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Modeling uncertainty in climate change : a multi-model comparison / Kenneth Gillingham, William Nordhaus, David Anthoff, Geoffrey Blanford, Valentina Bosetti, Peter Christensen, Haewon McJeon, John Reilly, and Paul Sztorc. NBER Working Paper No. 21637,October 2015 - Draft : http://cowles.yale.edu/sites/default/files/files/pub/d20/d2022.pdf The economics of climate change involves a vast array of uncertainties, complicating both the analysis and development of climate policy. This study presents the results of the first comprehensive study of uncertainty in climate change using multiple integrated assessment models. The study looks at model and parametric uncertainties for population, total factor productivity, and climate sensitivity. It estimates the pdfs of key output variables, including CO2 concentrations, temperature, damages, and the social cost of carbon (SCC). One key finding is that parametric uncertainty is more important than uncertainty in model structure. Our resulting pdfs also provide insights on tail events.COP21: building an unprecedented and sustainable agreement / Michel Colombier. Paris : IDDRI, octobre 2015, 16 p. (Working Papers N°13/2015) http://www.iddri.org/Publications/COP21-building-an-unprecedented-and-sustainable-agreementL’ambition de la COP21 n'est rien moins que d’établir un nouveau régime, contraignant et universel, destiné à supplanter l’accord de Kyoto. Faut-il pour atteindre cet objectif privilégier le succès diplomatique au succès climatique ? Ou y a-t-il, derrière le processus onusien de négociations quelque peu obscur et laborieux, une vision et une ambition réelles qui pourraient déboucher sur un accord utile et efficace ? Le cas échéant, où sont aujourd’hui les lignes de fractures, les potentiels points d’achoppement d’un tel accord qui révèlent, en creux, les enjeux de la discussion ?Encouraging Increased Climate Action by Non-Party  Stakeholders / Yoko Nobuoka , Jane Ellis and Sarah Pyndt Andersen. Paris : OECD, October 2015, 33 p. (Climate Change Expert Group working paper 2015-5) http://www.oecd.org/environment/cc/Encouraging-Increased-Climate-Action-by-Non-Party-Stakeholders.pdfLimiting the increase in global average temperature to below 2°C compared to pre-industrial levels will require ambitious mitigation action by a broad range of actors including Parties to the United Nations Framework Convention on Climate Change (UNFCCC), i.e., national governments, and non-party stakeholders (NPS). This paper focuses on three types of NPS, namely, sub-national governments, the private sector and financial institutions, and examines how the 2015 agreement could help the NPS encourage increased mitigation actions as well as the financing for such actions.  The paper identifies five barriers that can prevent NPS from enhancing their actions and assesses how the current process under the UNFCCC is addressing these barriers for the pre-2020 period. It also explores options to establish or enhance links between the UNFCCC and NPS in the 2015 agreement for post-2020, in order to further address the barriers and enhance actions by NPS.&#160;&#160;