TY - JOUR A1 - Bertram, Christoph A1 - Riahi, Keywan A1 - Hilaire, Jérôme A1 - Bosetti, Valentina A1 - Drouet, Laurent A1 - Fricko, Oliver A1 - Malik, Aman A1 - Nogueira, Larissa Pupo A1 - van der Zwaan, Bob A1 - van Ruijven, Bas A1 - van Vuuren, Detlef P. A1 - Weitzel, Matthias A1 - Longa, Francesco Dalla A1 - de Boer, Harmen-Sytze A1 - Emmerling, Johannes A1 - Fosse, Florian A1 - Fragkiadakis, Kostas A1 - Harmsen, Mathijs A1 - Keramidas, Kimon A1 - Kishimoto, Paul Natsuo A1 - Kriegler, Elmar A1 - Krey, Volker A1 - Paroussos, Leonidas A1 - Saygin, Deger A1 - Vrontisi, Zoi A1 - Luderer, Gunnar T1 - Energy system developments and investments in the decisive decade for the Paris Agreement goals JF - Environmental research letters N2 - 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. KW - Paris Agreement KW - energy investments KW - mitigation policies KW - climate policy KW - integrated assessment modelling Y1 - 2021 U6 - https://doi.org/10.1088/1748-9326/ac09ae SN - 1748-9326 VL - 16 IS - 7 PB - IOP Publishing CY - Bristol ER - TY - JOUR A1 - Harmsen, Mathijs A1 - Kriegler, Elmar A1 - van Vuuren, Detlef P. A1 - van der Wijst, Kaj-Ivar A1 - Luderer, Gunnar A1 - Cui, Ryna A1 - Dessens, Olivier A1 - Drouet, Laurent A1 - Emmerling, Johannes A1 - Morris, Jennifer Faye A1 - Fosse, Florian A1 - Fragkiadakis, Dimitris A1 - Fragkiadakis, Kostas A1 - Fragkos, Panagiotis A1 - Fricko, Oliver A1 - Fujimori, Shinichiro A1 - Gernaat, David A1 - Guivarch, Céline A1 - Iyer, Gokul A1 - Karkatsoulis, Panagiotis A1 - Keppo, Ilkka A1 - Keramidas, Kimon A1 - Köberle, Alexandre A1 - Kolp, Peter A1 - Krey, Volker A1 - Krüger, Christoph A1 - Leblanc, Florian A1 - Mittal, Shivika A1 - Paltsev, Sergey A1 - Rochedo, Pedro A1 - van Ruijven, Bas J. A1 - Sands, Ronald D. A1 - Sano, Fuminori A1 - Strefler, Jessica A1 - Arroyo, Eveline Vasquez A1 - Wada, Kenichi A1 - Zakeri, Behnam T1 - Integrated assessment model diagnostics BT - key indicators and model evolution JF - Environmental research letters N2 - Integrated assessment models (IAMs) form a prime tool in informing about climate mitigation strategies. Diagnostic indicators that allow comparison across these models can help describe and explain differences in model projections. This increases transparency and comparability. Earlier, the IAM community has developed an approach to diagnose models (Kriegler (2015 Technol. Forecast. Soc. Change 90 45–61)). Here we build on this, by proposing a selected set of well-defined indicators as a community standard, to systematically and routinely assess IAM behaviour, similar to metrics used for other modeling communities such as climate models. These indicators are the relative abatement index, emission reduction type index, inertia timescale, fossil fuel reduction, transformation index and cost per abatement value. We apply the approach to 17 IAMs, assessing both older as well as their latest versions, as applied in the IPCC 6th Assessment Report. The study shows that the approach can be easily applied and used to indentify key differences between models and model versions. Moreover, we demonstrate that this comparison helps to link model behavior to model characteristics and assumptions. We show that together, the set of six indicators can provide useful indication of the main traits of the model and can roughly indicate the general model behavior. The results also show that there is often a considerable spread across the models. Interestingly, the diagnostic values often change for different model versions, but there does not seem to be a distinct trend. KW - diagnostics KW - integrated assessment models KW - climate policy KW - Assessment Report IPCC KW - renewable energy KW - migration KW - AR6 Y1 - 2021 U6 - https://doi.org/10.1088/1748-9326/abf964 SN - 1748-9326 VL - 16 IS - 5 PB - IOP Publishing CY - Bristol ER - TY - JOUR A1 - Riahi, Keywan A1 - Bertram, Christoph A1 - Huppmann, Daniel A1 - Rogelj, Joeri A1 - Bosetti, Valentina A1 - Cabardos, Anique-Marie A1 - Deppermann, Andre A1 - Drouet, Laurent A1 - Frank, Stefan A1 - Fricko, Oliver A1 - Fujimori, Shinichiro A1 - Harmsen, Mathijs A1 - Hasegawa, Tomoko A1 - Krey, Volker A1 - Luderer, Gunnar A1 - Paroussos, Leonidas A1 - Schaeffer, Roberto A1 - Weitzel, Matthias A1 - van der Zwaan, Bob A1 - Vrontisi, Zoi A1 - Longa, Francesco Dalla A1 - Després, Jacques A1 - Fosse, Florian A1 - Fragkiadakis, Kostas A1 - Gusti, Mykola A1 - Humpenöder, Florian A1 - Keramidas, Kimon A1 - Kishimoto, Paul A1 - Kriegler, Elmar A1 - Meinshausen, Malte A1 - Nogueira, Larissa Pupo A1 - Oshiro, Ken A1 - Popp, Alexander A1 - Rochedo, Pedro R. R. A1 - Ünlü, Gamze A1 - van Ruijven, Bas A1 - Takakura, Junya A1 - Tavoni, Massimo A1 - van Vuuren, Detlef P. A1 - Zakeri, Behnam T1 - Cost and attainability of meeting stringent climate targets without overshoot JF - Nature climate change N2 - Global emissions scenarios play a critical role in the assessment of strategies to mitigate climate