Welcome! I am a fourth-year PhD student in Economics at the University of Southern California.
My research focuses on International Trade, Spatial Economics, and Environmental Economics.
Prior to my doctoral studies, I studied at SciencesPo Paris and Universitat Pompeu Fabra. I also worked at SciencesPo Paris, the European Central Bank, and the OECD. You can view my CV here.
Feel free to reach out via email: pcoster@usc.edu.
Working Papers
Firms’ Supply Chain Adaptation to Carbon Taxes
Co-authored with Julian di Giovanni and Isabelle Méjean
📚 CEPR Discussion Paper: No. 19644 - FRBNY Staff Report: No. 1136 (v.Nov24)
Abstract
This paper studies how firms adjust input sourcing in response to climate policy. Using the EU Emissions Trading System (ETS) as a natural experiment and French product-level import and production data, we show that firms increasingly shifted imports of ETS-regulated inputs to non-EU countries over the 2010s as the policy became more stringent, indicating carbon leakage. This leakage is economically significant: the share of ETS-regulated products sourced from outside the EU rose by 4.3 percentage points after the ETS was implemented. Motivated by these empirical findings, we estimate a heterogeneous firm model using pre-ETS data. Simulating the model under a EUR 100 carbon tax reproduces observed leakage, raises domestic prices and modestly reduces French emissions. Adding a carbon tariff similar to the EU’s Carbon Border Adjustment Mechanism (CBAM) reverses the leakage but further increases prices. The combined ETS+CBAM regime is seven times more effective than the ETS alone in reducing emissions.
Work in Progress
Supply Chain Composition and Carbon Pricing: Evidence from the EU ETS
with Hubert Massoni and Lauri Esala
Teaching
Teaching Assistant
Intermediate Macroeconomics (Undergraduate level)
University of Southern California, Prof. Robert Dekle – Fall 2025Macroeconomic Theory II (PhD level)
University of Southern California, Profs. Pablo Kurlat and Andy Neumeyer – Spring 2025Introduction to Macroeconomics (Undergraduate level)
University of Southern California, Prof. Lodovico Pizzati – Fall 2024
Student EvaluationsMacroeconomic Bootcamp (PhD level, core exam preparation, main instructor)
University of Southern California, Profs. Pablo Kurlat, Caroline Betts – Spring 2024
Tutoring and Grading Assistant
The Price of Democracy: Media, Participation, and Elections
(Translated from “Le prix de la démocratie : Médias, participation et élections”)
Sciences Po Paris, Prof. Julia Cagé – Spring 2022Introduction to Macroeconomics
Columbia University Undergraduate Programs in Paris – Fall 2021