ALBERT

Description: Non-traditional and transnational actors have become essential for environmental and climate change governance. One of these actors, the Climate and Clean Air Coalition (CCAC), has taken over a lead role in the governance of SLCPs. Since 2012, the CCAC has been pushing for an increased political dialogue on the one hand, and fostering technical expertise, projects, and a knowledge network on the other hand. This voluntary alliance is an interesting research subject because it brings together a mix of over 150 governmental, intergovernmental, NGO, and scientific members, who closely work on reducing global near term-warming as well as improving air quality, health, and further aspects of sustainable development. This chapter focuses on the CCAC’s role in the international policy landscape and on what it can contribute to SLCP governance. It describes the CCAC’s structure, modus of operation, and activities, and then scrutinizes its potential and challenges for SLCP governance. Furthermore, this text seeks to provide a perspective on the CCAC in the global climate and environmental policy landscape.

Description: Hydrological extremes, such as droughts and floods, can trigger a complex web of compound and cascading impacts (CCI) due to interdependencies between coupled natural and social systems. However, current decision-making processes typically only consider one impact and disaster event at a time, ignoring causal chains, feedback loops, and conditional dependencies between impacts. Analyses capturing these complex patterns across space and time are thus needed to inform effective adaptation planning. This perspective paper aims to bridge this critical gap by presenting methods for assessing the dynamics of the multi-sector CCI of hydrological extremes. We discuss existing challenges, good practices, and potential ways forward. Rather than pursuing a single methodological approach, we advocate for methodological pluralism. We see complementary or even convergent roles for analyses based on quantitative (e.g., data-mining, systems modeling) and qualitative methods (e.g., mental models, qualitative storylines). The data-driven and knowledge-driven methods provided here can serve as a useful starting point for understanding the dynamics of both high-frequency CCI and low-likelihood but high-impact CCI. With this perspective, we hope to foster research on CCI to improve the development of adaptation strategies for reducing the risk of hydrological extremes.

Description: Net-zero energy system configurations can be met in numerous ways, implying diverse economic effects. However, what is usually ignored in techno-economic and economy-wide analysis are the distinct social-political drivers and barriers, which might constrain certain elements of future energy systems. We thus apply a model ensemble that defines social-political storylines which constrain feasible net-zero configurations of the European energy system. Using these configurations in a macroeconomic general equilibrium model allows us to explore economy-wide effects and ultimately the cost-effectiveness of different systems. We find that social-political storylines provide valuable boundary conditions for feasible net-zero designs of the energy system and that the costliest energy sector configuration in fact leads to the highest European-wide welfare levels. This result originates in indirect effects, particularly positive employment effects, covered by the macroeconomic model. However, adverse public budget effects on the transition to net-zero energy may limit the willingness of policymakers who focus on shorter time-horizons to foster such a development. Our results highlight the relevance of considering the interaction of energy system-changes with labor, emission allowance and capital markets, as well as considering long-term perspectives.

Description: The Corona pandemic was one of the most challenging political events of the last decades in Europe in which many important political issues had to be decided within a very short space of time. Deliberative, sortition-based formats offer new approaches to strengthen democracy in times of crisis but have so far mainly been used for fundamental issues that have been under discussion for a long time. In Germany, four Corona Citizens’ Councils were organized at different levels to deal with the highly dynamic pandemic situation. The first was on local level and took place in the city of Augsburg, the next and most prominent one in the state of Baden-Wurttemberg (‘Bürgerforum Corona’), being held monthly over a period of 13 months. Another one was organized in the state of Saxony, a fourth one in Thuringia. The article examines the background, the methodological quality and the outcomes of three Corona Citizens’ Councils in Germany. The article compares the three Citizens’ Councils and draws conclusions about the crisis-management capacities of deliberative formats in dealing with pressing political issues in highly dynamic situations.

Description: Klimapolitik ist aufgrund ihrer Komplexität und Reichweite mehr denn je auf innovative Beteiligungsverfahren angewiesen. Mit Hilfe innovativer Formate wie dem analytisch-deliberativen Diskurs, erhalten betroffene Bürger:innen die Gelegenheit, in einem Klima gegenseitiger Anerkennung, sowie des Respekts vor der Legitimität unterschiedlicher Wertesysteme und Präferenzen Probleme neu zu definieren, alternative Handlungsoptionen zu diskutieren und die damit verbundenen Folgen und Implikationen zu bewerten. Solche verständigungsorientierte Diskurse können gerade in der Klimapolitik helfen, komplexe Sachverhalten zu klären, Ziele und Strategien zu reflektieren und gemeinsam eine sach- und wertgerechte Gestaltung der Klimapolitik vorzubereiten.

Description: Background This article asks the following question: how well are coal regions, affected by phase-out plans, represented in mediating commissions, to what extent do local communities participate in the decision-making process and how are the political negotiations perceived by the communities? We look at the case of the German lignite phase-out from a procedural justice perspective. Informed by literature on sociotechnical decline and procedural justice in energy transitions, we focus first on aspects of representation, participation and recognition within the German Commission on Growth, Structural Change and Employment (“Coal Commission”). Second, we analyze how to exnovate coal in two regions closely tied to the coal- and lignite-based energy history in Germany: Lusatia and the Rhenish Mining District. Results Based on interview series in both regions, we connect insights from local communities with strategies for structural change and participation programs in the regions. We find significant differences between the two regions, which is primarily an effect of the challenging historical experiences in Lusatia. Participation within existing arrangements is not sufficient to solve these problems; they require a comprehensive strategy for the future of the regions. Conclusions We conclude that the first phase-out process was a lost opportunity to initiate a community-inclusive sustainable transition process. As the phase-out process is not yet concluded, additional efforts and new strategies are needed to resolve the wicked problem of lignite phase-out.

Description: Bürgerräte basieren auf einer einfachen Idee: Per Los ausgewählte Menschen aus allen Teilen der Gesellschaft sollen stärker an politischen Entscheidungen beteiligt werden. Da das Instrument aber viel Gestaltungsfreiheit zulässt und je nach Thema und lokalen Gegebenheiten unterschiedlich umgesetzt werden kann, stellen sich bei der Ausgestaltung eines konkreten Verfahrens viele Fragen. Fast täglich erreichen uns Beratungsanfragen zu geplanten Bürgerräten durch Initiativen oder Mitarbeiterinnen und Mitarbeiter der Verwaltung. Diesen Bedarf greifen wir mit dem vorliegenden Handbuch auf. Es soll zivilgesellschaftliche und staatliche Akteurinnen und Akteure dabei unterstützen, Bürgerräte in der Praxis an für die jeweilige Kommune spezifischen Zielen und Bedingungen auszurichten. Aus der Erfahrung mit Bürgerräten in Deutschland und der Welt lassen sich entscheidende Faktoren für das Gelingen des Formats ableiten: Es hat sich gezeigt welche Praxis sich bewährt hat — und welche nicht. Das Handbuch bündelt dieses Wissen. Es bietet Orientierung für alle Phasen, die ein Bürgerrat durchläuft: von der ersten Idee bis zur Verwendung der Ergebnisse durch die Politik. Die Bürgerrat-Sitzungen betrachten wir in den folgenden Kapiteln also genauso wie die Initiierung des Verfahrens, dessen Vorbereitung und die Prozesse im Nachgang. Dabei formulieren wir Leitfragen für die Vorbereitung und Durchführung und weisen auf entscheidende Momente hin, in denen Richtungsentscheidungen getroffen werden müssen. Für alle Prozessschritte geben wir Anregungen zu möglichen Varianten, konkrete Tipps zur Umsetzung und Beispiele aus dem internationalen Kontext. Das Handbuch nimmt den Organisatorinnen und Organisatoren die Arbeit — und den Spaß — der Vorbereitung eines Bürgerrats nicht ab. Aber es ist eine unerlässliche Hilfe, um im Blick zu behalten, welche Entscheidung das Verfahren in welche Richtung führt. Wir hoffen, dass wir auf diese Weise viele Menschen in Initiativen und Verwaltungen, in der Politik und in Prozessgestaltungsunternehmen bei der Organisation von kommunalen Bürgerräten unterstützen können.

Description: The transport sector and especially private cars pose environmental, economic, and social challenges. For this reason, cargo bikes and shared mobility are considered viable alternatives for road transport. In order to understand the potential and barriers of alternative transport modes, it is essential to analyze underlying motives. Moreover, comparing sustainable alternatives (such as public transport) to cars in terms of motives has been established as a research approach (Steg, 2003). Despite increasing interest in cargo bikes and cargo bike sharing, research on this topic is relatively rare. Particularly, there exists a lack of research addressing the impact of cargo bike sharing on car ownership. Against this background, this study quantifies the car ownership reduction effect of cargo bike sharing. In addition, it is investigated how cargo bikes differ from cars with regard to the underlying motives of users which also helps understanding potential barriers. To answer these research questions, this study is based on a large-scale survey with n = 2,590 cargo bike sharing users. The results imply that cargo bike sharing has a notable impact on car ownership. In general, cargo bikes are rated superior in regard to affective, symbolic, and environmental motives as well as on flexibility and price. However, discrepancies to cars do exist in terms of other instrumental aspects (traffic safety, travel speed, comfort, weather-independence). Notably, users who reduced car ownership tend to rate cargo bikes superior compared to car-dependent users. The results imply that cargo bikes can play a marked role in reducing car dependency. Improving infrastructure and cargo bike technology as well as stimulating favorable social norms for cargo bikes have been identified as beneficial conditions that could help to leverage this potential.

Description: Die deutsche Energiewende bleibt eine Erfolgsgeschichte: Der Atomausstieg wurde 2023 planmässig vollendet und die Kohleverstromung konnte stark reduziert werden.

Description: Nur selten wissen wir, wo und wie das Gemüse, das wir essen, genau angebaut worden ist. Für Mitglieder einer Solidarischen Landwirtschaft sieht das anders aus: Sie teilen sich die Verantwortung für Planung, Anbau und Ernte mit den Landwirt:innen. Aber was bewegt Mitglieder, sich in einer Solidarischen Landwirtschaft zu engagieren?

