Scenario-based assessment of payment for ecosystem services and forest carbon finance in Costa Rica

National payment for ecosystem services programs and voluntary carbon standards differ substantially in their data structures, accounting rules, and institutional objectives, limiting direct comparison. This study develops a matched-baseline framework to compare Costa Rica’s Payments for Environmental Services program (PES), the Gold Standard for the Global Goals (GS4GG), and Verra’s Verified Carbon Standard (VCS/VERRA) over 2024–2060. The framework combines ecological-support reconstruction, point-based PSA diagnostics, common annual quantities, explicit price and selected-fee cases, present-value accounting, and conditional price-level simulation. The primary analysis applies 1000,000 Mg CO₂e yr⁻¹ identically to all pathways, while the secondary analysis applies the same harmonized Costa Rica CO₂-support quantity. Under Case A, common quantities, a common price of USD 50 Mg CO₂e⁻¹ , and no fees produced identical cumulative fee-adjusted revenue of USD 1.850 billion. Under Case B, selected fees reduced this value to USD 1.839 billion for GS4GG and USD 1.840 billion for VCS/VERRA, while PES remained unchanged. Cases C and D generated larger differences because pathway-specific price trajectories were introduced as structural sensitivities. Conditional simulations using 10,000 mean-preserving lognormal price draws showed that wider price dispersion increased P10–P90 interval widths, while quantities, fees, and discounting remained deterministic. Ecological and PSA indicators were retained as contextual support rather than certified carbon quantities. The framework provides a transferable approach for separating quantity, price, selected-fee, discounting, and conditional price-level effects when heterogeneous forest-carbon finance pathways cannot be directly compared. • A matched-baseline framework compares heterogeneous forest-carbon finance pathways. • Common quantities separate price and selected-fee effects across PES, GS4GG, and VCS/VERRA. • Cases A–B provide principal comparisons; Cases C–D are structural price sensitivities. • Conditional price-level intervals vary prices while quantities, fees, and discounting remain fixed. • Selected PES reforms require separate empirical evaluation before policy implementation.