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Making informed future decisions about solar radiation modification (SRM; also known as solar geoengineering)-approaches such as stratospheric aerosol injection (SAI) that would cool the climate by reflecting sunlight-requires projections of the climate response and associated human and ecosystem impacts. These projections, in turn, will rely on simulations with global climate models. As with climate-change projections, these simulations need to adequately span a range of possible futures, describing different choices, such as start date and temperature target, as well as risks, such as termination or interruptions. SRM modeling simulations to date typically consider only a single scenario, often with some unrealistic or arbitrarily chosen elements (such as starting deployment in 2020), and have often been chosen based on scientific rather than policy-relevant considerations (e.g., choosing quite substantial cooling specifically to achieve a bigger response). This limits the ability to compare risks both between SRM and non-SRM scenarios and between different SRM scenarios. To address this gap, we begin by outlining some general considerations on scenario design for SRM. We then describe a specific set of scenarios to capture a range of possible policy choices and uncertainties and present corresponding SAI simulations intended for broad community use.

The term “climate engineering” is an ambiguous label for two categories of technologies for mediating global warming, Carbon Dioxide Removal (CDR) and Solar Radiation Modification (SRM). Whether CDR and SRM should be grouped together under a common umbrella term, or whether they should be treated as two disparate problems in need of disparate solutions, has long been a matter of debate. This paper first provides an empirical analysis of disaggregation. Topic modelling the scientific literature on climate engineering, I highlight a trend towards disaggregation driven by growth in the specialized literature on CDR. Second, I explore inconsistencies in the theoretical rationale for disaggregation and challenges in its practical implications. Third, I elaborate on the theoretical and practical utility of maintaining an integrated concept of climate engineering for highlighting the challenges of governing large-scale, hypothetical technological interventions into the climate system subject to deep uncertainties and mitigation deterrence.

Meteorological hazards can lead farmers to resort to strategies such as weather modifications. In this paper, we study how the use of such strategies, in this case silver iodide ground generators aimed at protecting vineyards from hail, caused a conflict between farmers (wine producers and cattle breeders) in Burgundy, France. The conflict emerged as the installation of these generators coincided with 3 years of severe droughts (2018, 2019 and 2020), which incurred additional expenses and organisational difficulties for local cattle breeders and led them to suspect a potential link between the generators and the droughts. We followed a transdisciplinary research approach, based on local stakeholder input and their need to mitigate the negative impacts of the conflict. Based on this approach, we studied the links between generator use and precipitation, and carried out in-depth interviews to study farmers’ experiences of climate, generators and conflicts in the region. Whilst the climatic analysis shows no local or regional effects of the generators on precipitation volumes, the sociological study highlights the vulnerability of farmers to successive droughts, found to be part of a wider pattern of climate change based on water balance variables (temperature, precipitation, evapotranspiration potential, soil wetness index) over a long period (1959–2020). Our results suggest that the use of technical solutions to mitigate meteorological hazards, within a broader context of climate engineering, can lead to conflicts at the regional level, and that the climate change challenge in the context of agriculture requires a focus on wider social issues including vulnerability. [ABSTRACT FROM AUTHOR]

Global air temperatures continue to rise despite efforts to curb greenhouse gas emissions. Supplementary technological interventions may become necessary to avoid harmful consequences resulting from unabated temperature increases. One such intervention involves the artificial reduction of incoming solar radiation through the release of reflective particles into the stratosphere: stratospheric aerosol injection (SAI). The American public is generally unfamiliar with SAI, despite increasing media coverage. We conducted a content analysis of frames in US news focused on SAI between 2014 and 2022 to identify and catalogue the most prominent dimensions that are employed in news coverage. We then use these dimensions to design a two-wave survey experiment evaluating how combinations of positive and negative frames that appear in recent journalistic accounts affect the American public’s beliefs about SAI and support for research. The results demonstrate how exposure to framed communications can exert a powerful and durable impact on the public’s beliefs and general support for SAI. [ABSTRACT FROM AUTHOR]

Deliberations are underway to utilize increasingly radical technological options to help address climate change and stabilize the climatic system. Collectively, these options are often referred to as "climate geoengineering." Deployment of such options, however, can create wicked tradeoffs in governance and require adaptive forms of risk management. In this study, we utilize a large and novel set of qualitative expert interview data to more deeply and systematically explore the types of risk–risk tradeoffs that may emerge from the use of 20 different climate geoengineering options, 10 that focus on carbon dioxide or greenhouse gas removal, and 10 that focus on solar radiation management and reflecting sunlight. We specifically consider: What risks does the deployment of these options entail? What types of tradeoffs may emerge through their deployment? We apply a framework that clusters risk–risk tradeoffs into institutional and governance, technological and environmental, and behavioral and temporal dimensions. In doing so, we offer a more complete inventory of risk–risk tradeoffs than those currently available within the respective risk‐assessment, energy‐systems, and climate‐change literatures, and we also point the way toward future research gaps concerning policy, deployment, and risk management. [ABSTRACT FROM AUTHOR]