Description: In sustainability transitions research, the deliberate destabilisation of socio-technical regimes is increasingly recognised as a central intervention point. Absent, however, are granular approaches for assessing whether regime destabilisation actually occurs in processes of systemic change. We propose to assess regime destabilisation through shifts in the institutionalisation of field logics. Methodologically, we employ Socio-Technical Configuration Analysis to map changes over time in the composition and alignment of institutional and technological concepts embedded in sectoral policy. Empirically, we assess the extent to which post-Brexit agricultural policy reform in the United Kingdom marks the destabilisation of an unsustainable regime. Assessing legislative debate transcripts, we find that the previously dominant regime is only partly destabilised, as pre-existing development trajectories along established configurations of field logics, policy goals and instruments remain. These findings support the validity of our conceptual approach. Moreover, they nuance expectations about large-scale policy change as windows of opportunity for regime shifts.

Description: Where annual layers are found in stalagmites, these can be used to provide insights into palaeoclimate. Sebastian F.M. Breitenbach and Norbert Marwan present a low-cost and high-resolution method for acquisition and analysis of greyscale data from speleothems by means of the free open-source ImageJ software.

Description: Climate models are vital for understanding and projecting global climate change and its associated impacts. However, these models suffer from biases that limit their accuracy in historical simulations and the trustworthiness of future projections. Addressing these challenges requires addressing internal variability, hindering the direct alignment between model simulations and observations, and thwarting conventional supervised learning methods. Here, we employ an unsupervised Cycle-consistent Generative Adversarial Network (CycleGAN), to correct daily Sea Surface Temperature (SST) simulations from the Community Earth System Model 2 (CESM2). Our results reveal that the CycleGAN not only corrects climatological biases but also improves the simulation of major dynamic modes including the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole mode, as well as SST extremes. Notably, it substantially corrects climatological SST biases, decreasing the globally averaged Root-Mean-Square Error (RMSE) by 58%. Intriguingly, the CycleGAN effectively addresses the well-known excessive westward bias in ENSO SST anomalies, a common issue in climate models that traditional methods, like quantile mapping, struggle to rectify. Additionally, it substantially improves the simulation of SST extremes, raising the pattern correlation coefficient (PCC) from 0.56 to 0.88 and lowering the RMSE from 0.5 to 0.32. This enhancement is attributed to better representations of interannual, intraseasonal, and synoptic scales variabilities. Our study offers a novel approach to correct global SST simulations and underscores its effectiveness across different time scales and primary dynamical modes.

Description: We utilize a global warming level (GWL) lens to evaluate global and regional patterns of agricultural impacts as global surface temperature increases, providing a unique perspective on the experience of stakeholders with continued warming in the 21st century. We analyze crop productivity outputs from 11 crop models simulating 5 climate models under 3 emissions scenarios across 4 crops within the AgMIP/ISIMIP Phase 3 ensemble. We categorize regional productivity changes (without adaptation) into 9 characteristic climate change response patterns, identifying consistent increases and decreases as well as non-linear (peak or dip) responses indicative of inflection points reversing trends as GWLs increase. Many maize regions and pockets of wheat, rice and soybean show peak decrease patterns where initial increases may lull stakeholders into complacency or maladaptation before productivity shifts to losses at higher GWLs. Although the GWL perspective has proven useful in connecting diverse climate models and emissions scenarios, we identify multiple pitfalls that recommend proceeding with caution when applying this approach to climate impacts. Chief among these is that carbon dioxide (CO2) concentrations at any GWL depend on a climate model's transient climate response (TCR). Higher CO2 concentrations generally benefit crop productivity, so this leads to more pessimistic agricultural projections for so-called “hot” models and can skew multi-model ensemble results as models with high TCR are disproportionately likely to reach higher GWLs. While there are strong connections between many climatic impact-drivers and GWLs, vulnerability and exposure components of food system risk are strongly dependent on development pathways.

Description: Chapter 6 presents an introduction and sections on: earth system analysis from a nonlinear physics perspective; physics fields with relevance for energy technologies; towards green cities: the role of transport electrification; environmental safety; understanding and predicting space weather

Description: Wohngebäude sind für 11 % der Treibhausgasemissionen in Deutschland direkt verantwortlich und für bis zu 40 %, wenn Stromverbrauch mit einbezogen wird. Um die Klimaziele gemäß dem Bundes-Klimaschutzgesetz zu erreichen, ist ein höheres Ambitionsniveau der klimapolitischen Maßnahmen in diesem Sektor erforderlich. Dieser Bericht analysiert die Governance der Evaluierungsprozesse von Maßnahmen im deutschen Gebäudesektor. Wir analysieren die Rollen der beteiligten Akteure, das institutionelle Gefüge sowie die angewandten Metriken und Methoden der Evaluierungen.

Description: Residential buildings directly contribute 11% to local greenhouse gas emissions and up to 40% of total emissions when accounting for energy use for electricity generation. In order to achieve the climate targets in line with the Federal Climate Protection Act, increased ambition level of climate policy instruments is required in this sector. In this research, we are interested in the governance of this sector and the role of evaluation: the government-mandated processes used to evaluate policy in terms of the actors, organisations and ministries involved in executing and coordinating these processes; and the metrics and methods as well as the scope and granularity of evaluations.

Description: Real-world labs make the mobility transition tangible for residents. However, these experiences are not always positive, and often local conflicts arise. Based on in-depth interviews, the authors show that perceived procedural unfairness as well as the redistribution of space are the main drivers of a sceptical attitude towards redesign projects. Real-world labs (RwLs) are often used to explore and foster the mobility transition. Many RwLs dealing with mobility transition temporarily reallocate public spaces from motorized to active transport or to leisure activities. While some residents accept and enjoy the changes, others react with scepticism, rejection, or protest. This can lead to conflicts. Controversial perceptions and conflicts among residents make a permanent redesign rather challenging for the administration and the politicians. In this paper the authors investigate the related conflict types and counterarguments by studying the case of a temporary redesign of an intersection in Berlin. Based on in-depth interviews, they untangle procedural, distributional, and identity conflicts which might underlie the critical and ambivalent perceptions of residents. An abundance of conflict issues pertaining to procedural and distributional conflicts are revealed and emphasize the role of the RwL process.

Description: In order to avoid dangerous climate change and to satisfy the global energy needs energy systems have to change. Hopes are especially high in countries of the Global South for the low-carbon transition to propel sustainable development. Yet, while the energy transition provides opportunities, it also raises questions on how to avoid new global inequalities. This study presents the first quantitative approach to measure the extent to which the energy transitions in the Global South incorporate elements of energy justice. In doing so, this study builds on a rich literature on energy justice that differentiates between distributional, recognition, and procedural justice, thus taking into account social and development objectives such as affordability and accessibility of energy, the inclusion of marginalised parts of society, as well as broader community involvement and participation. Though much important conceptual and qualitative work has been done, what has been lacking so far is a quantitative measure of the degree to which the energy transition lives up to the imperative of energy justice, going beyond the much-studied Global North. The proposed energy justice index is designed and applied to select countries from Southeast Asia (Malaysia), sub-Saharan Africa (Kenya), the MENA region (Jordan), and Latin America (Chile). The index stands the test of the empirical application and demonstrates significant variation between countries along the different dimensions of energy justice. The study also emphasizes the importance of further testing and of improving data quality for informed policy making of energy justice issues in the Global South.

Description: Net zero targets have rapidly become the guiding principle of climate policy, implying the use of carbon dioxide removal (CDR) to compensate for residual emissions. At the same time, the extent of (future) residual emissions and their distribution between economic sectors and activities has so far received little attention from a social science perspective. This constitutes a research gap as the distribution of residual emissions and corresponding amounts of required CDR is likely to become highly contested in the political economy of low-carbon transformation. Here, we investigate what function CDR performs from the perspective of sectors considered to account for a large proportion of future residual emissions (cement, steel, chemicals, and aviation) as well as the oil and gas industry in the EU. We also explore whether they claim residual emissions to be compensated for outside of the sector, whether they quantify these claims and how they justify them. Relying on interpretative and qualitative analysis, we use decarbonization or net zero roadmaps published by the major sector-level European trade associations as well as their statements and public consultation submissions in reaction to policy initiatives by the EU to mobilize CDR. Our findings indicate that while CDR technologies perform an important abstract function for reaching net zero in the roadmaps, the extent of residual emissions and responsibilities for delivering corresponding levels of negative emissions remain largely unspecified. This risks eliding pending distributional conflicts over residual emissions which may intersect with conflicts over diverging technological transition pathways advocated by the associations.

Description: Wenn das noch was werden soll mit der Mobilitätswende, müssen wir Gas geben. Als Leserin oder Leser der mobilogisch! wissen Sie schon: Die Mobilitätswende ist eine große und komplexe Baustel- le, da geraten wir schnell ins Schleudern. Obwohl uns manchmal scheint, die Situation sei festgefah- ren, ist es wichtig, dass wir – als Gesellschaft – die Kurve kriegen.

Description: Nachhaltigkeit ist als normative Grundlage politischer Entscheidungen zur Transformation des Energiesystems nicht mehr wegzudenken. Sämtliche wirtschaftlichen Prozesse beruhen auf der Extraktion (vor allem) nicht-erneuerbarer Ressourcen, deren energetischer Umwandlung und Nutzung in Produktionsprozessen (von Gütern bzw. für die Bereitstellung von Dienstleistungen) sowie der daraus resultierenden negativen Externalitäten als ökologische Kosten, z. B. die Belastung ökologischer Senken (Atmosphäre, Wälder, Meere, etc.).

Description: The Paris Agreement requires countries to break away from carbon lock-in, a particular challenge for traditional oil and gas producers. How can these countries overcome path-dependencies to shift from a fossil fuel heavy system to one relying on renewable energy? Malaysia epitomizes this challenge: the country is the second-largest oil producer in Southeast Asia whilst the fossil fuel energy sector takes up nearly 80 % of total greenhouse gas (GHG) emissions, with coal energy occupying the largest share. To identify leverage points of energy transitions, we model the structural components influencing the Malaysian energy system and assess the dynamics of interrelating factors. Based on stakeholders' input, we identify main factors influencing Malaysia's energy transition, explore their interactions, and use Cross Impact Balances (CIB) to create scenarios. Our analysis reveals the need to simultaneously disperse the centralized political power to a more diverse set of actors whilst introducing green growth recovery packages to break the carbon lock-in. Whilst focused on Malaysia, the findings contribute more generally to our understanding how fossil fuel reliant emerging economies can break path-dependencies inhibiting the clean energy transition.

