Review of Experiment Earth in Science and Public Policy

Review of Experiment Earth in Science and Public Policy

This thoughtful review, by Robert J Lempert, is from the journal Science and Public Policy.


Experiment Earth: Responsible Innovation in Geoengineering by Jack Stilgoe Routledge,New York, 2015, 222 pages, US$145 (hardback), ISBN 9780415732376

A Case for Climate Engineering by David Keith MIT Press, Cambridge, MA, 2013, 112 pages, US$16.95 (hardback), ISBN 9780262019828

In 1991, the volcanic eruption of Mount Pinatubo in the Philippines lofted 17 megatons tons of sulfate aerosols into the stratosphere, cooling the Earth by about 0.5 °C for the next two years. This cooling temporarily offset most of the warming caused by all the greenhouse gases humans had accumulated in the atmosphere since the start of the industrial revolution.

Thus, one might ask: should humans consider conducting an expanded version of this natural experiment? In particular, should scientists and engineers now undertake research on so-called climate engineering in the hope that it will improve humanity’s ability to manage climate change?

Two recent books—David Keith’s A Case for Climate Engineering and Jack Stilgoe’s Experiment Earth—engage this question from very different points of view. Both recommend research, one more enthusiastically than the other. Both books are fascinating and informative. Together they clarify the challenge, but do not instill confidence that they have solved it. Keith takes an appropriately broad view of climate engineering and its potential role in humanity’s response to climate change. But he organizes his analysis in a manner seemingly designed to underestimate the risks. Stilgoe is more humble about humanity’s ability to understand the risks posed by geoengineering and offers a solution—treat the technology as an anticipatory social experiment governed by both scientists and non-scientists—but defines the scope of the experiments narrowly. His concept seems compelling, but the more broadly the experiments are framed, the less clear it becomes how they would work.

David Keith, perhaps the world’s most prominent climate engineering researcher, has been studying the topic for over 20 years. His book provides a brief, elegant, and clear survey of the field and a summary of his personal views. Keith argues that, if research demonstrates its technical viability, climate engineering could play a valuable role in humanity’s response to climate change. He notes that human greenhouse emissions are rising rapidly and our climate has begun to change significantly. The damage to things humans value—from ecosystems to agriculture to our coastal cities—depends at least as much on the rate as the magnitude of change. In an ideal world, humanity might quickly eliminate its greenhouse gas emissions. But to do so would require a radical transformation of much of the world’s economy, in particular its energy, transportation, and building infrastructure. At best, this transformation could occupy much of the 21st century.

Thus, Keith envisages a scenario in which increasing amounts of geoengineering are used to slow climate change over the coming decades, while emissions continue to rise. After that, both emissions and geoengineering would taper off together. If greenhouse gas emission rose indefinitely, the climate engineering needed to offset the impacts could itself have appalling side effects. But the amount of climate engineering needed to counterbalance a century of slowing rising then declining emissions could, Keith suggests, have benefits that far outweigh the costs. In particular, Keith argues that combining climate engineering with moderately paced emission reductions might prove particularly beneficial to the world’s poor, those most often vulnerable to the manifestations of climate change, such as extreme heat, powerful storms, and disruptions to agriculture.

Climate engineering could take many forms. But, as is common in this literature, Keith (and Stilgoe) focuses much attention on one type, known as solar radiation management (SRM), in which humans would inject aerosols, not dissimilar from those from Mount Pinatubo, into the stratosphere to cool the Earth. What makes SRM both so intriguing and frightening is that it is potentially so inexpensive and fast-acting. For a cost of a few hundred of millions to a few tens of billions of dollars a year, a small fleet of airplanes could deposit enough aerosols in the stratosphere to counteract (beginning within weeks) a significant fraction of the global warming caused by the last two centuries of human emissions. In contrast, in some scenarios, eliminating greenhouse gas emissions might take a century and cost hundreds of billions of dollars per year.

Would SRM actually work? What unintended side effects might it entail? What mix of climate engineering and emissions reductions might prove best? To answer such questions, Keith favors a vigorous and rapid program of research, ranging from computer modeling that estimates the effects of stratospheric aerosols on the climate, to demonstrations of the technology needed to disperse such aerosols, to actual injections sufficiently large to measure their effects.

