Given the inadequacy of current patterns of climate mitigation, calls for rapid climate protection are beginning to explore and endorse potentially radical options. Based on fieldwork involving original expert interviews (N = 23) and extensive site visits (N = 23) in Australia, this empirical study explores four types of climate interventions spanning climate differing degrees of radicalism: adaptation, solar geoengineering, forestry and ecosystems restoration, and carbon removal. It examines ongoing efforts to engage in selective breeding and assisted adaptation of coral species to be introduced on the Great Barrier Reef, as well as to implement regional solar geoengineering in the form of fogging and marine cloud brightening. It also examines related attempts at both nature-based and engineered forms of carbon removal vis-à-vis ecosystem restoration via forestry conservation and reforestation in the Wet Tropics of Queensland World Heritage Area, and enhanced weathering and ocean alkalinization. This portfolio of climate interventions challenges existing categorizations and typologies of climate action. Moreover, the study identifies positive synergies and coupling between the options themselves, but also lingering trade-offs and risks needing to be taken into account. It discusses three inductive themes which emerged from the qualitative data: complexity and coupling, risk and multi-scalar effects, and radicality and governance. It elucidates these themes with an attempt to generalize lessons learned for other communities around the world considering climate interventions to protect forests, preserve coral reefs, or implement carbon removal and solar geoengineering.
Citation: Sovacool BK, Baum CM, Low S, Fritz L (2023) Coral reefs, cloud forests and radical climate interventions in Australia’s Wet Tropics and Great Barrier Reef. PLOS Clim 2(10): e0000221. https://doi.org/10.1371/journal.pclm.0000221
Editor: Laurence L. Delina, The Hong Kong University of Science and Technology, HONG KONG
Received: February 6, 2023; Accepted: June 19, 2023; Published: October 4, 2023
Copyright: © 2023 Sovacool et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: Due to ethical restrictions the data underlying the results of this study are only available upon request to Universitetsledelsens Stab. Nordre Ringgade 1 8000 Aarhus C E-mail: firstname.lastname@example.org http://www.au.dk/om/uni/austab/.
Funding: The authors received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
Given the inadequacy of both current patterns of climate mitigation and adaptation, calls for rapid climate protection are beginning to endorse more radical options. Morrison et al.  recently state that meaningful climate action requires such interventions. Sovacool and Dunlap write that climate policy implementation seems woefully insufficient to tackle rising emissions, and that even daring, obstinate, transformative options need to be considered by scientists, policymakers, and even activists. Capstick et al.  argue in favor of urgent climate action via the civil disobedience of researchers and scientists.
Perhaps nowhere on earth are radical climate protection pathways being put into practice with as much urgency as on the Great Barrier Reef in northeastern Australia. Stopping climate change in practice is critically important for coral reefs, given that by 2070, all the coral reefs in the world could be gone due to global heating . Moreover, they note that from 1998 to 2018, heatwaves have bleached or killed more than 90% of the coral reefs listed in global World Heritage sites. In the Great Barrier Reef, the largest reef ecosystem in the world, half of corals died between 2016 and 2017 –though it is also the case that mostly shallow water corals were affected and that, for the most part, there has subsequently been a rapid recovery in coral health  Nonetheless, the long-term stability and resilience of coral reefs in response to recurring bleaching events is in question.
The loss of coral reefs would be devastating environmentally, but the socioeconomic consequences would also be significant. Although coral reefs cover only about 0.5% of the ocean, they support about 30% of marine fish species globally . Moreover, approximately 400 million people depend on reefs for food and protection from storms and floods across more than 100 countries, and coral reefs serve as a source of tourism revenues and of nonmaterial contributions of nature to people .
Deforestation and land use change is another significant climate change concern. Forests cover about one-third of global land area, storing 683 billion tons of carbon, more than the total amount of carbon contained in the atmosphere, and through the carbon cycle, forests remove an additional three billion tons of carbon dioxide each year through growth [7, 8]. Yet when forests are cleared, harvested, or catch fire, their stored carbon is emitted back into the atmosphere. Much of the world’s farming, livestock production, and changes in land use have taken place in former forests and tropical forests, with about half of global useable land now in pastoral or intensive agriculture [9, 10]. About 36 percent of the carbon added to the atmosphere from 1850 to 2000 came from the elimination and conversion of forests , along with 13–21% of global total anthropogenic greenhouse gas emissions in the period 2010–2019 .
Thus, forests can be a sink as well as a source of emissions, depending on how they are managed. The most recent Intergovernmental Panel on Climate Change report notes that the land use, agriculture, and forestry sector can provide 20–30% of the global mitigation needed for a 1.5°C or 2°C pathway towards 2050 . However, the ability to achieve these reductions is highly variable and contingent on strong mitigation strategies backed by robust governance mechanisms.
Based on extensive original data collection and field research, this paper explores a distinct portfolio of four radical options being implemented to protect coral reefs and tropical forests in Australia: adaptation via assisted evolution (genome sequencing and selective modification of coral reefs), regional solar geoengineering (fogging and shading through cloud brightening), forest and ecosystem restoration (community forestry conservation and reforestation), and carbon removal (enhanced weathering). The study asks: how are these four radical options being implemented? What are their benefits and barriers? Moreover, what are their potential couplings to the use of other forms of technology to promote the protection (and restoration) of coral reefs, and what multi-scalar risks may emerge?
In addressing these questions, the study aims to make multiple contributions. The first is empirical, although with an eye towards informing theory. Within the discourse on climate interventions and pathways, typologies and distinctions abound, notably, between the aims of mitigation from adaptation and “geoengineering” approaches , and around the need for split consideration of carbon removal vis-à-vis solar geoengineering [14, 15]. Other studies draw important distinctions between “natural” carbon removal options versus “chemical” or “engineered” options [16–19]. Still other work distinguishes between “hard,” centralized, scale-driven approaches versus “soft,” distributed, bespoke approaches . These distinctions, while useful, do not necessarily capture the reality of how some interventions are being assessed and implemented in practice, where they form a part of a portfolio or cocktail of interventions [21–23]. In practice, the lines between these categorizations become blurred, and pathways become mixed, an important finding that provokes further theory building and assessment.
