Environmental Development 2 (2012) 57–72
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Environmental Development
journal homepage: www.elsevier.com/locate/envdev
Climate engineering: The way forward?
Aaron Welch, Sarah Gaines n, Tony Marjoram 1, Luciano Fonseca 2
UNESCO, Natural Sciences Sector, 1, rue Miollis, 75732 Paris Cedex 15, France article info abstract
The deliberate large-scale manipulation of the climate is increas- Keywords: ingly being discussed as a potential tool to ensure the basic Geoengineering condition for a sustainable future: a habitable climate. While far Climate engineering from the ideal solution, the rate of climate change continues to Climate change outpace our attempts at a response, prompting some scientists Earth system and politicians to call for the consideration of climate engineering Solar radiation management or geoengineering to avoid catastrophic climate change, while Carbon dioxide removal political processes to reduce greenhouse gases catch up. A Governance November 2010 expert meeting was held at UNESCO to raise awareness of geoengineering, its potential to counteract climate change and its risks, and to broaden the discussion within the international community. Potential geoengineering methods include solar radiation management and carbon dioxide removal techniques that are largely theoretical and remain untested, despite a long history. Responsible research can only proceed, and informed decisions be made, once governance structures have been developed beyond mere principles insufficient to guide researchers and policy makers. At the same time, realistic communication on these activities must increase and improve so that civil society can play a role in determining acceptable levels and types of human intervention. Appropriate geoengineer- ing research should be considered for solar geoengineering methods that promise to quickly and affordably decrease global mean temperature, and for carbon geoengineering methods that target the core problem of climate change by directly removing carbon dioxide from the atmosphere. A small cadre of scientists and policy makers has advanced the discussion of geoengineering and its likely impacts, but the path to a sustainable future cannot
n Corresponding author. Tel.: þ33 1 45 68 40 71; fax: þ33 1 45 68 58 04. E-mail addresses: [email protected] (A. Welch), [email protected] (S. Gaines), [email protected] (T. Marjoram), [email protected] (L. Fonseca). 1 Formerly responsible for the engineering sciences programme at UNESCO, presently based in Melbourne, Australia, with interests in engineering, technology and development. 2 Present address: University of Brasilia, Brazil.
2211-4645/$ - see front matter & 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.envdev.2012.02.001 58 A. Welch et al. / Environmental Development 2 (2012) 57–72
be charted until the wider international community asks some fundamental questions about what kind of regulation is appro- priate, how it should be implemented and by whom and at what cost. This task is urgent, and only by raising awareness of geoengineering can we secure the participation of the interna- tional community in developing governance structures and ensuring that responsible research on geoengineering proceeds in a timely and consensual manner. & 2012 Elsevier B.V. All rights reserved.
1. Introduction
Previously the stuff of science fiction, man-made techniques to engineer climate are increasingly being discussed as a necessary tool in the pathway to a sustainable future. In most cases, climate engineering is proposed as an additional technique to cool the climate in a climate emergency, not as a replacement to the necessary reduction in greenhouse gases. While these debates carry on in the halls of Parliament and at academic meetings in the West, the majority of the world’s population remains unaware of the emerging subject although they are just as dependent on the climate system and more vulnerable to any engineered perturbations. This paper focuses attention on this trend in order to engage a wider international community and suggest a participative way forward. This paper is an extension of UNESCO’s involvement in the geoengineering discussion that began when the first UNESCO expert meeting on the subject was hosted in November 2010. To further raise international awareness, a UNESCO–SCOPE–UNEP Policy Brief explaining the state of research questions and policy implications of climate engineering was published in November 2011. In the organization’s role as an ‘honest broker’, UNESCO recognizes that geoengineering is a field with global impacts that demands an informed and engaged international scientific, policy, and civil society community. In this spirit, UNESCO has initiated a critical discussion of the efficacy of geoengineering, its possible benefits and potential for harm, and the status of both the science and governance of this rapidly evolving field. The organization’s involvement does not represent an endorsement of any geoengineering activity and the authors of this paper write in their personal capacities in order to contribute to this debate.
