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La persistance des champs d’épandage d’eaux usées de l’agglomération parisienne au cours du second XXe siècle
No full textInternational audienceLes champs d’épandage ont constitué, de la fin du XIXe siècle à la Seconde Guerre mondiale, la principale voie de traitement des eaux usées de l’agglomération parisienne. Situés en aval de la capitale, ils ont culminé autour de 1910 : ce sont alors plus de 5 000 ha de terres qui absorbent les excreta des parisiens et qui contribuent, en retour, à les approvisionner en productions légumières. Le bouclage des cycles biogéochimiques – azote, phosphore, etc. – du système alimentaire parisien atteint à cette date son summum. Trois décennies plus tard, cette technique d’épuration n’a plus le vent en poupe. Face à la hausse exponentielle des volumes à traiter, les difficultés conjuguées de trouver de nouvelles terres à irriguer et d’étendre les réseaux d’irrigation ont fini par détourner les ingénieurs en charge de l’assainissement de cette technique héritée des anciens usages d’utilisation agricole des matières de vidange. C’est désormais l’épuration en station (combinée à la dilution en rivière) qui est devenue la méthode rationnelle de l’assainissement moderne. Pour l'agglomération parisienne, si celle-ci se voit concrétisée en 1940 avec l’inauguration de la station d’Achères, elle tarde toutefois à monter en puissance. Les épandages ne disparaissent donc pas et, inversement, ils continuent de jouer leur rôle dans l’ombre de l’épuration en usine consacrée par les récits linéaires du progrès technique. Ils restent même longtemps indispensables et il n’est pas possible de les abandonner. Ainsi, face aux diverses menaces auxquelles ils doivent faire face (urbanisation croissante, exploitation de carrières de sable, modification de la qualité des eaux usées, etc.), ils demeurent et voient seulement lentement leur surface se réduire. C’est le récit de ce long retrait qui est esquissé dans cet article à partir de la mobilisation d’archives inédites issues des services de l’assainissement de l’agglomération parisienne
'Bad' Oil, 'Worse' Oil and Carbon Misallocation
No full textNot all barrels of oil are created equal: their extraction varies in both private cost and carbon intensity. Leveraging a comprehensive micro-dataset on world oil fields, alongside detailed estimates of carbon intensities and private extraction costs, this study quantifies the additional emissions and costs from having extracted the ’wrong’ deposits. We do so by comparing historical deposit-level supplies to counterfactualsthat factor in pollution costs, while keeping annual global consumption unchanged. Between 1992 and 2018, carbon misallocation amounted to at least 11.00 gigatons of CO2-equivalent (GtCO2eq), incurring an environmental cost evaluated at 2018). This translates into a significant supply-side ecological debt for major producers of high-carbon oil. Looking forward, we estimate the gains from making deposit-level extraction socially optimal at about 9.30 GtCO2eq, valued at $1.9 trillion, along a future aggregate demand pathway coherent with the objective of net-zero emissions in 2050, and document unequal reserve stranding across oil nations
Synthèse : climats hostiles
No full textSous la direction d’Éric Heyer et de Xavier TimbeauInternational audienc
Adoption of improved varieties and varietal preferences of cowpea growers in Senegal
No full textThis volume follows on from the Rencontres Francophone Légumineuses (RFL) held in March 2024, organized by CIRAD, INRAE, Terres Inovia and Terres Univia, and co-organized by the Institut Sénégalais de Recherches Agricoles (ISRA). This unique event brings together all those involved in development, the supply chains and research into grain and forage legumes. It's an opportunity to exchange views, share knowledge and accelerate innovation around legumes. The RFLs focus on seed, forage and woody legumes, and aim to cover the diversity of production systems, as well as the diversity of uses: food, feed and non-food. Pulses are a major lever for meeting the global challenges of climate change and food and nutritional security. All over the world, they play a strategic role, providing nutritional benefits and ensuring protein and food sovereignty. The many species of pulses also represent a formidable breeding ground for food innovation.International audienceCowpea is the most widely grown legume in Africa. In Senegal, it accounts for an average of 11% of total legume production. It is an important source of income for women, who are very active in the value chain (production, processing and marketing). Despite its advantages, cowpea yields are very low. This weakness can be explained by abiotic and biotic factors, including producers' limited access to seeds of improved varieties. However, drought-resistant varieties have been developed by the Institut Sénégalais de Recherches Agricoles (ISRA), in collaboration with other partners. In this article, we contribute to the analysis of the adoption of new varieties by studying the preferences of male and female cowpea growers in Senegal's major production zones. The data used come from a survey conducted in 2022, with a sample of 303 producers, 60 % of whom were women, and 383 cowpea fields. The methodology consists mainly of univariate and bivariate statistical analyses. Results show that adoption of improved varieties is low, with only 21 % of growers using them. The improved varieties Mélakh and Yacine are the most present, despite their age. The results also show that the criteria for choosing varieties are not homogeneous: women prefer big seed size, good taste and red color while men focus on yield, big seed size and short cycle
Beyond the Determiner “Al-”: Expanding the Determiner Class in Arabic, and Elimination of Lexical Ambiguities by Grammars
