TY  - JOUR
A1  - Kikstra, Jarmo S.
A1  - Nicholls, Zebedee R. J.
A1  - Smith, Christopher J.
A1  - Lewis, Jared
A1  - Lamboll, Robin D.
A1  - Byers, Edward
A1  - Sandstad, Marit
A1  - Meinshausen, Malte
A1  - Gidden, Matthew J.
A1  - Rogelj, Joeri
A1  - Kriegler, Elmar
A1  - Peters, Glen P.
A1  - Fuglestvedt, Jan S.
A1  - Skeie, Ragnhild B.
A1  - Samset, Bjørn H.
A1  - Wienpahl, Laura
A1  - van Vuuren, Detlef P.
A1  - van der Wijst, Kaj-Ivar
A1  - Al Khourdajie, Alaa
A1  - Forster, Piers M.
A1  - Reisinger, Andy
A1  - Schaeffer, Roberto
A1  - Riahi, Keywan
T1  - The IPCC Sixth Assessment Report WGIII climate assessment of mitigation pathways
BT  - from emissions to global temperatures
JF  - Geoscientific model development
N2  - 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.
Y1  - 2022
U6  - https://doi.org/10.5194/gmd-15-9075-2022
SN  - 1991-959X
SN  - 1991-9603
VL  - 15
IS  - 24
SP  - 9075
EP  - 9109
PB  - Copernicus
CY  - Katlenburg-Lindau
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  - 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  - Wilson, Charlie
A1  - Guivarch, Céline
A1  - Kriegler, Elmar
A1  - van Ruijven, Bas
A1  - van Vuuren, Detlef P.
A1  - Krey, Volker
A1  - Schwanitz, Valeria Jana
A1  - Thompson, Erica L.
T1  - Evaluating process-based integrated assessment models of climate change mitigation
JF  - Climatic change
N2  - Process-based integrated assessment models (IAMs) project long-term transformation pathways in energy and land-use systems under what-if assumptions. IAM evaluation is necessary to improve the models’ usefulness as scientific tools applicable in the complex and contested domain of climate change mitigation. We contribute the first comprehensive synthesis of process-based IAM evaluation research, drawing on a wide range of examples across six different evaluation methods including historical simulations, stylised facts, and model diagnostics. For each evaluation method, we identify progress and milestones to date, and draw out lessons learnt as well as challenges remaining. We find that each evaluation method has distinctive strengths, as well as constraints on its application. We use these insights to propose a systematic evaluation framework combining multiple methods to establish the appropriateness, interpretability, credibility, and relevance of process-based IAMs as useful scientific tools for informing climate policy. We also set out a programme of evaluation research to be mainstreamed both within and outside the IAM community.
KW  - process-based integrated assessment model
KW  - IAM
KW  - evaluation
KW  - climate mitigation
Y1  - 2021
U6  - https://doi.org/10.1007/s10584-021-03099-9
SN  - 0165-0009
SN  - 1573-1480
VL  - 166
IS  - 1-2
PB  - Springer Science + Business Media B.V.
CY  - Dordrecht
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  -