Since the early 2000s, proposals to deliberately modify the Earth's climate have gained political traction as a controversial last resort measure against dangerous global warming. The article provides a 'longue durée' picture of such climate engineering proposals. It traces their historical trajectory from the late 1950s to their most recent arrival on mainstream climate policy agendas. This perspective suggests that the history of climate engineering unfolds not only along historically specific modes of understanding climatic change. It also corresponds to changing alliances between climate science and the state. By bringing together historical scholarship with contributions from sociology and science policy studies, the article sheds new light on the rise of climate engineering proposals. It recontextualizes these proposals within the bigger history of the political cultivation of climate science. This perspective highlights how deeply entwined efforts to understand and efforts to govern climatic change have always been. This article is categorized under:Climate, History, Society, Culture > Ideas and KnowledgeThe Social Status of Climate Change Knowledge > Sociology/Anthropology of Climate KnowledgeThe Social Status of Climate Change Knowledge > Knowledge and Practice [ABSTRACT FROM AUTHOR]

Calls for moratoria are a frequent response to controversial issues in international diplomacy and control of technology, and are now prominent in debates over governance challenges posed by climate engineering (CE) – intentional modification of the global climate to reduce changes caused by human emissions of greenhouse gases. Based on twelve historical cases of moratoria in other areas of diplomatic conflict or controversial science and technology, we present a novel analytic framework to examine purposes, design characteristics, and conditions for effectiveness of moratoria, based on a taxonomy of three ideal moratorium types: risk-management moratoria, principled-conflict moratoria, and bargaining moratoria. We use this framework to examine potential contributions and design conditions for a moratorium on CE. A moratorium for CE could seek primarily to advance risk-management aims or bargaining aims, with distinct implications for its timing, scope, associated actors, and conditions for termination. Beyond the current, high-stakes case of CE, the proposed analytic framework has broader implications for critical examination of moratorium proposals, current and future, in other areas of controversial research, technology, and governance challenges.

In recent years, the idea of geoengineering, understood as large‐scale interventions in the planet's climate to counteract anthropogenic climate change, has steadily increased its visibility. Presented explicitly as an approach to climate change, geoengineering is positioned as a response, a reactive fix. Geoengineering, however, has a longer and broader history than the current climate crisis. It has long been an umbrella term for large‐scale projects in which various Earth sciences meet dreams about human ecosphere interventions, especially regarding lithosphere and climate and weather modifications. In this paper, we review the history of geoengineering, focusing specifically on climate geoengineering and lithosphere geoengineering. We draw attention to the difference between "proactive" ("high‐modernist"), aimed at mastery over nature, and "reactive" forms of geoengineering, hoping to address anthropogenic environmental degradation technologically. Additionally, we trace historical (dis)continuities between the older, proactive, form of geoengineering and their recent reframing as a technological fix—specifically around the question to what extent nature's complex systems can be known and controlled. Finally, we argue for the need to further research the intersections and shared histories between various forms of geoengineering. This article is categorized under:Climate, History, Society, Culture > Ideas and Knowledge [ABSTRACT FROM AUTHOR]

Religion will play an important role in public perceptions of geoengineering—the intentional manipulation of the planet’s environment to counteract anthropogenic climate change. Religious leaders and scholars can therefore be valuable contributors to the geoengineering debate that has already begun among scientists, engineers, and policy makers. The authors offer four reasons why religion should be part of this debate: Religion is fundamental to how most human beings and societies understand themselves and their place in the world; religion can both challenge and justify scientific authority; religious narratives and symbols can provide frames for understanding geoengineering; and religion offers vocabulary for moral debate. Scholars of theology, ethics, and religious studies can act as mediators between the scientific and faith communities, providing a critical voice in understanding how religion affects the climate conversation, and in engaging a wider public. [ABSTRACT FROM PUBLISHER]

In this interview, climate scientist Tom Wigley says that waiting to take significant action on climate change makes it more likely that geoengineering will be needed to address the problem. He advocates for research on a combination approach: climate engineering together with mitigation efforts aimed at reducing greenhouse gas emissions. Wigley says that geoengineering may become necessary to stabilize global sea level rise, because sea level has much greater inertia than temperatures in the atmosphere. He argues that the climate problem cannot be solved with renewable energy alone, and that, without turning to geoengineering, consideration of the nuclear energy pathway—in particular, resuming the development of fast reactors—should be an essential component of attempts to address the climate crisis. Wigley claims that his colleagues in climate science are generally supportive of nuclear engineering and less fearful of it than they are of geoengineering. [ABSTRACT FROM PUBLISHER]