Second, and conceptually, our study applies a recent typology of radical climate interventions, which identifies a set of positive synergies and couplings between radical options when it comes to climate protection and ecosystems restoration, but also lingering tradeoffs and risks –see Section 2 for further detail. We build upon reviews and studies of in situ experiments and pilot projects for climate interventions , novel interventions in terrestrial [25, 26] and marine environments [27, 28], and efforts specific to Australia and its iconic ecosystems, such as the Great Barrier Reef [29–31].
In doing so, we attempt to generalize lessons learned for other communities around the world where the use of potentially radical interventions could be considered in portfolio–to protect denuded forests of cultural-ecological value, preserve, restore, and assist the adaptation of coral reefs, or generally maintain important ecosystems. We aim to inform multi-disciplinary, multi-sectoral assessments of such interventions–on land [32, 33] and in coastal regions and the high seas [34–36], including those that focus on direct engagement with local actors and conditions [37, 38], as well as efforts to evaluate initiatives that pose co-benefits for climate, ecosystems, and local development [39, 40]. In this regard, the ongoing trials and insights gleaned in Australia serve as a crucial test laboratory, both conceptually and practically, for the onset of future and deeper efforts, if the pace of climate mitigation remains insufficient.
2. Background and context: World Heritage ecosystems, climate protection, and radical interventions
The two focal points of the study are both critically important ecosystems, as well as World Heritage Sites, one involving tropical cloud forests, and the other coral reefs.
The first is the Wet Tropics of Queensland World Heritage Area. This Heritage Area sits on the northeastern part of Queensland’s Great Dividing Range in Australia, occupying almost 9,000 square kilometers at elevations up to 1,600 meters. It encompasses both National Parks and State Forests in the high rainfall region of north Queensland, stretching from near the Bloomfield River in the north to Townsville in the south [41–43]. It was granted its World Heritage status in 1988 for four reasons: (i) offering outstanding examples representing the major stages of the Earth’s evolutionary history; (ii) outstanding examples representing significant ongoing ecological and biological processes in the evolution and development of terrestrial and fresh water ecosystems and communities of plants and animals; (iii) superlative natural phenomena or areas of exceptional natural beauty and aesthetic importance; and (iv) offering the most important and significant habitats for in situ conservation of biological diversity, including those containing threatened species of plants and animals of outstanding universal value from the point of view of science and conservation . The forest area is also rich in biodiversity, such that more than 80 species of trees can be found within a 0.25-hectare size of the park .
As Fig 1 (Panels A-D) indicates, it is home to beautiful rivers and waterfalls, and dense forest canopies. The biodiversity within the Heritage Area is lush with more than 3,300 species of plants, of which more than 700 are endemic, along with more than 700 vertebrate species, of which 88 are endemic. Of the 26 different lineages of flowering plants in the world, 15 are found within this Heritage Area, amounting to the highest concentration in a single protected area on the planet. The Wet Tropics region also hosts a diverse array of ecosystem types, from low-lying coastal areas and inland plains to subcoastal ranges and savannas. These ecosystems are a natural habitat for freshwater crocodiles, rhinoceros cockroaches, and python snakes. The Heritage Area protects the world’s oldest continuously surviving tropical rainforest dating back more than 130 million years. It also is home to one of the oldest indigenous cultures on the planet, the Rainforest Aboriginal Peoples, who have been living there for more than 5,000 years. The International Union for the Conservation of Nature has assessed it as the second most irreplaceable natural World Heritage site on Earth; that is, it is one of the 0.1% of the most important protected areas in the world .
Source: All photographs taken by the authors during field research. Note: A is the Wallaman Falls, B the Wooroonooran National Park, C the Crater Lakes National Park, and D the Barron Gorge National Park.
The second is the Great Barrier Reef, the largest coral reef system in the world spanning more than 348,000 square kilometers, which makes it the largest living organism on the planet [47, 48]. It was given its World Heritage status in 1981 as the world’s most extensive coral reef. In comparative terms, the Great Barrier Reef is approximately the size of Italy or Japan. It offers instrumental ecosystem services including a keystone marine habitat, shoreline protection, the provision of fisheries, and a popular location for tourism . It thus generates more than AUD$6.4 billion in annual reef tourism revenues (supporting more than 64,000 full time jobs)  and an additional AUD$500 million in fishing revenues. As Fig 2 (Panels A-E) partially illustrates, the Great Barrier Reef also protects more than 1,500 species of marine wildlife including anemonefish, red bass, coral trout, snapper, sharks and sea turtles. This is in addition to more than 400 different species of coral, and more than 4,000 mollusk variations.
Source: All photographs taken by the authors during field research or used with Permission from Reef Magic. Note: A shows a Barramundi cod on Moore reef, B sea turtles at Arlington Reef, C an aerial view of Michaelmas Reef, D an aerial view of Oyster Reef, E a clown fish on Moore reef.
Both the Wet Tropics of Queensland World Heritage Area and the Great Barrier Reef are threatened by climate change, among other issues. The Wet Tropics will be sensitive to heat stress, drought, flooding, and more intense cyclones. The Great Barrier Reef is at risk from accelerated crown-of-thorns starfish outbreaks, more severe tropical cyclones, heat stress leading to more aggravated coral morality, and mass bleaching events . Other parts of the reef are susceptible to environmental stressors in the form of pollution, flood plumes, and ocean acidification .
