News reports and international scientific assessments make clear that climate change is a pressing issue. Yet we face political gridlock, personal unwillingness to modify habits and lifestyles, and a hesitation to make the necessary radical changes to social structures. What are we to do? Perhaps out of desperation or due to our confidence in human technological prowess, the lack of a measured answer to global warming has led to more extreme proposals. One such proposal is geoengineering (sometimes called climate engineering), the possibility of large‐scale human technological manipulation of the climate in order to forestall temperatures associated with catastrophic global warming. Over the past decade, geoengineering has gone from fanciful science fiction to the pages of academic journals.

Although geoengineering has captured the attention of climate scientists, ethicists, and policy analysts, scant attention has been given to how religion and theology impact our understanding of geoengineering. This is unfortunate, because this lack of religious reflection results in a distorted understanding of the impact geoengineering might have. Furthermore, this lack limits our ability to assess how climate engineering currently is understood by society. Theology—broadly speaking, critical reflection on ultimacy, meaning and the sacred as these are manifested in existence—has much to say about geoengineering, and much to learn from it. In fact, theological reflection can uncover a wide variety of positions related to geoengineering, from a clear condemnation to a cautious acceptance (a spectrum described in more detail elsewhere; see Clingerman ). In order to promote further reflection on this subject, the present essay addresses one of the most important areas in which theological reflection should have a voice in the geoengineering debate: the interpretation of the nature of being human, or what can be identified as philosophical and theological theories of anthropology. Climate engineering challenges us to rethink our sense of being human in ways that have profoundly theological implications. I wish to show that a significant framework for our assessment of geoengineering is the balance of human capability and fallibility—a balance that is central to theological interpretations of the meaning of the human condition. My investigation contains two parts. First, I argue that geoengineering proposals entail an implicit interpretation of our humanness. Second, I argue that theological reflection offers an important frame through which to understand the anthropological underpinnings of geoengineering, while simultaneously geoengineering raises new challenges for contemporary theological anthropology.

Geoengineering as a Question of Being Human

The first step to my argument is to see why the debate surrounding climate engineering is not simply about technical feasibility or scientific knowledge, but instead entails a claim about human self‐interpretation. Specifically, geoengineering can be understood as a manifestation of a particular hermeneutical interpretation of human existence.

What is geoengineering? A basic definition for geoengineering comes from the 2009 British Royal Society report: “the deliberate large‐scale manipulation of the planetary environment to counteract anthropogenic climate change” (Royal Society , 1). This definition eliminates climate effects caused by unintentional human action, as well as projects aimed at changing regional weather.

To explain this definition further, we can elaborate on David W. Keith's comment that “[s]cale and intent play central roles in the definition” of geoengineering (2000, 247). On one hand, geoengineering proposes a novel form of human environmental intervention due to the scale involved. Jacob Haqq‐Misra comments, “[t]he ability for humans to use technology to modify their environment on a global scale is unprecedented in the history of life on Earth. Although climatic changes, such as the rise of atmospheric oxygen nearly 3 billion years ago, have occurred in Earth's history, humans are the first organisms that can deliberately and collectively manipulate their home planet” (Haqq‐Misra , 985). Geoengineering, then, follows the historical progression of human intervention that began with agriculture and animal domestication, but it is qualitatively different in light of its more comprehensive and invasive impacts. On the other hand, what is truly unique is that geoengineering projects seek to intentionally alter global climate systems. The deliberateness of geoengineering is essential for understanding its uniqueness because “[o]therwise we are geoengineering right now: burning fossil fuels changes the atmosphere's chemistry. To reduce fossil fuel combustion might be geoengineering because it is deliberately changing the chemistry of the atmosphere from what it was going to be…” (Schelling , 304). Geoengineering proposals purposely seek mechanisms to gain control over—or at least minimally to direct in some way—the climate systems of the Earth, with the goal of negating the worst effects of global warming. The scale and intention involved differentiates climate engineering from other human feats, even though we can still acknowledge that the technical and scientific ability to embark on this type of planetary experiment is an extension of the human ability to manipulate the environment more generally.