Solar geoengineering appears capable of reducing climate change and the associated risks. In part because it would be global in effect, the governance of solar geoengineering is a central concern. The Earth System Governance (ESG) Project includes many researchers who, to varying degrees, utilize a common vocabulary and research framework. Despite the clear mutual relevance of solar geoengineering and ESG, few ESG researchers have considered the topic in substantial depth. To stimulate its sustained uptake as a subject within the ESG research program, we identify significant contributions thus far by ESG scholars on the subject of solar geoengineering governance and survey the wider solar geoengineering governance literature from the perspective of the new ESG research framework. Based on this analysis, we also suggest specific potential lines of inquiry that we believe are ripe for research by ESG scholars: nonstate actors’ roles, polycentricity, public engagement and participation, and the Anthropocene.

Sunlight reflection and carbon removal proposals for "climate engineering" (CE) confront governance challenges that many emerging technologies face: their futures are uncertain, and by the time one can discern their shape or impacts, vested interests may block regulation, and publics are often left out of decision‐making about them. In response to these challenges, "responsible research and innovation" (RRI) has emerged as a framework to critique and correct for technocratic governance of emerging technologies, and CE has emerged as a prime case of where it can be helpfully applied. However, a critical lens is rarely applied to RRI itself. In this review, we first survey how RRI thinking has already been applied to both carbon removal and sunlight reflection methods for climate intervention. We examine how RRI is employed in four types of activities: Assessment processes and reports, principles and protocols for research governance, critical mappings of research, and deliberative and futuring engagements. Drawing upon this review, we identify tensions in RRI practice, including whether RRI forms or informs choices, the positionalities of RRI practitioners, and ways in which RRI activities enable or disable particular climate interventions. Finally, we recommend that RRI should situate CE within the long arc of sociotechnical proposals for addressing climate change, more actively connect interrogations of the knowledge economy with reparative engagements, include local or actor‐specific contexts, design authoritative assessments grounded in RRI, and go beyond treating critique and engagement as "de facto" governance. This article is categorized under:Policy and Governance > Private Governance of Climate ChangeSocial Status of Climate Change Knowledge > Climate Science and Decision Making [ABSTRACT FROM AUTHOR]

Climate engineering (CE) measures are increasingly discussed when dealing with the adverse impacts of climate change. While much research has focused on individual methods, few studies attempt to compare and rank the effectiveness of these measures. Furthermore, model uncertainties are seldom acknowledged and lesser still, estimated when CE scenarios are assessed. In this work, we quantify the variance in outcomes due to poorly constrained model parameters under several idealized CE scenarios. The four scenarios considered are (1) warming under the high emission scenario Representative Concentration Pathway 8.5 without CE applied and the same emission scenario with (2) afforestation,(3) solar radiation management, and (4) artificial ocean alkalinization. By considering the parametric uncertainty in model outputs, we demonstrate the problems with comparing these scenarios using a single parameter setting. Using statistical emulation, we estimate the probability distributions of several model outcomes. Based on such distributions, we suggest an approach to ranking the effectiveness of the scenarios considered according to their probability of avoiding climate thresholds. Plain Language Summary: Various intervention techniques have been proposed to manipulate the climate system at a large scale to combat the adverse effects of climate change. While many studies have focused on specific techniques, relatively little has been done to compare and rank the effectiveness of these methods within a single model. Furthermore, the uncertainties arising from the use of climate models are seldom acknowledged or assessed. In this work, we analyze the uncertainty in the model's simulated outcomes caused by poorly constrained model settings under four idealized future scenarios, with and without climate interventions. Our results highlight the importance of taking into account the model's uncertainty when analyzing or communicating the simulated outcomes. Moreover, we suggest an approach to ranking the effectiveness of the interventions considered based on goals of societal importance. Key Points: We demonstrate how uncertainty analysis can become an essential part in comparative studies on climate engineeringModel outcomes are probability distributions and should be treated as such when communicating the effects and impacts of climate engineeringThe probability of avoiding dangerous threshold is calculated for various climate engineering scenarios [ABSTRACT FROM AUTHOR]

