The history of the science and politics of climate change is rich with unintended consequences, paradoxes and conflicting goals. Recently, Science Magazine published an article titled “Cleaner air is adding to global warming” (Voosen 2022). Its subject are health-damaging aerosols that are released through the combustion of fossil fuels and account for countless deaths each year. According to the article, since 2000, technological advances have contributed to the reduction of the toxic substances by up to 30 percent and to the increase in global temperature in the range of 15 to 50 percent. Indeed, the air is now ‘cleaner’ because harmful particles are filtered out of the exhaust fumes of cars und airplanes. Yet, they can also no longer pollute the atmosphere and thus reflect solar radiation back. Since the goal of limiting global warming to 1.5°C is hard to reach given a temperature increase of already 1.2°C, the well-known climate scientist James Hansen proposes to turn the tables: “‘It will be necessary to take temporary corrective measures,’ he says, ‘almost surely including temporary purposeful use of aerosols to avoid catastrophic implications’” (Voosen 2022: 354).

Three books have recently been published that analyse the scientific and political debate around the deliberate modification of climate in order to avert inadvertent global warming. Geoengineering or climate engineering refers to a bundle of different technologies designed to address climate change. Basically, two approaches can be distinguished. One strategy, Carbon Dioxide Removal, aims at taking out emitted CO2 from the atmosphere. This includes using ‘natural’ carbon sinks through afforestation and reforestation or ‘artificial’ technologies that ‘suck’ CO2 out of the air. The second strategy, Solar Radiation Management, seeks to increase the reflectance of the atmosphere, for example, through the infusion of certain aerosols to reduce solar radiation. The climate scientist quoted above referred to this approach. There is now a widespread view that these more controversial technologies should not be used as substitutes, but only in combination with the conventional strategies mitigation and adaptation. In particular, geoengineering has gained prominence due to the international agreement reached in Paris in 2015. Upon the announcement of the target, Steve Rayner, an anthropologist who has been involved in the geoengineering debate for many years, commented that without massive investment in these technologies, “the 1.5–2°C target is not merely magical thinking, but profoundly flawed magical thinking” (Rayner 2016: 2).

The three monographs now published and based on PhD projects, address this debate along different lines: How has geoengineering been shaped into an object of governance (Möller), which imaginaries underlie climate engineering (Oomen), and how has climate modification become a reasonable measure against climate change (Schubert)? By combining diverse strands of literature, data, methodological approaches and theoretical frameworks, and by taking different directions and placing distinct emphases, each work develops its own perspective on geoengineering.

Ina Möller primarily draws on political science literature that emphasises the role of science in shaping political problems. On the one hand, she conceptualises geoengineering as a “governance object”. In doing so, she directs attention to the social process of shaping and constructing objects into politically relevant problems. On the other hand, to reconstruct through which discourses, scientific communities and organisations the governance object is created, carried and shaped, she borrows ideas from research on “knowledge networks”. Taking both perspectives together, she makes clear that governance objects and knowledge networks relate to each other like “one co-evolving amalgam” (8). Geoengineering is constructed and positioned as a political issue by the network, and conversely, it changes the composition and discourse of the network. Following these preliminary theoretical considerations, the author provides three chapters in which she traces how geoengineering entered the scientific and political stage (Ch. 2), subsequently takes a closer look at the interplay between network and object (Ch. 3), and finally contextualises her study with some reflections on the historical and cultural context of geoengineering (Ch. 4).

Möller’s study stands out especially through the social network analysis provided in chapter 3. Drawing on the programmes of 74 geoengineering related events with over a thousand speakers between 2006 and 2018 and interviews, she argues that the knowledge network is characterised by 1) a sense of belonging (social cohesion) as well as 2) the capacity to link different groups to each other (brokerage) and 3) a (in some respects) high degree of heterogeneity in its composition (diversity). Following political scientist Olaf Corry, she associates three corresponding processes of constructing and shaping the governance object with the network structure. First, she relates social cohesion to the construction of a distinct object. By creating shared problem definitions, narratives or causes, both the group and the object are delineated. Second, she addresses the role of knowledge brokers for the salience of geoengineering as a governance object. These provide bridges between different (geoengineering) groups, increase salience through shared narratives and framings, and raise attention within and outside of academia. Third, Möller looks at how the degree of diversity in the knowledge network interacts with the malleability of geoengineering as a governance object. Here, she finds that while an “overrepresentation of Western male perspectives” (47) proves relatively persistent, nevertheless, through disciplinary and organisational diversity, the involvement of non-academic actors and criticism by scientists and activists, geoengineering has successively become a malleable and adaptable object.

