Established by the Kyoto protocol, the Clean Development Mechanism (CDM) allows developed countries to meet part of their commitments to reduce their greenhouse gases emissions (GHGE) by investing in projects carried out in developing countries. So, developed countries can receive certified emissions reduction corresponding to the volume of GHGE avoided or reduced in developing countries, and developing countries can claim a clean development. The use of CDM has drawn a lot of criticism and even controversies: unproven GHGE reduction, weak transfer of clean technologies, uneven geographical and sectoral distribution of projects, lack of sustainable development that CDM projects are expected to generate in developing countries, etc.This paper identifies and assesses these criticisms, using two newsletters reporting on the implementation of CDM projects in the world (Nouvelles Francophones du marché du carbone et du MDP, and Moniteur du MDP et de la Mise en Oeuvre Conjointe). Criticisms identified and assessed were confronted with expert opinions of two International Non Governmental Organisations (INGO) specialised on the monitoring of the CDM implementation: CDM Watch and NOE 21. Interviews with managers of these INGO have permitted to evaluate the relevance of criticisms and the purpose and scope of the CDM. The results of this study raise questions about the effectiveness and the efficiency of the CDM, and about reforms proposed to ensure a better contribution of this mechanism to efforts to reduce GHGE. ; Institué par le protocole de Kyoto, le Mécanisme pour un Développement Propre (MDP) permet aux pays développés de remplir une partie de leurs engagements de réduction de leurs émissions de gaz à effet de serre (EGES) dans le cadre de projets réalisés dans des pays en développement. De la sorte, les pays développés peuvent être crédités d'EGES correspondant au volume évité ou réduit dans des pays en développement, et les pays en développement peuvent se targuer de se développer « proprement ». L'utilisation ...
Localisation : Centre de documentation P. Bartoli, UMR LAMETA, Montpellier (S WPL 2011-01) ; Safeguarding tropical rainforests is one of the most important challenges for the future, particularly to mitigate climate change. The international community has actively sought international policy solutions to curb deforestation in tropical countries. Debt-for-nature swaps and certification of sustainable forest management have been implemented by NGOs. Some states are currently negotiating the implementation of the REDD (Reduced Emissions from Deforestation and Degradation) mechanism, a North-South financial transfer to compensate countries for avoided deforestation. However, little is known about the efficiency of these instruments. We argue that they may have a double effect: an expected direct impact on deforestation linked to the conditionalities of instruments, and an indirect impact due to their feedback effects on macroeconomic variables, affecting in turn the drivers of deforestation. The second effect is often overlooked by policy makers. The objective of the paper is to disentangle the two effects for different categories of forest countries. We conducted a panel data analysis for the period 1990-2005 and show that cluster analysis of tropical forest countries would be more relevant if it were based on relative forest endowment. On the basis of econometric results, we can recommend differentiating policy instruments according to the relative forest abundance of each country. Debt reduction programs contribute to the reduction of deforestation in all countries. Countries with abundant forests are locked in a development pathway based on overexploitation of their forests making them less responsive to incentive measures. In countries with average forest endowment, we recommend output-based REDD, whereas in countries with low forest cover, either inputbased or output-based REDD mechanisms should be efficient.
Localisation : Centre de documentation P. Bartoli, UMR LAMETA, Montpellier (S WPL 2011-01) ; Safeguarding tropical rainforests is one of the most important challenges for the future, particularly to mitigate climate change. The international community has actively sought international policy solutions to curb deforestation in tropical countries. Debt-for-nature swaps and certification of sustainable forest management have been implemented by NGOs. Some states are currently negotiating the implementation of the REDD (Reduced Emissions from Deforestation and Degradation) mechanism, a North-South financial transfer to compensate countries for avoided deforestation. However, little is known about the efficiency of these instruments. We argue that they may have a double effect: an expected direct impact on deforestation linked to the conditionalities of instruments, and an indirect impact due to their feedback effects on macroeconomic variables, affecting in turn the drivers of deforestation. The second effect is often overlooked by policy makers. The objective of the paper is to disentangle the two effects for different categories of forest countries. We conducted a panel data analysis for the period 1990-2005 and show that cluster analysis of tropical forest countries would be more relevant if it were based on relative forest endowment. On the basis of econometric results, we can recommend differentiating policy instruments according to the relative forest abundance of each country. Debt reduction programs contribute to the reduction of deforestation in all countries. Countries with abundant forests are locked in a development pathway based on overexploitation of their forests making them less responsive to incentive measures. In countries with average forest endowment, we recommend output-based REDD, whereas in countries with low forest cover, either inputbased or output-based REDD mechanisms should be efficient.
