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Now showing 1 - 10 of 14
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    The Scenario Model Intercomparison Project (ScenarioMIP) for CMIP6
    (München : European Geopyhsical Union, 2016) O'Neill, Brian C.; Tebaldi, Claudia; van Vuuren, Detlef P.; Eyring, Veronika; Friedlingstein, Pierre; Hurtt, George; Knutti, Reto; Kriegler, Elmar; Lamarque, Jean-Francois; Lowe, Jason; Meehl, Gerald A.; Moss, Richard; Riahi, Keywan; Sanderson, Benjamin M.
    Projections of future climate change play a fundamental role in improving understanding of the climate system as well as characterizing societal risks and response options. The Scenario Model Intercomparison Project (ScenarioMIP) is the primary activity within Phase 6 of the Coupled Model Intercomparison Project (CMIP6) that will provide multi-model climate projections based on alternative scenarios of future emissions and land use changes produced with integrated assessment models. In this paper, we describe ScenarioMIP's objectives, experimental design, and its relation to other activities within CMIP6. The ScenarioMIP design is one component of a larger scenario process that aims to facilitate a wide range of integrated studies across the climate science, integrated assessment modeling, and impacts, adaptation, and vulnerability communities, and will form an important part of the evidence base in the forthcoming Intergovernmental Panel on Climate Change (IPCC) assessments. At the same time, it will provide the basis for investigating a number of targeted science and policy questions that are especially relevant to scenario-based analysis, including the role of specific forcings such as land use and aerosols, the effect of a peak and decline in forcing, the consequences of scenarios that limit warming to below 2°C, the relative contributions to uncertainty from scenarios, climate models, and internal variability, and long-term climate system outcomes beyond the 21st century. To serve this wide range of scientific communities and address these questions, a design has been identified consisting of eight alternative 21st century scenarios plus one large initial condition ensemble and a set of long-term extensions, divided into two tiers defined by relative priority. Some of these scenarios will also provide a basis for variants planned to be run in other CMIP6-Endorsed MIPs to investigate questions related to specific forcings. Harmonized, spatially explicit emissions and land use scenarios generated with integrated assessment models will be provided to participating climate modeling groups by late 2016, with the climate model simulations run within the 2017–2018 time frame, and output from the climate model projections made available and analyses performed over the 2018–2020 period.
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    Energy system developments and investments in the decisive decade for the Paris Agreement goals
    (Bristol : IOP Publ., 2021-6-29) Bertram, Christoph; Riahi, Keywan; Hilaire, Jérôme; Bosetti, Valentina; Drouet, Laurent; Fricko, Oliver; Malik, Aman; Pupo Nogueira, Larissa; van der Zwaan, Bob; van Ruijven, Bas; van Vuuren, Detlef; Weitzel, Matthias; Dalla Longa, Francesco; de Boer, Harmen-Sytze; Emmerling, Johannes; Fosse, Florian; Fragkiadakis, Kostas; Harmsen, Mathijs; Keramidas, Kimon; Kishimoto, Paul Natsuo; Kriegler, Elmar; Krey, Volker; Paroussos, Leonidas; Saygin, Deger; Vrontisi, Zoi; Luderer, Gunnar
    The Paris Agreement does not only stipulate to limit the global average temperature increase to well below 2 °C, it also calls for 'making finance flows consistent with a pathway towards low greenhouse gas emissions'. Consequently, there is an urgent need to understand the implications of climate targets for energy systems and quantify the associated investment requirements in the coming decade. A meaningful analysis must however consider the near-term mitigation requirements to avoid the overshoot of a temperature goal. It must also include the recently observed fast technological progress in key mitigation options. Here, we use a new and unique scenario ensemble that limit peak warming by construction and that stems from seven up-to-date integrated assessment models. This allows us to study the near-term implications of different limits to peak temperature increase under a consistent and up-to-date set of assumptions. We find that ambitious immediate action allows for limiting median warming outcomes to well below 2 °C in all models. By contrast, current nationally determined contributions for 2030 would add around 0.2 °C of peak warming, leading to an unavoidable transgression of 1.5 °C in all models, and 2 °C in some. In contrast to the incremental changes as foreseen by current plans, ambitious peak warming targets require decisive emission cuts until 2030, with the most substantial contribution to decarbonization coming from the power sector. Therefore, investments into low-carbon power generation need to increase beyond current levels to meet the Paris goals, especially for solar and wind technologies and related system enhancements for electricity transmission, distribution and storage. Estimates on absolute investment levels, up-scaling of other low-carbon power generation technologies and investment shares in less ambitious scenarios vary considerably across models. In scenarios limiting peak warming to below 2 °C, while coal is phased out quickly, oil and gas are still being used significantly until 2030, albeit at lower than current levels. This requires continued investments into existing oil and gas infrastructure, but investments into new fields in such scenarios might not be needed. The results show that credible and effective policy action is essential for ensuring efficient allocation of investments aligned with medium-term climate targets.