This paper identifies critical lessons from the climate change experience to guide how communications and engagement on negative emissions can be conducted to encourage functional public and policy discourse. Negative emissions technologies present a significant opportunity for limiting climate change, and are likely to be necessary to keep warming below 2°C. While the concept of negative emissions is still in its infancy, there is evidence of nascent polarization, and a lack of nuance in discussion of individual technologies. We argue that if negative emissions technologies are to be implemented effectively and sustainably, an effective governance regime is needed; built on functional societal discourse and avoiding the ideological baggage of the broader climate change debate or the controversies concerning geoengineering. At its core, our argument is to avoid the ideological bundling of negative emissions; this can be pursued directly and via careful selection of communication frames and the use of non-partisan, trusted messengers. Whether these lessons are heeded may determine if negative emissions are governed proactively, or are distorted politically, misused and delayed. [ABSTRACT FROM AUTHOR]

In this Perspective, we discuss whether in times of quickly proceeding global environmental change, radical global interventions like "climate engineering" may gain legitimacy in China and eventually be deployed or supported. We argue that one cornerstone for whether climate engineering, and solar radiation management in particular, could gain legitimacy in China, is its current weather modification programme. In China, weather modification is institutionalized and deployed on a large scale, and current narratives around the legitimacy to intervene into the local climate may provide a rationale for interventions such as solar radiation management. In the end, in the same way as Deng Xiaoping coined the phrase "stepping on stones to cross the river" in the era of China's Industrial Civilization, narrating China's "Ecological Civilization" may want to make use of "seeding the clouds to reach the sky". [See ESM for a summary of the article in Chinese.] [ABSTRACT FROM AUTHOR]

Most experts agree that the greatest risk associated with climate change is pretending that the problem does not exist, or that it does not require immediate attention and action. That said, the potential pathways for mitigating the effects of greenhouse gas emissions are not created equal in terms of the risks and benefits they entail. Public discourse tends to focus on the most optimistic scenarios for implementing new technologies and to ignore not only the hazards but also the non-climate-related benefits associated with some approaches. Climate mitigation strategies currently undergo economic and engineering analyses, but they are not consistently subjected to rigorous risk assessment and risk management. The author offers the beginnings of a more cohesive decision-support analysis framework. Assessments of various mitigation strategies by the world’s largest industry—insurance—are critically important in this process because insurers can provide a dispassionate view and internalize the costs of risk through pricing. Bank financing cannot be mobilized without insurance, and the public sector may be forced to assume many of the risks associated with emerging technologies if insurers opt out. A century of dangerously blending technological enthusiasm with lack of care in assessing the comparative risks of energy and land-use choices ushered in today’s climate crisis. Continued inattention threatens to saddle society with new risks from poorly prioritized efforts to solve the climate problem. Procrastination is painting humankind into a corner in which progressively riskier and unproven technologies will be required to mitigate climate change. [ABSTRACT FROM PUBLISHER]

The online video-sharing website YouTube is extremely popular globally, also as a tool for information on science and environmental topics. However, only little is known about what kind of information users find when they are searching for information about climate science, climate change, and climate engineering on YouTube. This contribution presents results from an exploratory research project that investigates whether videos found on YouTube adhere to or challenge scientific consensus views. Ten search terms were employed to search for and analyze 200 videos about climate and climate modification topics, which are contested topics in online media. The online anonymization tool Tor has been used for the randomization of the sample and to avoid personalization of the results. A heuristic qualitative classification tool was set up to categorize the videos in the sample. Eighty-nine videos of the 200 videos in the sample are supporting scientific consensus views about anthropogenic climate change, and climate scientists are discussing climate topics with deniers of climate change in four videos in the sample. Unexpectedly, the majority of the videos in the sample (107 videos) supports worldviews that are opposing scientific consensus views: 16 videos deny anthropogenic climate change and 91 videos in the sample propagate straightforward conspiracy theories about climate engineering and climate change. Videos supporting the scientific mainstream view received only slightly more views (16,941,949 views in total) than those opposing the mainstream scientific position (16,939,655 views in total). Consequences for the public communication of climate change and climate engineering are discussed in the second part of the article. The research presented in this contribution is particularly interested in finding out more about strategically distorted communications about climate change and climate engineering in online environments and in critically analyzing them.

Although solar geoengineering (alternatively ‘solar radiation management’ or ‘solar radiation modification’) appears to offer a potentially effective, inexpensive and technologically feasible additional response to climate change, it would pose serious physical risks and social challenges. Governance of its research, development and deployment is thus salient. This article reviews proposals for governing solar geoengineering. Its research may warrant dedicated governance to facilitate effectiveness and to reduce direct and socially mediated risks. Because states are not substantially engaging with solar geoengineering, non-state actors can play important governance roles. Although the concern that solar geoengineering would harmfully lessen abatement of greenhouse gas emissions is widespread, what can be done to reduce such displacement remains unclear. A moratorium on outdoor activities that would surpass certain scales is often endorsed, but an effective one would require resolving some critical, difficult details. In the long term, how to legitimately make decisions regarding whether, when and how solar geoengineering would be used is central, and suggestions how to do so diverge. Most proposals to govern commercial actors, who could provide goods and services for solar geoengineering, focus on intellectual property policy. Compensation for possible harm from outdoor activities could be through liability or a compensation fund. The review closes with suggested lines of future inquiry. [ABSTRACT FROM AUTHOR]