These threats have motivated a portfolio of climate interventions intended to stabilize the cloud forests and protect the reef. Our study focuses on four of these in particular: climate adaptation, solar geoengineering, forest and ecosystems restoration, and carbon removal. These operate as a potential suite or portfolio of techniques aimed at preempting future impacts of climate, with Lockie  warning that the longer policymakers take to act, the more expensive and difficult interventions will be, at any scale, and the greater the risk that windows of opportunity will close.
Collectively, these options are being supported in Australia through a variety of programs and schemes. On land and near the Wet Tropics, the Wet Tropics Conservation Strategy outlines actions from the government and private sector to achieve the conservation and rehabilitation of the Heritage Area. It builds on earlier advances from the Community Rainforest Reforestation Program. Furthermore, an ongoing project of the Leverhulme Centre for Climate Change Mitigation (LC3M) has been piloting terrestrial carbon removal and enhanced weathering since 2018. LC3M assumes the mantle of the first high-profile project on enhanced weathering in the world, and potential co-benefits for local agriculture underpins its decision to conduct trials on working sugarcane plantations in Queensland .
In terms of the reef, the Reef Trust Partnership (an AUD$443 million program administered by the Australian Government’s Reef Trust and the Great Barrier Reef Foundation) promotes reef restoration, community reef protection, and adaptation science. The Reef Restoration and Adaptation Program, or RRAP, is an AUD$120 million collaboration between government and multiple universities and conservation institutions to help the Great Barrier Reef recover from, and adapt to, the effects of climate change. As Fig 3 indicates, the RRAP has given consideration to more than 160 distinct interventions to protect the reef, and it has three intersecting goals: to protect and cool reefs most at risk to bleaching and heatwaves; to adapt and strengthen the tolerance of corals to climate change; and to restore and promote the recovery of degraded reefs. Two of the four radical options that we explore in this paper—adaptation and assisted evolution of coral reefs and solar geoengineering—are being researched and tested in small-scale feasibility trials by RRAP.
Source:  and republished under a CCBY license.
Finally, we term our interventions radical because they fit into a recent typology articulated in Morrison et al. . Morrison et al. argue that climate interventions can span a spectrum of radicality, ranging from having limited, slow change (phase 1, palliative, and phase 2, hopeful), deeper or faster change (phases 3 and 4 of tactical and partial, respectively), and deep and transformative change (phase 5, strategic, and phase 6, deep radical). Palliative interventions, according to the authors, encompass “extreme” or “unproven” technological solutions with the express purpose of responding to climate change such as carbon removal and solar geoengineering. By this definition, we could place engineered carbon removal (enhanced weathering) and regional solar geoengineering (fogging and cloud brightening), and assisted evolution and genetic modification (of coral reef) into this category, given their general focus on urgent harm reduction. Hopeful interventions are seen to address the climate emergency through soft economic changes such as carbon accounting schemes, renewable energy targets, and nature-based solutions to store carbon. By this definition, we place nature-based ecosystem restoration and forestry in this category, although we note the potential for greater radicality (i.e., deep radical) if coupled with deeper changes to prevailing systems and power structures. Tactical interventions represent radical options that seek to be disruptive and raise awareness about the root drivers of climate change. We would place coral reef regeneration into this category, especially where linked to broader attempts to raise awareness about climate change and the Great Barrier Reef. We will explore the degree to which a portfolio of such interventions can climb higher on the ladder of radicality, approaching strategic and deep radical actions, in Section 5.3.
3. Research design and data collection
With a lens on our four radical climate interventions, we collected original data via expert interviews and naturalistic observation through various site visits.
First, we conducted 23 semi-structured expert interviews over the course of October and November 2022. All experts had deep involvement with at least one of our four radical climate interventions, and some had knowledge of all four. Our sample was skewed strongly towards academic institutions and research institutes, given the breakthrough nature of the radical interventions as well as how the constituent organizations are allocating funding. This included the Queensland University of Technology, James Cook University, and Southern Cross University. It also however included government agencies working with research institutes to promote climate protection, notably the Australian Institute of Marine Sciences, Great Barrier Reef Marine Park Authority, and GBR Biology, the in-house biology team associated with one of the reef tourism operators.
Although anonymized for research ethics purposes, Table 1 shows the respondent numbers, dates of the interviews, and institutions of those being interviewed. Questions focused not only on technical performance and innovation for each of the four radical interventions but also barriers and risks, policy and governance, and public and stakeholder involvement.
Research interviews were supplemented with 23 site visits in October 2022, shown in Table 2, where we aimed to triangulate the insights of the interviews with naturalistic observation. These included a mix of reefs, forests, and experimental sites as well as research institutions and laboratories where prototypes were being tested and basic research undertaken. Included were 15 reefs within the Great Barrier Reef (the locations of the adaptation and solar geoengineering work); Barron Gorge National Park, Wooroonooran.
National Park, and Girringun National Park, which straddle and are connected to the Wet Tropics World Heritage Area and are thus where ecosystem restoration is ongoing; and Gordonvale, where the enhanced weathering trails are being undertaken. Fig 4 (Panels A-C) provides an overview of these site visits.
Source: All photographs taken by the authors during field research. Note: A the sugarcane plantation where the enhanced weathering trials were ongoing in Gordonvale; B the site of GBR biology research station on the Great Barrier Reef; C one member of the research team inspecting Moore reef. Image B is used with permission from Reef Magic.
As is perhaps evident by now, the paper presents numerous photographs collected during our fieldwork. Rather than bring frivolous, such images act as important sources of “physical evidence” that is just as precious as qualitative or quantitative data in advancing analysis. Photographs can serve as crucial points of “visual ethnography” that reveal deeper points of understanding that words cannot, assist with methodological triangulation, and enhance persuasion by commuting emotions and more complex feelings [52–55]. Though the practice of including images in research is more common in the disciplines of advertising, business, marketing, anthropology, sociology, communication studies, and rhetoric, we believe the images presented below add significant value to our study.