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    A new scenario framework for climate change research: The concept of shared climate policy assumptions
    (Heidelberg : Springer, 2014) Kriegler, Elmar; Edmonds, Jae; Hallegatte, Stéphane; Ebi, Kristie L.; Kram, Tom; Riahi, Keywan; Winkler, Harald; van Vuuren, Detlef P.
    The new scenario framework facilitates the coupling of multiple socioeconomic reference pathways with climate model products using the representative concentration pathways. This will allow for improved assessment of climate impacts, adaptation and mitigation. Assumptions about climate policy play a major role in linking socioeconomic futures with forcing and climate outcomes. The paper presents the concept of shared climate policy assumptions as an important element of the new scenario framework. Shared climate policy assumptions capture key policy attributes such as the goals, instruments and obstacles of mitigation and adaptation measures, and introduce an important additional dimension to the scenario matrix architecture. They can be used to improve the comparability of scenarios in the scenario matrix. Shared climate policy assumptions should be designed to be policy relevant, and as a set to be broad enough to allow a comprehensive exploration of the climate change scenario space.
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    Carbon budgets and energy transition pathways
    (Bristol : IOP Publishing, 2016) van Vuuren, Detlef P.; van Soest, Heleen; Riahi, Keywan; Clarke, Leon; Krey, Volker; Kriegler, Elmar; Rogelj, Joeri; Schaeffer, Michiel; Tavoni, Massimo
    Scenarios from integrated assessment models can provide insights into how carbon budgets relate to other policy-relevant indicators by including information on how fast and by how much emissions can be reduced. Such indicators include the peak year of global emissions, the decarbonisation rate and the deployment of low-carbon technology. Here, we show typical values for these indicators for different carbon budgets, using the recently compiled IPCC scenario database, and discuss how these vary as a function of non-CO2 forcing, energy use and policy delay. For carbon budgets of 2000 GtCO2 and less over the 2010–2100 period, supply of low carbon technologies needs to be scaled up massively from today's levels, unless energy use is relatively low. For the subgroup of scenarios with a budget below 1000 GtCO2 (consistent with >66% chance of limiting global warming to below 2 °C relative to preindustrial levels), the 2050 contribution of low-carbon technologies is generally around 50%–75%, compared to less than 20% today (range refers to the 10–90th interval of available data).
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    Introduction to the AMPERE model intercomparison studies on the economics of climate stabilization
    (Amsterdam [u.a.] : Elsevier Science, 2014) Kriegler, Elmar; Riahi, Keywan; Bosetti, Valentina; Capros, Pantelis; Petermann, Nils; van Vuuren, Detlef P.; Weyant, John P.; Edenhofer, Ottmar
    [No abstract available]
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    Exploring Global Climate Policy Futures and Their Representation in Integrated Assessment Models
    (Lisbon : Cogitatio Press, 2022) Hickmann, Thomas; Bertram, Christoph; Biermann, Frank; Brutschin, Elina; Kriegler, Elmar; Livingston, Jasmine E.; Pianta, Silvia; Riahi, Keywan; van Ruijven, Bas; van Vuuren, Detlef
    The Paris Agreement, adopted in 2015, paved the way for a new hybrid global climate governance architecture with both bottom‐up and top‐down elements. While governments can choose individual climate goals and actions, a global stocktake and a ratcheting‐up mechanism have been put in place with the overall aim to ensure that collective efforts will prevent increasing adverse impacts of climate change. Integrated assessment models show that current combined climate commitments and policies of national governments fall short of keeping global warming to 1.5 °C or 2 °C above preindustrial levels. Although major greenhouse gas emitters, such as China, the European Union, India, the United States under the Biden administration, and several other countries, have made new pledges to take more ambitious climate action, it is highly uncertain where global climate policy is heading. Scenarios in line with long‐term temperature targets typically assume a simplistic and hardly realistic level of harmonization of climate policies across countries. Against this backdrop, this article develops four archetypes for the further evolution of the global climate governance architecture and matches them with existing sets of scenarios developed by integrated assessment models. By these means, the article identifies knowledge gaps in the current scenario literature and discusses possible research avenues to explore the pre‐conditions for successful coordination of national policies towards achieving the long‐term target stipulated in the Paris Agreement.