In the context of global climate change and rapid urbanization, climate governance has become one of the unavoidable challenges of human society. Therefore, climate engineering is increasingly mentioned in the international climate negotiations. For solar radiation management with the most controversy in climate engineering method, based on two scenarios of climate engineering (G4) and non climate engineering ( RCP4.5) of BNU-ESM model. 95% and 99% percentiles of daily rainfall data during 2010-2099 were taken as thresholds of heavy rainfall and extreme rainfall events. The data of over threshold sampling (POT) were fitted by Weibull distribution to diagnose the heavy rainfall and extreme rainfall in 10, 20. 50 and 100 years of return period. The results showed that: in two scenarios, strength of heavy rainfall and extreme rainfall enhanced with return period increased, and they showed a southeast high-northwest low spatial characteristics. Climate engineering, in general, contributes to the increase in heavy rainfall and extreme rainfall in China, as well as spatial heterogeneity, which represents the suppression of heavy rainfall and extreme rainfall in parts of the country. This research is of great significance for the future global climate control and regional climate adaptation. [ABSTRACT FROM AUTHOR]

Lessons from the literature on multi-stakeholder dialogue (MSD) that are relevant to the debate on climate engineering (CE) are examined. MSDs have been used to prod slow-to-develop intergovernmental regulatory processes on a range of transnational and global controversies. A CEMSD might push forward anticipatory governance of CE by promoting social learning, sharpening and legitimizing governance norms, and starting to arrange the political space for governance by states. However, significant challenges and risks are also identified, including questions about the ripeness of the issue for stakeholder dialogue; difficult trade-offs in the design of dialogues, particularly around issues of participation and knowledge-power; and inherent tensions in the various purposes a CEMSD might serve. Given these challenges, steps forward that would better prepare a space for legitimate and effective dialogue are recommended. [ABSTRACT FROM AUTHOR]

Technologies for Solar Radiation Management (SRM) could limit global warming by manipulating the Earth's radiation balance. A major objection to SRM is the termination problem: the catastrophic consequences that are likely to result from its sudden discontinuation. The termination problem limits the reversibility of policy choices and poses the risk of inadvertent or enforced program collapse. It is often considered a major impediment to the governability of SRM. In a first attempt to systematically engage with the question of institutional design for resolving the termination problem, the scenarios in which the termination problem arises as well as their respective drivers are identified. Scenarios and drivers are then used to derive institutional solutions in the form of excludable benefits, scientific oversight and phase-out mechanisms. While other objections to SRM may remain valid, it is concluded that the termination problem raises fewer challenges for international governance than is usually assumed. [ABSTRACT FROM AUTHOR]

Analyses of climate engineering (CE) governance have accelerated in the last decade. A key claim is that CE remains a largely ungoverned space, with shared norms, institutional arrangements, and formal rules to regulate CE not yet present. In contrast, here it is argued that de facto governance of CE is underway, discernible in an ordering of this nascent field of inquiry by unacknowledged sources of steering. One key source of de facto governance is analyzed: high-level 'authoritative assessments' of CE. The focus is on how these assessments are constructing CE as an object of governance through demarcating and categorizing this emerging field of inquiry, and how this contributes to normalizing and institutionalizing CE research (and CE research communities). Scrutinizing the distinct nature and political implications of de facto governance, particularly of novel and speculative technological trajectories not yet subject to formal steering, remains a key task for governance scholars. [ABSTRACT FROM AUTHOR]

In this Forum, three scholars discuss how climate engineering will pose novel human rights challenges, and may well force reconsideration of how human rights are applied as a guide to action. Following a short introduction, the first section introduces three competing approaches to human rights, arguing views which emphasize fairness or attempt to maximize satisfaction are more promising than one viewing human rights as inviolable 'side-constraints'. The second section draws lessons from climate migration that are relevant for climate engineering in terms of incorporating a human rights approach to duties, rights, and participation. The final section compares the 'needs-based' and 'rights-based' approaches to humanitarian work in the face of climate change and climate engineering, raising concerns for duty-bearers and right-holders. The Forum's conclusion draws together points of overlap and suggests a path forward for policy and research on this topic. [ABSTRACT FROM AUTHOR]