Description: The topic of greenhouse gas emissions embodied in products is gaining in prominence and the possibilities for measuring and verifying them are improving. This provides fertile ground for those who demand that climate policy should address such embodied emissions. There are different design options for policies targeting embodied emissions. Such differences affect which groups can be mobilized in their favour. This paper shows that procurement standards which target intermediate products can mobilize the support of relatively low carbon producers of high carbon materials, while product standards which target final products can mobilize the support of producers of relatively low carbon materials and knowledge-intensive service providers.

Description: Im Rahmen des Projektes „Aufbau und Betrieb eines erweiterten umweltsensitiven Verkehrsmanagementsystems in Berlin (eUVM)“ wird die mögliche Aufhebung der Tempo-30-Zone in der Leipziger Straße und die Rückkehr zu Tempo 50 untersucht. In diesem Zwischenbericht werden die ersten Ergebnisse einer Messkampagne rund um die Leipziger Straße vorgestellt, insbesondere die Erfassung von Rad- und Fußverkehr und die Befragungen beider Gruppen bezüglich deren geschätzter Sicherheit.

Description: L’alimentation est à la fois un levier central pour engager la transition socio-écologique et un theme quotidien tangible pour chaque citoyen.ne. En Allemagne comme en France, quelques collectivités territoriales engagent des mesures innovantes pour promouvoir une alimentation locale et durable. Le Forum pour l’avenir franco-allemand s’est penché sur les expériences de certaines de ces collectivités et a facilité le dialogue entre elles durant plusieurs mois afin de comprendre quelles politiques nationales peuvent soutenir de telles initiatives locales. En associant des expert.e.s issus de la sphère scientifique, de l’administration et de la société civile, il a recommandé de « Donner la priorité au développement de systèmes alimentaires locaux et durables » avec cinq propositions d’action concrètes aux gouvernements français et allemand. Cette étude présente les initiatives françaises et allemandes ayant nourri les propositions d’action du Forum pour l’avenir.

Description: Food and food policy is central to social-ecological transformation. It is also an everyday issue that is easy to communicate to citizens. Municipalities in Germany and France have recognized the potential of innovative local food policies and have developed and tested innovative approaches to transforming local food systems. However, they are encountering structural barriers that cannot be overcome at the municipal level. The Franco-German Forum for the Future has researched the opportunities and obstacles of local nutritional change and brought engaged municipalities from both countries into exchange with each other. Together with experts from academia, public administrations and civil society, it has developed the seven recommendations for the national governments, one of which concerns "Prioritizing the development of local and sustainable food systems" with five proposals for action. This study is intended as a background paper to the Recommendation. With recourse to the concrete example of Mouans-Sartoux and other municipalities in France and Germany, it describes the potentials of a sustainable municipal food policy and provides – from concrete local practice – the background knowledge for each of the five proposals for action.

Description: Germany is known for its ambitious climate policy targets. By 2045, the country seeks to achieve climate neutrality. As an intermediate step, the government has determined emission thresholds for different economic sectors through the year 2030. The industrial sector has so far not been a frontrunner in Germany's emission reduction efforts. Much of the country's success in this context is owed to the successful ramp-up of renewables in the electricity sector. For German industries, this means that they have little time left to undergo a substantial climate-friendly transformation by 2030. But how can this be achieved? This chapter introduces five different building blocks of Germany's climate strategy for its emission-intensive industrial sector: (1) The expansion of renewable energy for electricity production; (2) electrification and energy efficiency improvements; (3) the establishment of a green hydrogen economy; (4) the transformation towards a circular economy; and lastly (5) carbon capture and storage (CCS) and carbon capture and utilization (CCU). In an in-depth case study, the chapter reviews the particular role of CCU as a strategic component, discussing its potential as a climate strategy, its regulatory and legal framework, as well as insights on the broader societal acceptance of this technological approach.

Description: Ausgehend von der Diskussion um Formalität und Informalität aus der Perspektive der Organisationssoziologie, der Regierungsforschung und der Politikberatung werden zunächst empirische Befunde aus einer Befragung von deutschen und polnischen Politikberatern, Lobbyisten und Experten zu ihren Wahrnehmungen der Zugangswege von Experten zur Politik und von der Politik zu Experten in Deutschland und Polen untersucht und ausgewertet. Welche Zugangswege werden gewählt und warum, wie offen sind sie, und welche Ungleichgewichte bestehen beim Zugang zu Experten und beim Zugang von Experten zur Politik? Ein zweiter Abschnitt befasst sich mit dem Grad der Formalisierung von deliberativen Prozessen und Zugangskanälen in beiden Ländern. In einem dritten Abschnitt liegt der Schwerpunkt auf der Interpretation der Wahrnehmung der Zugangskanäle und des Formalisierungsgrades und deren Implikationen für die Politikberatung in Deutschland und Polen.

Description: Klassische Ansätze der Politikberatung unterscheiden zwischen Anbietern (i.d.R. Experten) und Empfängern (i.d.R. Politiker) von Politikberatung. Das Konzept einer politikorientierten Gesellschaftsberatung erweitert dieses Verständnis um eine zusätzliche, eigenständige Rolle für die Bürgerinnen und Bürger. Unter Verwendung der Heuristik von Römmele & Schober (2011) betrachten wir Bürgerratsprozesse aus Deutschland und Polen, innerhalb derer zufällig geloste Bürgerinnen und Bürger dazu beitragen können, Lösungen für komplexe und konfliktäre gesellschaftspolitische Herausforderungen zu entwickeln. Deliberative Mini-Publics, wie diese Bürgerräte, ermöglichen die Einbeziehung der Bürgerinnen und Bürger als beratende Stimme in Gesellschaftsberatungs-Prozessen. In diesem Kapitel erörtern wir die Merkmale solcher Formate und beleuchten ihre Funktionen und Rahmenbedingungen, die erfüllt sein sollten, damit ihr Einsatz zielführend und wirksam ist. Außerdem vergleichen wir Bürgerräte in Polen und Deutschland mit Blick auf das Beratungsmandat dieser Gremien.

Description: Dataset of recurrence plot bibliography. Scripts to retrieve additional data (paper citations and authors' affiliations) and to perform some statistical bibliometric and bibliographic analysis of the recurrence plot bibliography. Scripts are forPython and MATLAB.

Description: MATLAB scripts and functions used to create spatial recurrence plots to study circular structures in higherdimensional data fields, and to reproduce the figures of M. Riedl, N. Marwan, J. Kurths: Extended generalized recurrence plot quantification of complex circular patterns, European Physical Journal B, 90(58), 1–9 (2017). DOI:10.1140/epjb/e2017-70560-7

Description: A transition to healthy diets like the EAT-Lancet Planetary Health Diet could considerably reduce GHG emissions. However, the specific contributions of dietary shifts for the feasibility of 1.5°C pathways remain unclear. Here, we use the open-source Integrated Assessment Modeling (IAM) framework REMIND-MAgPIE to compare 1.5°C pathways with and without dietary shifts. We find that a flexitarian diet increases the feasibility of the Paris Agreement climate goals in different ways: The reduction of GHG emissions related to dietary shifts, especially methane from ruminant enteric fermentation, increases the 1.5°C-compatible carbon budget. Therefore, dietary shifts allow to achieve the same climate outcome with less carbon dioxide removal (CDR) and less stringent CO2 emission reductions in the energy system, which reduces pressure on GHG prices, energy prices and food expenditures.

Description: Photovoltaics (PV) and wind are the most important energy-conversion technologies for cost-efficient climate change mitigation. To reach international climate goals, the annual PV module production must be expanded to multi-terawatt (TW) scale. Economic and resource restraints demand the implementation of cost-efficient multi-junction technologies, for which perovskite-based tandem technologies are highly promising. In this work, the resource demand of the emerging perovskite PV technology is investigated, considering two factors of supply criticality, namely, mining capacity for minerals and the production capacity for synthetic materials. Overall, the expansion of perovskite PV to a multi-TW scale may not be limited by material supply if certain materials, especially indium, can be replaced. Moreover, organic charge-transport materials face currently unresolved scalability challenges. This study demonstrates that, besides the improvement of efficiency and stability, perovskite PV research and development also need to be guided by sustainable materials choices and design-for-recycling considerations.

Description: Forests, critical components of global ecosystems, face unprecedented challenges due to climate change. This study investigates the influence of functional diversity—as a component of biodiversity—to enhance long-term biomass of European forests in the context of changing climatic conditions. Using the next-generation flexible trait-based vegetation model, LPJmL-FIT, we explored the impact of functional diversity on long-term forest biomass under three different climate change scenarios (video abstract: https://www.pik-potsdam.de/~billing/video/2023/video_abstract_billing_et_al_LPJmLFIT.mp4). Four model set-ups were tested with varying degrees of functional diversity and best-suited functional traits. Our results show that functional diversity positively influences long-term forest biomass, particularly when climate warming is low (RCP2.6). Under these conditions, high-diversity simulations led to an approximately 18.2% increase in biomass compared to low-diversity experiments. However, as climate change intensity increased, the benefits of functional diversity diminished (RCP8.5). A Bayesian multilevel analysis revealed that both full leaf trait diversity and diversity of plant functional types contributed significantly to biomass enhancement under low warming scenarios in our model simulations. Under strong climate change, the presence of a mixture of different functional groups (e.g. summergreen and evergreen broad-leaved trees) was found more beneficial than the diversity of leaf traits within a functional group (e.g. broad-leaved summergreen trees). Ultimately, this research challenges the notion that planting only the most productive and climate-suited trees guarantees the highest future biomass and carbon sequestration. We underscore the importance of high functional diversity and the potential benefits of fostering a mixture of tree functional types to enhance long-term forest biomass in the face of climate change.

Description: The question of how science can become a lever in achieving the Sustainable Development Goals permeates most recent sustainability research. Wide-ranging literature calling for a transformative approach has emerged in recent years. This ‘transformative turn’ is fueled by publications from fields such as sustainability science, social-ecological research, conservation science, sustainability transitions, or sustainability governance studies. However, there is a lack of a shared understanding specifically of what is meant for research to be transformative in this developing discourse around doing science differently to tackle sustainability problems. We aim to advance transformative research for sustainability. We define transformative research and outline six of its characteristics: (1) interventional nature and a theory of change focus; (2) collaborative modes of knowledge production, experimentation and learning; (3) systems thinking literacy and contextualization; (4) reflexivity, normative and inner dimensions; (5) local agency, decolonization, and reshaping power; (6) new quality criteria and rethinking impact. We highlight three tensions between transformative research and traditional paradigms of academic research: (1) process- and output-orientation; (2) accountability toward society and toward science; (3) methodologies rooted in scientific traditions and post-normal methodologies. We conclude with future directions on how academia could reconcile these tensions to support and promote transformative research.