While Möller’s work focuses on contexts, groups, mechanisms, and their interaction with the object of governance, Jeroen Oomen is primarily concerned with the production and circulation of perceptions, concerns and hopes regarding geoengineering. To this end, he combines approaches from Science and Technology Studies with contributions from the Environmental Humanities. He conceptualises the forms of meaning-making around geoengineering as “sociotechnical imaginaries” (Jasanoff), which are defined as shared visions about the future through and in support of science and technology. Oomen theorises that these are produced by and underlie specific individually and collectively held “ways of seeing” (Ch. 1). These ways of seeing are subject of ongoing negotiations about what geoengineering is, what its status is, and how it should be evaluated technically, politically and normatively. Based on ethnographic field studies at a privately funded U.S. geoengineering research group at Harvard University with a high public profile, and a more sceptical ‘Priority Programme’ funded by the German Research Foundation, he analyses the geoengineers’ ways of seeing climate and climate engineering in three chapters (Ch. 4-6).

First, he describes how perceptions about climate in general influence how geoengineering is evaluated (Ch. 4). A key indicator of this way of seeing is the degree of ‘climate knowledge optimism’ or ‘pessimism’ to which climate engineers tend. The optimism, that is widespread in the Harvard group, is also associated with an optimism about predicting the climate, and this also means a certain techno-optimism that suggests the controllability of the climate. The German research programme is much more pessimistic. Uncertainty, limits to knowledge and a scepticism about the scalability of geoengineering dominate their way of seeing the climate. Second, Oomen highlights the challenges that climate engineers relate to the climate policy discourse (Ch. 5). Among the widespread concerns are that mitigation measures could be downscaled, that climate deniers could hijack geoengineering or that the governability of the technology remains unclear. Third, he addresses the question of how climate engineers view technological control morally (Ch. 6). Here, the idea of a ‘Good Anthropocene’ comes into play (mostly in the Harvard group), according to which humans, if they have already changed nature to the negative, could just as well perform a ‘stewardship’ by technologically navigating the relationship between humans and nature. The German team tends to be concerned about the risks of further human intervention, which they view should only be considered if a catastrophe is unavoidable. The book concludes in chapter 7 with an analytical and summarising typology of climate engineers, including the ecomodernist, the pragmatist and the disprover (see the table on 199).

In complement to Oomen who emphasises the different “ways of seeing”, Schubert draws attention to the underlying “expert infrastructures” (including advisory panels or expert organisations) as formalised and institutionalised forms of linking science and politics and “expert modes of observation” (such as theories, models and satellites), through which sense is made of climate engineering (22 ff.). In doing so, she primarily addresses a social science audience with a general interest in the historical emergence of social phenomena, the sociology of expertise and the relationship between science and politics. She tracks what she refers to as a “career”, meaning the evolution of geoengineering “from curious scientific idea to serious politics” (17) through the production of ever new “science-state alliances”. Starting from the observation that a shift occurred in the 2000s that turned the urgency to act into a choicelessness to resort to climate engineering (Part I), she draws on a corpus of policy documents from 1990 to 2020, expert interviews, and historiographic literature to analyse how notions of climate change and climate control, and relatedly the relationship between science and politics, have changed.

After being devoted to the long history of climate modification (Part II, more detailed below), the book returns to the recent past (Part III). In this period, the early 21st century and with it the transition from the Bush to the Obama administration, climate research as a former “problem-defining authority” took on the status of a “problem-addressing authority”. Not only did it define what problems policymakers had to deal with, but it also posed itself as a problem-solver – as a political tool to deal with climate change. With this transition, Schubert observes that geoengineering gained scientific and political traction (Ch. 5). For example, 1) a ‘sceptical’ government began to take an interest in geoengineering and framed it as a national enterprise, 2) experts in congressional hearings were openly controversial, critical or supportive of the possibilities and limitations of geoengineering, and 3) the business sector began to express interest in the technologies as a solution to looming economic risks from climate change mitigation. Finally, Schubert focuses on the more recent period since the Obama administration took over (Ch. 6). In this phase, it becomes apparent that, on the one hand, geoengineering has become one of the tools of climate policy, incorporated into the political bureaucracy and legitimised by plausibility indicators such as natural analogies (e.g., volcanic eruptions) and computer simulations, which are also common to conventional climate research. On the other hand, geoengineering retains its controversial character insofar as it is continuously problematised in expert hearings.

In sum, the analyses of the three monographs can thus be read as complementary. Certainly, some overlap in content can be found. For example, they share a consensus that geoengineering is a speculative and controversial measure, and they also share the assumption that geoengineering poses a distinct challenge to the relationship between science and politics in particular and science and society in general. One overlap, partly in content but mainly in concept, is particularly striking. In their explorations of this very up-to-date debate, they take the view that a look at the history of climate modification can inform an understanding of the present. In doing so, however, they tend to develop different readings.

