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Novel, potentially radical climate intervention technologies like carbon dioxide removal and solar geoengineering are attracting attention as the adverse impacts of climate change are increasingly felt. The ability of publics, particularly in the Global South, to participate in discussions about research, policy, and deployment is restricted amidst a lack of familiarity and engagement. Drawing on a large-scale, cross-country exercise of nationally representative surveys (N = 30,284) in 30 countries and 19 languages, this article establishes the first global baseline of public perceptions of climate-intervention technologies. Here, we show that Global South publics are significantly more favorable about potential benefits and express greater support for climate-intervention technologies. The younger age and level of climate urgency and vulnerability of these publics emerge as key explanatory variables, particularly for solar geoengineering. Conversely, Global South publics express greater concern that climate-intervention technologies could undermine climate-mitigation efforts, and that solar geoengineering could promote an unequal distribution of risks between poor and rich countries.

Solar geoengineering and negative-emissions technologies are attracting greater attention as prospective ways to tackle and mitigate the worst impacts of climate change. Until now, such options have rarely been examined in a comprehensive manner. Rather, insofar as this has been done, research focused on one or the other, rather than considering a portfolio contribution and, more often, has taken a sectoral approach that looks at the options germane to the agriculture or energy sectors, but not in relation to climate change. Arguing for the need for a wider lens, the current article aims to understand the kinds of couplings and linkages most germane for the effectiveness of a particular option. In specific, we employed a novel dataset garnered from a large expert-interview exercise (N = 125) to conceptualize and consider crucial couplings to solar radiation management and carbon dioxide removal at many levels (across different sectors, differing dimensions of sustainability, productive or destructive impacts, and direct and indirect relationships). Our analysis thereby provides insights into the understanding of climate transitions by explicitly considering the most salient couplings in general as well as how, and to what extent, the various options relate to each other, as a portfolio for climate intervention, and together to climate mitigation and adaptation.

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.

The scientific literature on the co-impacts of low-carbon energy systems—positive and negative side effects—has focused intently on climate mitigation, or climate adaptation. It has not systematically examined the prospective co-impacts of carbon removal (or negative emissions) and solar geoengineering. Based on a large sample of diverse expert interviews (N = 125), and using a sociotechnical approach, in this study we identify 107 perceived co-impacts related to the deployment of carbon removal and solar geoengineering technologies. Slightly less than half (52) were identified as positive co-impacts (38 for carbon removal, 14 for solar geoengineering), whereas slightly more than half (55) were identified as negative co-impacts (31 for carbon removal, 24 for solar geoengineering). We then discuss 20 of these co-impacts in more depth, including positive co-impacts for nature-based protection, the expansion of industry, and reduction of poverty or heat stress as well as negative co-impacts for water insecurity, moral hazard, limited social acceptance and path dependence. After presenting this body of evidence, the paper then discusses and theorizes these co-impacts more deeply in terms of four areas: relationality and risk-risk trade-offs, co-deployment and coupling, intentional or unintentional implications, and expert consensus and dissensus. It concludes with more general insights for energy and climate research, and policy.

The impacts of global climate change on international security and geopolitics could be of historic proportion, challenging those of previous global threats such as nuclear weapons proliferation, the Great Depression, and terrorism. But while the evidence surrounding the security impacts of climate change is fairly well-understood and improving, less is known about the security risks to climate-technology deployment. In this study, we focus on the geopolitical, security, and military risks facing negative emissions and solar geoengineering options. Although controversial, these options could become the future backbone of a low-carbon or net-zero society, given that they avoid the need for coordinated or global action (and can be deployed by a smaller group of actors, even non-state actors), and that they can “buy time” for mitigation and other options to be scaled up. We utilize a large and diverse expert-interview exercise (N = 125) to critically examine the security risks associated with ten negative emission options (or greenhouse gas removal technologies) and ten solar geoengineering options (or solar radiation management technologies). We ask: What geopolitical considerations does deployment give rise to? What particular military applications exist? What risks do these options entail in terms of weaponization, misuse, and miscalculation? We examine such existing and prospective security risks across a novel conceptual framework envisioning their use as (i) diplomatic or military negotiating tools, (ii) objectives for building capacity, control, or deterrence, (iii) targets in ongoing conflicts, and (iv) causes of new conflicts. This enables us to capture a far broader spectrum of security concerns than those which exist in the extant literature and to go well beyond insights derived from climate modelling or game theory by drawing on a novel, rich, and original dataset of expert perceptions.

