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• Mardi 22 novembre 2022 : Tanguy Bernard (Université de Bordeaux) - "Contracting and quality upgrading: evidence from an experiment in Senegal".

Nous menons une expérience randomisée avec des producteurs d'arachide au Sénégal pour aborder les obstacles à l'amélioration de la qualité. Nous proposons un contrat groupé pour encourager l'utilisation d'une nouvelle technologie d'amélioration de la qualité. Les producteurs à qui le contrat a été proposé de manière aléatoire sont beaucoup plus susceptibles d'acheter la technologie. Dans les zones où la qualité est autrement plus faible en raison des conditions agro-climatiques, les producteurs sont significativement plus susceptibles de se conformer aux normes internationales. Au niveau du marché, la présence d'acheteurs insensibles à la qualité mine l'arrangement contractuel relationnel entre les agriculteurs et les coopératives. Nous constatons que les producteurs augmentent en moyenne leurs ventes de produits aux coopératives, mais cette augmentation est de faible ampleur.

• Jeudi 29 Septembre 2022 : Markus Herrmann (Département d'Economie, Université Laval, Québec) - "Amending Pigou: private and social value of environmental consciousness and habit formation".

Nous examinons l'introduction d'une nouvelle version d'un produit présentant des caractéristiques environnementales supérieures sur un marché qui était auparavant desservi par une industrie concurrente produisant un produit de type brun. Grâce à la marque et à la publicité, les consommateurs, bien qu'incapables de distinguer les producteurs de produits bruns entre eux, sont capables de distinguer le nouveau produit du produit traditionnel. Les consommateurs sont conscients de l'environnement, leur conscience s'exprimant par une réduction de leur volonté de payer pour toute unité d'un type de produit donné en fonction du dommage total généré par la production de ce type. En même temps, ils font preuve d'inertie dans leurs choix de consommation, étant incapables d'imposer instantanément des modifications drastiques dans leurs habitudes de consommation. Selon nos hypothèses, si le produit vert présente un avantage en termes de différenciation des produits, la formation d'habitudes l'empêche de gagner instantanément la part de marché correspondante. Nous mettons en place un modèle dynamique en temps continu afin d'étudier comment une taxe environnementale de second rang peut induire le marché à transiter vers un nouvel équilibre, dans lequel le produit vert a gagné sa part de marché à long terme, et nous comparons cette taxe au taux d'imposition Pigouvien classique. Notre modèle comprend également une analyse du bien-être, qui nous permet de déterminer la valeur sociale des habitudes en prenant la structure du marché comme donnée.

• 20 Septembre 2022 : Olga Bernard (PSAE,INRAe) - "Citizen Science, Platforms, and Project Implementation"

"We examine the impact of citizen science on the digital economy by investigating the incentives of citizens, scientists, and digital platforms to implement a scientific project. We build a simple model where a two-sided platform supplies citizen science services to two scientists on one side, and a representative citizen on the other side. Project implementation brings a social value benefiting each project contributor. When there is no platform, a scientist decides between citizen science project implementation and an outside option. A project may be implemented with some probability depending on citizen's attention devoted to the project. We find three possible scenarios of project implementation depending on the social value of a project, the probability of implementation, and the opportunity cost of citizen science. With a platform, scenarios of project implementation can be reversed compared to the benchmark with no platform, and citizen science projects with lower social value could be implemented."

• Mardi 5 Juillet 2022 : Charlotte Janssens (KU Leuven) - "Trade, Storage and Climate Extremes: Evidence from Sub-Saharan Africa"