Keith’s book is elegant and clear, in part, because he writes well. But Keith’s clarity also derives from his framing, which lays out the case for climate engineering in a classic deductive argument. Keith begins with an idealized world with a single rational decision-maker pursuing the interests of all humankind. The uncertainties prove tame, meaning that experts can confidently enumerate the potential consequences of decision-makers’ climate engineering-related choices and confidently calculate the odds of beneficial and adverse outcomes. Keith lays out the rational for SRM in this idealized world, and then explores how the messiness of the world in which we live might alter his conclusions. Because the greenhouse blanket traps heat at different altitudes than the radiation reflected by SRM’s aerosols, an engineered climate would be different from one without climate change. Many people might come to regard climate engineers as responsible for the entirety of an engineered climate, demanding compensation for every damaging storm or drought. Even Keith’s basic scenario of agreeing on and maintaining an appropriate level of climate engineering over the generations of rising then falling emissions would require a rare level of international cooperation persisting over decades. Reviewing these challenges only strengthens Keith’s interest in a vigorous research program so that debates over the politics and ethics of climate engineering can rest on a firm technical understanding of its potential benefits and costs.

Jack Stilgoe, a lecturer in science and technology studies at University College London, begins his explorations of what he calls geoengineering with a specific and concrete story. He recalls the fate of the Stratospheric Particle Injection for Climate Engineering (SPICE) experiment, one of the first attempts to test components of SRM technology in the field. In SPICE, a balloon was to carry aloft a kilometer-long tube over Norfolk in the UK, inject a spray of water into the stratosphere, and enable scientists to study how to keep such a balloon steady in the wind and its long tube from tangling. SPICE’s scientists and engineers, Stilgoe reports, conducted a textbook risk assessment prior to their experiment to ensure, for instance, that the balloon would not harm anyone by tumbling to Earth or that the water spray would not cause environmental harm. Despite this precaution, SPICE evoked a storm of controversy, taking the scientists by surprise and eventually causing them to cancel the experiment.

Many people, it turns out, viewed SPICE not as an isolated test of technology, but rather as an unwelcome first step towards actualizing what Stilgoe calls a perpetual global-scale experiment with our planet.

Stilgoe spent three years as a sociologist advising and studying the SPICE experimenters. Building on this experience, he offers a prescription for better managing SRM geoengineering. Stilgoe’s book argues that, from the very beginning, geoengineering must be regarded and governed as a social experiment, without artificial boundaries between the technology and the society it may profoundly affect. Stilgoe notes that much literature, including Keith’s book, assesses the risks and ethics of intentionally altering the Earth’s climate. But this work generally tries to separate geoengineering’s scientific and social parts. Stilgoe aims to reconnect the two, by focusing on the overall, integrated process of innovation. He emphasizes the potential for large-scale technology lock-in, in which early choices about discourse and experimentation can adversely shape the subsequent evolution of a social system and its supporting technological artifacts. This framing helps explain why so many people find SRM geoengineering frightening. The early steps seem easy, but may then lead inexorably down a path that many people do not trust will turn out well.

Stilgoe urges using the phrase geoengineering as a verb, not a noun. By this, he means that no part of the sociotechnical system that would constitute geoengineering currently exists. Thus, as a noun, geoengineering represents a speculative, idealized, and imagined thing that can take on a life of its own and begin to shape emerging norms, technology choices, and institutions. As a verb, however, geoengineering becomes something that people are only beginning to consider and to do.

This framing begs the question: which people and doing what? Stilgoe’s book answers that geoengineering (the verb) should proceed as a broad sociotechnical experiment jointly managed by scientists and non-scientists. In contrast to Keith, who argues that science and technological research ought to move quickly so that the decision-makers understand what options are and are not available, Stilgoe argues that the experiment ought to move slowly so that the necessary institutions of shared governance have time to take root. To reach this conclusion, Stilgoe lays a broad theoretical framework for anticipatory governance of science and technology, surveys the recent rise of geoengineering research, describes the seminal report on geoengineering (Royal Society 2009) as a case study on technology assessment, delves into the history of the SPICE experiment, critiques what he sees as overconfidence in the climate model forecasts used to estimate the impacts of geoengineering, studies the dynamics of interdisciplinarity within the SPICE project, and then concludes with suggestions for democratizing the governance of society’s sociotechnical geoengineering experiments.