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    Taking stock of national climate policies to evaluate implementation of the Paris Agreement
    ([London] : Nature Publishing Group UK, 2020) Roelfsema, Mark; van Soest, Heleen L.; Harmsen, Mathijs; van Vuuren, Detlef P.; Bertram, Christoph; den Elzen, Michel; Höhne, Niklas; Iacobuta, Gabriela; Krey, Volker; Kriegler, Elmar; Luderer, Gunnar; Riahi, Keywan; Ueckerdt, Falko; Després, Jacques; Drouet, Laurent; Emmerling, Johannes; Frank, Stefan; Fricko, Oliver; Gidden, Matthew; Humpenöder, Florian; Huppmann, Daniel; Fujimori, Shinichiro; Fragkiadakis, Kostas; Gi, Keii; Keramidas, Kimon; Köberle, Alexandre C.; Aleluia Reis, Lara; Rochedo, Pedro; Schaeffer, Roberto; Oshiro, Ken; Vrontisi, Zoi; Chen, Wenying; Iyer, Gokul C.; Edmonds, Jae; Kannavou, Maria; Jiang, Kejun; Mathur, Ritu; Safonov, George; Vishwanathan, Saritha Sudharmma
    Many countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario analysis, we show that implementation of current policies leaves a median emission gap of 22.4 to 28.2 GtCO2eq by 2030 with the optimal pathways to implement the well below 2 °C and 1.5 °C Paris goals. If Nationally Determined Contributions would be fully implemented, this gap would be reduced by a third. Interestingly, the countries evaluated were found to not achieve their pledged contributions with implemented policies (implementation gap), or to have an ambition gap with optimal pathways towards well below 2 °C. This shows that all countries would need to accelerate the implementation of policies for renewable technologies, while efficiency improvements are especially important in emerging countries and fossil-fuel-dependent countries.
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    Making or breaking climate targets: The AMPERE study on staged accession scenarios for climate policy
    (Amsterdam [u.a.] : Elsevier Science, 2014) Kriegler, Elmar; Riahi, Keywan; Bauer, Nico; Schwanitz, Valeria Jana; Petermann, Nils; Bosetti, Valentina; Marcucci, Adriana; Otto, Sander; Paroussos, Leonidas; Rao, Shilpa; Currás, Tabaré Arroyo; Ashina, Shuichi; Bollen, Johannes; Eom, Jiyong; Hamdi-Cherif, Meriem; Longden, Thomas; Kitous, Alban; Méjean, Aurélie; Sano, Fuminori; Schaeffer, Michiel; Wada, Kenichi; Capros, Pantelis; van Vuuren, Detlef P.; Edenhofer, Ottmar
    This study explores a situation of staged accession to a global climate policy regime from the current situation of regionally fragmented and moderate climate action. The analysis is based on scenarios in which a front runner coalition – the EU or the EU and China – embarks on immediate ambitious climate action while the rest of the world makes a transition to a global climate regime between 2030 and 2050. We assume that the ensuing regime involves strong mitigation efforts but does not require late joiners to compensate for their initially higher emissions. Thus, climate targets are relaxed, and although staged accession can achieve significant reductions of global warming, the resulting climate outcome is unlikely to be consistent with the goal of limiting global warming to 2 degrees. The addition of China to the front runner coalition can reduce pre-2050 excess emissions by 20–30%, increasing the likelihood of staying below 2 degrees. Not accounting for potential co-benefits, the cost of front runner action is found to be lower for the EU than for China. Regions that delay their accession to the climate regime face a trade-off between reduced short term costs and higher transitional requirements due to larger carbon lock-ins and more rapidly increasing carbon prices during the accession period.