There is no single technical paradigm for geoengineering proposals, even though all share the same goal of global temperature reduction. The variety of proposals that have emerged can be divided into two categories. On one hand, some proposals focus on the reduction of greenhouse gases currently in the atmosphere, thereby lowering the rate that the planet retains or absorbs solar energy. Primarily these proposals are attempts to recapture carbon dioxide—thus these methods are classed as “carbon dioxide removal” (CDR) or “industrial air capture” methods. These methods include methods that enhance or mimic natural processes: massive reforestation, iron fertilization of the ocean, artificial “trees,” or large‐scale scrubbers to capture carbon dioxide. Although such methods are not necessarily tied to any reduction of emission of carbon dioxide, they do seek to maintain a certain level of greenhouse gases, and thus presumably will limit the environmental effects related to greenhouse gases. Such methods introduce other environmental effects, however. For instance, iron fertilization schemes would have significant effects on marine ecosystems and ocean chemistry.

On the other hand, some proposals are oriented toward reducing the amount of sunlight absorbed by the planet; these methods are referred to as “solar radiation management” (SRM). Arguably, SRM can be subdivided further: some proposals attempt to increase the planetary reflectivity, or albedo, whereas others seek to reduce the amount of solar radiation that actually hits the Earth. Thus, SRM proposals vary greatly, from painting roofs white to thousands of small‐scale space mirrors placed between Earth and the Sun. The most commonly discussed SRM proposal is the introduction of particles in the atmosphere to increase albedo (for further analysis, see Rasch et al. ). Compared to CDR, SRM proposals are frequently economically cheaper (in some cases cheaper than the reduction of initial emissions or adaptation), as well as faster in their effects. Further, they rely on novel applications of current technology rather than the invention of new technology. However, SRM has drawbacks not present in CDR: “[w]hile SRM may be relatively cheap and fast, it is also imperfect” (Morgan and Ricke , 5). SRM also does not alleviate the problems of increased carbon dioxide in the atmosphere, meaning that these proposals are more technologically invasive and also do not mitigate for things such as changes in plant growth, the effect of carbon dioxide on the oceans, and the like.

Although proposals for geoengineering schemes have a long history, it has only been in the last decade or so that climate engineering has emerged from the shadows to be considered a possible mainstream response to anthropogenic climate change. Two articles published in 2006 mark a symbolic “tipping point” in the geoengineering debate, especially since the subsequent responses to these essays have moved the topic of climate engineering from a small group of scientists to the broader intellectual arena of climate policy and environmental ethics. The first article was by Paul Crutzen (), who advocated research into the injection of sulfur into the atmosphere to mimic the 1991 “Pinatubo event.” Crutzen's essay was pivotal because he, as a Nobel laureate and coiner of the term “Anthropocene,” persuasively offered a justification for the need to debate human technological intervention in the global changing climate.

The second article, by climate scientist Tom Wigley, was similarly influential. Like Crutzen, Wigley () was pessimistic about the adequacy of our current regimes to respond to climate change. Due to the magnitude of the problem and current inaction, he argued that mitigation alone was insufficient, although he also showed that mitigation is necessary to avert excessive ocean acidification and other problems. Instead, Wigley argued that a combination of mitigation and geoengineering must be seriously considered in order to overcome the gridlock concerning policy, the technological problems surrounding mitigation, and the potential catastrophic impacts of temperature rise. He proposed an integrated approach: “Mitigation is therefore necessary, but geoengineering could provide additional time to address the economic and technological challenges faced by a mitigation‐only approach” (Wigley , 452).

The arguments of Crutzen and Wigley suggest a turning point in our approach to anthropogenic climate change. This turn is not limited to the assessment of the technical feasibility of climate engineering, although both Crutzen and Wigley address this. More importantly, the arguments presented by Crutzen and Wigley attempt to introduce a more nuanced reflection on ethical and social implications of “hacking the planet” to a broader audience. Unintentionally, these authors raised questions about the human role in managing the planet's resources, and about our self‐image as seen through the technological mediation of the environment. While they do not explicitly address these concerns, their provocative discussions of climate engineering imply the need to radically revise our understanding of being human in the world. Quite simply, geoengineering has an implicit theory of anthropology.

To draw out the repercussions of this implicit theory, we can turn to theology. In many respects, theologians offer a number of resources to address an important question: If climate engineering implies a revision of our sense of being human, what vision of humanity does it offer? In fact, the model of human being that emerges from climate engineering is best understood by detecting the differences in anthropological insights found in an anti‐geoengineering stance compared to those found in the positions of geoengineering proponents. On one side, critics of geoengineering define the human in terms of limitation and arrogance—a stance that has strong resonance with many positions found in the theological tradition. From this one might argue that global warming is the result of the fallibility of the human being. As clearly shown by our environmental “sins,” we are already unwitting and inept manipulators of the climate, and geoengineering is seen to be an extension of the corrupt worldview that caused anthropogenic climate change in the first place. From this perspective, any attempts to curb global warming with a “techno‐fix”—a frame Dane Scott () explored in relation to geoengineering—must be approached with skepticism and derision.

