Australia, we need to talk about solar geoengineering

With climate change now a reality and its impacts being felt, geoengineering is emerging as a major (if controversial) point of discussion and debate regarding international responses to climate change.

In 2013, the Intergovernmental Panel on Climate Change defined ‘geoengineering’ as ‘methods that aim to deliberately alter the climate system to counter climate change’ (IPCC 2013, 29). By most accounts, technological interventions that fit within this broad label of geoengineering take one of two forms: carbon dioxide removal (CDR) and solar radiation management (SRM) (or more simply solar geoengineering). The former describes ‘anthropogenic activities removing CO₂ from the atmosphere and durably storing it in geological, terrestrial or ocean reservoirs or in products’ (IPCC 2018) and includes activities such as afforestation, soil carbon sequestration, ocean fertilisation and direct air capture. Solar geoengineering, on the other hand, involves reducing impacts of climate change by reflecting some of the sun’s energy into space. Here, stratospheric aerosol injection (using aircraft to disperse sulphur, for example) is the most likely technique envisaged to achieve this.

Not only is CDR widely used (primarily afforestation, see Smith 2023) but it is increasingly recognised as crucial for reaching net zero targets and addressing climate change (Maher and Symons 2022). Australian CDR policies are currently less developed than those in the United States, but Australia has pioneered soil carbon methodologies and in 2022 the CSIRO published a major report on other CDR opportunities (CSIRO 2022). While understanding of and even support for CDR is growing, however, solar geoengineering remains acutely controversial, and Australia has paid little attention to issues around its use, impact or governance.

Critics have raised a series of concerns about solar geoengineering. For some, it involves playing God with nature (see Hamilton 2014). Some see a significant risk of it deterring mitigation action (McLaren and Corry 2023) or empowering the actors who control the technology (Biermann et al. 2022). Others note the potential for dangerous ‘termination shock’ from stopping use of global solar geoengineering once deployed (Parker and Irvine 2018). Still others caution that not enough is known about solar geoengineering’s consequences for ecosystems and planetary functions (Biermann et al. 2022), or that regulating its use will be difficult if not impossible (Brent 2023; Reynolds 2019). However, as global warming creeps past 1.5°C above pre-industrial levels (Ripple et al. 2023) and the impact of changing rainfall patterns, warmer temperatures and disasters is being felt, a range of interventions that might potentially minimise harms are arriving on global policy agendas. This includes solar geoengineering.

Solar geoengineering on the international agenda

At the 2024 session of the UN Environment Assembly in Nairobi, Switzerland proposed that a United Nations expert group be asked to ‘examine risks and opportunities’ associated with solar geoengineering. Amid deep international disagreement the resolution was first revised and then rejected (McLaren and Corry 2024). Yet, whereas a previous Swiss proposal in 2019 was wholly opposed by the Trump Administration, it was noteworthy that the Biden Administration worked to ensure the 2024 resolution was presented in a form it could support.¹

The debate in Nairobi saw an increasing number of states contributing to debate and outlining their positions on the issue (McLaren and Corry 2024). Australia was not among them. Indeed to date, Australia has played virtually no role in global discussion of solar geoengineering. Australia also stands out among comparable nations for its limited examination of potential national impacts. One explanation attributes this inattention to Australia’s ‘role conception’. By this account, Australian policy-makers identify as faithful US allies and so commonly defer to US leadership on global issues (Horton 2023). Yet, Australia’s climate and geography are quite dissimilar to North America’s. If global solar geoengineering were implemented it would have highly distinct impacts on Australian agriculture, biodiversity, costal protection, rainfall patterns and fire risks. Australian and US interests therefore appear quite distinct.

While we have not seen global agreement on the governance of solar geoengineering, around the world nationally focused research is proceeding rapidly. Since 2023 alone, the White House Office of Science and Technology Policy has commenced a congressionally mandated ‘five-year plan’ for a ‘scientific assessment of solar and other rapid climate interventions in the context of near-term climate risks and hazards’ (OSTP 2023); the United Kingdom has asked its Natural Environment Research Council (NERC) to conduct a five-year ‘Modelling Environmental Responses to Solar Radiation Management’ programme and allocated £10.5 million ($20 million AUD) to the work; and Canada has incorporated study of solar geoengineering into its 2024–2029 science strategy (E&CC 2024).

These initiatives build on a longer history of national research. In the US, the National Academies of Sciences (2021), the National Research Council (2015) and the Government Accountability Office (US GAO 2011) have all delivered landmark reports. Outside of the US research has been conducted by the Office for Technology Assessment at the German Bundestag and the German Research Foundation (Klepper 2016; Maher and Symons 2022), the UK’s Royal Society (Royal Society 2009), successive EU-funded research projects (Schäfer 2015; European Research Council) and a major study funded by the Chinese Ministry of Science and Technology (see Horton 2023). Meanwhile, Degrees Modelling Fund grants have supported over 150 researchers to conduct solar geoengineering research in 21 developing countries.

A role for Australia?