1.1. Definitions
Geoengineering is the deliberate large-scale manipulation of environmental processes that affect the Earth’s climate with the intent to counteract the effects of global warming. The term ‘geoengineering’ was originally coined to describe a theoretical mechanism utilizing ocean currents to remove CO2 from the atmosphere (Marchetti, 1977). Since its first use a generation ago, the term has been expanded to apply to a suite of proposals that intentionally manipulate the Earth’s climate in an attempt to counter human-induced change, but does not include activities for which the climatic impact is a side-effect or unintended consequence. By design, geoengineering proposals have the potential for international impact. Similar alternative terms such as ‘climate engineering’ are also sometimes used for clarity’s sake, but in accordance with the dominant usage, the term geoengineering is predominantly used in this paper. The suite of proposed interventions range from ocean fertilization to extensive tree planting to favoring lighter more reflective crops to large-scale cloud seeding, exist at various degrees of modeling and experimental testing and carry uncertain consequences. Geoengineering is being considered alongside adaptation and mitigation in response to the threat of climate change. Increasingly, geoengineering is taken seriously as a reaction to concerns that the Earth’s climate is changing more rapidly than previously observed or estimated, and since there has neither been enough progress towards reducing greenhouse gas emissions nor evidence that A. Welch et al. / Environmental Development 2 (2012) 57–72 59 mitigation and adaptation measures now proposed are sufficient to avoid unfavorable, even catastrophic, climate change in the future. Often, geoengineering is proposed as an emergency stop- gap to prevent the climate from passing critical tipping points of change, while adaptation and mitigation policies take effect.
1.2. History
The modern conceptualization of geoengineering derives from more than a century of the application of technology to the weather, and predates the current focus on climate change (Fleming, 2010). Keith (2000) presents a twentieth-century history of geoengineering that more fully describes this arc, but for the purposes of this paper, geoengineering is understood to have passed through three important phases beginning after World War II. Geoengineering was shaped by (1) the Cold War race to control weather, (2) the rise of environmentalism and the focus on climate change, and (3) a twenty-first century renaissance spurred by the apparent failure of mitigation efforts. This controversial field of research has grabbed recent headlines over some of its more outlandish proposals, but is a legitimate scientific concern with a long history and is worthy of further inquiry.
1.2.1. Cold War weather makers Measures to control rainfall were advanced in the early years of the Cold War by competition between the USSR and US to establish a strategic supremacy in weather modification. Despite focusing on some of the same techniques – namely cloud seeding – the two nations arrived at a concern for climate change from separate corners. The USSR began cloud seeding field experiments before the war and expressed, in the 1950s and 1960s, an overt desire to control climate (Zikeev and Doumani, 1967). The Soviets were first to conceive of solar radiation management by injecting aerosols into the upper atmosphere (Budyko, 1977). Soviet investigations of climate modification would persist throughout the Cold War, while in the US, a burgeoning weather modification industry dominated any concern for climate until CO2-induced climate change was first identified as a threat in a seminal 1965 climate assessment by President Johnson’s Science Advisory Committee (Keith,
2000). The report assessed the impact of global fossil fuel combustion on atmospheric CO2 concentration in order to estimate rises in the planet’s temperature (President’s Science Advisory Committee (PSAC), 1965)). Although dismissed by the President, the only response to a warming climate presented in the assessment was a geoengineering scheme to increase the albedo of the sea surface.