Such suspicion culminates in what Christopher Preston characterizes as the “presumptive argument” against climate engineering. In many versions of the presumptive argument, science identifies an objective understanding of “how the world works” in its supposedly “natural” state. The consensus position on climate change, thus, is accepted as an objective description and normative definition of “the climate” (a problematic claim that Mike Hulme has investigated in depth; see Hulme ). Using this supposedly objective scientific description of climate change, environmentalists transform the supposedly passive certainty of the change of the “natural” into the need for political, ethical, and worldview change. Thus, the presumptive argument against geoengineering leads us to see how politics and ethics are to be considered pragmatic tools through which to adapt to the natural climate system, while science is the passive but omnipotent director of these mechanisms.

I suggest that the suspicion of the anti‐geoengineering stance is built upon a complex and perhaps even contradictory understanding of what it means to be human (note that while it might seem logically contradictory, this understanding has a powerful and important existential force, especially in how it focuses our self‐interpretation on aspects of humanness that invariably ring true). This anthropology emphasizes the finitude of human knowledge against a backdrop of the progressive ideal of our ability to know, the recognition of the fallibility of our actions, and our culpability in past fossil fuel use. Furthermore, a great deal of value is placed on the need for prudence and humility, lest we fall into a moral hazard and use geoengineering as an excuse to do nothing. Therefore, the anti‐geoengineering stance advances a sense of the human as a steward who must maintain the separation of the natural and the artificial; in this state of “betweenness,” we see that human knowledge is fragmentary, our abilities are situational, and thus our responsibility is inevitably provisional and must be marked by humility. Yet this betweenness creates a dilemma: if we are to foster the “natural,” it is only because we start apart from mere nature—for good and for ill.

Thus, the implicit anthropology of an anti‐geoengineering stance sees humans as strangely un/natural beings. The natural world and its climate functions independently of and transcends humanity, who are left to integrate themselves imperfectly through a culture that is a danger to the natural world. And in this light, the self can be defined in response to the changing climate in ambiguous terms. We must scientifically learn about the world to ameliorate our destructive tendencies, while at the same time we must not presume to have overarching control or transcendent responsibility. And so because we unwittingly influence the climate, the way forward is through a chastened ethical lens: Do we have the moral authority to seek to control “the domain of the gods,” to evoke Simon Donner's () insight that the sky is traditionally beyond humans and under the control of the divine? For many, the answer is an unqualified “No,” because human beings are not created for such a task.

What, on the other hand, is the anthropology that emerges from proponents of geoengineering? Fascinatingly, proponents of climate engineering have a similarly complex and contradictory perspective on the human condition. This position also places humans “in between,” but interprets this placement as a reflexive engagement with the world. Proponents see geoengineering as the use of science and technology to actively redefine or recreate the natural, instead of a mere passive observation of nature. In this sense, humans are defined through the active mediation with their surroundings, and it is somehow only natural to accept our capacity to “humanize” the atmosphere. Thus, geoengineering renders the distinction between artifice and nature indistinct in an effort to undertake a restoration of the planet. This view acknowledges that the climate is unavoidably influenced by human actions, and can be manipulated in significant and global ways by humanity. And furthermore, since we already influence and manipulate the climate, then it is prudent to self‐consciously and humbly define the terms in which we are meant to assert control. More provocatively, climate engineering does not simply alter the climate, but productively alters the definition of humanness, insofar as climate engineering proposals reflexively situate the self in one's climate.

While this might appear surprising, proponents do not appear to be arguing for this reflexivity as a forceful domination of the environment, although geoengineering is undoubtedly an extension of the human desire to master nature. Instead, the mastery of the climate is unwillingly accepted as necessary to overcome the previous mastery of nature. Geoengineering is argued as a form of transforming our environmental failures through an ever more radical humanization of nature. In a contradictory fashion, geoengineering becomes an attempt to reintegrate humans with the global environment, not by redefining the human self in terms of being “natural,” but by rendering the climate a domesticated participant, as it were, in such human betweenness. Geoengineering proponents combine what they deem to be chastened self‐responsibility with intellectual confidence; geoengineering thus paradoxically places humans in the position of intentionally exerting an all‐encompassing control in order to release the planet from a hitherto unintentional mastery. Whether morally acceptable or not, geoengineering proposals rest on this type of reflexive mastery, this humanization of the climate.