Global warming is associated with changes in the frequency, intensity, spatial extent, duration and timing of temperature and precipitation extremes. Agriculture is particularly vulnerable to such climate extremes, resulting at times in large production losses and a strong reliance on market mechanisms to ensure local food availability. However, the impact of trade and storage market mechanisms on local food security has not yet been clearly established, theoretically nor empirically. This study aims to address this gap and focuses on Sub-Saharan Africa, a hotspot for food insecurity and climate extremes and characterized by high trade costs and diverse market policies. A theoretical model combining household level consumption smoothing with market level trade and storage is presented. Variable stock levels and trade balances are shown to have a direct relation with intertemporal household asset transfers. Based on a numerical simulation exercise, three qualitative predictions are derived that can be taken to the data. First, when households are isolated from markets, climate extremes have a stronger upward pressure on local food prices. Second, as a consequence of the negative local price-harvest relationship, storage and trade have a smaller buffering effect on local food security in isolated markets. Third, trade and storage can act both as substitutes and complements, depending on the temporal and spatial correlation of climate extremes. The predictions are empirically tested by estimating local food security impacts of dry and wet climatic conditions in 1,400 secondary administrative units across 12 countries in SSA over the time period 2010 - 2016. Results of local and country-wide climate extremes, interacted with local travel times to market and country-level trade and stock dynamics are broadly consistent with the theoretical predictions. Future work on adaptation to future variability under climate change should explicitly consider the interaction between micro- and macro-level dynamics, as well as the spatial and temporal correlation of climate shocks.

• Mardi 21 juin 2022 : Alejandra Giraldo (CESAER - INRAE) - "How much do uncertainty and information asymmetry matter? The case of soil carbon storage practices in the agricultural sector" (joint with Laure Bamière, Valentin Bellassen and Sophie Legras)

This paper explores the welfare implications of three alternative types of Monitoring, Reporting and Verification (MRV) requirements in the presence of information asymmetries. MRV requirements mandate how environmental benefits – here carbon storage – must be estimated and audited in order to monetize them, for example as carbon credits or public payments in an ecoscheme. Due to trade-offs between uncertainty and MRV costs, excessively flexible MRV requirements may compromise the carbon reduction goals, while highly stringent requirements may prevent some projects from being implemented. We build a simple adverse selection model to predict the behaviour of economic agents faced with different MRV requirements. We then calibrate this model and evaluate the welfare implication by using data on carbon storage for the four most promising carbon storage practices in the agricultural sector: agroforestry, hedges, temporary grasslands and cover crops. We identify the optimal set of MRV requirements in different information asymmetry settings and derive a decision tree to guide regulators in determining the best choice of MRV rules for payment for environmental services schemes.

• Mardi 31 mai 2022 : Dorothée Charlier (Université de Savoie Mont-Blanc) - "Energy poverty and mental health: parallel components of deprivation" (joint with Berangère Legendre)

Using a large and original survey precisely measuring mental disorders and energy deprivation, this paper assesses the impact of fuel poverty on mental health. Being fuel poor decreases the mental health score by 6.3 points out of 100. Energy deprivation affects individuals unequally depending on whether they appear vulnerable in terms of health. Finally, we explore the different channels through which mental health is affected, whether it be pathological disorders or the degradation of social health. Fuel poverty increases the depression score by 5.35 points, the anxiety score by 6.48 points, and decreases the social health score by 6.82 points.

• Mardi 17 mai 2022 : Fanny Moffette (University of Wisconsin-Madison) - “Agricultural Subsidies: Cutting into Forest Conservation?” (joint with Jennifer Alix-Garcia)

We examine how agricultural subsidies may induce deforestation and undermine conservation programs by analyzing two large-scale national programs in Mexico that have existed simultaneously for more than a decade: an agricultural subsidy for livestock (PROGAN) and a program of payments for ecosystem services (PES). Looking across the entire Mexican landscape, we exploit the surprises  in the timing of enrollment in PROGAN’s waves, fluctuations in program payments, and the change in the value of the subsidy induced by inflation and currency fluctuations to identify the impacts of the livestock subsidy on environmental outcomes. We find that PROGAN increased municipal deforestation by 7 percent, partly because the program did not induce intensification. The deforestation effects of PROGAN were smaller in municipalities with higher concentrations of PES recipients. Willingness to enroll in PES does not appear to be affected by PROGAN, nor does PES seem to have reduced PROGAN enrollment. We suggest that these subsidies could be better targeted to places with low deforestation risk and high livestock productivity to maximize food production and minimize negative externalities caused by deforestation.