1.2.2. Rise of environmentalism and the focus on the climate problem The 1970s and 1980s witnessed a marked shift away from the type of thinking that allowed geoengineering to be the sole proposed response to climate change. Despite a growing number of climate policy assessments that considered geoengineering, two developments caused the intentional manipulation of climate to be seen in a different light: attempts to wield weather as a weapon and an expanding ecological awareness. Attempts by the US to modify the weather in Vietnam had a lasting negative impact on the perception of geoengineering. Whether or not cloud seeding over the Ho Chi Minh trail dampened the progress of the Viet Cong, it did diminish the public’s appetite for weather modification and provoked a 1973 resolution by the US Senate urging the outright ban of environmental weapons (Harper, 2008). The United Nations followed suit in 1976 with an international convention prohibiting the hostile use of environmental modification techniques (United Nations, 1976). These events were part of a larger transition to an environmental understanding of humanity’s relationship with nature. An ecological awareness that saw the potential danger in applying technology to the climate was reflected in climate reports of the period that did not consider geoengineering as a countervailing measure to CO2-induced climate change (Study of Critical Environmental Problems (SCEP), 1970; Study of Man’s Impact Climate (SMIC), 1971). Other reports that did mention the intentional manipulation of climate did so with less optimism and always considered geoengineering to be less 60 A. Welch et al. / Environmental Development 2 (2012) 57–72 practical than mitigation (Geophysics Study Committee (GSC), 1977). Despite this departure from technological fixes to the climate problem, when geoengineering methods were considered, they were found to be a relatively low-cost option worthy of further investigation (Committee on Science Engineering and Public Policy (COSEPUP), 1992). The methods considered included reforestation, ocean fertilization, albedo modification and removal of atmospheric chlorofluorocarbons.
1.2.3. Renaissance of geoengineering
Geoengineering as a countervailing measure to CO2-induced climate change commanded renewed interest in the first decade of the twenty-first century when the prospects for greenhouse gas mitigation sufficient to stabilize the climate began to wane, observed rates of temperature change emerged to be faster than those predicted by the early US climate assessments of the 1960s and 1970s, and climate model studies increasingly confirmed the feasibility of stratospheric aerosol geoengineer- ing techniques. These three factors have encouraged a re-examination of the intentional manipulation of climate and have marshaled a geoengineering renaissance that is the focus of this analysis. The suite of currently proposed geoengineering activities, as shown in Table 1, fall into two main categories: ‘solar geoengineering’ or solar radiation management (SRM) interventions that aim to reduce the amount of solar radiation – or insolation – absorbed by the Earth, to engineer lower global average temperatures; and ‘carbon geoengineering’ or carbon dioxide removal (CDR) interventions that would actively remove carbon dioxide from the atmosphere by using artificial structures or by the enhancement of ecosystem processes. Both types of intervention intend to reduce the detrimental impacts caused by the accumulation of greenhouse gases in the atmosphere. These concepts were revitalized when Paul Crutzen, the Nobel Prize winning atmospheric scientist, proposed to use solar geoengineering to resolve the dilemma posed by policies that mandate cleaner skies but carry the unintended consequence of enhanced global warming (Crutzen, 2006). In this scenario, the climate cooling lost by the necessary removal of sulfate particles in the lower atmosphere, where they damage human health, could be compensated for by sulfate particles intentionally injected in the upper atmosphere. The scientific feasibility of such schemes that would diminish insolation to stabilize climate – albeit while leaving the atmospheric concentration of carbon dioxide unaddressed – has been affirmed by climate model studies (Caldeira and Wood, 2008). Considerations of side-effects have shown that an insolation reduction of not quite 2%, considered sufficient for climate stabilization under the current warming scenario, would not necessarily limit terrestrial primary productivity (Govindasamy et al., 2002). In fact, according to models, crop yields are likely to improve in most regions as the spraying of stratospheric aerosols would dampen climate change impacts harmful to plants, like heat, but leave untouched the higher concentrations of carbon dioxide (Pongratz et al., 2012). This approach, however, brings with it the risks of regional drought, ozone depletion, diminished sunlight and a lesser blue in the sky, all of which need further quantification to allow for informed decision making (Robock et al., 2009). Even if insolation can be appropriately manipulated, these methods treat only the symptoms of a warming climate and leave the underlying problem of greenhouse gas emissions unaddressed. This is to say that geoengineering methods should not replace carbon-dioxide mitigation efforts but could buy time while we shift away from fossil fuels. We can conceivably push back the clock as far as
Table 1 Range of geoengineering interventions proposed.