This article discusses and illuminates the synergies and jeopardies or tradeoffs that exist between the 17 Sustainable Development Goals (SDGs) and net-zero or future climate protection options such as greenhouse gas removal (GGR) technologies and solar radiation management (SRM) deployment approaches, respectively. Through a large-scale expert-interview exercise (N = 125), the study finds firstly that numerous synergies and tradeoffs exist between GGR, SRM, and the SDGs. More specifically, we reveal that GGR deployment could enhance the attainment of 16 of the 17 SDGs, but this comes with possible tradeoffs with 12 of the SDGs. SRM deployment could not only enhance the attainment of 16 of the 17 SDGs, but also create possible tradeoffs with (a different) 12 SDGs. The findings further support the understanding of the complexity of SRM and GGR proposals and help policymakers and industrial pioneers understand, navigate, and benchmark between geoengineering approaches using sustainable development goals.

Negative emissions technologies and solar radiation management techniques could contribute towards climate stability, either by removing carbon dioxide from the atmosphere and storing it permanently or reflecting sunlight away from the atmosphere. Despite concerns about them, such options are increasingly being discussed as crucial complements to traditional climate change mitigation and adaptation. Expectations around negative emissions and solar radiation management and their associated risks and costs shape public and private discussions of how society deals with the climate crisis. In this study, we rely on a large expert survey (N = 74) to critically examine the future potential of both negative emission options (e.g., carbon dioxide removal) and solar radiation management techniques. We designed a survey process that asked a pool of prominent experts questions about (i) the necessity of adopting negative emissions or solar radiation management options, (ii) the desirability of such options when ranked against each other, (iii) estimations of future efficacy in terms of temperature reductions achieved or gigatons of carbon removed, (iv) expectations about future scaling, commercialization, and deployment targets, and (v) potential risks and barriers. Unlike other elicitation processes where experts are more positive or have high expectations about novel options, our results are more critical and cautionary. We find that some options (notably afforestation and reforestation, ecosystem restoration, and soil carbon sequestration) are envisioned frequently as necessary, desirable, feasible, and affordable, with minimal risks and barriers (compared to other options). This contrasts with other options envisaged as unnecessary risky or costly, notably ocean alkalization or fertilization, space-based reflectors, high-altitude sunshades, and albedo management via clouds. Moreover, only the options of afforestation and reforestation and soil carbon sequestration are e

In global climate governance, anticipatory assessments map future options and pathways, in light of prospective risks and uncertainties, to inform present-day planning. Using data from 125 interviews, we ask: How are foundational experts contesting the conduct of anticipatory assessment of carbon removal and solar geoengineering – as two emerging but controversial strategies for engaging with climate change and achieving Net Zero targets? We find that efforts at carbon removal and solar geoengineering assessment leverage and challenge systems modeling that has become dominant in mapping and communicating future climate impacts and mitigation strategies via IPCC reports. Both suites of climate intervention have become stress-tests for the capacity of modeling to assess socio-technical strategies with complex, systemic dimensions. Meanwhile, exploring societal dimensions demands new modes of disciplinary expertise, qualitative and deliberative practices, and stakeholder inclusion that modelling processes struggle to incorporate. Finally, we discuss how the patterns of expert contestation identified in our results speak to multiple fault-lines within ongoing debates on reforming global environmental assessments, and highlights key open questions to be addressed.

Carbon removal – also known as negative emissions technologies, or greenhouse gas removal – represents a core pillar of post-Paris climate policy, signaling for enhancing and constructing carbon sinks to balance emissions sources on route to ambitious temperature targets. We build on Amory Lovins’ “hard” and “soft” alternatives for energy pathways to illuminate how foundational experts, technologists, and policy entrepreneurs think about different modes of resource inputs, infrastructure and livelihoods, and decision-making, regarding ten nature-based and engineered carbon removal approaches. Based on 90 original interviews, we show that hard and soft paths reflect different conceptions of systems, spaces, and societal involvement. We highlight that pathways depend on diverging concepts of economies-of-scale (capturing carbon at the largest possible scale, versus catalyzing systemic co-benefits) and carbon management (a waste product within conventional climate governance, versus diverse end-uses and values to be diversely governed). Our analysis further emphasizes two key uncertainties: whether renewables can be upscaled to allow synergies rather than tradeoffs between carbon removal and more widespread energy demands, and whether carbon certification can expand spatially to navigate long supply chains, and conceptually to incentivize diverse co-benefits. Experts remain motivated by antecedent concerns over land-use management and extractive industries, and that exploitative systems will – without guardrails – be replicated by inertia.