• Mardi 10 Mai 2022 : Yann Bramoullé (CNRS - AMSE) - "Who gives, who cares?" (coécrit avec Rahul Deb et Ludovic Renou)

We derive the testable implications of a network model of altruism on data consisting of the transfers made between agents in an economy over a finitely many time periods. We precisely characterize rationalizable transfer data: that is, we characterize when we can find time invariant preferences and time varying initial incomes such that the transfers are obtained as an equilibrium of the network transfer game with altruistic agents. We show that, despite only observing transfers (and neither preferences nor initial incomes), the model can be refuted and moreover that the transfers reveal the strength of altruistic ties. Our model is computationally straightforward to test and this test is robust to measurement error in that only the direction of the transfers matters but not the actual transfer amount. Finally, we discuss the implications of our results to the economics of informal transfers.

• Mardi 19 avril 2022 - Michel Trommetter (GAEL - INRAE) - "Biodiversité, climat et société : où allons-nous et à quelle vitesse ?"
• Mardi 13 Avril 2022 : Frederic Ang (WUR) - "Robust nonparametric analysis of dynamic profits, prices and productivity: an application to French meat-processing firms" (joint with Pieter Jan Kerstens)

This article develops a statistically robust nonparametric framework to analyze profits, prices and productivity in a dynamic context that appropriately considers adjustment costs. The change in dynamic profit (current value of all future profits) is decomposed into dynamic price change and dynamic productivity change. These novel components respectively correspond to a dynamic Bennet price indicator and a dynamic Bennet quantity indicator. The latter is further decomposed into dynamic technical change, dynamic technical efficiency change and dynamic mix efficiency change. It is shown to be a superlative indicator for the dynamic Luenberger indicator for appropriately normalized prices: if the dynamic directional distance function can be represented by a quadratic functional form with time-invariant second-order coefficients and there is dynamic profit-maximizing behavior, then an appropriately price-normalized dynamic Bennet quantity indicator coincides with the dynamic Luenberger indicator. The application focuses on 1,638 observations of French meat-processing firms for the years 2012 ́2019. The decomposition framework uses data envelopment analysis, to which we apply a recently developed m-out-of-n bootstrap to obtain robust estimates and confidence intervals. Overall, this framework provides a powerful tool to analyze economic performance and guide the resource reallocation required for increasing profits and productivity in the long run. The dynamic profit increases by on average 0.320% p.a. in the studied period. It is driven by a modest dynamic productivity growth of on average 0.496% p.a., which is partly offset by dynamic price decline of on average 0.176% p.a. The components of dynamic productivity growth fluctuate substantially. However, they are often statistically insignificant, which highlights the importance of using the m-out-of-n bootstrap.

• Mardi 5 Avril 2022 : Arnaud Goussebaïle (ETH) - "Democratic Climate Policies"

While a large literature provides climate policy recommendations, these recommendations are a priori not supported democratically since the models used consider either infinitely-lived individuals or normative social objectives (or both). By contrast, the present paper provides policy recommendations that would go through democratic processes. I develop a model with overlapping generations and political processes. I analyze how democratic policies, which are directly and indirectly related to climate change, differ from standard recommended policies. I highlight that young generation voting power and individual altruism toward descendants are key determinants of democratic climate policy ambition.

• Mardi 29 Mars 2022 : Ilya Eryzhenskiy (CIRED - Ecole des Ponts) "Zero-Interest Green Loans and Home Energy Retrofits: Evidence from France" (joint Louis-Gaëtan Giraudet, Mariona Segú, Maryam Vahid Dastgerdi)

Zero-interest green loan programs (ZIGL) are gaining traction to address the tremendous financing needs implied by climate change mitigation. One such program, the French Éco-Prêt à Taux Zéro, significantly under-performed the expectations the government had for it at its inception in 2009. Using a difference-in-differences design applied to a panel survey of 10,000 households, we find that the program had a substantial, yet short-lived, impact on home energy retrofits. On the extensive margin, eligibility to the program significantly increased the rate of renovation by 3-4 percentage points (+25%) in the first two years, but not thereafter. The effect is strongest (7-8 p.p.) for low-income homeowners. On the intensive margin, the amount spent on renovation significantly increased only for the second year of the program, with at least an extra €1,100 (+9%). Our results are robust to a range of robustness checks, including placebo regressions and propensity score weighting. Our analysis points to unexplored barriers in both the demand and supply that can explain the short-lived effect of loans for home energy retrofits.