Localisation : Centre de documentation P. Bartoli, UMR LAMETA, Montpellier (S WPL 2011-01) ; Safeguarding tropical rainforests is one of the most important challenges for the future, particularly to mitigate climate change. The international community has actively sought international policy solutions to curb deforestation in tropical countries. Debt-for-nature swaps and certification of sustainable forest management have been implemented by NGOs. Some states are currently negotiating the implementation of the REDD (Reduced Emissions from Deforestation and Degradation) mechanism, a North-South financial transfer to compensate countries for avoided deforestation. However, little is known about the efficiency of these instruments. We argue that they may have a double effect: an expected direct impact on deforestation linked to the conditionalities of instruments, and an indirect impact due to their feedback effects on macroeconomic variables, affecting in turn the drivers of deforestation. The second effect is often overlooked by policy makers. The objective of the paper is to disentangle the two effects for different categories of forest countries. We conducted a panel data analysis for the period 1990-2005 and show that cluster analysis of tropical forest countries would be more relevant if it were based on relative forest endowment. On the basis of econometric results, we can recommend differentiating policy instruments according to the relative forest abundance of each country. Debt reduction programs contribute to the reduction of deforestation in all countries. Countries with abundant forests are locked in a development pathway based on overexploitation of their forests making them less responsive to incentive measures. In countries with average forest endowment, we recommend output-based REDD, whereas in countries with low forest cover, either inputbased or output-based REDD mechanisms should be efficient.
National audience. This article provides a summary of the literature on unitary root panel tests. Two main developments can be highlighted in this research path since the founding work of Levin and Lin (1992). On the one hand, there has been a trend since the late 90s to take account of the heterogeneity of the dynamic properties of the series studied, in particular with the work of Im, Pesaran and Shin (1997) and Maddala and Wu (1999). On the other hand, a second type of recent developments in this literature tends to introduce a dichotomy between two generations of tests: the first generation is based on an assumption of independence between individuals, which seems implausible, particularly in the case of certain macroeconomic applications. The second generation, currently under development, incorporates various possible forms of interpersonal dependencies (Bai and Ng (2001), Phillips and Sul (2003a), Moon and Perron (2004), Choi (2002), Pesaran (2003) and Chang (2002)). These two generations of tests are presented in this literature review. ; This article proposes an overview of the recent developments relating to panel unit root tests. After a brief review of the first generation panel unit root tests, this paper focuses on the tests belonging to the second generation. The latter category of tests is characterized by the rejection of the cross-sectional independence hypothesis. Within this second generation of tests, two main approaches are distinguished. The first one relies on the factor structure approach and includes the contributions of Bai and Ng (2001), Phillips and Sul (2003a), Moon and Perron (2004a), Choi (2002) and Pesaran (2003) among others. The second approach consists in imposing few or none restrictions on the residuals covariance matrix and has been adopted notably by Chang (2002, 2004), who proposed the use of nonlinear instrumental variables methods or the use of bootstrap approaches to solve the nuisanceparameter problem due to cross-sectional dependency. ; National audience. This ...
Diffusion du document : publique Diplôme : Dr. d'Université ; International economic instruments for the reduction of tropical deforestation: the example of REDD+ (Reducing Emissions from Deforestation and forest Degradation). Abstract: Curbing deforestation in tropical countries is one of the main current challenges for international community in the United Nations Framework Convention on Climate Change. Indeed, deforestation is the second leading cause of greenhouse gas emissions just behind industrial emissions. Since 2005, a new instrument to slow down CO2 emissions from tropical deforestation is under negotiations at the UNFCCC. This mechanism, called REDD+ (for Reducing Emissions from Deforestation and forest Degradation) is supported by a simple principle: it consists to reward developing countries for their efforts to avoid deforestation. However, the national and international implementations of REDD+ raise lot of methodological questions and meet several hurdles. The aims of the thesis are twofold. First, it proposes a description and an analysis of the REDD+ mechanism. Second, it is composed by three essays, which raise some questions about REDD+ design and implementation, in order to offer new perspectives on this mechanism. The first essay develops a game-theoretic bargaining model, simulating the on-going negotiation process over the REDD+ mechanism. It shows that the conditions under which developing countries are left to bargain over the allocation of the global forest fund may lead to an ineffective system of incentives. The second essay used a panel data analysis to reveal contrasted deforestation behaviors of tropical countries according to their relative endowment in forest cover. The aim of the third essay offered an illustration of REDD+ implementation, comparing the outcomes in terms of avoided deforestation and utility of two payments for environmental services designs for two types of governments. The model developed in this article is applied in the Indonesian context of deforestation, ...