Solar geoengineering Carbon geoengineering
Injecting sulfate aerosols into the stratosphere Fertilizing the ocean with iron Bio-engineering crops to be a lighter color, thus more reflective Enhancing natural rock weathering Suppressing high-altitude cirrus clouds Encouraging intensive large-scale forestry Installing space mirrors Building carbon dioxide scrubbers Spraying seawater into low-altitude clouds to brighten Injecting carbon dioxide underground or into the ocean or increase them Painting streets and roofs white Large scale Bio-char
Fast, inexpensive, uncertain Slow, expensive, effective A. Welch et al. / Environmental Development 2 (2012) 57–72 61 we require by taking carbon dioxide out of the atmosphere. In one category of proposals, engineered ‘‘carbon banks’’ of fast growing trees or peat that trap carbon in the topsoil could exploit the natural ability of plants to absorb carbon dioxide from the atmosphere (Dyson, 1977). Similarly, carbon dioxide could be captured from the air by engineered structures that would use vented grids to chemically remove carbon dioxide, readying it for permanent storage underground in a process that accelerates the natural carbon cycle (Keith et al., 2005). So too, the oceans could lock up excess carbon dioxide, according to the iron hypothesis that posits phytoplankton productivity to be limited by iron deficiency and suggests that fertilization of the ocean with iron could seed a massive phytoplankton bloom that would sequester carbon once the phytoplankton die and settle to the deep ocean (Martin, 1990; Martin et al., 1994). Perhaps together these CDR methods could stabilize the climate if deployed at sufficiently large scale. The most significant recent assessment to consider the full spectrum of geoengineering methods was conducted by the UK’s Royal Society in 2009. The report deems that the global effort to reduce greenhouse gas emissions has not yet been sufficiently successful to avoid dangerous climate change and sees no credible scenario in which global mean temperature will decline in this century. Actions beyond mitigation then, like geoengineering, may therefore be essential should it become necessary to cool the climate in this century (Royal Society, 2009). A major conference to guide such actions and minimize the risks of climate geoengineering was held in March 2010 at the Asilomar Conference Center near Monterey, California, where, a generation before, guidelines for genetic engineering were established. Five tenets promoting the safe, responsible and effective pursuit of research on climate engineering, shown in Table 2, were adopted and, after much discussion, the conference’s scientific organization committee upheld geoengineering as a feasible way to avoid catastrophic climate change and expressed the hope that the open and collegial ‘spirit of Asilomar’ ‘‘will help the international community to better understand potential responses to the increasingly serious climate change issue’’ (Asilomar Scientific Organizing Committee (ASOC), 2010). Far from clarifying the debate, some members of the pressweredissatisfiedbytheclosednatureofthe proceedings and some scientists were distressed by what some perceived as the commercial orientation of the conference in general, and by the positioning of a private ocean fertilization enterprise in particular. The Intergovernmental Panel on Climate Change (IPCC) made its first overt inquiry into geoengineering by convening an expert working group in June 2011 tasked with the scientific assessment of geoengineering. The first four reports of the IPCC, beginning in the early 1990s, focus on mitigation and give only peripheral consideration to geoengineering. Although the outcomes of the working group will not be published until the release of the Fifth IPCC Assessment Report in 2014, they will include a scientific accounting of geoengineering methods and their likely impacts, but will not contain policy recommendations. We anticipate that the IPCC’s accounting will perhaps support research on geoengineering as a potential response to catastrophic climate change, but only for those solar geoengineering methods already known to be feasible and relatively low cost.
Table 2 Five tenets to guide geoengineering research.
Oxford principles (Rayner et al., 2009) Geoengineering to be regulated as a public good Public participation in geoengineering decision-making Disclosure of geoengineering research and open publication of results Independent assessment of impacts Governance before deployment
Principles for responsible conduct of climate engineering research (ASOC, 2010)