Keith’s crisp deductive argumentation has important shortcomings. In particular, anchoring an argument in an idealized world hinders unfettered consideration of all the ways in which things might go wrong. Keith acknowledges the potential for unknown unknowns and points to governance as climate engineering’s potentially largest challenge. But he retreats from the implications by noting that well-established methods exist for managing risk, while citing those methods most appropriate for risks that are well understood, as opposed to deeply uncertain.

Grappling with such uncertainties often requires stepping outside of the deductive framing. For instance, one could start with the proposition that an aggressive program of SRM research is justified and ask, in the style of a Red Team analysis (Zenko 2015), how such a policy might lead to catastrophe. For instance, research might lead engineers and governments to wrongly conclude that climate engineering would work, make plans that rely on it, and then have it fail when needed (Lempert and Prosnitz 2011). In perhaps the most obvious failure scenario, the option to geoengineer in the near-term could make it impossible to summon the political will to reduce emissions over the long-term.

This type of deep uncertainty proves central to Stilgoe’s concept of geoengineering as a broadly inclusive sociotechnical experiment. As one stated aim, his book intends to:… draw attention away from risk assessment towards uncertainties: the things we don’t know, that we can’t calculate, and that may remain incalculable. (p. 5)

He advocates an anticipatory governance whose aim is not to predict the future, but rather to think through various possibilities, and seek to:… construct agendas for socially robust risk research and risk management. (p. 33)

Such anticipatory governance would focus, not on risk, but rather on defining the conditions for legitimate experimentation (p. 45). As one key condition, the design of sociotechnical experiments that guide innovation should involve people beyond the scientific community, both because they are affected by the results but also because their perspectives help scientists to ask the right questions and to add resilience and variety to the resulting system (p. 48). The SPICE experiment, for instance, might have evolved very differently had it involved such inclusive, anticipatory governance from the start.

Stilgoe draws his concept of experiment from the science policy literature. But his arguments have strong resonance with concepts of ‘democratic experimentalism’ (Ansell 2011), rooted in pragmatist philosophy, that aim to resolve the tensions between public administration in highly technical areas and democratic governance in the context of so-called wicked problems (Rittel and Webber 1973). Based in a philosophy of evolutionary learning, democratic experimentalism acknowledges the uncertainty and ambiguity inherent in complex societal problems, the partial perspectives we bring to them, the necessary incompleteness of any current understanding, and the importance of a well-structured and empirically grounded process of social experimentation. Similarly to Stilgoe, this democratic experimentalism emphasizes the importance of widening the public discourse. But, in contrast to a science-based experimentalism which ultimately emphasizes a search for universal truths, democratic experimentalism places great value on the open-ended process of refining both values and knowledge. It emphasizes a diversity of views and objectives as a fundamental characteristic of our world. It stresses the importance of problem framing—jointly constructed hypotheses to test and metrics for success. It recognizes that success reflects not only a narrow ‘what works’ but also how our actions give meaning to our lives, and also the centrality of institutions, not culture or technology, as the locus for considering how societies learn (Ansell 2011).

Stilgoe’s call to pursue geoengineering as a broadly inclusive, sociotechnical experiment has much to recommend it. But he draws the boundaries of that experiment too narrowly. First, Stilgoe may focus too narrowly on the process and governance of science and too little on the broader societal forces in which science is embedded. For instance, his Chapter 3 places great emphasis on the role of an influential paper by Nobel-laureate Paul Crutzen (Crutzen 2006) in breaking a long-standing taboo in the scientific community against serious discussion of SRM. Stilgoe analyzes the scientific discourse before and after Crutzen’s paper, and how that paper shaped people’s thinking. But at the same time real-world pressures were pushing SRM onto scientists’ agendas. Growing emissions, increasingly vivid signs of a changing climate, and declining confidence that sufficient emission reductions would occur anytime soon all had begun to overwhelm the scientists’ taboo. Had Crutzen not provided the spark, something else would probably have set the discourse ablaze.