We introduce a special issue on a holistic assessment of solar geoengineering via stratospheric SO2 injection in the state‐of‐the‐art climate model, Community Earth System Model, version 1 with the Whole Atmosphere Community Climate Model as its atmospheric component (CESM1(WACCM)). This model has numerous complexities that allow it to represent some of the most important nonlinearities associated with stratospheric SO2 injection, including aerosol microphysical growth and stratospheric chemistry. The studies described herein represent the steps toward and first attempt in a state‐of‐the‐art climate model to use solar geoengineering to meet multiple simultaneous objectives via SO2 injection at multiple locations. First, a set of simulations was carried out to better understand the response of the model to variations in latitude, altitude, and amount of sulfur dioxide injections. Subsequently, in a century‐long simulation, a feedback algorithm was employed to meet specific objectives and manage uncertainty, wherein the injection amount at each location was adjusted every model year. Most of the analyses contained in this special issue focus on surface climate and stratospheric changes in the simulations. In addition, 20 ensemble members of the feedback simulation have been carried out and provided to the community (the Geoengineering Large Ensemble) to expand the scope of analyses to low signal‐to‐noise ratio fields, including regional effects, impacts assessment, and extreme events. The demonstration provided by these simulations is a step toward understanding the space of achievable climate objectives via solar geoengineering or, phrased differently, determining what solar geoengineering can do and what it cannot do. Key Points: CESM1(WACCM) is a state‐of‐the‐art climate model suitable for stratospheric aerosol geoengineering studiesFeedback can manage uncertainty even in complicated, nonlinear Earth System ModelsFurther research is needed to understand the space of achievable climate objectives via geoengineering [ABSTRACT FROM AUTHOR]

The last decade has seen broad exploratory research into stratospheric aerosol (SA) geoengineering, motivated by concern that reducing greenhouse gas emissions may be insufficient to avoid significant impacts from climate change. Based on this research, it is plausible that a limited deployment of SA geoengineering, provided it is used in addition to cutting emissions, could reduce many climate risks for most people. However, "plausible" is an insufficient basis on which to support future decisions. Developing the necessary knowledge requires a transition toward mission-driven research that has the explicit goal of supporting informed decisions. We highlight two important observations that follow from considering such a comprehensive, prioritized natural-science research effort. First, while field experiments may eventually be needed to reduce some of the uncertainties, we expect that the next phase of research will continue to be primarily model-based, with one outcome being to assess and prioritize which uncertainties need to be reduced (and, as a corollary, which field experiments can reduce those uncertainties). Second, we anticipate a clear separation in scale and character between small-scale experimental research to resolve specific process uncertainties and global-scale activities. We argue that the latter, even if the radiative forcing is negligible, should more appropriately be considered after a decision regarding whether and how to deploy SA geoengineering, rather than within the scope of "research" activities. [ABSTRACT FROM AUTHOR]

Climate engineering with stratospheric sulfate aerosol injections (SSAI) has the potential to reduce risks of injustice related to anthropogenic emissions of greenhouse gases. Relying on evidence from modeling studies, this paper makes the case that SSAI could have the potential to reduce many of the key physical risks of climate change identified by the Intergovernmental Panel on Climate Change. Such risks carry potential injustice because they are often imposed on low-emitters who do not benefit from climate change. Because SSAI has the potential to reduce those risks, it thereby has the potential to reduce the injustice associated with anthropogenic emissions. While acknowledging important caveats, including uncertainty in modeling studies and the potential for SSAI to carry its own risks of injustice, the paper argues that there is a strong case for continued research into SSAI, especially if attention is paid to how it might be used to reduce emissions-driven injustice. [ABSTRACT FROM AUTHOR]

Faced with the urgency of climate change, Climate Engineering has been framed as a fast and feasible technological solution. At the same time, however, critique against it is getting increasingly louder. This paper articulates a critical analysis of Climate Engineering technologies from a point of view situated within the degrowth discourse. In the first part two approaches discussed within the degrowth debate are presented: the concept of viability based on a biophysical perspective and the concept of conviviality based on a socio-cultural approach. In a second step formalized arguments from the point of view of applied ethics are articulated and applied to three Climate Engineering Technologies: Sulfate Aerosol Injection, Bio-energy with Carbon Capture and Storage, and Afforestation. In a third step, an extended version of the trade-off argument about mitigation versus Climate Engineering solution is discussed from a degrowth perspective: accordingly, within the current dominant growth paradigm, climate engineering technologies might lead to reduced mitigation efforts. The paper follows the argumentative turn in applied ethics and displays a formalization of arguments that can help clarify decision-making and identify the different dimensions at stake. The paper articulates arguments against the deployment of CE technologies and advances a new version of the trade-off-argument based on a degrowth perspective. From the point of view of a degrowth-based critique of technology, the only type of Climate Engineering Technology ethically acceptable would be afforestation under specific conditions. [ABSTRACT FROM AUTHOR]

