I'm a member of scientific staff at the Sector Integral Policy Analysis at PBL Netherlands Environmental Assessment Agency. My work is focussed on the effectiveness of environmental policy instruments.

The effectiveness of carbon pricing: a global evaluation
What has carbon pricing ever done for our planet? Our answer: it reduced cumulative global CO2 emissions by at least 13 Gt up to 2017. We estimate the effect of the adoption of carbon pricing policies across the globe up to 2017 on per capita CO2 emissions from fossil fuel combustion. We apply recent econometric techniquesrobusgt to treatment effect heterogeneity and find reductions of 8 to 12 percent on average. The estimated dynamic treatment effects increase in absolute terms in the post-implementation period and stabilize after 10 years. The total estimated reduction in emissions per capita after 10 years is around 19-23 percent. This reduction in emissions was triggered by substitution of CO2-intensive fuels with clean alternatives. The observed carbon prices in our sample do not have much explanatory power on the variation in emission levels. Hence, our results are likely to be driven by anticipatory responses due to a shift in expectations, induced by carbon pricing policies, toward higher prices in the future. The paper, published in Environmental and Resource Economics, is joint work with Suphi Sen, Serhan Sadikoglu and Changjing Ji and can be found [here] (open access!).

Doeltreffendheid en doelmatigheid van geselecteerde stikstofbronmaatregelen: Monitoring en Evaluatie van het Programma Stikstofreductie en Natuurverbetering 2026
Als onderdeel van de monitoring en evaluatie van het beleid voor stikstofreductie en natuurverbetering (uitgevoerd door PBL, RIVM en WUR) heb ik bijgedragen aan het rapport 'Doeltreffendheid en doelmatigheid van geselecteerde stikstofbronmaatregelen'. In dit rapport analyseren we de doeltreffendheid en doelmatigheid van vier beëindigingsregelingen in de landbouw en twee subsidieregelingen voor de aanschaf van schonere technologieën. We concluderen dat de grootste beëindigingsregelingen (de Lbv en de Lbv-plus) tenminste in enige mate doeltreffend zijn: ze hebben geleid tot emissiereducties die zonder de regelingen niet zouden hebben plaatsgevonden. Melkveehouders nemen relatief minder vaak deel aan deze regelingen dan varkenshouders. Daarnaast nemen vooral oudere veehouders, vaak zonder opvolger, deel. Belangrijke redenen om niet deel te nemen aan de regelingen zijn het doorstartverbod en gunstige marktprijzen. Een zinvolle analyse van de verhouding tussen kosten en effecten van de regeling bleek onmogelijk. De Subsidieregeling verduurzaming binnenvaart leidt waarschijnlijk tot emissiereducties die zonder de regeling niet zouden hebben plaatsgevonden. De synthese van het onderzoek van het consortium staat [hier]. Het rapport over doeltreffendheid en doelmatigheid staat [hier].

Adoption of inland valley farming and rice production practices: Evidence from smallholder farmers in Côte d’Ivoire and Ghana
Inland valley wetlands in West African countries are considered to hold immense potential for rice-based production systems. Policies to increase rice production in inland valleys have until now not lived up to expectations. Previous studies have examined biophysical factors that affect the adoption of inland valley farming, but little empirical work has explored the socio-economic drivers of adoption. This study explores the determinants of farmers’ decisions to adopt inland valley farming and rice production in Côte d’Ivoire and Ghana using probit model with data collected from 742 farmers. We show that owners of perennial tree crops are less likely to adopt inland valley farming and rice production than non-owners. This could be because perennial tree crops yield higher economic returns and provide financial stability, also for the next generation, than inland valley farming and rice production. Furthermore, farm size positively correlates with inland valley farming, but households with larger farms tend not to opt for rice production. Our results underscore that the relation between farm size and agricultural production decisions may depend on the type of agricultural practice. These results suggest that policymakers could strengthen local institutions and service providers to target specific groups of farmers when promoting inland valley farming and rice production. The paper, published in Agricultural and Resource Economics Review , is joint work with Tesfahun Alemayehu Belew and can be found [here] (open access!).

Did the German aviation tax have a lasting effect on passenger numbers?
The taxation of aviation is a frequently discussed component of governments’ efforts to mitigate greenhouse gas emissions. This study examines the impact of the German aviation tax on passenger numbers during the period 2011–2019 using five panel data estimators and a Specification Curve Analysis (SCA) to assess the robustness of the results to changes in the specifications of the econometric model. Employing five base models, we find that the tax induced a 6–11% reduction in the number of passengers departing annually from Germany in the first two years after implementation. For later years, estimated effects are more ambiguous. The SCA, comprising 175 alternative specifications, corroborates our main findings while showing a slightly wider range of effect sizes, especially on the upper bound. The results show that the choice of econometric method can affect research outcomes, especially for the fourth year of the tax and onward. The paper, published in Transportation Research Part D: Transport and Environment is joint work with Viola Helmers, can be found [here]. (open access!!)