Description: Dominant ways of doing research are not enough to achieve the UN Sustainable Development Goals. The typical response of science to dealing with the current local and global sustainability crises is to produce and accumulate more knowledge. Transformative research seeks to couple knowledge production with co-creating change. This paper defines the transformative way of doing research to pro-actively support society's fight against pressing societal and environmental problems. We present six characteristics of transformative research. We reflect on the challenges related to implementing these characteristics in scientific practice and on how academia can play its part.

Description: Zentrale Aushandlungs- und Gestaltungsprozesse in der Energiewende finden vor Ort in den Regionen und Kommunen statt. Wie gelingt es hier, die Transformation demokratisch zu gestalten und das politische Versprechen von Teilhabe und Mitgestaltung einzulösen? Dieser Frage widmet sich die vorliegende Studie. Um herauszufinden, welche Erfolgsfaktoren und Herausforderungen in Ansätzen der finanziellen Beteiligung sowie in dialogischen und konfliktsensiblen Formaten liegen, haben wir drei unterschiedliche Fallbeispiele zu materieller und immaterieller Beteiligung in der Energiewende analysiert. Auf dieser Grundlage benennt die Studie fünf konkrete Handlungsempfehlungen zur Stärkung von kommunalen Transformationskapazitäten für Bund und Länder.

Description: Strategies for mitigating climate change today include plans for removing carbon dioxide from the atmosphere through “Negative Emissions Technologies” (NETs). NETs create new opportunities for scientific research, technology development, and the development of financial products, but also new conceptual possibilities, for example of declaring one’s ambition to become “climate neutral.” NETs thus constitute a novel frontier in climate science and politics whose conditions of possibility, characteristics, and consequences can be studied by social scientists and humanists. For environmental sociologists, NETs pose numerous opportunities for engaging with questions around future-making, imaginaries, promises, expertise, markets, infrastructure, justice, publics, and generally, the shape and role of science and technology in a form of social life that is increasingly organized around “planetary” concepts.

Description: CrossGov D2.1 EU and international policy landscape - Mapping EU policies and Green Deal objectives: general observations for policy coherence in the marine domain aims to provide a mapping of the European Green Deal policy landscape relevant to the marine domain and the CrossGov project. It also offers a general introduction into how policy coherence, embedded within the design of (selected) EU policies, supports or impedes progress towards the EGD’s objectives in the marine domain. A total of 36 policies were selected and mapped against five EGD strategies, namely the 2030 Climate Target Plan, the EU Climate Change Adaptation Strategy, the Biodiversity Strategy for 2030, the Zero Pollution Action Plan, and the Sustainable Blue Economy Strategy. These five strategies lay out a total of 25 specific objectives to implement the vision of the EGD, identified as relevant to the marine domain and the focus of the CrossGov project – i.e. climate change, biodiversity loss, and pollution.

Description: Technologien für CO₂-Abscheidung und -Speicherung machen Hoffnung, werden aber gleichzeitig als Rechtfertigung für die geringe Reduktion von Emissionen aus fossilen Energiequellen genutzt. Das ist nicht vereinbar mit dem Ziel, die Erderwärmung auf 1,5 oder 2 °C zu begrenzen.

Description: The PermaGov Deliverable focuses on exploring the EU policy landscape within the context of the European Green Deal (EGD), structured around four regime complexes: marine life, marine plastics, marine energy, and maritime transport. These complexes provide a framework for analysing the EU's approach to achieving the EGD's vision for sustainable marine governance. This report aims to offer a descriptive overview of marine EU policies relevant to the PermaGov project, focusing on policies identified as relevant to the overarching goals set forth in the EGD. It also considers relevant initiatives at global and regional levels. The marine life regime sees the EU Biodiversity Strategy for 2030 as its overarching strategy, essential for the EGD’s element of preserving and restoring ecosystems and biodiversity. Tackling the challenges of marine waste pollution, the marine plastics regime is guided by the EU Circular Economy Action Plan and the EU Action Plan: Towards Zero Pollution for Air, Water, and Soil, targeting the EGD’s elements of a mobilising industry for a clean and circular economy and a zero-pollution ambition for a toxic-free environment. The marine energy regime is shaped by the European Climate Law and the Offshore Renewable Energy Strategy, which are the overarching instruments that contribute to the EGD’s elements of increase the EU’s climate ambition for 2030 and 2050 and ensure the supply of clean, affordable, and secure energy. Lastly, the maritime transport regime sees the 'Fit for 55' Package and the 'Sustainable and Smart Mobility Strategy' as the two main instruments to achieve the EGD’s elements of increase the EU’s climate ambition for 2030 and 2050 and Accelerating the Shift to Sustainable and Smart Mobility. An additional aspect of this report is an initial screening of institutional barriers through the lens of policy documents. This is intended to be a starting point for the case studies of the PermaGov project, which will be further investigated in more depth later in the project. Institutional barriers are understood as obstacles within the structure and processes of governance systems that hamper decision-making processes and policy implementation. These barriers often arise from established rules, norms, and practices. The report considers the analytical framework developed by Oberlack (2017), focusing on attributes of institutions such as actor eligibility, responsibility, control, social connectivity, conflict, social learning, accountability, temporal and spatial scale, adaptiveness, and formality. These attributes describe the characteristics of how institutions are organised and operate, providing insights into potential challenges in policy design and implementation. The report provides a mapping of instruments relevant to the PermaGov four regime complexes and concludes by identifying potential institutional barriers, underlining the importance of conducting further detailed research in upcoming tasks of the PermaGov projects to effectively address the challenges of sustainable marine governance in line with the EGD’s ambitions.

Description: In this discourse, we present the unveiling of an open-source software package designed to facilitate engagement with the atmospheric model, Aeolus 2.0. This particular iteration stands as a self-contained model of intermediate complexity. The model's dynamical core is underpinned by a multi-layer pseudo-spectral moist-convective Thermal Rotating Shallow Water (mcTRSW) model. The pseudo-spectral problem-solving tasks are handled by the Dedalus algorithm, acknowledged for its spin-weighted spherical harmonics. The model captures the temporal and spatial evolution of vertically integrated potential temperature, thickness, water vapour, precipitation, and the intricate influence of bottom topography. It comprehensively characterizes velocity fields in both the lower and upper troposphere, employing resolutions spanning a spectrum from the smooth to the coarse, enabling the exploration of a wide range of dynamic phenomena with varying levels of detail and precision.

Description: We study the impact of California’s cap-and-trade system on carbon emissions in the electricity and industrial sectors. We use US state-level panel data covering the period 2005–2019 and apply the synthetic control method to construct an optimal counterfactual for per capita emissions in each sector. In our experiment, emissions in the power sector fall below counterfactual emissions by 48%. In the industrial sector, the state’s emissions are 6% higher than those of the synthetic control unit by the end of the observation period. Thus, cap-and-trade failed to deliver decarbonization across both sectors. While the abatement in the power sector was facilitated by complementary policies and driven by a switch from natural gas to renewables, California’s policy mix has disincentivized emission reductions in the industrial sector.

Description: Human activities have had a significant impact on Earth's systems and processes, leading to a transition of Earth's state from the relatively stable Holocene epoch to the Anthropocene. The planetary boundaries framework characterizes major risks of destabilization, particularly in the core dimensions of climate and biosphere change. Land system change, including deforestation and urbanization, alters ecosystems and impacts the water and energy cycle between land surface and atmosphere, while climate change can disrupt the balance of ecosystems and impact vegetation composition and soil carbon pools. These drivers also interact with each other, further exacerbating their impacts. Earth system models have been used recently to illustrate the risks and interacting effects of transgressing selected planetary boundaries, but a detailed analysis is still missing. Here, we study the impacts of long-term transgressions of the climate and land system change boundaries on the Earth system using an Earth system model with an incorporated detailed dynamic vegetation model. In our centennial-scale simulation analysis, we find that transgressing the land system change boundary results in increases in global temperatures and aridity. Furthermore, this transgression is associated with a substantial loss of vegetation carbon, exceeding 200 PgC, in contrast to conditions considered safe. Concurrently, the influence of climate change becomes evident as temperatures surge by 2.7–3.1 °C depending on the region. Notably, carbon dynamics are most profoundly affected within the large carbon reservoirs of the boreal permafrost areas, where carbon emissions peak at 150 PgC. While a restoration scenario to reduce human pressure to meet the planetary boundaries of climate change and land system change proves beneficial for carbon pools and global mean temperature, a transgression of these boundaries could lead to profoundly negative effects on the Earth system and the terrestrial biosphere. Our results suggest that respecting both boundaries is essential for safeguarding Holocene-like planetary conditions that characterize a resilient Earth system and are in accordance with the goals of the Paris Climate Agreement.

Description: The majority of signatories to The United Nations Climate Change Conference in 2021 (COP26) made a declaration to end deforestation by 2030. Here, we quantify future changes in land use and associated CO2 emissions to examine the impact of ending deforestation by 2030 on global land dynamics and emissions using an open-source land-use model. We show that if the COP26 declaration to end deforestation is fully implemented globally, about 167 Mha of deforestation could be avoided until 2050, compared to a baseline scenario which does not have extended forest protection. However, avoided deforestation and associated emissions come at the cost of strongly increased conversion of unprotected non-forested land to agricultural land, while land-use intensification in most regions is similar compared to a baseline scenario. Global initiatives are needed to facilitate a common dialogue on addressing the possible carbon emissions and non-forest leakage effects due to the expedited loss of non-forested land under a policy aimed at halting deforestation by 2030.

Description: As the Earth system is exposed to large anthropogenic interferences, it becomes ever more important to assess the resilience of natural systems, i.e., their ability to recover from natural and human-induced perturbations. Several, often related, measures of resilience have been proposed and applied to modeled and observed data, often by different scientific communities. Focusing on terrestrial ecosystems as a key component of the Earth system, we review methods that can detect large perturbations (temporary excursions from a reference state as well as abrupt shifts to a new reference state) in spatio-temporal datasets, estimate the recovery rate after such perturbations, or assess resilience changes indirectly from stationary time series via indicators of critical slowing down. We present here a sequence of ideal methodological steps in the field of resilience science, and argue how to obtain a consistent and multi-faceted view on ecosystem or climate resilience from Earth observation (EO) data. While EO data offers unique potential to study ecosystem resilience globally at high spatial and temporal scale, we emphasize some important limitations, which are associated with the theoretical assumptions behind diagnostic methods and with the measurement process and pre-processing steps of EO data. The latter class of limitations include gaps in time series, the disparity of scales, and issues arising from aggregating time series from multiple sensors. Based on this assessment, we formulate specific recommendations to the EO community in order to improve the observational basis for ecosystem resilience research.

