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Valeurs carbone implicites des contributions nationales et trajectoires 2°C / L. Coindoz, P. Criqui, S. Mathy &#38; S. Mima. Grenoble: GAEL, mars 2017, 46 p. (Working paper GAEL ; 2/2017) https://hal.archives-ouvertes.fr/hal-01496223Ce document de travail analyse le degré d'effort nécessaire à l'atteinte des objectifs INDC des 13 pays du Deep Decarbonization Pathway Project. L'objectif est d'évaluer et de comparer les degrés d'effort requis pour atteindre les objectifs INDC, entre les pays, d'une part et, d'autre part, au regard de trajectoires de plus long terme (2050) s'inscrivant dans l'objectif global de limiter la hausse des températures en deçà de 2°C. Une méthodologie est mise en place pour transcrire les INDC en niveaux d'émissions de CO2 nettes du LULUCF. Le modèle POLES est ensuite utilisé pour révéler la valeur carbone implicite des INDC et permettre une comparabilité des objectifs nationaux entre eux. Enfin, la création d'un scénario INDCext permet d'appréhender les INDC au regard d'objectifs nationaux de plus long terme (2050) compatibles avec l'objectif global de limiter la hausse des températures en deçà de 2°C.A Simple Framework for Climate-Change Policy under Model Uncertainty / S. Athanasoglou,  V. Bosetti, L. Drouet. Milan : Fondazione Eni Enrico Mattei, 2017, 25 p. (Nota di Lavoro 13.2017) http://www.feem.it/userfiles/attach/2017371211554NDL2017-013.pdfWe propose a novel framework for the economic assessment of climate-change policy. Our main point of departure from existing work is the adoption of a "satisficing", as opposed to optimizing, modeling approach. Along these lines, we place primary emphasis on the extent to which different policies meet a set of goals at a specific future date instead of their performance vis-à-vis some intertemporal objective function. Consistent to the nature of climate-change policy making, our model takes explicit account of model uncertainty. To this end, the value function we propose is an analogue of the well-known success-probability criterion adapted to settings characterized by model uncertainty. We apply this decision criterion to probability distributions constructed by Drouet et al. (2015) linking carbon budgets to future consumption. The main result that emerges is the superiority of "medium" carbon budgets in line with a 3°C target (i.e., 2000-3000 GtCO2) in preventing large future consumption losses with high probability. Insights from computational geometry facilitate computations considerably, and allow for the efficient application of the model in high-dimensional settings.A roadmap for rapid decarbonization : Emissions inevitably approach zero with a “carbon law” / Johan Rockström, Owen Gaffney, Joeri Rogelj, Malte Meinshausen, Nebojsa Nakicenovic, Hans Joachim Schellnhuber, Science, 24 March 2017, vol. 355, n° 6331, pp. 1269-1271 http://science.sciencemag.org/content/355/6331/1269/tab-pdfTo bridge the gap between science-based targets focused on cutting greenhouse gases, and national commitments to such efforts, international experts propose in the highly renowned journal ‘Science’ a decadal roadmap strategy for achieving net-zero emissions by mid-century. They base this on a simple “carbon law” of halving anthropogenic carbon-dioxide (CO2) emissions each decade. “A carbon law applies to all sectors and countries at all scales and encourages bold action in the short term,” say Johan Rockström and colleagues. Rockström, Director of the Stockholm Resilience Centre, and Hans Joachim Schellnhuber, Director of the Potsdam Institute for Climate Impact Research, argue that a “carbon law” that links short-term targets to long-term goals will “provide key elements for national and international climate strategies.” Such a broad decadal roadmap would focus on four dimensions: innovation, institution, infrastructure, and investment, and it would encompass sectors such as agriculture, construction, finance, manufacturing, and transport.Environmental Integrity under Article 6 of the Paris Agreement / Lambert Schneider, Jürg Füssler, Stephanie La Hoz Theuer, Anik Kohli, Jakob Graichen, Sean Healy and Derik Broekhoff. Oeko-Institut, Stockholm Environment Institute and INFRAS for the German Environment Agency (UBA), March 2017, 53 p. (Discussion Paper) https://www.dehst.de/SharedDocs/Downloads/EN/JI-CDM/Discussion-Paper_Environmental_integrity.pdfThe paper explores key issues and options to achieve environmental integrity under Article 6 of the Paris Agreement. It proposes that environmental integrity in context of Article 6 means that using international transfers does not result in higher global GHG emissions than if mitigation targets of NDCs had been achieved only through domestic mitigation action. The paper identifies four issues that can affect the global GHG emissions outcome from international transfers: robust accounting for international transfers; the quality of units from mechanisms; the ambition of the NDC target of the transferring country; and presence of incentives and disincentives for further mitigation action. A particular risk is the international transfer of „hot air“. Based on global GHG emissions and the communicated NDCs, it is estimated that global mitigation action be undermined by up to 68 % if all hot air in current NDCs would be transferred. The paper identifies and discusses seven options to mitigate environmental integrity risks from international transfers, including principles for international guidance on mechanism design and communication of NDCs, international reporting and review, eligibility criteria, limits on international transfers, exchange or discount rates, green investment schemes, and carbon clubs. Finally, the paper explores for crediting mechanisms how additionality could be demonstrated and how emission baselines could be set under the new framework of the Paris Agreement where nearly all Parties have communicated a mitigation target in their NDC.L'urgence climatique / Bernard Perret, Sens-Dessous, 2017/1 (N° 19) http://www.cairn.info/revue-sens-dessous-2017-1-page-19.htmParler d’urgence climatique, c’est prendre acte de faits que personne ne peut ignorer. Le réchauffement du climat est une menace mortelle pour la civilisation et nous ne parviendrons pas à le limiter sans changements drastiques dans l’orientation de notre modèle de développement. Pourquoi est-il si difficile de « croire ce que nous savons » et d’agir en conséquence ?Comparaison des modèles météorologiques, climatiques et économiques : quelles capacités, quelles limites, quels usages ? / Alain Grandjean et Gaël Giraud. Chaire énergie &#38; prospérité, mars 2017, 54 p. (working paper) http://www.chair-energy-prosperity.org/publications/comparaison-modeles-meteorologiques-climatiques-economiques/Le diagnostic du changement climatique et de ses conséquences physiques repose sur une représentation modélisée et assez solide des phénomènes en cause. Les effets économiques du changement climatique, de diverses stratégies d’atténuation et d’adaptation, peuvent également être modélisés, en recourant alors à des théories économiques pas toujours explicitées et dont la validité est plus discutable. Tous ces modèles, influents dans la décision publique, ont des capacités et des limites bien différentes, et ce pour plusieurs raisons que la présente note a pour but de mettre en lumière. Elle se conclut par une série de recommandations relatives au bon usage des modèles économiques.