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    The IPCC Sixth Assessment Report WGIII climate assessment of mitigation pathways: from emissions to global temperatures
    (Katlenburg-Lindau : Copernicus, 2022) Kikstra, Jarmo S.; Nicholls, Zebedee R. J.; Smith, Christopher J.; Lewis, Jared; Lamboll, Robin D.; Byers, Edward; Sandstad, Marit; Meinshausen, Malte; Gidden, Matthew J.; Rogelj, Joeri; Kriegler, Elmar; Peters, Glen P.; Fuglestvedt, Jan S.; Skeie, Ragnhild B.; Samset, Bjørn H.; Wienpahl, Laura; van Vuuren, Detlef P.; van der Wijst, Kaj-Ivar; Al Khourdajie, Alaa; Forster, Piers M.; Reisinger, Andy; Schaeffer, Roberto; Riahi, Keywan
    While the Intergovernmental Panel on Climate Change (IPCC) physical science reports usually assess a handful of future scenarios, the Working Group III contribution on climate mitigation to the IPCC's Sixth Assessment Report (AR6 WGIII) assesses hundreds to thousands of future emissions scenarios. A key task in WGIII is to assess the global mean temperature outcomes of these scenarios in a consistent manner, given the challenge that the emissions scenarios from different integrated assessment models (IAMs) come with different sectoral and gas-to-gas coverage and cannot all be assessed consistently by complex Earth system models. In this work, we describe the "climate-assessment"workflow and its methods, including infilling of missing emissions and emissions harmonisation as applied to 1202 mitigation scenarios in AR6 WGIII. We evaluate the global mean temperature projections and effective radiative forcing (ERF) characteristics of climate emulators FaIRv1.6.2 and MAGICCv7.5.3 and use the CICERO simple climate model (CICERO-SCM) for sensitivity analysis. We discuss the implied overshoot severity of the mitigation pathways using overshoot degree years and look at emissions and temperature characteristics of scenarios compatible with one possible interpretation of the Paris Agreement. We find that the lowest class of emissions scenarios that limit global warming to "1.5 ° C (with a probability of greater than 50 %) with no or limited overshoot"includes 97 scenarios for MAGICCv7.5.3 and 203 for FaIRv1.6.2. For the MAGICCv7.5.3 results, "limited overshoot"typically implies exceedance of median temperature projections of up to about 0.1 ° C for up to a few decades before returning to below 1.5 ° C by or before the year 2100. For more than half of the scenarios in this category that comply with three criteria for being "Paris-compatible", including net-zero or net-negative greenhouse gas (GHG) emissions, median temperatures decline by about 0.3-0.4 ° C after peaking at 1.5-1.6 ° C in 2035-2055. We compare the methods applied in AR6 with the methods used for SR1.5 and discuss their implications. This article also introduces a "climate-assessment"Python package which allows for fully reproducing the IPCC AR6 WGIII temperature assessment. This work provides a community tool for assessing the temperature outcomes of emissions pathways and provides a basis for further work such as extending the workflow to include downscaling of climate characteristics to a regional level and calculating impacts.
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    Locked into Copenhagen pledges - Implications of short-term emission targets for the cost and feasibility of long-term climate goals
    (Amsterdam [u.a.] : Elsevier Science, 2013) Riahi, Keywan; Kriegler, Elmar; Johnson, Nils; Bertram, Christoph; den Elzen, Michel; Eom, Jiyong; Schaeffer, Michiel; Edmonds, Jae; Isaac, Morna; Krey, Volker; Longden, Thomas; Luderer, Gunnar; Méjean, Aurélie; McCollum, David L.; Mima, Silvana; Turton, Hal; van Vuuren, Detlef P.; Wada, Kenichi; Bosetti, Valentina; Capros, Pantelis; Criqui, Patrick; Hamdi-Cherif, Meriem; Kainuma, Mikiko; Edenhofer, Ottmar
    This paper provides an overview of the AMPERE modeling comparison project with focus on the implications of near-term policies for the costs and attainability of long-term climate objectives. Nine modeling teams participated in the project to explore the consequences of global emissions following the proposed policy stringency of the national pledges from the Copenhagen Accord and Cancún Agreements to 2030. Specific features compared to earlier assessments are the explicit consideration of near-term 2030 emission targets as well as the systematic sensitivity analysis for the availability and potential of mitigation technologies. Our estimates show that a 2030 mitigation effort comparable to the pledges would result in a further “lock-in” of the energy system into fossil fuels and thus impede the required energy transformation to reach low greenhouse-gas stabilization levels (450 ppm CO2e). Major implications include significant increases in mitigation costs, increased risk that low stabilization targets become unattainable, and reduced chances of staying below the proposed temperature change target of 2 °C in case of overshoot. With respect to technologies, we find that following the pledge pathways to 2030 would narrow policy choices, and increases the risks that some currently optional technologies, such as carbon capture and storage (CCS) or the large-scale deployment of bioenergy, will become “a must” by 2030.