Sarah Meier

Sarah Meier, Ben Balmford, Michela Faccioli & Ben Groom

Biodiversity is a multifaceted component of natural capital and challenges traditional valuation methods. We therefore propose a cost-based approach, novel in its application to biodiversity, and seek to define a metric that accurately reflects within-class substitutability of different biodiversity attributes. Preferences from the British public over key biodiversity attributes are elicited through a choice experiment, while eschewing problematic money-biodiversity trade-offs, and compared to the preferences of experts. The findings indicate a consensus between public and expert preferences regarding within-class substitutability, prioritising species richness and reduced extinction risk over increased intactness. Furthermore, we apply the preference-derived metric in a case study of optimal conservation restoration policy for Great Britain to determine shadow prices which enable policymakers to value biodiversity within cost-benefit analyses. Targeting the Kunming-Montreal Global Biodiversity Framework 30-by-30 commitment, our proposed utility metric suggests a biodiversity shadow price of approximately £45 million per 1% of the available uplift. Thus, this paper establishes preference-aligned marginal rates of substitution for within-class attributes, determining a metric which is applied to calculate a robust cost-based shadow price for across-class substitution.

Sarah Meier, Ben Balmford & Ville Inkinen

The world has lost one-third of its forests, with those in the tropics facing the most rapid decline despite their substantial ecological and climate benefits. Protected areas (PAs) have become the primary policy instrument to curb deforestation, yet they are often established where deforestation pressure is relatively low and potential conservation gains are limited. We evaluate how endogenous policy targeting shapes the additionality of PAs established in Bolivia between 1991 and 2023. We employ a staggered difference-in-differences design, matching treated and control units on a novel measure of predicted deforestation risk in the absence of protection, generated using a Random Survival Forest model. This framework allows us to evaluate treatment effects across the distribution of baseline deforestation risk. Our estimates indicate that, on average, PAs reduce deforestation by approximately 0.19 percentage points (pp), corresponding to a 68% reduction relative to the national deforestation rate over the study period. However, average treatment effects mask substantial heterogeneity across the deforestation risk distribution, with no evidence of additionality in low-risk areas and the largest effects emerging under high deforestation pressure, where PAs reduce deforestation by up to 0.50~pp. Furthermore, while PAs are disproportionately established in low-risk areas, we find limited evidence that this reflects systematically greater biodiversity or carbon gains, or that protection in high-risk areas substantially hinders economic development. Overall, our findings suggest that endogenous targeting is a key determinant of conservation additionality, highlighting the importance of prioritising conservation in high-deforestation-risk regions.

Christopher Knittel, Benjamin Krebs & Sarah Meier

Climate change shapes population movements globally. While extreme weather events such as hurricanes and heat waves have drawn much attention for their impact on migration, gradual environmental deterioration remains underexplored. One such stressor is wildfire smoke, which in the United States has reversed decades of air quality improvements. We show that in California, higher wildfire-specific fine particulate matter (PM2.5) concentrations significantly increase out-migration, both within the state and across state borders, with effects concentrated in years of extreme smoke. Using 2006-2019 county-level migration data linked to high-resolution smoke exposure estimates, we find that a 1 μg/m3 increase in average annual smoke PM2.5 raises within-state and cross-state border out-migration by 2.2% and 3.6%, respectively, with wealthier residents disproportionately driving the effects. These results reveal that wildfire smoke acts as a sustained driver of relocation, thereby exacerbating environmental inequalities as lower-income populations face greater barriers to adaptation and remain more exposed. Our results provide novel empirical evidence on the consequences of climate-driven environmental degradation, highlighting migration as a long-term adaptation strategy with broad relevance for other slow-onset environmental hazards worldwide.