Description: Die Entscheidung für den Austausch oder Ersatz eines Heizsystems ist eine, die für mehr als ein Jahrzehnt getroffen wird. Oftmals berücksichtigen Verbraucherinnen und Verbraucher dabei vor allem die einmal anfallende Einbau-Investition. Die Kosten über den gesamten Lebenszyklus sind deutlich schwerer zu ermitteln und unsicher, daher werden sie häufig zu wenig in die finanzielle Überlegung mit einbezogen. In einer neuen Analyse haben Ariadne-Forschende berechnet, wie hoch unterm Strich die Kosten für verschiedene Heiztechniken in bestehenden Wohngebäuden über einen Zeitraum von 20 Jahren angesichts zukünftiger Energieträgerpreise sowie der zu erwartenden CO2-Preisentwicklung sind.

Description: Global flood impacts have risen in recent decades. While increasing exposure was the dominant driver of surging impacts, counteracting vulnerability reductions have been detected, but were too weak to reverse this trend. To assess the ongoing progress on vulnerability reduction, we combine a recently available dataset of flooded areas derived from satellite imagery for 913 events with four global disaster databases and socio-economic data. Event-specific flood vulnerabilities for assets, fatalities and displacements reveal a lack of progress in reducing global flood vulnerability from 2000—2018. We examine the relationship between vulnerabilities and human development, inequality, flood exposure and local structural characteristics. We find that vulnerability levels are significantly lower in areas with good structural characteristics and significantly higher in low developed areas. However, socio-economic development was insufficient to reduce vulnerabilities over the study period. Nevertheless, the strong correlation between vulnerability and structural characteristics suggests further potential for adaptation through vulnerability reduction.

Description: Simulating the ozone variability at regional scales using chemistry transport models (CTMs) remains a challenge. We designed a multi-model intercomparison to evaluate, for the first time, four regional CTMs on a national scale for Germany. Simulations were conducted with LOTOS-EUROS, REM-CALGRID, COSMO-MUSCAT and WRF-Chem for January 1st to December 31st, 2019, using prescribed emission information. In general, all models show good performance in the operational evaluation with average temporal correlations of MDA8 O3 in the range of 0.77-0.87 and RMSE values between 16.3 mu g m3 and 20.6 mu g m- 3. On average, better models' skill has been observed for rural background stations than for the urban background stations as well as for springtime compared to summertime. Our study confirms that the ensemble mean provides a better model-measurement agreement than individual models. All models capture the larger local photochemical production in summer compared to springtime and observed differences between the urban and the rural background. We introduce a new indicator to evaluate the dynamic response of ozone to temperature. During summertime a large ensemble spread in the ozone sensitivities to temperature is found with (on average) an underestimation of the ozone sensitivity to temperature, which can be linked to a systematic underestimation of mid-level ozone concentrations. During springtime we observed an ozone episode that is not covered by the models which is likely due to deficiencies in the representation of background ozone in the models. We recommend to focus on a diagnostic evaluation aimed at the model descriptions for biogenic emissions and dry deposition as a follow up and to repeat the operational and dynamic analysis for longer timeframes.

Description: Transdisciplinary processes deal with transdisciplinary problems that are (i) complex, (ii) societally relevant, (iii) ill-defined, and (iv) real-world problems which often show a high degree of ambiguity resulting in contested perceptions and evaluations among and between scientists and practitioners. Therefore, they are susceptible to multiple trade-offs. Transdisciplinary processes construct socially robust orientations (SoROs) particularly for sustainable transitioning. The integration of science and practice knowledge on equal footing (1) is considered the core of transdisciplinary processes. Yet other forms of knowledge integration contribute essentially to construct SoROs. Individuals may (2) use different modes of thought; (3) refer to various cultures with diverse value and belief systems; and (4) problems are perceived and prioritized based on roles and interests. Coping with transdisciplinary problems, (5) purposeful differentiation and integration and (6) an integration of evolutionary evolving codes of representing knowledge are necessary. Finally, (7) what systems to integrate requires consensus-building among participating scientists and practitioners. This paper is Part I of a two-part publication. It provides a conceptualization of the different types of knowledge integration. Part II analyzes tasks, challenges, and barriers related to different types of knowledge integration in five transdisciplinary processes which developed SoROs for sensitive subsystems of Germany affected by the irresponsible use of digital data.

Description: Transdisciplinary problems are complex, ill-defined, societal real-world problems with high ambiguity that are contested and require multiple trade-offs. Part I of this paper showed that transdisciplinary processes include seven types of knowledge integration: system (ontological), epistemological, cultural, cognitive, social conflict, evolutionary (levels of representation), and complexity-theory-based types of knowledge integration. The epistemological integration of the different modes of reasoning from science and practice is a unique selling point of the transdisciplinary process. Part II presents five transdisciplinary processes for the responsible use of digital data in different vulnerable/sensitive subsystems of Germany (mobility, health, agriculture, SME, and social media). Between 10 and 18 participants (equally representing science and practice in each group) synchronously constructed socially robust orientations as pillars of a white book. We elaborate that outcomes of a transdisciplinary process can be improved, and barriers diminished by reflecting on which of the seven types of knowledge integration are applied (see Part I). This is done for the six phases of a transdisciplinary process: (1) triggering, (2) initiation, (3) preparation, (4) planning, (5) core, and (6) post-processing. We particularly address researchers and practitioners who seek insights into how the production and integration of knowledge can be improved by transdisciplinary processes.

Description: Introduction Current urban and transport planning practices have significant negative health, environmental, social and economic impacts in most cities. New urban development models and policies are needed to reduce these negative impacts. The Superblock model is one such innovative urban model that can significantly reduce these negative impacts through reshaping public spaces into more diverse uses such as increase in green space, infrastructure supporting social contacts and physical activity, and through prioritization of active mobility and public transport, thereby reducing air pollution, noise and urban heat island effects. This paper reviews key aspects of the Superblock model, its implementation and initial evaluations in Barcelona and the potential international uptake of the model in Europe and globally, focusing on environmental, climate, lifestyle, liveability and health aspects. Methods We used a narrative meta-review approach and PubMed and Google scholar databases were searched using specific terms. Results The implementation of the Super block model in Barcelona is slow, but with initial improvement in, for example, environmental, lifestyle, liveability and health indicators, although not so consistently. When applied on a large scale, the implementation of the Superblock model is not only likely to result in better environmental conditions, health and wellbeing, but can also contribute to the fight against the climate crisis. There is a need for further expansion of the program and further evaluation of its impacts and answers to related concerns, such as environmental equity and gentrification, traffic and related environmental exposure displacement. The implementation of the Superblock model gained a growing international reputation and variations of it are being planned or implemented in cities worldwide. Initial modelling exercises showed that it could be implemented in large parts of many cities. Conclusion The Superblock model is an innovative urban model that addresses environmental, climate, liveability and health concerns in cities. Adapted versions of the Barcelona Superblock model are being implemented in cities around Europe and further implementation, monitoring and evaluation are encouraged. The Superblock model can be considered an important public health intervention that will reduce mortality and morbidity and generate cost savings for health and other sectors.

Description: In academia and political debates, the notions of ‘degrowth’ has gained traction since the dawn of the 21st century. While some uncertainty around its exact definition remains, research on degrowth revolves around the idea of reducing resource and energy throughput as a unifying theme. We employ a mixed-methods design to systematically review the scientific peer-reviewed English literature from 2008 to 2022 that refers to ‘degrowth’ or ‘post-growth’ in title, keywords or abstract (N = 951). We find a lack of concrete distributional and monetary policy proposals in the sample analyzed, and a low overall degree of collaboration among authors in relation to degrowth's age and size. The scientific peer-reviewed literature analyzed can be grouped into seven clusters along two major gradients, one along methodology (qualitative-quantitative) and the other along scale-of-analysis (individual-societal). We conclude that the academic literature about degrowth would benefit from a more prominent discussion of the political implications of its ideas and proposals, and that in particular the debate about distributional policy implications of degrowth should be more prominent and concrete, with a stronger focus on distributional policies in a degrowing economy.

Description: The Yangtze River Delta (YRD) region frequently experiences ozone pollution events during the summer and autumn seasons. High-concentration events are typically related to synoptic weather patterns, which impact the transport and photochemical production of ozone at multiple scales, ranging from the local to regional scale. To better understand the regional ozone pollution problem, studies on ozone source attribution are needed, especially regarding the contributions of sources at different vertical heights based on tagging the region or time periods. Between September 3 and 8, 2020, an episode of ozone concentration anomaly high was observed in Hefei through ground-based stations and ozone Lidar. The mechanism behind this event was uncovered through synoptic weather pattern analysis and using the Weather Research and Forecasting Chemistry model (WRF-Chem). Because an approaching typhoon caused variable wind direction, the O3-rich air masses (ORMs) arising from the YRD region were transported to Hefei via the nocturnal residual layer and descended to the ground through horizontal advection and vertical mixing processes the next day. Based on geographic source tagging, the anthropogenic NOx emissions (ANEs) from local and regional sources were the main contributors to the heavy ozone pollution over Hefei on September 6. Furthermore, the intra-regional transported ozone from southern Jiangsu (SJS), southern Anhui (SAH), and Zhejiang (ZJ) in the YRD was the main driving factor of the surface and upper atmosphere ozone pollution. Based on time period tagging, The ozone generated due to ANEs from September 3 to 5 significantly contributed to this episode. It is important to pay attention to the impact of ANEs on September 5 on the surface peak ozone concentration the following day (i.e., September 6). Our findings provide significant insights into the regional ozone transport mechanism in the YRD and optimization of measures to prevent and control heavy ozone pollution on spatiotemporal scales.