Diffusion du document : publique Diplôme : Dr. d'Université ; International economic instruments for the reduction of tropical deforestation: the example of REDD+ (Reducing Emissions from Deforestation and forest Degradation). Abstract: Curbing deforestation in tropical countries is one of the main current challenges for international community in the United Nations Framework Convention on Climate Change. Indeed, deforestation is the second leading cause of greenhouse gas emissions just behind industrial emissions. Since 2005, a new instrument to slow down CO2 emissions from tropical deforestation is under negotiations at the UNFCCC. This mechanism, called REDD+ (for Reducing Emissions from Deforestation and forest Degradation) is supported by a simple principle: it consists to reward developing countries for their efforts to avoid deforestation. However, the national and international implementations of REDD+ raise lot of methodological questions and meet several hurdles. The aims of the thesis are twofold. First, it proposes a description and an analysis of the REDD+ mechanism. Second, it is composed by three essays, which raise some questions about REDD+ design and implementation, in order to offer new perspectives on this mechanism. The first essay develops a game-theoretic bargaining model, simulating the on-going negotiation process over the REDD+ mechanism. It shows that the conditions under which developing countries are left to bargain over the allocation of the global forest fund may lead to an ineffective system of incentives. The second essay used a panel data analysis to reveal contrasted deforestation behaviors of tropical countries according to their relative endowment in forest cover. The aim of the third essay offered an illustration of REDD+ implementation, comparing the outcomes in terms of avoided deforestation and utility of two payments for environmental services designs for two types of governments. The model developed in this article is applied in the Indonesian context of deforestation, ...
Diffusion du document : publique Diplôme : Dr. d'Université ; International economic instruments for the reduction of tropical deforestation: the example of REDD+ (Reducing Emissions from Deforestation and forest Degradation). Abstract: Curbing deforestation in tropical countries is one of the main current challenges for international community in the United Nations Framework Convention on Climate Change. Indeed, deforestation is the second leading cause of greenhouse gas emissions just behind industrial emissions. Since 2005, a new instrument to slow down CO2 emissions from tropical deforestation is under negotiations at the UNFCCC. This mechanism, called REDD+ (for Reducing Emissions from Deforestation and forest Degradation) is supported by a simple principle: it consists to reward developing countries for their efforts to avoid deforestation. However, the national and international implementations of REDD+ raise lot of methodological questions and meet several hurdles. The aims of the thesis are twofold. First, it proposes a description and an analysis of the REDD+ mechanism. Second, it is composed by three essays, which raise some questions about REDD+ design and implementation, in order to offer new perspectives on this mechanism. The first essay develops a game-theoretic bargaining model, simulating the on-going negotiation process over the REDD+ mechanism. It shows that the conditions under which developing countries are left to bargain over the allocation of the global forest fund may lead to an ineffective system of incentives. The second essay used a panel data analysis to reveal contrasted deforestation behaviors of tropical countries according to their relative endowment in forest cover. The aim of the third essay offered an illustration of REDD+ implementation, comparing the outcomes in terms of avoided deforestation and utility of two payments for environmental services designs for two types of governments. The model developed in this article is applied in the Indonesian context of deforestation, thanks to a database supplied by the NGO Conservation International. ; Réduire la déforestation dans les pays tropicaux est un des principaux défis pour la communauté internationale dans le cadre du processus de négociations de la Convention Cadre des Nations Unies sur le Changement Climatique (CCNUCC). En effet, la déforestation est la seconde source d'émissions de gaz à effets de serre, juste derrière les émissions industrielles. Depuis 2005, un nouvel instrument international pour réduire les émissions de carbone liées à la déforestation tropicale est en négociation à la CCNUCC. Ce mécanisme, appelé REDD+ (Réduction des Emissions liées à la Déforestation et Dégradation des forêts) repose sur un système de compensation financière des pays en développement pour leurs efforts en termes de déforestation évitée. Cependant, la mise en oeuvre du mécanisme REDD+ à l'échelle nationale et internationale soulève de nombreux problèmes méthodologiques et rencontre de nombreux obstacles. Le but de la thèse est double. Dans une première partie, une description