TY  - JOUR
A1  - Luderer, Gunnar
A1  - Madeddu, Silvia
A1  - Merfort, Leon
A1  - Ueckerdt, Falko
A1  - Pehl, Michaja
A1  - Pietzcker, Robert C.
A1  - Rottoli, Marianna
A1  - Schreyer, Felix
A1  - Bauer, Nico
A1  - Baumstark, Lavinia
A1  - Bertram, Christoph
A1  - Dirnaichner, Alois
A1  - Humpenöder, Florian
A1  - Levesque, Antoine
A1  - Popp, Alexander
A1  - Rodrigues, Renato
A1  - Strefler, Jessica
A1  - Kriegler, Elmar
T1  - Impact of declining renewable energy costs on electrification in low-emission scenarios
JF  - Nature energy
N2  - Cost degression in photovoltaics, wind-power and battery storage has been faster than previously anticipated. In the future, climate policy to limit global warming to 1.5–2 °C will make carbon-based fuels increasingly scarce and expensive. Here we show that further progress in solar- and wind-power technology along with carbon pricing to reach the Paris Climate targets could make electricity cheaper than carbon-based fuels. In combination with demand-side innovation, for instance in e-mobility and heat pumps, this is likely to induce a fundamental transformation of energy systems towards a dominance of electricity-based end uses. In a 1.5 °C scenario with limited availability of bioenergy and carbon dioxide removal, electricity could account for 66% of final energy by mid-century, three times the current levels and substantially higher than in previous climate policy scenarios assessed by the Intergovernmental Panel on Climate Change. The lower production of bioenergy in our high-electrification scenarios markedly reduces energy-related land and water requirements.
KW  - climate-change mitigation
KW  - energy modelling
KW  - renewable energy
Y1  - 2021
U6  - https://doi.org/10.1038/s41560-021-00937-z
SN  - 2058-7546
N1  - Corrigendum: https://doi.org/10.1038/s41560-022-01000-1
VL  - 7
IS  - 1
SP  - 32
EP  - 42
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Malik, Aman
A1  - Bertram, Christoph
A1  - Kriegler, Elmar
A1  - Luderer, Gunnar
T1  - Climate policy accelerates structural changes in energy employment
JF  - Energy policy
N2  - The employment implications of decarbonizing the energy sector have received far less attention than the technology dimension of the transition, although being of critical importance to policymakers. In this work, we adapt a methodology based on employment factors to project future changes in quantity and composition of direct energy supply jobs for two scenarios - (1) relatively weak emissions reductions as pledged in the nationally determined contributions (NDC) and (2) stringent reductions compatible with the 1.5 °C target. We find that in the near-term the 1.5°C-compatible scenario results in a net increase in jobs through gains in solar and wind jobs in construction, installation, and manufacturing, despite significant losses in coal fuel supply; eventually leading to a peak in total direct energy jobs in 2025. In the long run, improvements in labour productivity lead to a decrease of total direct energy employment compared to today, however, total jobs are still higher in a 1.5 °C than in an NDC scenario. Operation and maintenance jobs dominate future jobs, replacing fuel supply jobs. The results point to the need for active policies aimed at retraining, both inside and outside the renewable energy sector, to complement climate policies within the concept of a “just transition”.
KW  - energy supply
KW  - employment
KW  - just transition
KW  - political feasibility
KW  - mitigation pathways
KW  - integrated assessment models
Y1  - 2021
U6  - https://doi.org/10.1016/j.enpol.2021.112642
SN  - 0301-4215
VL  - 159
PB  - Elsevier Science
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Auer, Cornelia
A1  - Kriegler, Elmar
A1  - Carlsen, Henrik
A1  - Kok, Kasper
A1  - Pedde, Simona
A1  - Krey, Volker
A1  - Müller, Boris
T1  - Climate change scenario services
BT  - from science to facilitating action
JF  - One earth
N2  - The goal of limiting global warming to well below 2°C as set out in the Paris Agreement calls for a strategic assessment of societal pathways and policy strategies. Besides policy makers, new powerful actors from the private sector, including finance, have stepped up to engage in forward-looking assessments of a Paris-compliant and climate-resilient future. Climate change scenarios have addressed this demand by providing scientific insights on the possible pathways ahead to limit warming in line with the Paris climate goal. Despite the increased interest, the potential of climate change scenarios has not been fully unleashed, mostly due to a lack of an intermediary service that provides guidance and access to climate change scenarios. This perspective presents the concept of a climate change scenario service, its components, and a prototypical implementation to overcome this shortcoming aiming to make scenarios accessible to a broader audience of societal actors and decision makers.