Although Australia has taken no steps to investigate the national impacts of global solar geoengineering, Australia is a world leader in trialling local climate interventions. Australian governments have supported the Great Barrier Reef Marine Park Authority as it conducted small-scale trials of ‘cloud-brightening’ above the reef (in 2020 and 2021) with the goal of testing equipment that might be used to prevent coral bleaching during ocean heatwaves (see Butcherine 2023; Horton 2023). These trials are arguably the world’s first significant outdoor trial of a solar geoengineering technique (McDonald et al. 2019). The trials were opposed by environmental organisations such as Friends of the Earth and the German Greens (Böll-Stiftung 2020; Sales 2019), but for the most part attracted surprisingly limited public attention.

Cloud brightening is a relatively localised intervention, but at some point in the coming decades it seems increasingly likely that larger-scale climate interventions will be considered or indeed implemented by some actors in the international system. If the 2024 negotiations are indicative, not only is the issue likely to prove divisive, but Australia’s Pacific neighbours are likely to take quite a different position from the United States. When negotiations over the governance of these forms of climate interventions eventually do begin, it is important that Australia should have an informed understanding of likely regional impacts. There are at least two major elements of this work: scientific and social/political.

In the absence of any field trials, most scientific research into solar geoengineering utilises scenarios developed within the Geoengineering Model Intercomparison Project (GeoMIP). These scenarios include intervention involving stratospheric sulphur-injection, marine cloud brightening and cirrus cloud thinning (a proposed technique that would cool the earth by allowing more infrared radiation to be reflected into space) (Visioni et al. 2023; Kravitz et al. 2021). A basic understanding of regional impacts from these techniques could be gained by funding climate scientists to take existing GeoMIP scenarios and specify their anticipated regional impacts on temperature and rainfall patterns for Australia and the Asia-Pacific. Translation of these data to more localised contexts would allow scholars to identify the range of possible material impacts on ecology, agricultural productivity and fire risk, for example. Ideally, Australia would work with neighbouring countries (e.g. Timor-Leste, Indonesia and the Pacific Island Forum) to develop a detailed understanding of regional impacts.

A second body of work could explore social and political impacts at local and international levels. In the social context, while public awareness is limited, deeper understanding of perspectives on and likely responses to solar geoengineering within Australian society is needed. In political terms, consideration of potential international governance arrangements and Australia’s role in contributing to these is clearly required. This is necessary not least because in the absence of such arrangements, solar geoengineering use may have important security implications (McDonald 2023). With no global agreement in place and climate change effects worsening, there is growing concern that an actor might seek to deploy solar geoengineering unilaterally (Horton 2023). While states facing significant climate harms are often viewed as potential early users, this option might also be attractive to actors that view a possible technological ‘silver bullet’ as preferable to the end of a global fossil fuel economy. Opponents of solar geoengineering worry that its use – although intended to reduce climate harms – might potentially create significant harms, including for other states, through affecting monsoon patterns or rainfall, for example (Ricke et al. 2012). Unilateral deployment could also fuel perceptions that adversaries have caused harmful weather events, or that the dual-use potential of SG equipment (e.g. patrols by stratospheric aircraft) represent a threat to sovereignty. Opposing states might also seek to sabotage or counter deployment that lacked multilateral support (see Surprise 2020).

These scenarios are at the heart of concerns that SG might contribute to international tensions, instability and even violent conflict. Perhaps the greatest risk for Australia would be if the United States and China took opposing positions on deployment of solar geoengineering, and deployment became another flash-point in great-power rivalry (Lockyer and Symons 2019). Here, Australia’s interest in minimising the risk of conflict between its primary security guarantor and largest trading partner gives it a clear independent interest.

Conclusion

Solar geoengineering is a deeply controversial idea. It is now well understood that growing atmospheric concentrations of greenhouse gases have placed the global climate in a perilous and unprecedented situation. Solar geoengineering is either a dangerous distraction from the urgent work of decarbonising economic process, or possibly a flawed, imperfect and partial response that might limit climate harms while the international community gets serious about urgent mitigation action.

While Australia and its neighbours are among the most climate-vulnerable countries, they are currently among the least informed about the possible consequences of solar geoengineering. Australian climate scientists are well represented among scholars modelling solar geoengineering scenarios. However, to date there has been no effort to detail implications for Australia. Regardless of whether Australia and its Pacific neighbours ultimately support or oppose climate interventions, Australian policy-makers and researchers need to start taking the potential implications and governance of solar geoengineering seriously.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Jonathan Symons

Jonathan Symons is Associate Professor in the Macquarie School of Social Sciences at Macquarie University.

Courtney Fung

Courtney Fung is Associate Professor in the Department of Security Studies and Criminology at Macquarie University.

Dhanasree Jayaram

Dhanasree Jayaram is Assistant Professor in the Department of Geopolitics and International Relations at the Manipal Academy of Higher Education.

Sofia Kabbej

Sofia Kabbej is a PhD candidate in the School of Political Science and International Studies at the University of Queensland.

Matt McDonald

Matt McDonald is Professor of International Relations in the School of Political Science and International Studies at the University of Queensland.

Notes

1 UNEP also prepared a preliminary report on solar geoengineering following the earlier debate. https://www.unep.org/resources/report/Solar-Radiation-Modification-research-deployment.