In this study, we utilize a large and diverse expert interview exercise (N = 125) to critically examine the whole systems justice issues associated with ten negative emissions and ten solar geoengineering technologies. We ask: What equity and justice concerns arise with these 20 options? What particular vulnerable groups could be affected? What risks do these options entail for communities or the climate? Utilizing a “claims making” approach, we examine existing and prospective injustices across a pluralistic whole systems framework analyzing (i) resource extraction issues including minerals, chemicals, and fertilizers (ii) manufacturing, labor and ownership concerns, (iii) transportation-network and land-grabbing dynamics, (iv) unfair and exclusionary policymaking and planning, (v) operational injustices resulting from deployment and use, and (vi) waste flows, liabilities and disposal requirements. We then explore how these potential concerns culminate in a milieu of injustice cutting across the dimensions of distribution (who gets what), recognition (who counts), participation (who gets heard), capabilities (what matters), and responsibility (who does what). We conclude with insights for both policy and future research.

Direct Air Capture with Carbon Storage (DACCS) technologies represent one of the most significant potential tools for tackling climate change by making net-zero and net-negative emissions achievable, as deemed necessary in reports from the Intergovernmental Panel on Climate Change and the European Green Deal. We draw from a novel and original dataset of expert interviews (N=125) to distil ten recommendations for future DACCS policy. After providing a literature review on DACCS and explaining our methods of data collection, we present these recommendations as follows: (1) follow governance principles that ensure "negative" emissions; (2) prioritize long-term carbon storage; (3) appreciate and incentivize scale; (4) co-develop with capture, transport, and storage (5) phase in a carbon price; (6) couple with renewables; (7); harness hub deployment; (8); maintain separate targets; (9) embrace certification and compliance; and (10) recognize social acceptance. All ten recommendations are important, and all speak to the urgency and necessity of better managing and shaping the potentially impending DACCS transition.

Large-scale and highly experimental interventions are being considered as strategies to address climate change. These include carbon dioxide removal approaches that are becoming a key pillar of post-Paris assessment and governance, as well as the more controversial suite of solar geoengineering methods. In this paper, we ask: Who defends and opposes these experiments, and why? After screening 44 early-stage experiments, we conduct a qualitative comparative analysis of 21 of them in five areas: ocean fertilization, marine cloud brightening, stratospheric aerosol injection, ice protection, and enhanced weathering. We develop a common framework of analysis, treating experiments as sites in which the risks and appropriate governance of early-stage science and technology are envisioned and disputed among scientists and other social groups. Our contribution is to map and explain the key issues of contention (why), actors (who), and tactics (how) that have shaped opposition across these linked fields of experimentation and technological development, from the 1990s till today. In doing so, we build upon and connect past studies on particular climate experiments and develop insights relevant to governance outlooks perceptions, discourses, and intents surrounding immature but potentially crucial climate technologies.

Space-based geoengineering is gaining attention, if not necessarily traction, as a possible “break the glass” solution to mitigate the worst impacts of climate change and facilitate the transition to a low-carbon future. Though still on the periphery of discussions around climate mitigation and geoengineering, space-based methods that would deflect or block incoming sunlight, and thereby diminish how much radiation ultimately reaches the Earth, could offer advantages, notably, by avoiding the need for difficult trade-offs and decisions in terms of land and resource use on Earth. Aside from a few specialist-oriented studies, the literature on space-based geoengineering remains limited. In this study, we utilize a large and diverse expert-interview exercise (N = 125) to provide a first critical examination of the promise and relevance of space-based geoengineering for tackling climate change, including perhaps as a source of renewable energy, its feasibility and prospective risks, as well as key actors and issues related to commercialization and governance. To our knowledge, no other study has employed empirical data of any kind to examine perceptions of space-based geoengineering, let alone in relation to other kinds of climate-intervention technologies. Not only does the current research represent the first of its kind, it also provides a foundation for more informed, comprehensive deliberations around this interesting, possibly even necessary solution to climate change.