KW  - climate change scenarios
KW  - climate change scenario services
KW  - climate services
KW  - co-production
KW  - visualization
KW  - capacity building
KW  - mitigation scenarios
KW  - adaptation scenarios
KW  - impact projections
Y1  - 2021
U6  - https://doi.org/10.1016/j.oneear.2021.07.015
SN  - 2590-3322
VL  - 4
IS  - 8
SP  - 1074
EP  - 1082
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - THES
A1  - Kriegler, Elmar
T1  - Imprecise probability analysis for integrated assessment of climate change
T1  - Anwendung der Theorie der unscharfen Wahrscheinlichkeit in der integrierten Analyse des Klimawandels
N2  - We present an application of imprecise probability theory to the quantification of uncertainty in the integrated assessment of climate change. Our work is motivated by the fact that uncertainty about climate change is pervasive, and therefore requires a thorough treatment in the integrated assessment process. Classical probability theory faces some severe difficulties in this respect, since it cannot capture very poor states of information in a satisfactory manner. A more general framework is provided by imprecise probability theory, which offers a similarly firm evidential and behavioural foundation, while at the same time allowing to capture more diverse states of information. An imprecise probability describes the information in terms of lower and upper bounds on probability.  For the purpose of our imprecise probability analysis, we construct a diffusion ocean energy balance climate model that parameterises the global mean temperature response to secular trends in the radiative forcing in terms of climate sensitivity and effective vertical ocean heat diffusivity. We compare the model behaviour to the 20th century temperature record in order to derive a likelihood function for these two parameters and the forcing strength of anthropogenic sulphate aerosols. Results show a strong positive correlation between climate sensitivity and ocean heat diffusivity, and between climate sensitivity and absolute strength of the sulphate forcing.  We identify two suitable imprecise probability classes for an efficient representation of the uncertainty about the climate model parameters and provide an algorithm to construct a belief function for the prior parameter uncertainty from a set of probability constraints that can be deduced from the literature or observational data. For the purpose of updating the prior with the likelihood function, we establish a methodological framework that allows us to perform the updating procedure efficiently for two different updating rules: Dempster's rule of conditioning and the Generalised Bayes' rule. Dempster's rule yields a posterior belief function in good qualitative agreement with previous studies that tried to constrain climate sensitivity and sulphate aerosol cooling. In contrast, we are not able to produce meaningful imprecise posterior probability bounds from the application of the Generalised Bayes' Rule. We can attribute this result mainly to our choice of representing the prior uncertainty by a belief function.  We project the Dempster-updated belief function for the climate model parameters onto estimates of future global mean temperature change under several emissions scenarios for the 21st century, and several long-term stabilisation policies. Within the limitations of our analysis we find that it requires a stringent stabilisation level of around 450 ppm carbon dioxide equivalent concentration to obtain a non-negligible lower probability of limiting the warming to 2 degrees Celsius. We discuss several frameworks of decision-making under ambiguity and show that they can lead to a variety of, possibly imprecise, climate policy recommendations. We find, however, that poor states of information do not necessarily impede a useful policy advice.  We conclude that imprecise probabilities constitute indeed a promising candidate for the adequate treatment of uncertainty in the integrated assessment of climate change. We have constructed prior belief functions that allow much weaker assumptions on the prior state of information than a prior probability would require and, nevertheless, can be propagated through the entire assessment process. As a caveat, the updating issue needs further investigation. Belief functions constitute only a sensible choice for the prior uncertainty representation if more restrictive updating rules than the Generalised Bayes'Rule are available.