4. Results: Radical climate interventions in practice
Serving as a test laboratory to orient and inform other such efforts that might be required in the future, Queensland, Australia represents a place where adaptation, geoengineering, ecosystem restoration and enhanced weathering are all done in tandem, as part of an integrated and exploratory approach to climate protection. This includes four distinct measures (mentioned in Section 2):
- Coral reef adaptation which involves reef regeneration, selective breeding and assisted evolution of coral, coral larvae dissemination, repairing reefs from cyclones and testing the thermal tolerance of different reef varieties.
- Solar geoengineering which involves shading by fogging and cooling by cloud brightening.
- Nature-based ecosystem restoration which involves community land management via forests and mangroves, to offer a protective buffer around the reef.
- Engineered carbon removal which involves enhanced weathering and ocean alkalization.
Up until these projects, R08 cautioned that generally in Australia, climate protection made “no headway beyond fancy logos on old programs”. R23 added that researchers and planners in Australia have come to recognize that “classic conservation strategies are no longer possible for the reef, classical methods of leaving it alone are unlikely to work, given the seriousness of climate change… business as usual is completely incompatible with the continued existence of the Great Barrier Reef.”
This Results section draws from our interviews, site visits, and supporting literature. It focuses on each of the four interventions via the following structure, beginning with a summary of how the intervention works, what its prospective benefits are, and what real or prospective barriers it must confront along with the potential risks which deployment could entail. The Discussion section then teases out recurring themes connected to complexity, risk, and future research gaps.
4.1 Adaptation: Coral reef regeneration, selective breeding and assisted evolution
As part of the RRAP discussed in Section 2, researchers began by conducting a feasibility assessment of 160 possible interventions to protect the reef. Forty-three of these were recommended for further research and exploration, based on an assessment of their potential benefits, costs, and scalability . Two of these shortlisted priorities involved the regeneration and repair of coral reefs, and the selected breeding and assisted evolution of reefs to be more resistant to heat waves and climate change . Condie et al.  add that genetically modified and thermally tolerant corals would be capable of interbreeding with exiting corals, furthering resilience.
R08 spoke about how reefs with heat resistant properties can be grown in the lab, and then transferred to degraded reefs. Other techniques emphasize reseeding efforts in aquaculture to be placed on natural reefs, and larval seeding to help reefs under heat stress recover. R17 explained the staged management approach being adopted, noting that:
“rather than deploy it all at once, [there is] continual field testing every year, at very small scales, nothing large scale, until at least 2025, [with] this staged approach, things done in the lab, then at small scale at a few isolated reefs, moving up towards larger reefs, with key questions for the reef managers along the way so we have adaptive feedback and can learn.”
Fig 5 (Panels A-D) shows some of these activities being undertaken at the Australian Institute of Marine Sciences, in a state-of-the-art facility where it is possible to conduct experiments in conditions that simulate those in the real world, whether historical, current, or projected.
Source: All photographs taken by the authors during field research. Note: A shows coral larvae propagation, B thermal tolerance testing, C simulated coral bleaching exposed to indoor light, D simulations exposed to outdoor light.
Other components of RRAP and AIMS research involve measuring coral growth and reef function with more advanced 3D surveys and installing sensors throughout the GBR to detail chemical and biological features of reef recovery. A final component involves using human-made structures for coral settlement to help reefs recover from cyclones, including removing rubble and providing a stronger foundation for coral larvae. R01 collectively framed these efforts as “regional ecosystem adaptation” and “large-scale ecosystem restoration” or “assisted ecosystem adaptation” (see also ).
The prospective benefits from these interventions could be “vast, revolutionary, and groundbreaking,” as R04 put it, given they “could literally save some to all of the GBR.” R20 added that “90% of Australians associate the reef with national identity, so we’re helping the reef which helps us as a whole.” Others spoke about how Australia could pilot and perfect these efforts on the GBR, after which they could be deployed worldwide in other reefs threatened by climate change. Indeed, in Fig 6, Morrison et al.  plotted 100 different reef locations at risk to bleaching events where the techniques being deployed on the GBR could ostensibly be adapted to. Multiple experts observed that the reason for such research currently being done in Australia, rather than in such other locations, stemmed from the more established and robust governance regime in Australia as well as to avoid any sense of colonialism or shunting such untested practices into the Global South. Nonetheless, there was the hope and expectation that, if any of the techniques were successful in Australia, these could be readily translated to other locales, including through the involvement of the researchers from Australian institutions.
Source: , republished under a CC-BY 4.0 license.
Nevertheless, potential barriers and risks facing deployment could be stark. Condie et al.  noted that the same interventions that lead to restoring and preserving reefs could also nourish Crown-of-Thorns-Starfish, their greatest predator, and a significant cause of coral reef decline. Such risks are intertwined with another challenge related to the temporality of interventions, addressed by R14:
“Radical interventions are playing out faster than we can keep up with them, than agencies can manage them. If done poorly, they risk being a giant waste of money, with feasibility and effectiveness of interventions not sorted out. There is a risk they are too speculative, trading on climate change as an issue, lots of cowboys involved.”
R07 spoke about the scale and safety of the assisted evolution and genetic modification of reef systems, noting that “it’s hard to make a judgment about what the impacts will be ramped up to larger scales, where the release of artificial organisms could become a huge vulnerability, even affecting species in the sea or on land.” R14 elaborated on problems of scale, articulating that:
“All the stuff underwater is sexy, but it’s not scalable, it hasn’t been proven in effectiveness. My concern is it is sucking up scientific resources, distracting people from what needs to be done, like a science fiction movie: intriguing and entertaining high-profile media stories, money from philanthropic billionaires, but I do not think it will have any long-term impact whatsoever.”
