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 - 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 - 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 - 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 - Roe, Stephanie A1 - Streck, Charlotte A1 - Beach, Robert A1 - Busch, Jonah A1 - Chapman, Melissa A1 - Daioglou, Vassilis A1 - Deppermann, Andre A1 - Doelman, Jonathan A1 - Emmet-Booth, Jeremy A1 - Engelmann, Jens A1 - Fricko, Oliver A1 - Frischmann, Chad A1 - Funk, Jason A1 - Grassi, Giacomo A1 - Griscom, Bronson A1 - Havlik, Petr A1 - Hanssen, Steef A1 - Humpenöder, Florian A1 - Landholm, David A1 - Lomax, Guy A1 - Lehmann, Johannes A1 - Mesnildrey, Leah A1 - Nabuurs, Gert-Jan A1 - Popp, Alexander A1 - Rivard, Charlotte A1 - Sanderman, Jonathan A1 - Sohngen, Brent A1 - Smith, Pete A1 - Stehfest, Elke A1 - Woolf, Dominic A1 - Lawrence, Deborah T1 - Land-based measures to mitigate climate change BT - potential and feasibility by country JF - Global change biology N2 - Land-based climate mitigation measures have gained significant attention and importance in public and private sector climate policies. Building on previous studies, we refine and update the mitigation potentials for 20 land-based measures in >200 countries and five regions, comparing “bottom-up” sectoral estimates with integrated assessment models (IAMs). We also assess implementation feasibility at the country level. Cost-effective (available up to $100/tCO2eq) land-based mitigation is 8–13.8 GtCO2eq yr−1 between 2020 and 2050, with the bottom end of this range representing the IAM median and the upper end representing the sectoral estimate. The cost-effective sectoral estimate is about 40% of available technical potential and is in line with achieving a 1.5°C pathway in 2050. Compared to technical potentials, cost-effective estimates represent a more realistic and actionable target for policy. The cost-effective potential is approximately 50% from forests and other ecosystems, 35% from agriculture, and 15% from demand-side measures. The potential varies sixfold across the five regions assessed (0.75–4.8 GtCO2eq yr−1) and the top 15 countries account for about 60% of the global potential. Protection of forests and other ecosystems and demand-side measures present particularly high mitigation efficiency, high provision of co-benefits, and relatively lower costs. The feasibility assessment suggests that governance, economic investment, and socio-cultural conditions influence the likelihood that land-based mitigation potentials are realized. A substantial portion of potential (80%) is in developing countries and LDCs, where feasibility barriers are of greatest concern. Assisting countries to overcome barriers may result in significant quantities of near-term, low-cost mitigation while locally achieving important climate adaptation and development benefits. Opportunities among countries vary widely depending on types of land-based measures available, their potential co-benefits and risks, and their feasibility. Enhanced investments and country-specific plans that accommodate this complexity are urgently needed to realize the large global potential from improved land stewardship. KW - AFOLU KW - co-benefits KW - demand management KW - feasibility KW - land management KW - land sector KW - mitigation KW - natural climate solutions KW - nature-based solutions Y1 - 2021 U6 - https://doi.org/10.1111/gcb.15873 SN - 1365-2486 VL - 27 IS - 23 SP - 6025 EP - 6058 PB - Wiley-Blackwell CY - Oxford ER -