Description: In this paper, the authors discuss the role of China in the emerging geopolitics of hydrogen. It begins with a review of China's external energy policy and its evolution over the past decades, highlighting China's transition to a net-energy importer as an important inflection point in that process. It then goes on to describe the main pillars of China's national hydrogen policy. Building on this the paper provides and overview of China's external hydrogen policy and how this aligns with both its broader energy foreign policy and its hydrogen policy objectives. The paper finds that China’s hydrogen strategy – both internal and external – are still at an emergent stage. National targets remain modest, and policy remains ambiguous regarding the preferred production pathway. China’s long-term vision clearly emphasizes the role of renewable hydrogen to help balance an energy system dominated by wind and solar energy. However, current policy provides ample space for the promotion of other forms of hydrogen production. Rather, than a strong, centralized policy approach, local and provincial governments along with SOEs have been driving investment and policy experimentation in the sector, which includes efforts to boost fossil-based hydrogen production.

Description: As a variant of Support Vector Machine (SVM), Large Margin Distribution Machine (LDM) has been validated to outperform SVM both theoretically and experimentally. Due to the inevitable noise in real applications, the credibility of different samples is not necessarily the same, which is neglected by most existing LDM models. To tackle the above problem, this paper first introduces fuzzy set theory into LDM, and proposes a Fuzzy Large Margin Distribution Machine (FLDM) with better robustness and performance. Considering the noise and uncertainty in datasets, sample points farther from the center of homogenous class are less reliable. Therefore, a fuzzy membership function based on the distance to the class center is utilized to characterize the confidence of each sample, i.e., the degree to which the sample belongs to a certain category. Furthermore, different strategies are developed to obtain class centers for linearly separable and linearly inseparable problems. Experiments conducted on both artificial and UCI datasets verified the superiority of FLDM from different perspectives.

Description: The problem of network disintegration, such as suppression of an epidemic spread and destabilization of terrorist networks, possesses extensive applications and has lately been the focus of growing interest. Many real-world complex systems are represented by spatial networks in which nodes and edges are spatially embedded. However, existing disintegration approaches for spatial network disintegration focus on singular aspects such as geospatial information or network topography, with insufficient modeling granularity. In this paper, we propose an effective and computationally efficient virtual node model that essentially integrates the geospatial information and topology of the network by modeling edges as virtual nodes with weights. Moreover, we employ Kernel Density Estimation, a well-known non-parametric technique for estimating the underlying probability density function of samples, to fit all nodes, comprising both network and virtual nodes, to identify the critical region of the spatial network, which is also the circular geographic region where disintegration occurs. Extensive numerical experiments on synthetic and real-world networks demonstrate that our method outperforms existing methods in terms of both effectiveness and efficiency, which provides a fresh perspective for modeling spatial networks.

Description: Bioenergy with carbon capture and storage (BECCS) can help stabilize the climate by extracting carbon dioxide from the atmosphere while producing renewable energy. However, biomass availability would limit the potential of BECCS, and biomass cropland expansion may threaten biodiversity, food security, and water supply. Replacing land-intensive foods can help unlock sustainable biomass production. Here, we estimated BECCS energy and negative emissions using biomass grown on freed-up land when replacing animal-source foods. Biomass production excludes agricultural expansion to protect biodiversity, ensures enough food supply globally to safeguard food security, and constrains irrigation to secure water for people and ecosystems. Negative emissions consider supply chain emissions and the forgone sequestration from natural revegetation. Results show that replacing 50% of animal products by 2050 could release enough land for BECCS to generate 26.4–39.5 EJelec/year, the scale of coal power today, while removing 5.9–9.3 GtCO2e/year from the atmosphere, almost what coal power emits today.

Description: We investigated the influence of the El Niño-Southern Oscillation (ENSO) on inter-annual precipitation variability in the far-eastern Pacific (FEP) and northern South America (NSA) using an approach based on phase synchronization (PS). First, we carried out a detailed analysis of observational data to define the inter-annual variability, eliminate the seasonal residual frequencies in hydro-climatic anomalies, and assess the statistical significance of PS. Additionally, we characterized the seasonality of regional patterns of sea surface temperature, surface pressure levels, low-level winds and precipitation anomalies associated with the ENSO states. We found that the positive (negative) precipitation anomalies experienced in the FEP and NSA differ from those previously reported in the literature. In particular, the Guianas (northeastern Amazon) and the Caribbean constitute two regions with negative (positive) rainfall anomalies during El Niño (La Niña), separated by a zone of non-significant anomalies along the Orinoco Low-level Jet corridor. Moreover, we showed that the ENSO signal is phase-locked with inter-annual rainfall and low-level wind variability in most of the study regions. Furthermore, we found consistency in the PS between the Central and Eastern Pacific El Niño indices and hydroclimatic anomalies over the Pacific. However, some areas exhibited PS, although they did not show significant precipitation anomalies, suggesting that the influence of ENSO on tropical climatology manifests not only in terms of the magnitude of anomalies but also in terms of the phases only. Our approach advances the understanding of climatic anomalies in tropical regions and provides new insights into the non-linear interactions between ENSO and hydroclimatic processes in tropical Americas.

Description: Lack of nitrogen limits food production in poor countries while excessive nitrogen use in industrial countries has led to transgression of the planetary boundary. However, the potential of spatial redistribution of nitrogen input for food security when returning to the safe boundary has not been quantified in a robust manner. Using an emulator of a global gridded crop model ensemble, we found that redistribution of current nitrogen input to major cereals among countries can double production in the most food insecure countries, while increasing global production of these crops by 12% with no notable regional loss or reducing the nitrogen input to the current production by one third. Redistribution of the input within the boundary increased production by 6–8% compared to the current relative distribution, increasing production in the food insecure countries by two thirds. Our findings provide georeferenced guidelines for redistributing nitrogen use to enhance food security while safeguarding the planet.

Description: Oil seed crops are the second most important field crops after cereals in the agricultural economy globally. The use and demand for oilseed crops such as groundnut, soybean and sunflower have grown significantly, but climate change is expected to alter the agroecological conditions required for oilseed crop production. This study aims to present an approach that utilizes decision-making tools to assess the potential climate change impacts on groundnut, soybean and sunflower yields and the greenhouse gas emissions from the management of the crops. The Decision Support Tool for Agrotechnology Transfer (DSSAT v4.7), a dynamic crop model and the Cool Farm Tool, a GHG calculator, was used to simulate yields and estimate GHG emissions from these crops, respectively. Four representative concentration pathways (RCPs 2.6, 4.5, 6.0, and 8.5), three nitrogen (0, 75, and 150 kg/ha) and phosphorous (0, 30 and 60 P kg/ha) fertilizer rates at three sites in Limpopo, South Africa (Ofcolaco, Syferkuil and Punda Maria) were used in field trials for calibrating the models. The highest yield was achieved by sunflower across all crops, years and sites. Soybean yield is projected to decrease across all sites and scenarios by 2030 and 2050, except at Ofcolaco, where yield increases of at least 15.6% is projected under the RCP 4.5 scenario. Positive climate change impacts are predicted for groundnut at Ofcolaco and Syferkuil by 2030 and 2050, while negative impacts with losses of up to 50% are projected under RCP 8.5 by 2050 at Punda Maria. Sunflower yield is projected to decrease across all sites and scenarios by 2030 and 2050. A comparison of the climate change impacts across sites shows that groundnut yield is projected to increase under climate change while notable yield losses are projected for sunflower and soybean. GHG emissions from the management of each crop showed that sunflower and groundnut production had the highest and lowest emissions across all sites respectively. With positive climate change impacts, a reduction of GHG emissions per ton per hectare was projected for groundnuts at Ofcolaco and Syferkuil and for sunflower in Ofcolaco in the future. However, the carbon footprint from groundnut is expected to increase by 40 to 107% in Punda Maria for the period up to 2030 and between 70-250% for 2050, with sunflower following a similar trend. We conclude that climate change will potentially reduce yield for oilseed crops while management will increase emissions. Therefore, in designing adaptation measures, there is a need to consider emission effects to gain a holistic understanding of how both climate change impacts on crops and mitigation efforts could be targeted.

Description: The planetary boundaries framework defines a safe operating space for humanity. To date, these boundaries have mostly been investigated separately, and it is unclear whether breaching one boundary can lead to the transgression of another. By employing a dynamic global vegetation model, we systematically simulate the strength and direction of the effects of different transgression levels of the climate change boundary (using climate output from ten CMIP6 models for CO2 levels ranging from 350 ppm to 1000 ppm). We focus on climate change-induced shifts of Earth’s major forest biomes, the control variable for the land-system change boundary, both by the end of this century and, to account for the long-term legacy effect, by the end of the millennium. Our simulations show that while staying within the 350 ppm climate change boundary co-stabilizes the land-system change boundary, breaching it (〉450 ppm) leads to its critical transgression with greater severity, the higher the ppm level rises and the more time passes. Specifically, this involves a poleward treeline shift, boreal forest dieback (nearly completely within its current area under extreme climate scenarios), competitive expansion of temperate forest into today’s boreal zone, and a slight tropical forest extension. These interacting changes also affect other planetary boundaries (freshwater change and biosphere integrity) and provide feedback to the climate change boundary itself. Our quantitative process-based study highlights the need for interactions to be studied for a systemic operationalization of the framework.

Description: Ecosystems are under multiple stressors and impacts can be measured with multiple variables. Humans have altered mass and energy flows of basically all ecosystems on Earth towards dangerous levels. However, integrating the data and synthesizing conclusions is becoming more and more complicated. Here we present an automated and easy to apply R package to assess terrestrial biosphere integrity which combines 2 complementary metrics: The BioCol metric quantifies the human colonization pressure exerted on the biosphere through alteration and extraction (appropriation) of net primary productivity, whereas the EcoRisk metric quantifies biogeochemical and vegetation structural changes as a proxy for the risk of ecosystem destabilization. Applied to simulations with the dynamic global vegetation model LPJmL5 for 1500–2016, we find that presently (period 2007–2016), large regions show modification and extraction of 〉25 % of the preindustrial potential net primary production, leading to drastic alterations in key ecosystem properties and suggesting a high risk for ecosystem destabilization. In consequence of these dynamics, EcoRisk shows particularly high values in regions with intense land use and deforestation, but also in regions prone to impacts of climate change such as the arctic and boreal zone. The metrics presented here enable global-scale, spatially explicit evaluation of historical and future states of the biosphere and are designed for use by the wider scientific community, not only limited to assessing biosphere integrity, but also to benchmark model performance. The package will be maintained on GitHub and through that we encourage application also to other models and data sets.