In describing this reflexivity, geoengineering proponents interpret climate engineering as something other than hubris—it is a redefinition of how we interact with the world in the “Anthropocene era.” The term “Anthropocene” was coined by Crutzen (, ) and Steffen et al. () to characterize the pervasive changes to the globe brought on by human activity, particularly population growth and fossil fuel use. But climate engineering takes this one step further, adding an element of reflexivity to the Anthropocene—that is to say, in climate engineering we are not only changing the globe, but we are knowingly planning and implementing the Anthropocene era. Preston describes the changes that climate engineering brings to the Anthropocene clearly: “If anthropogenic warming ended the era of untouched nature, then [solar radiation management], in some powerful sense, begins the era of global artificing” (Preston , 191).

By transforming the Anthropocene with human reflexivity—by making the choice to humanize the very atmosphere of existence and thereby self‐consciously enter a new geologic era—the very definition of humanity changes. Climate engineering becomes more than just a technical fix; it is the occasion for a new model of our place, of our relation to the nonhuman world, and of the human being itself. Galarraga and Szerszynski () seem to have this in mind when suggesting that climate engineering puts humans on course to be “makers” of the climate. As makers of the climate, we shape and mold the world system in ways never before attempted. That is to say, whereas humans have always manipulated local environments, and even unintentionally changed large‐scale (even global) systems, climate engineering redefines the possibility of changes, and this necessitates a new model of humans in relation to the world. They write: “Such technological interventions would, in an important sense, be making the climate. The very definition of geoengineering means that it is intentional and planned; the full‐scale implementation of [solar radiation management] would thus result in a climate that was an artifact—a climate that has not just been disturbed by human intervention but has been intentionally shaped by human intervention” (Galarraga and Szerszynski , 221).

As Galarraga and Szerszynski argue, to be makers of the climate—whether as architecture, artisan, or artist—is riddled with ambiguity. Crutzen, too, points out such ambiguity in his description of the Anthropocene when he writes, “Hopefully, in the future, the ‘anthropocene’ will not only be characterized by continued human plundering of Earth's resources and dumping of excessive amounts of waste products in the environment, but also by vastly improved technology and management, wise use of Earth's resources, control of human and domestic animal population, and overall careful manipulation and restoration of the natural environment” (Crutzen , Pr10–4). The reflexivity and intentionality of climate engineering creates a situation in which the world is humanized—or even overhumanized, which questions the morality of such proposed interventions into the atmosphere. Proponents of climate engineering assign this role with fear and trembling, and yet continue to forge ahead. And thus the need for a new approach to modeling the human being in the world comes from an ambiguous shift of our place as makers, from the haphazard disruption of the environment to the intentional and total re‐creation of the world in our image.

Geoengineering, Theology, and the Self

As we have seen, the debate surrounding climate engineering moves beyond ethics and technical feasibility, to the point of addressing human self‐understanding. Any interpretation of climate engineering implies a sense of who and what we are. The next step, therefore, is to draw out this implicit anthropology by asking: How can we effectively bring together the tensions and uncertainties of who we are in the midst of an engineered climate? I suggest that this task is best completed by theological reflection. In fact, I wish to argue that theology and climate engineering are mutually transformative: theological reflection provides a framework for understanding the anthropological dimensions of climate engineering. At the same time, theological reflection is challenged and changed by the reflexivity of geoengineering.

Acknowledgments

I wish to extend my thanks to Mark Lawrence and Stefan Schäfer of the Institute for Advanced Sustainability Studies, Potsdam; Dieter Gerten of the Potsdam Institute for Climate Impact Research; and Dane Scott of the University of Montana. During a groundbreaking workshop on “Religious and Spiritual Perspectives on Climate Engineering,” organized by Lawrence and Gerten in April 2013 in Potsdam, Germany, these scholars provided a great deal of insight and guidance on an earlier version of this paper. My thanks also go to Verna Marina Ehret of Mercyhurst University, who has been an important sounding board on this research.