et une analyse du mécanisme REDD+ est réalisée. Dans une deuxième partie, de nouvelles perspectives concernant le design du mécanisme REDD+ et sur sa mise en oeuvre sont offertes, en se basant sur trois essais rédigés en format article. Le premier essai propose un modèle de théorie des jeux reflétant le processus de négociation Nord-Sud du mécanisme REDD. Il étudie les conditions régissant le partage de fonds entre les pays en développement et leurs impacts sur l'efficacité du système d'incitations. Le deuxième essai utilise un modèle en économétrie de panel pour différencier des comportements nationaux de déforestation selon la dotation relative en forêts de chaque pays. Le troisième essai s'intéresse à la mise en oeuvre du mécanisme REDD+, en comparant les résultats de deux programmes de paiement pour services environnementaux pour deux types de gouvernements. Le modèle développé dans cet essai est ensuite testé dans le contexte de la déforestation en Indonésie, grâce à une base de données fournie par l'ONG Conservation International.
The article aims to determine the impacts of a policy to reduce pollutant emissions as part of a model of a small open economy, comprising two regions and two sectors, with endogenous growth. One of the two sectors is relatively more polluting and one of the two regions is more specialised in the production of this sector. The impact of environmental policy on the sectors depends crucially on their respective growth rates, which in turn depend on their respective initial capital injections. A priori counter-intuitive results are possible. If the growth rate of the polluting intensive sector is sufficiently low and inversely for the other sector, then the relatively more polluting sector is less affected by environmental policy than the other sector. Similarly, the region most specialised in producing the polluting good is less affected by emission reduction policy than the other region, if it is characterised by sufficiently low sectoral growth rates compared to the other region. ; L'article vise à déterminer les impacts d'une politique de réduction des émissions polluantes dans le cadre d'un modèle d'une petite économie ouverte, comprenant deux régions et deux secteurs, avec croissance endogène. L'un des deux secteurs est relativement plus polluant et l'une des deux régions est plus spécialisée dans la production de ce secteur. L'impact de la politique environnementale sur les secteurs dépend crucialement de leurs taux de croissance respectifs, qui dépendent à leur tour de leurs dotations initiales de capital respectives. Des résultats a priori contre-intuitifs sont possibles. Si le taux de croissance du secteur intensif en émissions polluantes est suffisamment faible et inversément pour l'autre secteur, alors le secteur relativement plus polluant est moins affecté par la politique environnementale que l'autre secteur. De même, la région la plus spécialisée dans la production du bien polluant est moins affectée que l'autre région par la politique de réduction des émissions, si elle se caractérise par des taux ...
International audience ; On behalf of the struggle against climate change: the Clean Development Mechanism and its drifts Established by the Kyoto protocol, the Clean Development Mechanism (CDM) allows developed countries to meet part of their commitments to reduce their greenhouse gases emissions (GHGE) by investing in projects carried out in developing countries. So, developed countries can receive certified emissions reduction corresponding to the volume of GHGE avoided or reduced in developing countries, and developing countries can claim a clean development. The use of CDM has drawn a lot of criticism and even controversies: unproven GHGE reduction, weak transfer of clean technologies, uneven geographical and sectoral distribution of projects, lack of sustainable development that CDM projects are expected to generate in developing countries, etc. This paper identifies and assesses these criticisms, using two newsletters reporting on the implementation of CDM projects in the world (Nouvelles Francophones du marché du carbone et du MDP, and Moniteur du MDP et de la Mise en Œuvre Conjointe). Criticisms identified and assessed were confronted with expert opinions of two International Non Governmental Organisations (INGO) specialised on the monitoring of the CDM implementation: CDM Watch and NOE 21. Interviews with managers of these INGO have permitted to evaluate the relevance of criticisms and the purpose and scope of the CDM. The results of this study raise questions about the effectiveness and the efficiency of the CDM, and about reforms proposed to ensure a better contribution of this mechanism to efforts to reduce GHGE. ; Institué par le protocole de Kyoto, le Mécanisme pour un Développement Propre (MDP) permet aux pays développés de remplir une partie de leurs engagements de réduction de leurs émissions de gaz à effet de serre (EGES) dans le cadre de projets réalisés dans des pays en développement. De la sorte, les pays développés peuvent être crédités d'EGES correspondant au volume évité ou réduit dans ...
