructure (measured by the proportion of land with high ecological integrity) and socioeconomic infrastructure (measured by the Human Development Index) interact dynamically. Applied to Costa Rica, we tested seven scenarios that combined conservation policies with varying levels of education investment from 2022 to 2050. Our results reveal that current policies produce negative SDPI values (−56.82 to −56.69), indicating unsustainable development trajectories, despite Costa Rica's environmental reputation. However, strategic policy combinations can shift this trajectory toward sustainability. Zero-loss policies for lands with high ecological integrity improve SDPI scores by 12.76 %, while combining zero-loss with active restoration achieves improvements of 15.43–15.58 %. Critically, increasing education investment to 8 % of GDP eliminates the economic costs associated with conservation policies. This study demonstrates that apparent trade-offs between environmental protection and socioeconomic development can be resolved through strategic policy integration. The modeling framework provides policymakers with a quantitative tool for developing evidence-based sustainable development strategies.