WORKING PAPERS 2026


2026-4

The Unequal Burden of Heat: Spatial Heterogeneity in Productivity Responses in French Agriculture

Thomas Jacquet

Abstract
This article assesses the short- and medium-term effects of extreme heat on agricultural productivity across French departments during 1980-2023. Using high-resolution ERA5-Land temperature data and CORINE Land Cover, we construct a sector-specific Extreme Degree Days (EDD) index, weighted by cropland and pasture shares to capture sector-specific thermal stress. We estimate department-specific impulse responses via local projections and find significant and persistent productivity losses following heat shocks above 29 °C, with effects intensifying over a four-year horizon and attenuating only modestly thereafter. A Wald test confirms substantial regional heterogeneity in sensitivity to extreme temperatures. The negative impacts are particularly pronounced in lower-productivity, livestock-oriented departments clustered between 44.5° and 46° north latitude. These findings underscore the macroeconomic relevance of a spatially disaggregated measure of exposure to extreme temperatures and highlight the urgency of region-specific adaptation strategies as these episodes intensify.
Mot(s) clé(s)
Agriculture; Climate change; Extreme heat; France; Productivity
2026-3

Fostering energy transition and transport fluidity in European port cities

César Ducruet, Mariantonia Lo Prete

Abstract
Europe as a whole is often regarded as a frontrunner in the domain of port-city sustainability, thanks to a wide set of international, national, and local initiatives. This paper is a review of local initiatives that are either individual (single port city) or collective (partnerships among several port cities), in the domains of energy transition and transport fluidity. We find that individual initiatives concentrate in northern Europe, in the largest ports, and at a few southern ones like Valencia or Marseilles. Conversely, collective actions are more concentrated in the south, including mostly small and medium-sized port cities, through projects financed by the European Commission. Besides, we show that port-urban congestion and PM2.5 pollution concentrate in the demographically and logistically largest port cities, which also dominate container throughput rankings and have the highest number of initiatives. We discuss the imperatives of ensuring a better regional balance across the continent and its port-city hierarchy.
Mot(s) clé(s)
congestion; energy transition; Europe; population exposure; port cities; transport fluidity
2026-2

Towards a Demand for Money Measurement ? Application to the German hyperinflation of the early 1920s

Georges Prat

Abstract
An accounting measure of the demand for money is deduced from the Allais’ “Fundamental Equation of Monetary Dynamics”. Data from German hyperinflation in the early 1920s illustrate the method we propose. The spread between money supply and money demand is found to be rather moderate but is not white noise. Our approach can be applied to any country and over any period, provided that the aggregate expenditure can be approximated using available data. This new way can help improve the estimation of the money demand function while avoiding arbitrary assumptions about the dynamics of the spread between money supply and money demand.
Mot(s) clé(s)
demand for money, measure
2026-1

Low-Carbon Hydrogen Deployment Under Trade Liberalization Policies

Benjamin Trouve

Abstract
Reaching global net-zero by 2050 requires rapidly scaling low-carbon hydrogen, but deployment is hindered by market uncertainty, high capital costs, and weak supply-demand coordination. This paper examines whether liberalizing international hydrogen and ammonia trade can accelerate deployment and how such policies interact with technological innovation. We develop a hybrid framework combining a global TIMES-based energy-system model (KiNESYS-IFPEN) with a stochastic logistic diffusion model calibrated to historical renewable energy growth under imperfect expectations. We find that trade liberalization alone has limited global impact, and mainly reallocates production geographically: the Middle East, North America, Latin America, and China expand as exporters, while Asia Pacific, Europe and Africa become structural importers. Innovation-driven electrolyzer cost reductions raise significantly global deployment success shifting production toward electrolysis. When policies are combined, innovation dominates, while trade openness reinforces regional specialization. These results underscore the central role of technological progress, credible expectations, and the trade-off between cost-efficient specialization and hydrogen supply security.
Mot(s) clé(s)
Hydrogen, Trade Policies, Technology diffusion, TIMES-Markal model.
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