International audience ; On behalf of the struggle against climate change: the Clean Development Mechanism and its drifts Established by the Kyoto protocol, the Clean Development Mechanism (CDM) allows developed countries to meet part of their commitments to reduce their greenhouse gases emissions (GHGE) by investing in projects carried out in developing countries. So, developed countries can receive certified emissions reduction corresponding to the volume of GHGE avoided or reduced in developing countries, and developing countries can claim a clean development. The use of CDM has drawn a lot of criticism and even controversies: unproven GHGE reduction, weak transfer of clean technologies, uneven geographical and sectoral distribution of projects, lack of sustainable development that CDM projects are expected to generate in developing countries, etc. This paper identifies and assesses these criticisms, using two newsletters reporting on the implementation of CDM projects in the world (Nouvelles Francophones du marché du carbone et du MDP, and Moniteur du MDP et de la Mise en Œuvre Conjointe). Criticisms identified and assessed were confronted with expert opinions of two International Non Governmental Organisations (INGO) specialised on the monitoring of the CDM implementation: CDM Watch and NOE 21. Interviews with managers of these INGO have permitted to evaluate the relevance of criticisms and the purpose and scope of the CDM. The results of this study raise questions about the effectiveness and the efficiency of the CDM, and about reforms proposed to ensure a better contribution of this mechanism to efforts to reduce GHGE. ; Institué par le protocole de Kyoto, le Mécanisme pour un Développement Propre (MDP) permet aux pays développés de remplir une partie de leurs engagements de réduction de leurs émissions de gaz à effet de serre (EGES) dans le cadre de projets réalisés dans des pays en développement. De la sorte, les pays développés peuvent être crédités d'EGES correspondant au volume évité ou réduit dans ...
International audience ; On behalf of the struggle against climate change: the Clean Development Mechanism and its drifts Established by the Kyoto protocol, the Clean Development Mechanism (CDM) allows developed countries to meet part of their commitments to reduce their greenhouse gases emissions (GHGE) by investing in projects carried out in developing countries. So, developed countries can receive certified emissions reduction corresponding to the volume of GHGE avoided or reduced in developing countries, and developing countries can claim a clean development. The use of CDM has drawn a lot of criticism and even controversies: unproven GHGE reduction, weak transfer of clean technologies, uneven geographical and sectoral distribution of projects, lack of sustainable development that CDM projects are expected to generate in developing countries, etc. This paper identifies and assesses these criticisms, using two newsletters reporting on the implementation of CDM projects in the world (Nouvelles Francophones du marché du carbone et du MDP, and Moniteur du MDP et de la Mise en Œuvre Conjointe). Criticisms identified and assessed were confronted with expert opinions of two International Non Governmental Organisations (INGO) specialised on the monitoring of the CDM implementation: CDM Watch and NOE 21. Interviews with managers of these INGO have permitted to evaluate the relevance of criticisms and the purpose and scope of the CDM. The results of this study raise questions about the effectiveness and the efficiency of the CDM, and about reforms proposed to ensure a better contribution of this mechanism to efforts to reduce GHGE. ; Institué par le protocole de Kyoto, le Mécanisme pour un Développement Propre (MDP) permet aux pays développés de remplir une partie de leurs engagements de réduction de leurs émissions de gaz à effet de serre (EGES) dans le cadre de projets réalisés dans des pays en développement. De la sorte, les pays développés peuvent être crédités d'EGES correspondant au volume évité ou réduit dans ...