In this article, we ask how the approaches of climate engineering - mostly highly technological approaches to address the challenge of global climate change - might be organised in the age of the Anthropocene. We understand the term 'Anthropocene' to be characterised by crisis, on one hand, and by promise, on the other. In particular, we aim to raise doubts on the dominant perspective on the organisation of climate engineering, which assumes these approaches to be regulated through legalistic means. Drawing an analogy to the early development stages of nuclear weapons, we point out that, instead of following a legalistic rationale, climate engineering organisation might pursue a logic of technical feasibility, political acceptance and bureaucratic momentum. [ABSTRACT FROM AUTHOR]

It is increasingly recognised that meeting the obligations set out in the Paris Agreement on climate change will not be physically possible without deploying large-scale techniques for either removing greenhouse gases already in the atmosphere or reflecting sunlight away from the Earth. In this article we report on the findings of a scenarios method designed to interrogate how far these ‘climate engineering’ ideas may develop in the future and under what governance arrangements. Unlike previous studies in climate engineering foresight that have narrowly focussed on academic perspectives, a single climate engineering idea and a restricted range of issues, our approach sought to respond to theoretical imperatives for ‘broadening out’ and ‘opening up’ research methods applied to highly uncertain and ambiguous topics. We convened a one-day event with experts in climate change and climate engineering from across the sectors of government, industry, civil society and academia in the UK, with additional experts from Brazil, Germany and India. The participants were invited to develop scenarios for four climate engineering ideas: bioenergy with carbon capture and storage, direct air capture and storage, stratospheric aerosol injection and marine cloud brightening. Manifold challenges for future research were identified, placing the scenarios in sharp contrast with early portrayals of climate engineering research as threatening a ‘slippery slope’ of possible entrenchments, lock-ins and path dependencies that would inexorably lead to deployment. We suggest that the governance challenges for climate engineering should therefore today be thought of as less of a slippery slope than an ‘uphill struggle’ and that there is an increasingly apparent need for governance that responsibly incentivises, rather than constrains, research. We find that affecting market processes by introducing an effective global carbon price and direct government expenditure on research and development are incentives with broad potential applications to climate engineering. Responsibly incentivising research will involve a pluralistic architecture of governance arrangements and policy instruments that attends to collective ambitions as well as national differences and emerges from an inclusive and reflexive process. [ABSTRACT FROM AUTHOR]

Climate engineering (CE) and carbon capture and storage are controversial options for addressing climate change. This study compares public perception in Germany of three specific measures: solar radiation management (SRM) via stratospheric sulphate injection, large-scale afforestation, and carbon capture and storage sub-seabed (CCS-S). In a survey experiment we find that afforestation is most readily accepted as a measure for addressing climate change, followed by CCS-S and lastly SRM, which is widely rejected. Providing additional information decreases acceptance for all measures, but their ranking remains unchanged. The acceptance of all three measures is especially influenced by the perceived seriousness of climate change and by trust in institutions. Also, respondents dislike the measures more if they perceive them as a way of shirking responsibility for emissions or as an unconscionable manipulation of nature. Women react more negatively to information than men, whereas the level of education or the degree of intuitive vs reflective decision making does not influence the reaction to information. POLICY RELEVANCE Current projections suggest that the use of climate engineering (CE) technologies or carbon capture and storage (CCS) is necessary if global warming is to be kept well below 2°C. Our article focuses on the perspective of the general public and thus supplements the dialogue between policymakers, interest groups, and scientists on how to address climate change. We show that in Germany public acceptance of potentially effective measures such as SRM or CCS-S is low and decreases even more when additional information is provided. This implies that lack of public acceptance may turn out to be a bottleneck for future implementation. Ongoing research and development in connection with CCS-S and SRM requires continuous communication with, and involvement of, the public in order to obtain feedback and assess the public’s reservations about the measures. The low level of acceptance also implies that emission reduction should remain a priority in climate policy. [ABSTRACT FROM AUTHOR]

Geoengineering—the deliberate interference in the climate system to affect global warming—could have significant global environmental and social implications. How to shape formal geoengineering governance mechanisms is an issue of debate. This paper describes and analyses the geoengineering governance landscape that has developed in the absence of explicit geoengineering regulation. An Earth System Governance perspective provides insight into the formation of norms resulting from an overlap in international treaties and from the actions of engaged non-state agents. Specifically, the paper explores the instruments and actors having effect in existing formal and informal geoengineering governance mechanisms. It finds that geoengineering is subject to a form of ‘governance-by-default’. This is due to a situation in which state actors have not resolved the tension between two legal norms: that of ‘precaution’ and that of ‘harm minimisation’. This governance-by-default is characterised by uneven regulation from existing multilateral agreements established for other purposes, an absence of regulation specifically focused on geoengineering, guidance from an international ambition to hold global average warming below 2 °C and to achieve net-zero emissions in the second half of the century, and strong normative engagement by the research community. Governance-by-default is likely to be a stopgap development until more enduring and focused governance emerges. [ABSTRACT FROM AUTHOR]