No full textInternational audienceArabic nouns can be marked for definiteness or indefiniteness. The definite article is the prefix “Al-,” which confines the determiner class to a single element “Al-.” This topic is generally discussed under noun inflections, such as gender, number, definiteness, and case (GNDC), in grammar textbooks. The primary aim of this paper is to expand the Arabic determiner class (DET) by incorporating additional lexical items and providing a detailed description of their syntactic context within noun phrases (NPs). In traditional grammar, these lexical items are typically classified as noun adjectives and, at best, are referred to as noun specifiers since they modify the head noun. However, these “nouns” exhibit limited inflection compared to regular adjectives and occupy a specific position within the NP sequence. Additionally, the modified head nouns are constrained in their inflectional attributes, number and definiteness. Our approach is qualitative and guided by morpho-syntactic considerations. We conduct an in-depth analysis of the grammatical features of ten lexical items, focusing particularly on the dependencies between the determiner and the following noun. This analysis also addresses some semantic properties. By focusing on context-sensitive grammatical rules, the study shows how these methods can enhance precision in parsing and reduce ambiguity in NLP tasks, highlighting the potential for developing more refined grammar for Arabic. This work is a prototype for comprehensive studies in linguistics and NLP
From historical plastic pollution to environmental remediation scenarios. A case study in the Seine estuary
No full textInternational audienceThe Seine River basin, home to a quarter of the French population, faces the generation of around one million tons of plastic waste each year in the Paris region. Despite efficient plastic waste management, some of it escapes the systems and ends up in the Seine River, contributing to its pollution. Recent studies show that plastic debris remains in the river due to tides. This promotes the accumulation of plastic debris on the riverbanks, particularly during floods, creating historical accumulation zones in some areas. In this way, these plastics along with their chemical substances, pollute all environmental compartments. The aim of the TEDiPLAST project is to better understand the sources, stocks, fluxes, and dynamics of plastic debris in historical accumulation zones. How they build up and what do they become? First, innovative clean-up techniques will be tested to ensure effective collection of plastic debris, including those as small as preproduction industrial pellets. Second, adapted sampling and treatment protocols will be implemented to obtain representative results along a size class continuum, from macroplastics to coarse microplastics (> 500 µm), while considering their respective characteristics. Third, macroplastics will be sorted according to the OSPAR/TSG ML, whereas smaller plastic debris will be analysed by ATR-FTIR. Additionally, all data related to tracing debris sources and their lifespan in the environment will be recorded (dates, brand names, logos, etc.). One of the challenges consists in combining analytical techniques and sampling protocols to cover a large continuum of plastic sizes, while remaining representative of extensive and heterogeneous accumulation zones where up to 4 kg of plastic per square meter accumulates. Furthermore, preproduction industrial pellets will also be a focus, as they are one of the main plastic wastes found in these zones due to the vicinity of some producers and converters along the Seine River. At the end, remediation scenarios will be suggested to support mitigation policies and strategies
Financement local pour le climat global? Impact d'un programme d'efficacité énergétique local sur la consommation d'énergie et la création d'emplois
No full textSubsidy programs for home energy retrofits are a popular tool to reduce CO2 emissions. Should they be implemented at the national level to leverage economies of scale or at the local level to more finely identify the best opportunities? To examine this question, we evaluate a program introduced in the French department of Essonne and compare its performance to that of its national counterparts. In a difference-in-differences framework, we identify a 8% reduction in residential natural gas use induced by the program, implying a carbon abatement cost of €44/tCO2eq. In a triple-difference framework, we further identify a 27% increase in employment in the renovation sector in Essonne, as opposed to non-renovation sectors and neighboring departments, implying about 20 jobs created per million euro spent. Looking more carefully at contractors' origin, we find that households were more likely to hire an Essonian firm than an equally distant one based outside Essonne. Altogether, our results suggest that local programs perform better than their national counterparts, and that a fair share of their benefits are retained locally. This calls for a stronger involvement of local authorities in managing home renovation policies
Sur la valeur ajoutée du financement des programmes d'efficacité énergétique par les fournisseurs d'énergie: Le cas de la troisième période des Certificats d'économies d'énergie
No full textSince 2006, French energy suppliers provide subsidies for home energy retrofits to comply with an energy efficiency, or "White Certificate," obligation. The alleged advantage of utility-sponsored programs, compared to the public counterparts with which they often overlap, is in leveraging the private information energy suppliers may possess about energy efficiency potentials, allowing them to save energy more cost-effectively. We challenge this hypothesis and assess the value private funding adds to public funding. In a regression discontinuity design, we exploit two geographical discontinuities in subsidy amounts that prevailed during the third phase of the program (2015-2017). Comparing outcomes across the high-versus middle-subsidy border, we find that a 1% increase in subsidy amounts induced a 1.16% higher take-up. The effect only holds in three out of eight specifications, however. We moreover fail to identify a significant elasticity across the middle-versus low-subsidy border. In subsample