N2  - Diese Arbeit untersucht die Eignung der Theorie der unscharfen Wahrscheinlichkeiten für die Beschreibung der Unsicherheit in der integrierten Analyse des Klimawandels. Die wissenschaftliche Unsicherheit bezüglich vieler Aspekte des Klimawandels ist beträchtlich, so dass ihre angemessene Beschreibung von großer Wichtigkeit ist. Die klassische Wahrscheinlichkeitstheorie weist in diesem Zusammenhang einige Probleme auf, da sie Zustände sehr geringer Information nicht zufriedenstellend beschreiben kann. Die unscharfe Wahrscheinlichkeitstheorie bietet ein gleichermaßen fundiertes Theoriegebäude, welches jedoch eine größere Flexibilität bei der Beschreibung verschiedenartiger Informationszustände erlaubt. Unscharfe Wahrscheinlichkeiten erfassen solche Informationszustände durch die Spezifizierung von unteren und oberen Grenzen an zulässige Werte der Wahrscheinlichkeit.  Unsere Analyse des Klimawandels beruht auf einem Energiebilanzmodell mit diffusivem Ozean, welches die globale Temperaturantwort auf eine Änderung der Strahlungsbilanz in Abhängigkeit von zwei Parametern beschreibt: die Klimasensitivität, und die effektive vertikale Wärmediffusivität im Ozean. Wir vergleichen das Modellverhalten mit den Temperaturmessungen des 20. Jahrhunderts, um eine sogenannte Likelihood-Funktion für die Hypothesen zu diesen beiden Parametern sowie dem kühlenden Einfluss der Sulfataerosole zu ermitteln. Im Ergebnis zeigt sich eine stark positive Korrelation zwischen Klimasensitivität und Wärmediffusivität im Ozean, und Klimasensitivität und kühlendem Einfluss der Sulfataerosole.  Für die effiziente Beschreibung der Parameterunsicherheit ziehen wir zwei geeignete Modelltypen aus der unscharfen Wahrscheinlichkeitstheorie heran. Wir formulieren einen Algorithmus, der den Informationsgehalt beider Modelle durch eine sogenannte Belief-Funktion beschreibt. Mit Hilfe dieses Algorithmus konstruieren wir Belief-Funktionen für die A-priori-Parameterunsicherheit auf der Grundlage von divergierenden Wahrscheinlichkeitsschätzungen in der Literatur bzw. Beobachtungsdaten. Wir leiten eine Methode her, um die A-priori-Belief-Funktion im Lichte der Likelihood-Funktion zu aktualisieren. Dabei ziehen wir zwei verschiedene Regeln zur Durchführung des Lernprozesses in Betracht: die Dempstersche Regel und die verallgemeinerte Bayessche Regel. Durch Anwendung der Dempsterschen Regel erhalten wir eineA-posteriori-Belief-Funktion, deren Informationsgehalt qualitativ mit den Ergebnissen bisheriger Studien übereinstimmt, die eine Einschränkung der Unsicherheit über die Klimasensitivität und die kühlende Wirkung der Sulfataerosole versucht haben. Im Gegensatz dazu finden wir bei Anwendung der verallgemeinerten Bayesschen Regel keine sinnvollen unteren und oberen Grenzen an die A-posteriori-Wahrscheinlichkeit. Wir stellen fest, dass dieses Resultat maßgeblich durch die Wahl einer Belief-Funktion zur Beschreibung der A-priori-Unsicherheit bedingt ist.  Die A-posteriori-Belief-Funktion für die Modellparameter, die wir aus der Anwendung der Dempsterschen Regel erhalten haben, wird zur Abschätzung des zukünftigen Temperaturanstiegs eingesetzt. Wir betrachten verschiedene Emissionsszenarien für das 21. Jahrhundert sowie verschiedene Stabilisierungsziele für den Treibhausgasgehalt in der Atmosphäre. Im Rahmen unserer Analyse finden wir, dass sehr strikte Stabilisierungsziele im Bereich einer Kohlendioxid-Äquivalentkonzentration von ca. 450 ppm in der Atmosphäre notwendig sind, um nicht eine vernachlässigbar kleine untere Wahrscheinlichkeit für die Begrenzung der Erwärmung auf 2 Grad Celsius zu erhalten. Wir diskutieren verschiedene Kriterien für die Entscheidungsfindung unter unscharfer Wahrscheinlichkeit, und zeigen dass sie zu verschiedenen teilweise unscharfen Politikempfehlungen führen können. Nichtsdestotrotz stellen wir fest, dass eine klare Politikempfehlung auch bei Zuständen schwacher Information möglich sein kann.  