change. The current scenarios, however, are criticized because they feature strategies with pronounced overshoot of the global temperature goal, requiring a long-term repair phase to draw temperatures down again through net-negative emissions. Some impacts might not be reversible. Hence, we explore a new set of net-zero CO2 emissions scenarios with limited overshoot. We show that upfront investments are needed in the near term for limiting temperature overshoot but that these would bring long-term economic gains. Our study further identifies alternative configurations of net-zero CO2 emissions systems and the roles of different sectors and regions for balancing sources and sinks. Even without net-negative emissions, CO2 removal is important for accelerating near-term reductions and for providing an anthropogenic sink that can offset the residual emissions in sectors that are hard to abate. Y1 - 2021 U6 - https://doi.org/10.1038/s41558-021-01215-2 SN - 1758-678X SN - 1758-6798 VL - 11 IS - 12 SP - 1063 EP - 1069 PB - Nature Publishing Group CY - London ER - TY - JOUR A1 - van Soest, Heleen L. A1 - Aleluia Reis, Lara A1 - Baptista, Luiz Bernardo A1 - Bertram, Christoph A1 - Després, Jacques A1 - Drouet, Laurent A1 - den Elzen, Michel A1 - Fragkos, Panagiotis A1 - Fricko, Oliver A1 - Fujimori, Shinichiro A1 - Grant, Neil A1 - Harmsen, Mathijs A1 - Iyer, Gokul A1 - Keramidas, Kimon A1 - Köberle, Alexandre C. A1 - Kriegler, Elmar A1 - Malik, Aman A1 - Mittal, Shivika A1 - Oshiro, Ken A1 - Riahi, Keywan A1 - Roelfsema, Mark A1 - van Ruijven, Bas A1 - Schaeffer, Roberto A1 - Silva Herran, Diego A1 - Tavoni, Massimo A1 - Ünlü, Gamze A1 - Vandyck, Toon A1 - van Vuuren, Detlef P. T1 - Global roll-out of comprehensive policy measures may aid in bridging emissions gap JF - Nature communications N2 - Closing the emissions gap between Nationally Determined Contributions (NDCs) and the global emissions levels needed to achieve the Paris Agreement’s climate goals will require a comprehensive package of policy measures. National and sectoral policies can help fill the gap, but success stories in one country cannot be automatically replicated in other countries. They need to be adapted to the local context. Here, we develop a new Bridge scenario based on nationally relevant, short-term measures informed by interactions with country experts. These good practice policies are rolled out globally between now and 2030 and combined with carbon pricing thereafter. We implement this scenario with an ensemble of global integrated assessment models. We show that the Bridge scenario closes two-thirds of the emissions gap between NDC and 2 °C scenarios by 2030 and enables a pathway in line with the 2 °C goal when combined with the necessary long-term changes, i.e. more comprehensive pricing measures after 2030. The Bridge scenario leads to a scale-up of renewable energy (reaching 52%–88% of global electricity supply by 2050), electrification of end-uses, efficiency improvements in energy demand sectors, and enhanced afforestation and reforestation. Our analysis suggests that early action via good-practice policies is less costly than a delay in global climate cooperation. KW - climate-change mitigation KW - climate-change policy Y1 - 2021 U6 - https://doi.org/10.1038/s41467-021-26595-z N1 - Corrigendum: https://doi.org/10.1038/s41467-022-27969-7 VL - 12 IS - 1 PB - Nature Publishing Group UK CY - London ER - TY - JOUR A1 - Duan, Hongbo A1 - Zhou, Sheng A1 - Jiang, Kejun A1 - Bertram, Christoph A1 - Harmsen, Mathijs A1 - Kriegler, Elmar A1 - van Vuuren, Detlef P. A1 - Wang, Shouyang A1 - Fujimori, Shinichiro A1 - Tavoni, Massimo A1 - Ming, Xi A1 - Keramidas, Kimon A1 - Iyer, Gokul A1 - Edmonds, James T1 - Assessing China’s efforts to pursue the 1.5°C warming limit JF - Science N2 - Given the increasing interest in keeping global warming below 1.5°C, a key question is what this would mean for China’s emission pathway, energy restructuring, and decarbonization. By conducting a multimodel study, we find that the 1.5°C-consistent goal would require China to reduce its carbon emissions and energy consumption by more than 90 and 39%, respectively, compared with the “no policy” case. Negative emission technologies play an important role in achieving near-zero emissions, with captured carbon accounting on average for 20% of the total reductions in 2050. Our multimodel comparisons reveal large differences in necessary emission reductions across sectors, whereas what is consistent is that the power sector is required to achieve full decarbonization by 2050. The cross-model averages indicate that China’s accumulated policy costs may amount to 2.8 to 5.7% of its gross domestic product by 2050, given the 1.5°C warming limit. Y1 - 2021 U6 - https://doi.org/10.1126/science.aba8767 SN - 1095-9203 SN - 0036-8075 VL - 372 IS - 6540 SP - 378 EP - 385 PB - American Association for the Advancement of Science CY - Washington, DC ER -