regressions, we find that take-up was strong for insulation measures, which rank first in the cost-effectiveness merit order. These results together imply that the program's third phase was effective qualitatively, but not quantitatively. This suggests that energy suppliers could fulfill their obligation by merely free riding on overlapping programs -- a mechanism we confirm in complementary microsimulations.Depuis 2006, les fournisseurs d'énergie français accordent des subventions pour la rénovation énergétique des logements dans le cadre des Certificats d'économie d'énergie. L'avantage présumé des programmes financés par les fournisseurs d'énergie, par rapport aux dispositifs publics auxquels ils se superposent souvent, réside dans l'information privée possédée par les fournisseurs d'énergie quant aux potentiels d'efficacité énergétique, qui leur permettent d'identifier les opportunités les plus coût-efficaces. Nous questionnons cette hypothèse et évaluons la valeur ajoutée du financement privé par rapport au financement public. Dans un modèle de Regression Discontinuity, nous exploitons des frontières entre zones climatiques qui ont généré des montants des subventions différenciés au cours de la troisième période du programme (2015-2017). En comparant les résultats à la frontière entre les zones H1 et H2, nous constatons qu'une augmentation de 1 % des montants des subventions induit une augmentation de 1,16 % du taux de participation. Toutefois, l'effet ne se vérifie que dans trois spécifications sur huit. En outre, nous ne parvenons pas à identifier une élasticité significative à la frontière entre H2 et H3. Dans les régressions en sous-échantillon, nous constatons que la participation a été forte pour les mesures d'isolation, qui se classent au premier rang dans l'ordre de mérite de la rentabilité. L'ensemble de ces résultats implique que la troisième phase du programme a été efficace d'un point de vue qualitatif, mais pas quantitatif. Ce résultat suggère que les fournisseurs d'énergie ont pu remplir leur obligation en se contentant de valoriser des certificats attribuables à d'autres dispositifs -- un mécanisme que nous confirmons dans des microsimulations complémentaires
Crise du Covid-19 et transports collectifs urbains en France: Quels effets à court, moyen et long terme sur l’offre et leur financement ?
No full textInternational audienceWhile the development of urban public transport (UPT) is considered a priority to promote the ecological transition, the Covid-19 health crisis has affected its operation. It results from constraints on supply, made necessary by travel restrictions and limitations on economic activity during periods of confinement. Existing literature has focused mainly on the use of different modes of transport, changes in mobility practices and the way governments managed the crisis. This article focuses instead on the effects of covid-19 on the supply and financing of UPT, and analyses whether this crisis has given rise to new dynamics in the mobility organising authorities (AOMs). Using data from 95 AOMs (i.e. 35% of all AOMs in 2019) and a survey of some 39 AOMs (14%), three main results are established. First, there is a big fall in fare revenue, whatever the category of AOM in France. However, due to the small proportion of UPT funding paid for by users, this decline is easily offset by a variation in the mobility tax (versement mobilité), government subsidies and an increase in the contribution from local authorities. Second, the AOMs seem confident about the funding for prospects, through an expected increase in UPT patronage and a stability, or even an expected dynamic, in the mobility tax in the future. As a result, the health crisis does not seem to have encouraged the AOMs to find new resources to finance the development of their UPT services in the medium-to-long term. Third, and finally, the health crisis has contributed to shift travel policy priorities in the AOMs, in particular when it comes to investment strategies, by raising the importance of developing the use of bicycles.Alors que le développement des transports collectifs urbains (TCU) est considéré comme une priorité pour favoriser la transition écologique, la crise sanitaire de la Covid-19 a affecté leur fonctionnement par des contraintes en matière d’adaptation de l’offre, rendues nécessaires du fait des restrictions de déplacements et des limitations de l’activité économique pendant les périodes de confinement. La littérature existante s’est principalement focalisée sur la fréquentation des différents modes de transports, l’évolution des pratiques de mobilité et la manière dont les gouvernements ont géré cette crise. Cet article s’intéresse plutôt aux effets de la Covid-19 sur l’offre et le financement des TCU et analyse si cette crise a été à l’origine de nouvelles dynamiques d’investissement et une redéfinition des priorités dans les Autorités Organisatrices de la Mobilité (AOM). En mobilisant les données de 95 AOM (35% des AOM en 2019) et d’une enquête auprès de 39 AOM (14%), trois principaux résultats ont été établis. Le premier est la forte diminution des recettes tarifaires, quelles que soient les catégories d’AOM en France. Toutefois, compte tenu de la contribution limitée des usagers au financement des TCU, celles-ci ont pu être facilement compensées par une augmentation du versement mobilité, des aides de l’Etat ou encore par une contribution des collectivités territoriales. Le deuxième résultat est qu’en dépit de la baisse des recettes tarifaires les AOM demeurent assez confiantes dans leur capacité à financer le développement des TCU dans le futur , via notamment une hausse attendue de la fréquentation et une stabilité, voire une dynamique attendue du VM dans le futur. En conséquence, la crise sanitaire ne semble pas avoir incité les AOM à chercher de nouvelles ressources pour le financement du développement de l’offre de TCU à moyen-long terme. Enfin, le troisième résultat est que la crise sanitaire semble avoir incité les AOM à revoir leurs priorités en termes d’investissement, notamment sur le développement de l’usage du vélo