Second, Stilgoe largely focuses on the uncertainties and ambiguities directly associated with geoengineering, but not on related sociotechnical systems whose uncertainties may at least be as large. Keith argues for climate engineering because he doubts society will transition to a society with net-zero greenhouse gas emissions sufficiently quickly. Some advocates of nuclear power argue that neglecting this zero-carbon technology only makes a geoengineering deployment more likely. In general, how one views geoengineering is often deeply intertwined with how one judges the questions of whether, how, and how fast society can reach net-zero emissions. No less than geoengineering, decarbonization is also a verb, and thus would also seem to require a broadly inclusive, sociotechnical experiment. Stilgoe does not engage with the similarities and differences between the geoengineering and decarbonization experiments and, most crucially, if and how one can separate the governance of the two.

Finally, for a book that extols broadly inclusive deliberation, Stilgoe seems inattentive to the potential and consequences of a diversity of opinions. For instance, he faults the Royal Society for never resolving the ‘single purpose’ (p. 117) behind their 2009 reports central figure ranking various geoengineering techniques according to four different attributes (effectiveness, affordability, safety, and timeliness). As Stilgoe well understands, this figure had become a politically impactful artifact. But there is no reason that a consensus on a political document needs to rest on a single purpose. In an earlier discourse on flawed technological fixes and their inability to address the ‘root cause’ of social problems, Stilgoe offered the example of Edward Teller’s advocacy of the Strategic Defense Initiative (SDI) as a means to end nuclear war, without acknowledging that many of the SDI’s proponents may have seen the program as a means to other ends (such as bankrupting the Soviet government). Similarly, once it leaves the confines of science, the governance of sociotechnical geoengineering experiments will likely include people pursuing a wide diversity of root causes, ranging from a defense of free markets, to a battle against consumerism, to creating a path out of poverty for billions of people worldwide, to achieving a cost-effective approach to reducing the impacts of climate change.

Keith’s book adopts a quite appropriate scope in considering the tradeoffs among climate engineering, decarbonization, and climate impacts. But his deductive framing seems insufficient to fully understand, and to provide a foundation for managing, such wickedly complex sociotechnical systems. Stilgoe’s book makes a compelling argument for governing geoengineering as a broadly inclusive sociotechnical experiment, one that recognizes the limits to our foresight and the inseparability of the science and society of geoengineering. But despite these important insights, his prescriptions seem too rooted in the management of scientific experiments, without any clear consideration of how to place them in a larger context. What one thinks of the SPICE experiment is inexorably connected with one’s views of decarbonization and how well one thinks society will manage this transformative process.

Both books end on notes of hope: Keith that humanity might combine its ability to develop wondrous new tools with humility in using them; Stilgoe that the unique challenges of SRM can provide a proving ground for a new participatory governance of science. Both recommend proceeding with SRM research. Keith argues for a fast pace to better understand our options for addressing our unfolding climate emergency. Stilgoe argues for a slow pace to give the institutions of shared governance time to gel.

Ultimately, Stilgoe brings his own, important, values to the discussion, in particular his faith in participatory governance and belief in its intrinsic worth. One motivation for defining his experiments narrowly might be to keep their governance tractable. But geoengineering has global consequences and judgments about it intertwine with views regarding humanity’s experiment with decarbonization. It may prove difficult to organize Stilgoe’s participatory approach sufficiently narrowly to manage, but sufficiently broadly to be truly inclusive. Participatory governance can also break down, particularly when people become frightened and change comes too fast. Stilgoe provides an important and valuable step forward in thinking about managing geoengineering and how scientists might see their role in the process. But he stops short of providing a framework capable of engaging the fundamental questions: should we pursue this geoengineering path because we might need it, or block it because we do not trust ourselves to manage it wisely? Should we proceed quickly because we face an emergency, or take this opportunity to strengthen our institutions for participatory governance of innovation? How to best design participatory governance for geoengineering so that it can succeed even when things inevitably go wrong? If such a framework does emerge, it will have Keith’s scope, but build on Stilgoe’s foundations.

Robert J Lempert, RAND Pardee Center for Longer-Range Global Policy and the Future Human Condition, 1776 Main Street, Santa Monica, CA 90407-2138, USA; 



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