Wir schließen, dass unscharfe Wahrscheinlichkeiten tatsächlich ein geeignetes Mittel zur Beschreibung der Unsicherheit in der integrierten Analyse des Klimawandels darstellen. Wir haben Algorithmen zur Generierung und Weiterverarbeitung von Belief-Funktionen etabliert, die eine deutlich größere A-priori-Unsicherheit beschreiben können, als durch eine A-priori-Wahrscheinlichkeit möglich wäre. Allerdings erfordert die Frage des Lernprozesses für unscharfe Wahrscheinlichkeiten eine weitergehende Untersuchung. Belief-Funktionen stellen nur dann eine vernünftige Wahl für die Beschreibung der A-priori-Unsicherheit dar, wenn striktere Regeln als die verallgemeinerte Bayessche Regel für den Lernprozess gerechtfertigt werden können.
KW  - Anthropogene Klimaänderung
KW  - Klima / Umweltschutz
KW  - Unschärfe
KW  - Intervallwahrscheinlichkeit
KW  - Entscheidung bei Unsicherheit
KW  - Climate Change
KW  - Integrated Assessment
KW  - Uncertainty
KW  - Imprecise Probability
KW  - Decision Making under Ambiguity
Y1  - 2005
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-5611
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  - 
TY  - JOUR
A1  - Piontek, Franziska
A1  - Kalkuhl, Matthias
A1  - Kriegler, Elmar
A1  - Schultes, Anselm
A1  - Leimbach, Marian
A1  - Edenhofer, Ottmar
A1  - Bauer, Nico
T1  - Economic Growth Effects of Alternative Climate Change Impact Channels in Economic Modeling
JF  - Environmental & resource economics : the official journal of the European Association of Environmental and Resource Economists
N2  - Despite increasing empirical evidence of strong links between climate and economic growth, there is no established model to describe the dynamics of how different types of climate shocks affect growth patterns. Here we present the first comprehensive, comparative analysis of the long-term dynamics of one-time, temporary climate shocks on production factors, and factor productivity, respectively, in a Ramsey-type growth model. Damages acting directly on production factors allow us to study dynamic effects on factor allocation, savings and economic growth. We find that the persistence of impacts on economic activity is smallest for climate shocks directly impacting output, and successively increases for direct damages on capital, loss of labor and productivity shocks, related to different responses in savings rates and factor-specific growth. Recurring shocks lead to large welfare effects and long-term growth effects, directly linked to the persistence of individual shocks. Endogenous savings and shock anticipation both have adaptive effects but do not eliminate differences between impact channels or significantly lower the dissipation time. Accounting for endogenous growth mechanisms increases the effects. We also find strong effects on income shares, important for distributional implications. This work fosters conceptual understanding of impact dynamics in growth models, opening options for links to empirics.
KW  - Climate change
KW  - Damages
KW  - Economic growth
KW  - Impact channels
KW  - Production factors
KW  - Persistence
Y1  - 2018
U6  - https://doi.org/10.1007/s10640-018-00306-7
SN  - 0924-6460
SN  - 1573-1502
VL  - 73
IS  - 4
SP  - 1357
EP  - 1385
PB  - Springer
CY  - Dordrecht
ER  - 
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  - Soergel, Bjoern
A1  - Kriegler, Elmar
A1  - Weindl, Isabelle
A1  - Rauner, Sebastian
A1  - Dirnaichner, Alois
A1  - Ruhe, Constantin
A1  - Hofmann, Matthias
A1  - Bauer, Nico
A1  - Bertram, Christoph
A1  - Bodirsky, Benjamin Leon
A1  - Leimbach, Marian
A1  - Leininger, Julia
A1  - Levesque, Antoine
A1  - Luderer, Gunnar
A1  - Pehl, Michaja
A1  - Wingens, Christopher
A1  - Baumstark, Lavinia
A1  - Beier, Felicitas
A1  - Dietrich, Jan Philipp
A1  - Humpenöder, Florian
A1  - von Jeetze, Patrick
A1  - Klein, David
A1  - Koch, Johannes
A1  - Pietzcker, Robert C.