R08 commented on how existing governance arrangements on the GBR were not conducive to the research being undertaken, and could even germinate into new risks:
“Existing coral reef field trials do not sit comfortably with existing governance arrangements. The Marine Park Act makes provision for research, but it wasn’t written with this type of research envisaged. It creates problems: the assumption is that we should only be observing the reef, not actually modifying it. With RRAP, [there is] actually tampering with the reef, putting living things into the reef, taking them out, genetically altering them. For example, experiments with making restoration more effective: coral larvae settle on plates, throwing the plates off the back of a boat, but some of those plates got carried away and deposited larvae well beyond the GBR. This is the problem with living things: they have a mind of their own, they do not behave as we anticipated, and these experiments are not anticipated with the Marine Park Act.”
Another concern remains the focus of these interventions on coral, instead of the broader ecosystems within the GBR, which according to R04 notably relates to a “charisma gap” with seagrass:
“There is a charisma gap between sea grasses and corals; we should focus much more on the former, not the latter, [which] don’t have the same panache but have a much higher importance in terms of ecosystem function and stability, and ecosystem services provision.”
R08 agreed and noted that:
“Most of the Great Barrier Reef is not covered by coral, but by sand, seagrass, other types of seascape that are healthy. I worry that researchers are too obsessed with coral diversity, not focused on blue carbon or seagrass, or shellfish reefs which are not coral.”
R01 lastly noted other significant barriers to the program including scientific debate over the facts of climate change, social barriers including lack of awareness, the risk of transboundary impacts (some of which are already noted above, like drifting of coral larvae) and lack of accountability for consequences, as well as concerns over how to manage uncertainty and who has authority.
4.2 Solar geoengineering: Fogging and marine cloud brightening
A second class of radical interventions, also supported by RRAP, involves solar geoengineering in the form of artificially shading by fogging coral reefs, as well as cooling through marine cloud brightening. RRAP initially considered multiple options for regional solar geoengineering, including surface films, a few microns thick, to reflect more sunlight back, or the pumping of water columns, artificial upwelling, to cool reefs. But these were deemed unfeasible, and instead shading efforts by means of fogging were put forward as better techniques to mimic the effects of sea fog, reducing the amount of sunlight reaching the ocean surface. Given that it is done at a higher altitude, cloud brightening could offer regional reef protection, potentially for a longer period of time, by deflecting more sunlight back into space, cooling and shading the reefs below.
R21 helpfully distinguished fogging from cloud brightening in the following manner:
“Fogging and cloud brightening are both deployed from ships, though with different types of nozzles and different types of purposes and scales. Fogging involves spraying on “doldrum days” of little wind and rain over more localized areas, which dissipates in a matter of hours, with very small particles, i.e., 100 nanograms, in order to help shield from bleaching events. Marine cloud brightening is not as targeted and is 4x larger than shading and fogging (particles around 1 micron in size), quite different than Sky River and “cloud seeding”, i.e., because the goal is to keep clouds stable rather than causing precipitation and having it rain. Cloud brightening would be typically focused on biologically important reefs, i.e., healthy reefs that act as “source” or “mother reefs” as well as where there is more movement between Reefs.”
R23 notes a “favorable energy leverage” in contrast to artificial upwelling, which “involves pumping up a lot of water, only get a similar amount of energy back in the cooling”. They continued:
“With cloud brightening, put in energy, get salt crystals, natural processes, grow some 500,000 times in size, without you doing a thing, or adding more energy, magnified again by reflection of sunlight, separates it from all other ideas, engineeringly feasible, at ecosystem type scale, very good energetic leverage. You atomize seawater for cloud brightening, both techniques are the same, pumping and atomizing water, difference in size, everything else is different. Cloud brightening involves targeting dry sea-salt crystals after water evaporates, as small as 30–40 nm.”
R22 added, regarding the differing degrees of knowledge and uncertainty, that:
“Relying on cloud processes in order to provide protection is sound science but for fogging, the particles are not going up into super-saturated conditions in order to create shading, thus [there are] larger particles but also more energy along with greater volume.”
Both fogging and cloud brightening consequently involve different deployment dynamics, and are currently at different stages of development. R15 argued that fogging and shading efforts “are ready to be deployed now, and scaled up in 2025, and can be mainstreamed during a sustained bleaching event, leading to increased survivorship of reefs.” Cloud brightening, by contrast, can be deployed at a more regional scale, unlike fogging, which is more localized. Moreover, while fogging only reduces light penetration, cloud brightening can decrease local temperature over large scales. But it is further off in terms of development, possibly ten years away. Lending support to this claim, one recent expert survey of geoengineering found a consensus that marine cloud brightening would not be broadly deployable until 2040 .
While fogging could persist for hours to days (see Fig 7 Panels A-C), cloud brightening, if successful, would be more sustained and last for weeks to months. As R08 explained, “marine cloud brightening involves using small particles of water and salt to increase reflectivity of the cloud, possibly mix other things in there… flying airplanes around or using high powered jets at sea level to fire stuff into atmosphere–[there might be a] network of 100s of these things.” Condie et al.  noted these techniques have strong efficacy, concluding that:
“when solar radiation management is applied at regional or GBR-wide scales… more uniform reductions in heat stress may be achievable. For example, modelling the effect of radiative forcing on ocean temperatures over GBR reefs indicates that a 30% increase in low-level cloud albedo (corresponding to a 6.5% increase in average albedo) would have reduced heat stress by 7.5 ± 3.5 Degree Heating Weeks over the summer of 2015–2016 and 8.3 ± 3.7 Degree Heating Weeks over the summer of 2016–2017.”
Source: Photographs courtesy of Southern Cross University. A shows a balloon being launched for marine cloud brightening, B fogging off the back of a ferry near Magnetic Island, C researchers testing various nozzle sizes and diffusion patterns.
R22 adds that cloud brightening is essential to reef protection, arguing that it “takes precedence as the only wide-scale method we have that would give the Reef a fighting chance to survive climate change in the coming decades.” The benefits of solar geoengineering could extend beyond local protection of the Great Barrier Reef to engender applications to damaged reefs elsewhere, and even lead to future “export” opportunities.