• Mardi 22 Mars 2022 : Can Askan Mavi (PSAE, INRAE) - "Pandemic Impacts on Sustainability and Hartwick’s Rule" (joint with Benteng Zou)

In this study, we present a modified Hartwick rule encompassing the dynamics of pandemic, such as COVID-19. In our setting, the labor productivity gradually improves after the pandemic shock and may even go beyond its pre-pandemic level due to the remote work and digitalization as also suggested by the empirical evidence. We demonstrate that a gradual labor productivity increase helps to conserve natural resources. We provide a theoretical foundation for a“sooner-the-better" strategy to control a pandemic, and we show that policy maker should implement a “whatever it costs” response to ensure that the transmission rate of the virus is below the recovery rate from the very beginning of the pandemic. Otherwise, the economy cannot have a sustained utility. We also analyze the implications of an “uncertain” pandemic on the  intertemporal dynamics of natural resource and capital accumulation under the maximin criterion. Another important finding is that there exists a new economic and public health trade-off since a strong prevention policy is shown to decrease capital accumulation.

• Mardi 8 Mars 2022 : Emmanuel Paroissien (PSAE, INRAE) - "The High Cost of Noncompliance with Mandatory Pest Control" (joint with Jean-Sauveur Ay and Estelle Gozlan)

Controlling pests and infectious diseases requires coordination through coercive policies. Self-interested agents facing limited inspections and penalties may not comply on these policies, which generates further infections and potentially large costs. Estimating these costs is challenging because local pest levels both depend on and drive strategic compliance. This reverse causality issue impedes the ex-post evaluation of control policies for which only observational data is available. We estimate the economic costs of noncompliance with a policy targeting Flavescence dorée, an epidemic pest disease plaguing European vineyards. To identify causal effects, we leverage variations in the incentives to comply generated by historically determined earning differences across vineyards. These differences stem from century-old Appellations d’Origine Contrôlée (AOCs) delineations, so they are unaffected by current infection risk but do correlate with local compliance rates. Our estimates indicate that increasing average compliance rate by 10 points decreases the average probability of disease presence by 4.5 points. This corresponds to a discounted cost of noncompliance of €171 million nationally and to an average benefit-cost ratio of 2.45 for more compliance. Increasing compliance is therefore highly economically desirable for winegrowers, and can increase social welfare as long as the cost of environmental and health damages from one insecticide application is below €50/ha.

• Jeudi 24 février 2022 - Stéphane Turolla (INRAE-SMART-LERECO) - “Spatial Competition with Demand Uncertainty: A Laboratory Experiment” (joint with Aurélie Bonein​)

Motivated by recent research on product differentiation, we conduct laboratory experiments to study how (aggregate) demand uncertainty influences location choices and price competition in the original Hotelling (1929)’s model. We provide new predictions on the effect of risk attitudes on both decisions under demand uncertainty and confront them with the data. Our experimental results support the predictions that demand uncertainty acts as a differentiation force for riskneutral and risk-lover subjects. By contrast, we do not verify that demand uncertainty leads risk-averse subjects to agglomerate. This is explained primarily by learning effects and heterogeneous behaviors within this risk profile. Finally, we observe various price-setting behaviors, ranging from an attempt to collude to a price war, depending on the level of differentiation.