A1  - Strefler, Jessica
A1  - Lotze-Campen, Hermann
A1  - Popp, Alexander
T1  - A sustainable development pathway for climate action within the UN 2030 Agenda
JF  - Nature climate change
N2  - Ambitious climate policies, as well as economic development, education, technological progress and less resource-intensive lifestyles, are crucial elements for progress towards the UN Sustainable Development Goals (SDGs). However, using an integrated modelling framework covering 56 indicators or proxies across all 17 SDGs, we show that they are insufficient to reach the targets. An additional sustainable development package, including international climate finance, progressive redistribution of carbon pricing revenues, sufficient and healthy nutrition and improved access to modern energy, enables a more comprehensive sustainable development pathway. We quantify climate and SDG outcomes, showing that these interventions substantially boost progress towards many aspects of the UN Agenda 2030 and simultaneously facilitate reaching ambitious climate targets. Nonetheless, several important gaps remain; for example, with respect to the eradication of extreme poverty (180 million people remaining in 2030). These gaps can be closed by 2050 for many SDGs while also respecting the 1.5 °C target and several other planetary boundaries.
KW  - climate-change mitigation
KW  - climate-change policy
KW  - socioeconomic scenarios
KW  - sustainability
Y1  - 2021
U6  - https://doi.org/10.1038/s41558-021-01098-3
SN  - 1758-678X
SN  - 1758-6798
VL  - 11
IS  - 8
SP  - 656
EP  - 664
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  - Soergel, Bjoern
A1  - Kriegler, Elmar
A1  - Bodirsky, Benjamin Leon
A1  - Bauer, Nico
A1  - Leimbach, Marian
A1  - Popp, Alexander
T1  - Combining ambitious climate policies with efforts to eradicate poverty
JF  - Nature Communications
N2  - Climate change threatens to undermine efforts to eradicate extreme poverty. However, climate policies could impose a financial burden on the global poor through increased energy and food prices. Here, we project poverty rates until 2050 and assess how they are influenced by mitigation policies consistent with the 1.5 degrees C target. A continuation of historical trends will leave 350 million people globally in extreme poverty by 2030. Without progressive redistribution, climate policies would push an additional 50 million people into poverty. However, redistributing the national carbon pricing revenues domestically as an equal-per-capita climate dividend compensates this policy side effect, even leading to a small net reduction of the global poverty headcount (-6 million). An additional international climate finance scheme enables a substantial poverty reduction globally and also in Sub-Saharan Africa. Combining national redistribution with international climate finance thus provides an important entry point to climate policy in developing countries. Ambitious climate policies can negatively impact the global poor by affecting income, food and energy prices. Here, the authors quantify this effect, and show that it can be compensated by national redistribution of the carbon pricing revenues in combination with international climate finance.