Description: Advances in the field of extreme event attribution allow to estimate how anthropogenic global warming affects the odds of individual climate disasters, such as river floods. Extreme event attribution typically uses precipitation as proxy for flooding. However, hydrological processes and antecedent conditions make the relation between precipitation and floods highly nonlinear. In addition, hydrology acknowledges that changes in floods can be strongly driven by changes in land-cover and by other human interventions in the hydrological system, such as irrigation and construction of dams. These drivers can either amplify, dampen or outweigh the effect of climate change on local flood occurrence. Neglecting these processes and drivers can lead to incorrect flood attribution. Including flooding explicitly, that is, using data and models of hydrology and hydrodynamics that can represent the relevant hydrological processes, will lead to more robust event attribution, and will account for the role of other drivers beyond climate change. Existing attempts are incomplete. We argue that the existing probabilistic framework for extreme event attribution can be extended to explicitly include floods for near-natural cases, where flood occurrence was unlikely to be influenced by land-cover change and human hydrological interventions. However, for the many cases where this assumption is not valid, a multi-driver framework for conditional event attribution needs to be established. Explicit flood attribution will have to grapple with uncertainties from lack of observations and compounding from the many processes involved. Further, it requires collaboration between climatologists and hydrologists, and promises to better address the needs of flood risk management.

Description: Natural hazards pose significant risks to people and assets in many regions of the world. Quantifying associated risks is crucial for many applications such as adaptation option appraisal and insurance pricing. However, traditional risk assessment approaches have focused on the impacts of single hazards, ignoring the effects of multi-hazard risks and potentially leading to underestimations or overestimations of risks. In this work, we present a framework for modelling multi-hazard risks globally in a consistent way, considering hazards, exposures, vulnerabilities, and assumptions on recovery. We illustrate the approach using river floods and tropical cyclones impacting people and physical assets on a global scale in a changing climate. To ensure physical consistency, we combine single hazard models that were driven by the same climate model realizations. Our results show that incorporating common physical drivers and recovery considerably alters the multi-hazard risk. We finally demonstrate how our framework can accommodate more than two hazards and integrate diverse assumptions about recovery processes based on a national case study. This framework is implemented in the open-source climate risk assessment platform CLIMADA and can be applied to various hazards and exposures, providing a more comprehensive approach to risk management than conventional methods.

Description: On the path to climate neutrality, global production locations and trade patterns of basic materials might change due to the heterogeneous availability of renewable electricity. Here we estimate the ‘renewables pull’, which is the energy-cost savings, for varying depths of relocation for three key tradable energy-intensive industrial commodities: steel, urea and ethylene. For an electricity-price difference of €40 MWh−1, we find respective relocation savings of 18%, 32% and 38%, which might, despite soft factors in the private sector, lead to green relocation. Conserving today’s production patterns by shipping hydrogen is substantially costlier, whereas trading intermediate products could save costs while keeping substantial value creation in renewable-scarce importing regions. In renewable-scarce regions, a societal debate on macroeconomic, industrial and geopolitical implications is needed, potentially resulting in selective policies of green-relocation protection.

Description: This analysis assesses the financial viability of legally investing in native Cerrado vegetation deforestation for crop production, considering climate change. The study uses data from twelve different crop models based on three different climate models to evaluate potential future crop yields in cleared land for growing soy and maize. The outcomes show that in many micro-regions, investments in clearing land for crop production would destroy economic value, that is, generate a negative net present value because of low/negative and volatile cashflows driven primarily by future yields as affected by climate. Our analysis was carried out based on present agricultural practices and technology. As climate changes, farmers may adapt their practices, which can lead to more resilient and productive crops, or grow different crops, which could provide better returns on investment in clearing land than the ones resulting from our analysis. Despite various uncertainties, farmers, policy makers and financial institutions should be aware of the climatic and financial risks associated with land clearing in Brazil, mainly in micro-regions in which all scenarios resulted in negative outcomes in the investment analysis. This study indicates that land expansion opportunities on degraded land should be prioritized over additional land clearing.

Description: The IPCC Assessment Reports offer the scientific foundation for international climate negotiations and constitute an unmatched resource for climate change researchers. However, the assessment cycles take multiple years. As a contribution to cross- and interdisciplinary understanding across diverse climate change research communities, we have streamlined an annual process to identify and synthesise essential research advances. We collected input from experts on different fields using an online questionnaire and prioritised a set of ten key research insights with high policy relevance. This year we focus on: (1) looming overshoot of the 1.5°C warming limit, (2) urgency of phasing-out fossil fuels, (3) challenges for scaling carbon dioxide removal, (4) uncertainties regarding the future of natural carbon sinks, (5) need for join governance of biodiversity loss and climate change, (6) advances in the science of compound events, (7) mountain glacier loss, (8) human immobility in the face of climate risks, (9) adaptation justice, and (10) just transitions in food systems. We first present a succinct account of these Insights, reflect on their policy implications, and offer an integrated set of policy relevant messages. This science synthesis and science communication effort is also the basis for a report targeted to policymakers as a contribution to elevate climate science every year, in time for the UNFCCC COP.

Description: This paper looks into the crucial macroeconomic feedback mechanisms emerging from the interplay among the goods market, the labor market, the financial sector, and monetary policy, particularly in the context of transitioning towards a climate-neutral economy. The investment decisions of firms, pivotal in this interaction, can trigger feedback loops with potentially destabilizing effects, underscoring the critical role of investment within the complex interplay of market and sector dynamics in the macroeconomy. Governmental intervention is highlighted as a key factor in steering the green transition while preserving economic stability. A carbon tax on fossil fuel consumption is proposed as a primary tool for facilitating this green transition. Our investigation employs a disequilibrium model of monetary growth, a la Keynes-Metzler-Goodwin (KMG), incorporating a portfolio perspective across three asset markets - money, bonds, and stocks. This framework allows for an in-depth analysis of how a carbon tax influences real production, inflation, and inequality during the transition. Our findings indicate that imposing a carbon tax on production does not markedly disrupt economic stability, as long as the carbon pricing and its growth rate remain within low bounds.

Description: Climate policy needs to set incentives for investors who face imperfect, distorted markets and large uncertainties about the costs and benefits of abatement. These investors decide on uncertain investments according to their expected return and risk (carbon beta). We study carbon pricing and financial incentives in a consumption-based asset pricing model distorted by technology spillovers and time-inconsistency. We find that both distortions reduce the equilibrium asset return and delay investment in abatement. However, their effect on the carbon beta and the risk premium for abatement can be decreasing (when innovation spillovers are not anticipated) or increasing (when climate policy is not credible). We show that the distortions can be overcome by modified carbon pricing by a regulator, or by financial incentives, implemented in our model by a long-term investment fund. The fund pays a subsidy to reduce technology costs or offers financial contracts to boost investment returns to complement the carbon price. The investment fund can thus pave the way for carbon pricing in later periods by preventing a capital misallocation that would be too expensive to correct, thus improving the feasibility of ambitious carbon pricing.

Description: Die Änderungen wichtiger Klimakenngrößen wie Temperatur und Niederschlag sowie der Konzentration von Spurengasen in der Atmosphäre beeinflussen unmittelbar physiologische Prozesse in Kulturpflanzen und damit die Ernte und die Landwirtschaft insgesamt. Zudem wirken sich Klimaänderungen indirekt auf die Pflanzenproduktion aus, indem sie strukturelle und funktionelle Eigenschaften von Agrarökosystemen verändern. Zu erwarten sind sowohl negative als auch positive Konsequenzen für die deutsche Landwirtschaft. Betrachtet werden neben direkten Auswirkungen auch mögliche Folgen für Schadorganismen und Nutztiere sowie die zu erwartende Entwicklung der Agrarproduktion. Entscheidend dafür, wie diese Effekte ausfallen, sind zum einen die Art und Intensität der Klimaveränderungen selbst, zum anderen die Empfindlichkeit der jeweils betrachteten Produktionssysteme und die Implementierung von Anpassungsmaßnahmen, mit deren Hilfe sich die Folgen des Klimawandels nutzen, vermeiden oder mildern lassen.

Description: Der Wissenschaftszweig der Klimaattribution analysiert den Zusammenhang zwischen beobachteten Aspekten des Klimas und menschlichen Klimaeinflussfaktoren. Mit formalen, statistisch sorgfältigen Nachweis- und Attributionsmethoden sind globale Veränderungen im Klima unzweifelhaft nachgewiesen und erhöhten Treibhausgaskonzentrationen zugeordnet. Auch auf kontinentaler und nationaler Ebene ist dieser Nachweis für Änderungen in Temperaturmitteln sowie -extremen und manchen Niederschlagsindizes erbracht. Mit verwandten Methoden, vor allem denen der probabilistischen Ereignisattribution, werden beobachtete Ereignisse wie eine einzelne Hitzewelle oder ein einzelner Sturm untersucht. Dabei wird typischerweise quantifiziert, ob und wie sich die Auftrittswahrscheinlichkeit der Ereignisse durch den menschengemachten Klimawandel geändert hat. Attributionsergebnisse können Bewusstsein für den Klimawandel schaffen und für Fragen der Klimagerechtigkeit und möglicher Entschädigungen für Klimafolgen relevant sein.

Description: We study the impact of recent global warming on extreme climatic events in Central Asia (CA) for 1901-2019 by comparing the composite representation of the observational climate with a hypothetical counterfactual one that does not include the long-term global warming trend. The counterfactual climate data are produced based on a simple detrending approach, using the global mean temperature (GMT) as the independent variable and removing the long-term trends from the climate variables of the observational data. This trend elimination is independent of causality, and the day-to-day variability in the counterfactual climate remains preserved. The analysis done in the paper shows that the increase in frequency and magnitude of extreme temperature and precipitation events can be attributed to global warming. Specifically, the probability of experiencing a +7 K temperature anomaly event in CA increases by up to a factor of seven in some areas due to global warming. The analysis reveals a significant increase in heatwave occurrences in Central Asia, with the observational climate dataset GSWP3-W5E5 (later called also factual) showing more frequent and prolonged extreme heat events than hypothetical scenarios without global warming. This trend, evident in the disparity between factual and counterfactual data, underscores the critical impact of recent climatic changes on weather patterns, highlighting the urgent need for robust adaptation and mitigation strategies. Additionally, using the self-calibrated Palmer drought severity index (scPDSI), the sensitivity of dry and wet events to the coupled precipitation and temperature changes is analyzed. The areas under dry and wet conditions are enhanced under the observational climate compared to a counterfactual scenario, especially over the largest deserts in CA. The expansion of the dry regions aligns well with the pattern of desert development observed in CA in recent decades.