• Mardi 15 février 2022 - Florence Puech (RITM - Université Paris-Saclay) - "Hétérogénéité spatiale ou diversité spatiale ? Une approche unifiée pour évaluer la biodiversité" (coécrit avec Eric Marcon)

Pour évaluer la biodiversité, différents indicateurs existent comme les indices de Shannon, de Simpson ou ceux de richesse. Ces indicateurs permettent de caractériser la biodiversité d’un point de vue externe car ils divisent le territoire en différentes zones exclusives. En milieu urbain, ils peuvent être mobilisés pour évaluer la biodiversité des espaces verts ou des cimetières par exemple. Dans ce travail, nous proposons une approche complémentaire permettant, cette fois-ci, de caractériser la biodiversité d’un point de vue interne, telle que perçue par un observateur autour de lui. Pour cela, une nouvelle approche de l’espace est considérée, sans zonage, et une nouvelle famille d’indicateurs est introduite, les mesures spatialement explicites. Ces dernières permettent de relier la biodiversité à la concentration spatiale des espèces. Une application sur les arbres à Paris est proposée pour illustrer la méthode.

• Mardi 8 Février 2022 - Mélanie Gittard (PSE) - "Climate variability, migration and population in Kenya"

Over the past decades, East Africa has faced repetitive climate extremes and changes in precipitation trends, driving modification of demographic patterns. This paper studies the effects of past climate variability on internal migration in Kenya. It contributes to the micro-oriented literature on climate-induced migration by decompressing history, using long term, local, precise and representative data. We match, over twenty years, population data at the sub-location level, from three exhaustive administrative censuses (1989, 1999, and 2009), with high spatial and temporal resolution precipitation and temperature data sets from the Climate Hazard Center (CHIRPS/CHIRTS-ERA). It is also a methodological contribution, advocating for the use of relevant climatic indicators (and data) and local demographic effects in order to understand the impacts of climate variability on internal migration. Particular attention is devoted to the definition and analysis of climate variability and changes in precipitation trends over the country. The main empirical strategy uses a two-way fixed effect model, exploiting the temporal and spatial variation of dry events that occurred in Kenya during 1999-1989 and 2009-1999. The goal is to understand the incidence of climate variability on migration behaviors at the sublocation level, and to investigate the heterogeneity of the demographic movements. The main contribution of this paper is a demographic record of migration, giving the demographic decomposition of the migration according to gender, economic activity, age brackets and educational level. Overall Kenya, the results suggest that an additional dry rainy season over the decades implies a decrease of -2 percentage points (p.p) of the decadal population growth rate. The fuzzy design shows that results are mainly borne by rural sub localities where pastoralism is the main sector of activity, and a Sharp Difference-in-Difference identifies the effect in the West-Center of the country. The demographic record suggests that the migration is balanced in terms of gender (48 % female), and mainly driven by individuals in their working age (no effects on inactive population and infantile mortality). Climate migrants have attended at least primary education, while the population from the low end of the skill distribution signicantly stays in affected areas (in line with a poverty trap story). The results according to the economic activity show different results between rural and urban areas. It suggests an out-migration of the working population involved in agricultural activity in rural areas, while it suggests a change in the labor allocation in urban areas as business owners seem to fall into unemployment when exposed to climate variability.

• Mardi 25 Janvier 2022 - Valentin Gueye (PSAE - INRAE & MCC) - "Indirect land use change from biofuels: empirical evidence from the US Renewable Fuel Standards and pan-tropical deforestation"

Globalized and interdependent agricultural markets mediate supply and demand shocks across commodities, space and time. In particular, increasing demand for biofuels can have indirect land use change (ILUC) effects on tropical forests, with severe consequences. This has been vastly theorized and simulated, but is inherently difficult to confirm empirically. In this paper, I provide the first empirical tests of ILUC theories at comprehensive commodity, spatial and time scales, and I quantify from high-resolution data the deforestation for soy and oil palm caused by the United-States Renewable Fuel Standards (RFS), one of the major biofuel policies worldwide. I use the early-determined agenda of biofuel mandates under the RFS, interacted with the orthogonal distribution of potential yields from 20 land uses, to causally investigate several predictions from ILUC theories. Results show that RFS mandates increased deforestation in locations relatively more suited for crops that are substitutes (as a land use and/or for consumption) with maize, the main biofuel feedstock under RFS. This confirms market-mediated theories of ILUC, and that biofuel policies can cause tropical deforestation. This evidence is clearer in America than in Asia and Africa. Deforestation for soy in America, and for oil palm in Asia, does react to biofuel mandates, but magnitude estimates are not yet available.