Y1  - 2021
U6  - https://doi.org/10.1038/s41467-021-22315-9
SN  - 2041-1723
VL  - 12
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Merfort, Leon
A1  - Bauer, Nico
A1  - Humpenöder, Florian
A1  - Klein, David
A1  - Strefler, Jessica
A1  - Popp, Alexander
A1  - Luderer, Gunnar
A1  - Kriegler, Elmar
T1  - Bioenergy-induced land-use-change emissions with sectorally fragmented policies
JF  - Nature climate change
N2  - Controlling bioenergy-induced land-use-change emissions is key to exploiting bioenergy for climate change mitigation. However, the effect of different land-use and energy sector policies on specific bioenergy emissions has not been studied so far. Using the global integrated assessment model REMIND-MAgPIE, we derive a biofuel emission factor (EF) for different policy frameworks. We find that a uniform price on emissions from both sectors keeps biofuel emissions at 12 kg CO2 GJ−1. However, without land-use regulation, the EF increases substantially (64 kg CO2 GJ−1 over 80 years, 92 kg CO2 GJ−1 over 30 years). We also find that comprehensive coverage (>90%) of carbon-rich land areas worldwide is key to containing land-use emissions. Pricing emissions indirectly on the level of bioenergy consumption reduces total emissions by cutting bioenergy demand but fails to reduce the average EF. In the absence of comprehensive and timely land-use regulation, bioenergy thus may contribute less to climate change mitigation than assumed previously.
KW  - agriculture
KW  - climate-change mitigation
KW  - energy policy
KW  - energy supply and demand
KW  - environmental economics
Y1  - 2023
U6  - https://doi.org/10.1038/s41558-023-01697-2
SN  - 1758-678X
SN  - 1758-6798
VL  - 13
IS  - 7
SP  - 685
EP  - 692
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Merfort, Leon
A1  - Bauer, Nico
A1  - Humpenöder, Florian
A1  - Klein, David
A1  - Strefler, Jessica
A1  - Popp, Alexander
A1  - Luderer, Gunnar
A1  - Kriegler, Elmar
T1  - State of global land regulation inadequate to control biofuel land-use-change emissions
JF  - Nature climate change
N2  - Under current land-use regulation, carbon dioxide emissions from biofuel production exceed those from fossil diesel combustion. Therefore, international agreements need to ensure the effective and globally comprehensive protection of natural land before modern bioenergy can effectively contribute to achieving carbon neutrality.
KW  - agriculture
KW  - climate-change mitigation
KW  - energy policy
KW  - energy supply and demand
KW  - environmental economics
Y1  - 2023
U6  - https://doi.org/10.1038/s41558-023-01711-7
SN  - 1758-678X
SN  - 1758-6798
VL  - 13
IS  - 7
SP  - 610
EP  - 612
PB  - Nature Publ. 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  - Warszawski, Lila
A1  - Kriegler, Elmar
A1  - Lenton, Timothy M.
A1  - Gaffney, Owen
A1  - Jacob, Daniela
A1  - Klingenfeld, Daniel
A1  - Koide, Ryu
A1  - Costa, María Máñez
A1  - Messner, Dirk
A1  - Nakicenovic, Nebojsa
A1  - Schellnhuber, Hans Joachim
A1  - Schlosser, Peter
A1  - Takeuchi, Kazuhiko
A1  - van der Leeuw, Sander
A1  - Whiteman, Gail
A1  - Rockström, Johan
T1  - All options, not silver bullets, needed to limit global warming to 1.5 °C
BT  - a scenario appraisal
JF  - Environmental research letters
N2  - Climate science provides strong evidence of the necessity of limiting global warming to 1.5 °C, in line with the Paris Climate Agreement. The IPCC 1.5 °C special report (SR1.5) presents 414 emissions scenarios modelled for the report, of which around 50 are classified as '1.5 °C scenarios', with no or low temperature overshoot. These emission scenarios differ in their reliance on individual mitigation levers, including reduction of global energy demand, decarbonisation of energy production, development of land-management systems, and the pace and scale of deploying carbon dioxide removal (CDR) technologies. The reliance of 1.5 °C scenarios on these levers needs to be critically assessed in light of the potentials of the relevant technologies and roll-out plans. We use a set of five parameters to bundle and characterise the mitigation levers employed in the SR1.5 1.5 °C scenarios. For each of these levers, we draw on the literature to define 'medium' and 'high' upper bounds that delineate between their 'reasonable', 'challenging' and 'speculative' use by mid century. We do not find any 1.5 °C scenarios that stay within all medium upper bounds on the five mitigation levers. Scenarios most frequently 'over use' CDR with geological storage as a mitigation lever, whilst reductions of energy demand and carbon intensity of energy production are 'over used' less frequently. If we allow mitigation levers to be employed up to our high upper bounds, we are left with 22 of the SR1.5 1.5 °C scenarios with no or low overshoot. The scenarios that fulfil these criteria are characterised by greater coverage of the available mitigation levers than those scenarios that exceed at least one of the high upper bounds. When excluding the two scenarios that exceed the SR1.5 carbon budget for limiting global warming to 1.5 °C, this subset of 1.5 °C scenarios shows a range of 15–22 Gt CO2 (16–22 Gt CO2 interquartile range) for emissions in 2030. For the year of reaching net zero CO2 emissions the range is 2039–2061 (2049–2057 interquartile range).