The stringency of the 1.5 degree goal under the Paris Agreement, coupled with the mismatch between that goal and domestic mitigation pledges, inevitably directs attention onto the potential future role of solar radiation management (SRM) technologies. Such technologies, however, remain controversial, and analysis of their environmental, social and ethical implications is at an early stage. In this context, this paper distils four key governance objectives and proposes three specific policy interventions for the near-term governance of SRM technologies. Specifically, we build from existing literature to argue that SRM governance must simultaneously: guard against the risks of uncontrolled SRM development; enable potentially valuable research; build legitimacy for research and any future policy through broad public engagement and ensure that SRM is only considered as one part of a broader mitigation agenda. We propose three interventions to work towards those objectives in the near term by: developing a transparency mechanism for research; creating a global forum for public engagement and including consideration of SRM in the global stocktake under the Paris Agreement. Finally, we argue that carrying out these interventions requires a shared or ‘polycentric’ SRM governance structure that can build on the site-specific capabilities and preferences of existing international institutions. Key policy insightsDespite their highly controversial nature, large-scale technological interventions, such as solar radiation management (SRM), must be considered (albeit possibly rejected) for their potential contribution towards meeting the 1.5 degree target established under the Paris Agreement.Existing governance mechanisms for SRM need further development to ensure that unnecessary threats to social and/or natural systems are not incurred.There are at least three governance mechanisms that should be pursued immediately to protect against some of these potential threats, including: a transparency mechanism for SRM research, a global forum to facilitate public engagement and incorporating evaluation of SRM technologies into the global stocktake under the Paris Agreement. [ABSTRACT FROM PUBLISHER]

This study contributes to a growing body of research that studies how different societal actors view climate engineering (CE) in an effort to 'open up' received framings and make them amenable to deliberations. CE is an umbrella term for different proposals of how to counteract global warming with technological means, some of which have sparked controversy. Drawing on fifteen interviews, the study explores how scientists who advise the European Commission on research funding priorities regarding climate change and sustainability view CE. They considered CE as treating the symptoms rather than the causes of climate change, as interfering in complex and unpredictable natural systems, and as engendering questions of distributive justice. They also stressed the complexity of governing climate change and expressed support for basic CE research. The concluding discussion dwells on the implications of foresight, the division of labor in research governance, and the challenge of poverty for governing technologies in the service of climate action. [ABSTRACT FROM AUTHOR]

The potential of climate engineering to substitute or complement abatement of greenhouse gas emissions has been increasingly debated over the last years. The scientific assessment is driven to a large extent by assumptions regarding its effectiveness, costs, and impacts, all of which are profoundly uncertain. We investigate how this uncertainty about climate engineering affects the optimal abatement policy in the near term. Using a two period model of optimal climate policy under uncertainty, we show that although abatement decreases in the probability of success of climate engineering, this relationship is concave implying a rather ‘flat’ level of abatement as the probability of climate engineering becomes a viable policy option. Using a stochastic version of an integrated assessment model, the results are found to be robust to a wide range of specifications. Moreover, we numerically evaluate different correlation structures between climate engineering and the equilibrium climate sensitivity. [ABSTRACT FROM AUTHOR]

This article expounds a Buddhist perspective on the rapidly emerging topic of Climate Engineering, i.e. the deliberate, large-scale manipulation of the environment as a proposed means to counteract anthropogenic climate change or some of its specific aspects like global mean temperature increase. It sets the stage with two orthogonal aspects: an overview of the topic of Climate Engineering, and a broader analysis of the Buddhist perspective on mankind's relationship with nature. Linking these together, we show that as one of the world's major faiths, Buddhism can provide valuable insights and perspectives for the evolving global discourse on Climate Engineering methods, and that it advocates some basic requirements concerning their further development and possible future deployment. [ABSTRACT FROM AUTHOR]

This paper analyses how new information shapes public perception of a controversially discussed technology over time. The test case analysed in this paper is solar radiation management (SRM), a potentially risky, environmental engineering technology, which aims to fight climate change by the injection of sulphate aerosols into the stratosphere. Using panel survey data, we show that most respondents initially show strong negative emotions towards SRM and reject the technology. However, public perception is not stable over time as emotions cool off and acceptance increases. The increase in acceptance is greater, the longer the cooling-off period between two surveys. Furthermore, we show that the cooling-off effect is more pronounced for more impulsive respondents. [ABSTRACT FROM AUTHOR]