For example, one might conclude that Schubert reads the history of climate change as the history of climate engineering, while Oomen reads the history of climate engineering as the history of climate change. In the case of the latter, one reads how environmental destruction, the atomic bomb, Chernobyl, and especially attempts at intentional modification of the weather – in short, experimentation with planetary boundaries – led to a rising environmental consciousness that increasingly and successively delegitimised the intentional and unintentional manipulation of climate (Ch. 2 & 3). In contrast, Schubert understands the early speculations about the greenhouse effect as the first discovery of the prospect of modifying the climate in favour of humans. In concern about an impending ice age at the beginning of the 20th century, the possibility of manipulating the climate by CO2 emissions seemed like good news, though not realistic in the near future (Ch. 3 & 4).

Möller’s work also includes a historical, albeit brief, outline of the prehistory of the current geoengineering discourse, focusing primarily on the recent past from the mid-2000s onward (e.g., mainstreaming of geoengineering with setting the 1.5–2°C target, rise of critical watchdog organisations) (Ch. 2). In exchange, some historically informed reflections, especially the reflections on “colonial legacies” are worth highlighting here (Ch. 4). She points out a disproportion, which lies in the fact that regions in which geoengineering is to be applied have at the same time a colonial history behind them and/or have low emission levels, while the former colonial states and high-emitters of the Global North hope to get through climate change without profound changes.

As geoengineering is recently and incrementally moving from its status as speculative and controversial technology to a policy tool that is increasingly regarded as a necessary measure (cf. Schenuit et al. 2021), it is only welcome that the social sciences devote themselves to the debate. However, it is noticeable that exactly this fact – that social scientists contribute considerably to the debate around geoengineering – is not, only marginally or implicitly addressed. This is all the more surprising in view of their intended contribution: Möller hopes to draw the attention of decision-makers to the “political, social, cultural, and historical context” of geoengineering and to motivate them to “take this into account when deciding how to engage with it” (6). Oomen concludes that there is a need to “to reorient our ways of seeing away from the numerical to the cultural and political” (206). And Schubert views her book as a contribution to the question of “why and how it might be productive to pluralise policy-relevant expert perspectives on climate change” (226).

In doing so, they echo what numerous social scientists are calling for: to re-politicise the climate debate (Lövbrand et al. 2015), to reorient disciplinary focuses (Lever-Tracy 2008), to return society into future imaginations (Hulme 2011) and to re-socialise natural science knowledge (Stehr and von Storch 1995). In the context of geoengineering alone, there is now a vast amount of social science research and stimulating debate, including analyses of justificatory emergency framings (Markusson et al. 2014), of metaphors (Nerlich and Jaspal 2012), of the peacebuilding potentials of geoengineering (Buck 2022), on the social risks, controversies and preconditions for implementing geoengineering (Zürn and Schäfer 2013) or on the entanglement of the Paris 1.5°C target and climate engineering (Beck and Mahony 2018). It is not surprising, however, because the authors are not unaware of the state of research and the ongoing discussions. On the contrary, they work through the state of research, identify its gaps, and build on it. Yet, they only marginally notice how their subject is changing through social science research. The fact that they are dealing with a subject that has been reactively shaped by the social sciences is not itself the object of their analyses.

It has long since ceased to be the case that the social sciences observe the climate debate unnoticed, in the background and at high altitude. They are directly and indirectly involved. Indirectly, they contribute to changing the debate through publications such as those cited above, which diffuse throughout society and in which social scientists (subliminally) communicate their stance, which is why Oomen advises readers that “my analyses here should always be treated with skepticism” (22). Directly, they add social science expertise to the debate by debating in newspapers,Footnote 1 by writing open letters,Footnote 2 and by being involved in the expert infrastructure, as Schubert notes in “A note on interdisciplinarity” (185 ff.). The increasing social science involvement is most extensively addressed in Möller’s work (e.g. fn. 5, 32 f.). But even here it remains a remark (“heralds engagement”, “questioning”, “25 per cent”, “motor”, 44 f.) on this circumstance instead of analysing in-depth how social scientists shape the object of governance.

Little has been done in this direction so far, notably by Steve Rayner, who has analysed the strategic use of ignorance in the social sciences (Rayner 2015), and examined the value systems that underlie social science attitudes toward geoengineering (Heyward and Rayner 2018), or by Jack Stilgoe (2012), who has reflected in this journal on his involvement in projects on geoengineering. The potential that geoengineering offers, to study the multiple expert roles – scientists, specialists, advisors and commentators (cf. Grundmann 2023: Ch. 1) – as well as the self-understandings, values, worldviews and models that underlie social science expertise as much as in case of the natural sciences, is far from exhausted. Therefore, future work should take into account the increasing participation of the social sciences and explore their making of “governance objects” (Möller), their “ways of seeing” (Oomen) and their “modes of observation” (Schubert) and how they contribute to shaping the science and politics of geoengineering.