Researchers argued that deployment on the GBR could be the “ideal exemplar” with broad future deployability “readily used in reefs elsewhere” (R21), and that could “export intellectual property and technology and knowledge” to “protect ecosystems, but also infrastructure, such as power plants, dams, and even military installations” (R20). R04 agreed about cross-applications in other areas, such as using fogging to shade cities or lower temperature change and heat stress in urban environments as well as improve animal welfare in intensive feedlots.
Regional solar geoengineering is not without barriers and risks, however. While fogging could be done locally, R18 warned that cloud brightening would need to be done “at the scale of half the GBR, which is huge”, thereby precluding any sort of targeted efforts, and which could also as a result face greater barriers over feasibility, social acceptance, financing, and political support. R23 picked up on this theme of scale as well, stating that:
“0.7% of the Earth’s surface is the GBR. There is an immense challenge even scaling up to that, still the size of Italy. The idea that you can just roll it out anytime soon, hundreds to thousands of times larger than current testing, is quite unrealistic.”
R21 commented on how both forms of geoengineering are energy intensive, sort of akin to running a perpetual snow blower: “when you do shading, the orientation of nozzles and speed of ships matters; they may have to use a diluting fan to blow it away, and you have to be on top of how quickly are the particles coming out: sort of like an artificial snow blower running all the time”. Given the scale involved, cloud brightening would most likely require energy-intensive aircraft, which then creates its own set of obstacles, with R21 explaining that this needs, in the context of Australia, a “whole extra level of regulation and approval, need permission to fly into clouds, which requires extra certification from pilots and plane owners, which is expensive and time-consuming.”
R22 added that quantifying the impact that is being achieved is difficult, including if there are complications (e.g., fogging and effects of cloud cover or variable wind conditions, slow wind speeds under doldrum days), so one cannot just put a radiometer underneath and measure (e.g., since one “can get appreciable shading from a practically invisible plume”). R22 also noted the need for network of sensors, but that is expensive. In the absence of the requisite infrastructure, it can be difficult to gain the necessary validation that cloud brightening (or fogging) has been successful, which is a severe limitation for broader funding and deployment. Instead, R21 described that, at present, the best that can be done is to get a limited number of measurements and then extrapolate from that to gain a sense of effectiveness. As one potential solution, they noted that satellites were recently used for the first time but, even then, this led to difficulties with getting them overhead at the right time, in order to detect and assess the plumes.
Moreover, both R21 and R22 noted the general lack of public involvement, commenting that “the public is not really involved, not any kind of citizen science, and limited engagement with Aboriginal peoples.” The latter in particular represents a potential obstacle for such efforts to have a more deeply radical impact, in the sense of Morrison et al.  and is reminiscent of well documented tensions and power imbalances in conservation efforts more generally . With regard to public acceptability, R23 also touched on the issue of costs, and how sustaining a cloud brightening program for the GBR would amount to “hundreds of millions to a billion dollars a year, easily, and that’s only assuming you did the whole reef at once every year, but the whole reef doesn’t bleach, nor does it bleach the whole year.”
Lastly, R04 cautioned that deployment could harm cloud cover over, and thus the weather patterns of, inland forests, noting that:
“we know so little about cloud dynamics, and all of the rainforests in Australia don’t get moisture from rain, they get it from clouds, so they are cloud forests, where water condensed onto leaves and structures… changing clouds with artificial technology could have serious negative risks to world heritage sites, like the Gondwana Rainforests of Australia, changing clouds in unknown ways. Events initiated at sea could have an effect at land.”
R23 agreed and elaborated that solar geoengineering could “make it harder for it to rain in the tropical forests,” and that “weather patterns will change, which could even impact negatively other parts of the reef or agriculture on land.” R01 spoke about how geoengineering deployment could also negatively affect coastal ecosystems and water-table systems, while also worrying that such measures might end up providing uneven spatial protection, unintentionally or not, with water flowing more towards Brisbane and Cairns, not other indigenous areas, which could interfere with, inter alia, the ability of indigenous groups to undertake fishing and diving.
4.3 Nature-based ecosystem restoration: Community forestry conservation and protection
Nature-based ecosystem restoration within the Wet Tropics Heritage Area in the form of community forestry conservation and protection is a third radical intervention. Such methods have included both restrictions on deforestation and degradation, and afforestation and reforestation efforts. In terms of restrictions, there have been prohibitions on deforestation and logging since the 1970s , followed by quotas on hunting and restrictions on fishing . R08 spoke about how these efforts have “enhanced the resilience of the forest,” and led to the “preservation of biodiversity, especially large predators in the forest.”
In terms of community-led afforestation and reforestation, strategies to reverse forest fragmentation have centered on restoring existing habits and linking them together in corridors, maximizing the ability for species to replenish restored areas and move between previously isolated fragments . Efforts were also undertaken to reduce erosion, to rehabilitate riverbanks, and to revegetate degraded areas with endemic tree species. Rather than implement these solely in a top-down manner, the Queensland Department of Environment’s Community Nature Conservation Program and Trees for the Tablelands has run an extensive community tree-planting group with hundreds of thousands of plantings between 1995 and 1998. More recently, a Community Rainforest Reforestation Program has facilitated small-area plantings of a range of species including local cabinet-timber species, with many of the plantings being done along watercourses and adjoining native forest, areas long recognized for their importance in biodiversity conservation . Some reforestation programs are managed entirely by local groups, such as the Girringun Aboriginal Corporation, an association of Australian Aboriginal groups in north-eastern Australia. Other efforts, in ecosystems such as those illustrated in Fig 8 (Panels A-B), have focused on protecting forest canopies or replenishing mangroves.
Source: All photographs taken by the authors during field research. Note: A shows forest regeneration near the Crater Lakes, B mangrove restoration in the Wet Tropics near Etty Bay.