• Mardi 18 janvier 2022 - Julien Jacob (Université de Strasbourg - BETA) - "Information disclosure under liability: an experiment on public bads" (coécrit avec Eve-Angéline Lambert, Mathieu Lefebvre & Sarah Van Driessche)

We experimentally investigate the impact of information disclosure on managing collective harms that are caused jointly by a group of liable agents. Subjects interact in a public bad setting and must choose ex ante how much to contribute in order to reduce the probability of causing a common damage. If a damage occurs, subjects bear a part of the loss according to the liability-sharing rule in force.We consider two existing rules: a per capita rule and a proportional rule. Our aim is to analyze the relative impact of information disclosure under each rule. We show that information disclosure increases contributions only under a per capita rule. This result challenges the classical results regarding the positive effects of information disclosure, since we show that this impact may depend upon the legal context. We also show that while a proportional rule leads to higher contributions than a per capita one, the positive effect of disclosure on a per capita rule makes it as efficient as a proportional rule without information disclosure.

• Mardi 11 janvier 2022 - Roxane Photinodellis (PSAE - INRAE) - "Towards carbon neutrality : Modeling the cost-effective timing of agricultural practices uptake to mitigate net greenhouse gas emissions"

France has set a carbon neutrality objective by 2050, as part of its contribution to the Paris Agreement. The agricultural sector is the second most emitting sector, accounting for about 20% of French GHG emissions. Its emissions can be mitigated mainly by reducing N2O and CH4 emissions, and by increasing soil organic carbon stocks. Mitigation levers can consist in changing the production system (e.g., by changing land use, feed rations, or herd size) or adopting new agricultural practices (such as developing intra-plot agroforestry or using nitrification inhibitors). Determining how and at what cost the French agricultural sector can contribute to the national mitigation effort is essential for designing cost-effective public policies. Our aim is therefore to model the cost-effective timing of mitigation levers implementation in the French context, in order to achieve the sector's climate objectives. To do so, we develop a dynamic agricultural supply model that maximizes farmers' income under a net GHG emissions level constraint. An originality of our approach is that we consider both changes in agricultural practices and production systems, as well as GHG emissions and carbon sequestration. Another is that we take into account carbon sequestration in a dynamic way. We apply this model to 18 farm types in the Grand-Est region.

• Mardi 4 janvier 2022 - François Bareille (PSAE - INRAE) - "The impact of Climate Change on Farmland Prices: a Repeat-Ricardian analysis" (joint with Raja Chakir)

Ricardian analyses of farmland values have become a cornerstone of the literature valuing the impacts of climate change on agriculture. However, concerns about the lack of a formal econometric strategy to deal with omitted farmland characteristics have raised doubts about the identification of such impacts. This paper proposes an original method for estimating Ricardian models of farmland price with plot fixed effects to control for confounding omitted variables. Specifically, we use plot-level repeat-sale data to investigate how differences in farmland prices are explained by differences in climate conditions between two sale dates in France from 1996 to 2019. We show that, in comparison to our repeat-Ricardian estimates, standard Ricardian analyses result in artificially low benefits of climate change. In particular, our repeat-Ricardian estimates indicate that hotter summers should benefit French agriculture, in complete opposition to our pooled Ricardian estimates or to the remainder of the literature. Our repeat-Ricardian results are robust to several specifications, length-definitions of climate and sub-samples. Our simulations suggest that the omitted variable bias in standard Ricardian analyses leads to an underestimation of the impacts of future climate changes of between 56% and 96%.