Description: In der Vergangenheit haben sich Wälder an die geringen Veränderungen des am Wuchsort herrschenden Klimas angepasst. Die gegenwärtige Geschwindigkeit des Klimawandels in Verbindung mit der aktuellen Verteilung der Baumarten überfordert jedoch die natürliche Anpassungsfähigkeit. Vegetationszonen, Verbreitungsgebiete der Baumarten und Artzusammensetzung der Wälder verschieben sich. Das Kapitel charakterisiert die Folgen, die der Klimawandel für die Wälder mit sich bringt, stellt Schadfaktoren im Einzelnen vor und schildert die Auswirkungen auf die Produktivität. Darüber hinaus wird detailliert auf die Rolle des Waldes als Kohlenstoffspeicher eingegangen, denn Wälder produzieren nicht nur den nachwachsenden Rohstoff Holz, sondern sie leisten auch viel für die Umwelt und wirken ausgleichend auf das Klima. Auch mögliche Anpassungsoptionen werden dargestellt.

Description: This study investigates the attribution of climate change to trends in river discharge during six decades from 1955 until 2014 in 12 selected river catchments across six Central Asian countries located upstream of the main rivers. For this purpose, the semi-distributed eco-hydrological model SWIM (Soil and Water Integrated Model) was firstly calibrated and validated for all study catchments. Attributing climate change to streamflow simulation trends was forced by factual (reanalysis) and counterfactual climate data (assuming the absence of anthropogenic influence) proposed in the framework of the ISIMIP (Inter-Sectoral Impact Model Intercomparison Project) or ESM without anthropogenic forcing that were firstly tested and then compared. The trend analysis was performed for three variables: mean annual discharge and high flow (Q5) and low flow (Q95) indices. The results show that trends in the annual and seasonal discharge could be attributed to climate change for some of the studied catchments. In the three northern catchments (Derkul, Shagan, and Tobol), there are positive trends, and in two catchments (Sarysu and Kafirnigan), there are negative streamflow trends under the factual climate, which could be attributed to climate change. Also, our analysis shows that the average level of discharge in Murghab has increased during the historical study period due to climate change, despite the overall decreasing trend during this period. In addition, the study reveals a clear signal of shifting spring streamflow peaks in all catchments across the study area.

Description: Hochwasser in Flussgebieten werden in lokale und plötzliche Sturzfluten in kleinen Gebieten und in Hochwasser an größeren Flüssen unterschieden. Für verschiedene Hochwasserindikatoren und Flusseinzugsgebiete ergeben sich erhebliche Unterschiede, wobei sowohl überwiegend aus Regen als auch überwiegend aus Schmelzwasser gespeiste Hochwasserereignisse betrachtet werden. Besondere Aufmerksamkeit finden Hochwasserereignisse in den großen Flussgebieten von Rhein, Donau, Elbe, Weser und Ems in Deutschland sowie die Entwicklung von Sturzfluten infolge von Extremniederschlägen kurzer Dauer, wobei die Beobachtungen und Trends zu Modellierungsergebnissen in Beziehung gesetzt werden. Auch die Notwendigkeit von Anpassungsmaßnahmen wird diskutiert.

Description: Klimarelevante Naturgefahren sind auf vielfältige Faktoren zurückzuführen, deren Zusammenwirken in der Gesamtheit betrachtet werden muss. Die vorbereitenden, auslösenden und kontrollierenden Faktoren werden in unterschiedlichster Weise vom Klimawandel beeinflusst. Der Beitrag beschreibt verschiedene Arten von Dürren und damit verbundene Folgen und Risiken. Es wird diskutiert, inwieweit Waldbrände tatsächlich ausschließlich dem Klimawandel zuzuschreiben sind, wie sich der Trend bei Waldbränden in der Vergangenheit darstellt und wie sich der Klimawandel in Zukunft auf die Häufigkeit von Waldbränden auswirken könnte.

Description: Wasser ist für den Menschen und seine Umwelt von zentraler Bedeutung. Seine jahreszeitliche Verfügbarkeit prägt Ökosysteme wie auch Kulturen und Gesellschaften. Die Herausforderung, zu viel, zu wenig oder zu schmutziges Wasser zu bewältigen, begleitet den Menschen seit Jahrtausenden. Mit der globalen Klimaänderung verändert sich auch der Wasserkreislauf, insbesondere die Quelle erneuerbaren Süßwassers, nämlich der Niederschlag. Grund ist die mit der globalen Erwärmung einhergehende Intensivierung des Wasserkreislaufs, die zu vergrößerten atmosphärischen Energieumsätzen führt. Aufgrund der Wechselwirkung von Atmosphärendynamik und Landoberflächen sind so in manchen Regionen heftigere Niederschläge, in anderen Regionen aber entgegengesetzte Extreme, wie längere und häufigere Trockenperioden und Dürren, möglich. Die Abschätzung der zukünftigen räumlichen und zeitlichen Verteilung der terrestrischen Wasserverfügbarkeit gehört zu den zentralen wissenschaftlichen Herausforderungen des 21. Jahrhunderts.

Description: This paper applies a mental model approach to study the role of tenure security in farmers’ decisionmaking on agricultural investment in Uganda. We investigate the role that both perceived tenure security and formal land rights, measured by the possession of land certificates, play. Our focus is on investment in improved seeds, a widely applied strategy in agricultural development and climate change adaptation. The study design leverages the roll-out of a large land demarcation and registration project, which creates exogenous variation in farmers’ tenure security. Results show that, in contrast to expectations derived from economic theory, tenure security plays only a minor role in farmers’ decision-making process to invest in improved seeds. Out of 15 potential factors determining a farmer’s investment decision, both perceived tenure security and possession of a land certificate are among the least chosen factors, regardless of whether or not households participated in the land registration project. A heterogeneity analysis reveals that female-headed households value formalized land rights more than male-headed households.

Description: In this paper we ask: why do people in rural agrarian communities facing increasing migration pressures from changing climatic conditions, stay? We aim to understand why people stay, who stays, what are the impacts of migration on those who stay, and what are their needs for adaptation? We study a population of people who do not migrate from Himalayan communities of Uttarakhand, India, despite their livelihoods being already severely disrupted by climate change climate change and high outmigration has led to abandoned so-called ‘ghost villages’. Semi-structured interviews (n = 72) were held with affected communities, experts, and policymakers. Results show that motivations for immobility are shaped by place attachment; place-based resource advantages; social milieu; dependence on subsistence agriculture and gender roles. We find that immobility experiences are differentiated by gender, age and in situ resources. Those who stay are negatively impacted by migration via loss of labour in agriculture, changes in population size and composition, loss of community, in addition to the negative impacts of climate change. Our results are likely relevant on a global scale, to other subsistence smallholder communities who stay despite increasing climate risks. These populations will need gender-sensitive support to adapt in place.

Description: To address climatic risks to human security, various climate security risk assessment (CSRA) tools have been developed. We have systematically reviewed 28 such tools against state-of-the-art research to (i) define best practices in CSRAs, (ii) identify related gaps in these tools and derive recommendations on how to address them, and (iii) outline a policy-relevant research agenda. We suggest the following measures to improve CSRA tools: Global South actors need to be more strongly involved in priority setting, conceptualization, risk analysis, and intervention design. CSRA tools should offer geographically disaggregated analyses, transparently explain choices regarding tools’ temporal and geographical foci, and assess their implications for the evidence. In this regard, any type of sampling bias should be avoided. Mixed methods can offer clear advantages to study the context-specific climate security dynamics across different time scales. The main gaps in the tools’ conceptualizations evolve around comprehensive consideration of risk determinants (climatic hazards, exposure, and vulnerability) and complex climate–security linkages, communication of uncertainty, and implementation of validation routines. These factors need to be better accounted for. To advance CSRAs, future research should, for example, develop methodologies to systematically integrate quantitative and qualitative approaches, improve the performance of risk predictions, and develop conflict projections.

Description: We analyze if exposure to weather risk affects the tenure security of smallholder farmers in rural Tanzania. Drawing on a household panel survey with three waves and high-resolution weather data, our identification strategy exploits exogenous variation in precipitation across time and space. Results from household fixed effects estimations show that exposure to weather risk significantly lowers farmers’ perceived tenure security, while it increases land conflicts. Moreover, weather risk influences the likelihood that farmers acquire land certificates. These findings suggest that both land formalization and land dispute resolution mechanisms are needed to cushion the impacts of weather risk.

Description: Forestation efforts are accelerating across the globe in the fight against global climate change, in order to restore biodiversity, and to improve local livelihoods. Yet, so far the non-local effects of forestation on rainfall have largely remained a blind spot. Here we build upon emerging work to propose that targeted rainfall enhancement may also be considered in the prioritization of forestation. We show that the tools to achieve this are rapidly becoming available, but we also identify drawbacks and discuss which further developments are still needed to realize robust assessments of the rainfall effects of forestation in the face of climate change. Forestation programs may then mitigate not only global climate change itself, but also its adverse effects in the form of drying.

Description: The planetary boundaries framework defines a safe operating space for humanity. To date, these boundaries have mostly been investigated separately, and it is unclear whether breaching one boundary can lead to the transgression of another. By employing a dynamic global vegetation model, we systematically simulate the strength and direction of the effects of different transgression levels of the climate change boundary (using climate output from ten phase 6 of the Coupled Model Intercomparison Project models for CO2 levels ranging from 350 ppm to 1000 ppm). We focus on climate change-induced shifts of Earth's major forest biomes, the control variable for the land-system change boundary, both by the end of this century and, to account for the long-term legacy effect, by the end of the millennium. Our simulations show that while staying within the 350 ppm climate change boundary co-stabilizes the land-system change boundary, breaching it (〉450 ppm) leads to critical transgression of the latter, with greater severity the higher the ppm level rises and the more time passes. Specifically, this involves a poleward treeline shift, boreal forest dieback (nearly completely within its current area under extreme climate scenarios), competitive expansion of temperate forest into today's boreal zone, and a slight tropical forest extension. These interacting changes also affect other planetary boundaries (freshwater change and biosphere integrity) and provide feedback to the climate change boundary itself. Our quantitative process-based study highlights the need for interactions to be studied for a systemic operationalization of the planetary boundaries framework.