Given the importance of tourism both to the local economy and its cultural importance, including the status as a World Heritage Site, an additional solution has been the implementation of minimally invasive ways for visitors to tour the parks. This includes the creation of canopy walks and sky trains, which reduce the number of visitors entering the forest floor , and a concentration of tourist activities in a limited number of areas , with walking tracks, camping areas, day-use areas and off-road vehicle use of old forestry roads and tracks all concentrated near the periphery of the forests. R06 spoke about how these actions mean that “tourist activities generate huge revenue for the park, but have almost no environmental damage, as they occupy less than 0.1% of the total land area.” Other examples include the construction of board walks, artificial surfacing, and compaction of walking tracks with durable materials, rotation of heavily used camp sites to allow for recovery and closure of some water holes to swimming in the dry season .
A final protective measure is a progressive climate adaptation plan for the entire Heritage Area . The Wet Tropics Management Authority  runs an “Accept, Act, Adapt: Climate Adaptation Plan for the Wet Tropics 2020–2030” program which was developed in consultation with local stakeholders. It focuses on a tripartite set of measures: establishing inclusive regional adaptation planning frameworks; improving landscape resilience; and facilitating transition to adaptive communities and industries. As R17 surmised, “The Climate Adaptation Plan is one of the most progressive in Australia in terms of protecting forests and including alternative views from Traditional Owners.”
Most importantly, these interventions have protected the forest and enabled it to recover from previous degradation. The entire Heritage Area now boasts strong land management practices, low rates of illegal activity, and high rates of recovery, with Weber et al.  calling it “one of the most effectively regulated and managed protected Areas in the world.” Fig 9 shows a rapid shift in land tenure from private holdings and even active logging and timber production to preservation and park management. In addition, these collective ecosystem restoration efforts have culminated in myriad benefits to local communities, including enhanced ecosystem services provided by the forest, better environmental maintenance, personal benefits and even spiritual significance (see Table 3). Some of these benefits flow particularly to groups of Aboriginal Australian Traditional owners (Indigenous groups), given that they both help preserve cultural values and custodial rights but also generate tourism revenues, training, and local employment [59, 63–65]. On this point, R14 underscored the positive impacts of “regional transition plans” and “structural adjustment packages” for helping workers in the logging industry to develop new livelihoods, suggesting that this could provide a template for the mining sector. The Commonwealth’s Environment Protection and Biodiversity Conservation Act of 1999 provides an additional layer of protection because it restricts any action that has, will have, or is likely to have a significant impact on the World Heritage values of a World Heritage property.
Source: , based on data from the Wet Tropics Management Authority.
Notwithstanding these benefits, some barriers do exist. The first is inconsistent and often declining funding for park protection, with the park being perpetually undervalued for many of the services it provides . MacLean et al.  caution that funding for Aboriginal forest management is largely limited to protected area management, and then mainly where Aboriginal people own and/or co-manage the land, with only modest levels of support overall. Moreover, multiple industrial activities adjacent to the Heritage Area continue to pollute and degrade it, and contribute to climate change, including some of those shown in Fig 10 such as crude oil refining and transport (Panel A), coal-fired power generation (Panel B), sugarcane refining (Panel C), and cobalt and nickel refining (Panel D). R14 noted that these activities could greatly threaten both forests and the Great Barrier Reef:
The real threat to climate protection is the continued industrialization of the terrestrial catchment that drains into the reef. There you have ample farming and mining, pushing sedimentation into the reef, port development, a coal mining boom, shipping, building an LNG terminal, all of these erode the reef and contribute to climate change.
Source: All photographs taken by the authors during field research. Note: A shows crude oil tankers being unfueled in the Port of Townsville, B a power plant fueled by coal seam gas near the Forest Boundary, C the Tully Sugar Refinery, D the coal- and oil-fired Palmer Nickel and Cobalt Refinery.
Lastly, reforestation sets restrictions on forest activity, some of which could constrain agriculture and, Indigenous practices. As noted by R07, the potential benefits of protection can be very inconsistent for local communities, specifically invoking Vanuatu: “In some countries around the world, World Heritage means ‘jack all’… that means we cannot go to that place anymore”.
4.4 Engineered carbon removal: Enhanced weathering and ocean alkalinization
The final radial climate intervention is enhanced weathering, a form of carbon removal, and ocean alkalinization, a potential way of addressing ocean acidification. Field trials for enhanced weathering on a working plantation in Gordonvale, Australia began in 2018, involving sugarcane and a multi-year crop cycle as well as the application of basalt to agricultural environments . R09 explained how it works in the following manner:
“Enhanced weathering is about making the natural carbon cycle more rapid. Without intervention, it takes a long time, there is a centuries- to millennia-long cycle of weathering and accumulation of calcium carbonate, in the form of limestone rock, which got their naturally. When silicate rocks weather, during that process carbon dioxide is converted to bicarbonate, that leaches together into the water and sea. That process has been going on, but in geological time, [there is a] big drawdown of CO2.
[Here it is accelerated] by crushing rocks, increasing their surface area, then distributing them on fields, where weathering is accelerated. If we can accelerate that enough, to a human rather than geological time scale, it could be an interesting way of reducing atmospheric CO2.”
Multiple respondents—R08, R10, R11—articulated how enhanced weathering seems to work most effectively in the tropics, that is, given the hot and humid environment and consistent rainfall, the weathering occurs faster. R10 also spoke about how the technology has strong connections to natural processes, noting that: “the idea is that enhanced weathering is essentially natural, it’s doing something in a place and time that is happening already; it’s not changing the environment, it’s organic, doing a natural process just in a faster and more useful manner.” R09 further indicated that the basalt, shown in Fig 11 (Panels A-C), could, as it weatherizes in the sugarcane field, end up storing (small amounts of) carbon for up to 1,000 years, making it a very durable form of storage–moreover, one that is distinct from the sequestration capacity of other forms of carbon removal such as soil carbon sequestration and biochar.