Shape memory alloys (SMA) undergo a solid-solid phase transformation called martensitic transformation, involving a "high temperature" phase, austenite, and a "low temperature" phase, martensite. The crystalline microstructure of the alloy alters mechanisms of transformations, and its pseudo-elastic behavior. The reduction of the grains to nanometric size shows new and unknown thermal and mechanical characteristics. Knowledge of thermomechanical behavior is however essential for the validation of multiaxial models to democratize the use of these materials. This work presents the development of innovative biaxial dynamic tests for the study of the pseudo-elastic mechanical behavior of a nickel titanium under biaxial dynamic compression. A single projectile, launched on a complex system of 45 ^ { circ} triangles, bars and transmitters, creates a biaxial solicitation of the sample. This mechanism ensures that the loads are synchronized along the two axes. Thanks to its architecture, the system makes possible many cases of multiaxial dynamic stress, unexplored until now. The forces and displacements across the sample are calculated independently, along both axes, from strain gauges glued on bars. The use of a thermal and optical camera allows strain and heating sources fields to be identified. The stress field is estimated by combining the information from the strain gauges placed on the bars and a finite element analysis of the specimen. The deformation appears homogeneous in the biaxial loading region of interest where a significant rise in temperature due to the phase change latent heat is observed. On the other hand the dynamic testing allows an equivalent dynamic stress/strain curve under biaxial and quasi-adiabatic conditions to be plotted. Experiments are finally compared to the results of finite difference axisymmetric model where the constitutive law is given by a fully coupled stochastic multiscale model. ; La microstructure cristalline de l'alliage joue un rôle vis-à-vis des mécanismes de transformations, ...
Most countries recognize that a coordinated worldwide action to limit greenhouse gas (GHG) emissions has to be implemented. However, the countries inability to coordinate their efforts led to the failure of the top-down climate architecture. Today, the international climate governance adopts a different direction, which based on bottom-up approach. This approach promotes polycentric and multi-level governances, that induce several independent policy-makers in different administrative scales (province, state and region). Therefore, the actual implemented Emission Trading Systems (ETS), as well as the emerging ones, grow in a domestic context. This context, in terms of economic development, political commitment and geographical coverage, determine the ETS design. Then, there is no harmonized design among ETS, no universal diffusion of these mechanisms in the world and a lack of integral inclusion of all sectors in these carbon markets. While researchers and policy-makers discuss the optimal features of such systems, this thesis examines different configuration options and coverage areas for the tradable permit schemes.Using a world energy-economy partial equilibrium simulation model (POLES) and drawing on experiences with real-world ETSs (based on empirical literature), we recommend two types of adjustments: the restrictions on trade permits between sectors, in one hand, and the control of international permit exchange between ETS, in the second hand. Indeed, we demonstrate firstly the necessity to separate ETS by sector and adapt them considering the specificities of each sector. This kind of policy will stimulate innovation in each sector. Also, it will limit the impacts on the international competitiveness and it will lead climate policy to other economic policies. Secondly, we develop a model to describe the effects of exchange permits emissions considering international linking among emissions trading systems. We prove that restriction exchange mechanisms are necessary to insure the redistribution of exchange ...
In a context of reducing the impacts of agricultural practices on human health andecosystems, it is necessary to better account for ammonia (NH3) volatilization in the inventories of NH3 emissions, the understanding of the nitrogen behavior after fertilization and the modeling of air quality.Given the considerable weight of nitrogen fertilizer (55%) in the total national NH3 emissions, nitrogen fertilization is an important lever for reducing NH3 emissions. Current national inventories are based on the use of default emission factors (EF) and suffer from a lack of fine spatial and temporal NH3 emissions descriptions making it difficult to develop effective emission reduction policies. Moreover, even if there are currently models that globally simulate the fate of nitrogen on the crop cycle, their do not always take into account the volatilization of NH3, and if it is, the volatilization modules are often very frustrating and have not been validated. There are models dedicated exclusively to the volatilization of NH3 in the field, but their requirements for data and input parameters and their calculation time limit their large-scale use (e.g, at national scale) in many geographical locations for several years as well as their