KW  - climate change
KW  - emissions scenarios
KW  - 1.5 ◦C
KW  - negative emissions
Y1  - 2021
U6  - https://doi.org/10.1088/1748-9326/abfeec
SN  - 1748-9326
N1  - Corrigendum: 10.1088/1748-9326/acbf6a
VL  - 16
IS  - 6
PB  - IOP Publishing
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Schultes, Anselm
A1  - Piontek, Franziska
A1  - Soergel, Bjoern
A1  - Rogelj, Joeri
A1  - Baumstark, Lavinia
A1  - Kriegler, Elmar
A1  - Edenhofer, Ottmar
A1  - Luderer, Gunnar
T1  - Economic damages from on-going climate change imply deeper near-term emission cuts
JF  - Environmental research letters
N2  - Pathways toward limiting global warming to well below 2 ∘C, as used by the IPCC in the Fifth Assessment Report, do not consider the climate impacts already occurring below 2 ∘C. Here we show that accounting for such damages significantly increases the near-term ambition of transformation pathways. We use econometric estimates of climate damages on GDP growth and explicitly model the uncertainty in the persistence time of damages. The Integrated Assessment Model we use includes the climate system and mitigation technology detail required to derive near-term policies. We find an optimal carbon price of $115 per tonne of CO2 in 2030. The long-term persistence of damages, while highly uncertain, is a main driver of the near-term carbon price. Accounting for damages on economic growth increases the gap between the currently pledged nationally determined contributions and the welfare-optimal 2030 emissions by two thirds, compared to pathways considering the 2 ∘C limit only.
KW  - climate change
KW  - climate mitigation
KW  - climate impacts
KW  - integrated assessment
Y1  - 2021
U6  - https://doi.org/10.1088/1748-9326/ac27ce
SN  - 1748-9326
VL  - 16
IS  - 10
PB  - IOP Publishing
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Strefler, Jessica
A1  - Kriegler, Elmar
A1  - Bauer, Nico
A1  - Luderer, Gunnar
A1  - Pietzcker, Robert C.
A1  - Giannousakis, Anastasis
A1  - Edenhofer, Ottmar
T1  - Alternative carbon price trajectories can avoid excessive carbon removal
JF  - Nature communications
N2  - The large majority of climate change mitigation scenarios that hold warming below 2 °C show high deployment of carbon dioxide removal (CDR), resulting in a peak-and-decline behavior in global temperature. This is driven by the assumption of an exponentially increasing carbon price trajectory which is perceived to be economically optimal for meeting a carbon budget. However, this optimality relies on the assumption that a finite carbon budget associated with a temperature target is filled up steadily over time. The availability of net carbon removals invalidates this assumption and therefore a different carbon price trajectory should be chosen. We show how the optimal carbon price path for remaining well below 2 °C limits CDR demand and analyze requirements for constructing alternatives, which may be easier to implement in reality. We show that warming can be held at well below 2 °C at much lower long-term economic effort and lower CDR deployment and therefore lower risks if carbon prices are high enough in the beginning to ensure target compliance, but increase at a lower rate after carbon neutrality has been reached.
KW  - climate-change mitigation
KW  - climate sciences
KW  - environmental sciences
Y1  - 2021
U6  - https://doi.org/10.1038/s41467-021-22211-2
SN  - 2041-1723
VL  - 12
IS  - 1
PB  - Nature Publishing Group
CY  - London
ER  -