integration into airquality prediction models or decision support or environmental assessment tools in terms of nitrogen fertilization.This thesis proposes new tools. The first tool, CADASTRE_NH3 makes it possible to describe and analyze the spatio-temporal variability of NH3 emissions from nitrogen fertilization. It combines the Volt'Air process-based model with geo-referenced databases on agro-soil-meteorological factors at the national level. This approach has demonstrated its ability to capture the spatio-temporal variability ofnitrogen use and resulting NH3 emissions, and to take into account the effect of soil and climate factor interactions on emissions. The comparison of CADASTRE_NH3 results with the official French inventories shows strong convergences regarding the quantities of nitrogen used and NH3 emissions in France for the year 2005-06, but also divergences especially for the case of organic waste products. Thesecond type of tool corresponds to meta-models derived from Volt'Air for predicting NH3 emission rates after nitrogen fertilizer applications. These meta-models have many practical advantages because of their simplicity and operability. They have promising potential uses to support decision-making in terms of fertilizer use conditions and also to support emission reduction policies through, for example, scenario testing.However, it would be interesting to compare the tools developed in this thesis with experimental data to evaluate their respective performance and validate all our approaches. It would also be interesting to develop dynamic meta-models of Volt'Air that can describe the dynamics of NH3 fluxes related to nitrogen fertilizer applications and to be integrated as simple modules of NH3 volatilization in agronomic and atmospheric models. ; Dans un contexte de réduction des impacts des pratiques agricoles sur la santé humaine et sur les écosystèmes, il est nécessaire de bien prendre en compte la volatilisation d'ammoniac (NH3) dans les inventaires d'émissions, la compréhension du devenir de l'azote après fertilisation et la modélisation de la qualité de l'air. Etant donné le poids de la fertilisation azotée (55%) dans le total des émissions nationales de NH3, cette dernière constitue un levier important pour réduire les émissions de NH3. Les inventaires nationaux actuels, basés sur l'utilisation de facteurs d'émission par défaut, souffrent d'un manque de description spatiale et temporelle, rendant difficile l'élaboration des politiques de réduction efficaces des émissions. Par ailleurs, même s'il existe à l'heure actuelle des modèles qui simulent de manière globale le devenir de l'azote sur le cycle de la culture, la volatilisation de NH3 n'est pas toujours prise en compte, et si elle l'est, les modules de volatilisation sont souvent relativement frustres et n'ont été que partiellement validés. Il existe pourtant des modèles dédiés exclusivement à la volatilisation de NH3 au champ, mais leurs exigences en données et paramètres d'entrée et leur temps de calcul limitent leur utilisation à grande échelle (exemple, échelle nationale…) sur de nombreux sites géographiques pendant plusieurs années, ainsi que leur intégration dans des modèles opérationnels de prédiction de la qualité de l'air, ou des outils d'aide à la décision ou d'évaluation environnementale en termes de fertilisation azotée.Cette thèse propose des nouveaux outils. Le premier outil, CADASTRE_NH3, permet de décrire et d'analyser la variabilité spatio-temporelle des émissions de NH3 liées à la fertilisation azotée. Il couple le modèle de processus Volt'Air avec des bases de données géo-référencées sur les facteurs agro-pédoclimatiques à l'échelle nationale. Cette approche d'inventaires des émissions a montré sa capacité à capturer les variabilités spatio-temporelles de l'utilisation d'azote et des émissions de NH3 qui en résultent, et à prendre en compte l'effet des interactions des facteurs pédologiques et/ou climatiques sur les émissions. La confrontation des résultats de l'outil CADASTRE_NH3 avec les inventaires officiels français montrent de fortes convergences en ce qui concerne les quantités d'azote utilisé et les émissions de NH3 en France pour l'année 2005-06, mais aussi des divergences notamment pour le cas des produits résiduaires organiques. Le deuxième type d'outils correspond aux méta-modèles dérivés de Volt'Air pour prédire les taux d'émissions de NH3 après application d'engrais azotés. Ces méta-modèles présentent de nombreux avantages pratiques du fait de leur simplicité et opérationnalité. Ils ont des potentiels d'utilisation prometteurs pour accompagner la prise de décision en terme de conditions d'utilisation des engrais et également pour appuyer les politiques de réduction des émissions à travers par exemple la réalisation des tests de scénarios.Il serait cependant intéressant de confronter les outils développés dans le cadre de cette thèse avec des données expérimentales pour évaluer leur performance respective et valider l'ensemble de nos approches. Il serait également intéressant de développer des méta-modèles dynamiques dérivés du modèle Volt'Air capables de décrire la dynamique des flux de NH3 liés à l'application des engrais azotés pour être intégrés comme modules simples de volatilisation de NH3 dans des modèles agronomiques et atmosphériques.