Source: All photographs taken by the authors during field research. Note: A shows the sugarcane crop before application, B the soil amendments and C the weathered basalt that had been in the field for approximately one year.
In addition to storing carbon, other potential benefits from and applications of enhanced weathering can be “trace metal mobilization,” whereby the process collects and removes metals out of the ecosystem (R09). In this regard, the experts envisioned that materials might be strewn on the Tablelands of Far North Queensland, thereby helping to remediate these damaged ecosystems and rectify a source of downstream contamination, e.g., for the Great Barrier Reef. Furthermore, by helping to enrich soils and provide necessary minerals, there was discussion of improvements to crop yields, also with possible benefits for the Great Barrier Reef, with R10 suggesting that “application has seen a 1–3% increase in crop yields, and enhanced weathering can also help protect the Great Barrier Reef by providing a form of ocean alkalization and reducing fertilizer and nutrient runoff, also better managing silicon, nitrogen, and reducing algae.” Given that other forms of climate intervention, including all solar geoengineering approaches, are unlikely to be of assistance with ocean acidification, this presents enhanced weathering as potentially unique. Although generally at field-trial stage, Low et al.  offer evidence for broader discussion of the potential for enhanced weathering to facilitate higher production yields, crop protection from pests and diseases, offering a substitute for expensive fertilizers and pesticides, and improved water quality (e.g., in Great Barrier Reef catchments).
Barriers to enhanced weathering include uncertain levels of broader public support, including some confusion around the name itself. R09 spoke about how it has “a public relations problem as far as people are concerned: mining is thought of as bad, putting mined stuff on soils is bad, it’s thus hard to counter that thought.” Indeed, studies of enhanced weathering in other contexts have found strong concerns raised about it on behalf of the public [68, 69]. Other respondents (R08, R14) spoke about problems of scaling the technology up, and R10 spoke about the danger of “heavy metal concentration, [given that] some forms of enhanced weathering use slags and mineral byproducts, ores that are specifically mined due to high metal content, making high rates of environmental pollution an issue.” Lastly, R10 noted that if enhanced weathering was to scale up, it could lead to a very “industrialized form of management of agricultural land”, namely:
5. Discussion: Complexity, risk, and radicality
Treating adaptation, solar geoengineering, community reforestation, and carbon removal as prospective parts of an integrated portfolio for climate intervention yields insights related to complexity, risk, and radicality.
5.1 Complexity, coupling and land-sea interactions
Even though they are being deployed in the same geographic region (Queensland) and with the same stated goal (climate protection), the four radical interventions have invariably different actor coalitions, drivers, and dynamics related to timing, distribution of costs and benefits, sectoral incidence, and their relationship to uncertainty. As Table 4 indicates, adaptation in the form of coral reef regeneration holds costs for planners now, with benefits accruing mostly to later generations, whereas solar geoengineering, which acts more quickly, sees costs incurred now along with benefits occurring now. Nature-based restoration via forestry only accrues its benefits over decades given the time it takes for new trees to grow and because emissions reductions must outlast risks related to forest fires, logging, and disease, with the former especially germane in Australia. Enhanced weathering, like adaptation, has long term benefits in carbon storage (over the next millennia) but incurs costs now–although possible co-benefits in the present should also be kept in mind. Moreover, the distribution of where costs and benefits will accrue is skewed, with some of the methods (adaptation, geoengineering, and nature-based restoration) having benefits primarily at the local level (the reef, the forest) whereas carbon removal predominantly benefits the planet through general carbon storage and emissions displacement. Furthermore, all the approaches involve different sectors—spanning fisheries (adaptation, geoengineering), tourism (adaptation and reforestation), shipping and aviation (solar geoengineering), forests (reforestation), agriculture (reforestation, enhanced weathering), and the extractive industries (enhanced weathering). Lastly, they all have different relationships with uncertainty. Some (adaptation) demand action be taken now despite uncertainty, whereas others (geoengineering, for example) could lend themselves to action being taken later only after uncertainty and risks are reduced.
Interesting couplings emerge with our four radical interventions as well. R22 noted how the nozzle technology being developed for solar geoengineering could also see widespread use in the “humidification of greenhouses”, in the “distribution of pesticides”, in “industrial mining applications”, and even in “pollution control via sprayers to tamp down coal dust on coal trains.” R08 also added that solar geoengineering vis-à-vis cloud brightening need not be limited to the coral reef, and that it could be used to reduce temperatures and manage heat stress within forests, helping assist with nature-based ecosystem restoration, or even to reduce the heat island effect in urban environments. This sees a crossover between land-sea interactions of a kind that is an emergent issue in such discussions, where cloud brightening or fogging can come to protect forests and enhance land-based management and, more generally, demand greater attention be paid to these coastal and littoral areas.
Enhanced weathering, as previously noted, can assist with reef management and reducing ocean acidification. R09 and R10 both commented how enhanced weathering can lead to alkalinity, which keeps moving dissolved bicarbonate through the ecosystem. Given that carbon dioxide is a weak acid, when it dissolves in water, one of its main effects is ocean acidification. But enhanced weathering has the potential to enable the opposite of that process, i.e., alkalinization. It can thus become a tool of climate adaptation in addition to its role vis-à-vis engineered carbon removal, not to mention representing a compelling “boundary object”  whereby land-based measures can intersect and interact with sea-based measures.
5.2 Risk, system-risk, and multi-scalar effects
Our data in Section 4 revealed both myriad benefits for climate protection, but also that these are counterbalanced—at the individual technology level—by myriad risks. In other words, for every benefit a form of climate protection might offer, it comes with a collection of risks as well. We conceptualize and wrestle with these through Fig 12. No option is free of risks, but no option either has only risks (that is, these also have real, albeit prospective, benefits). Moreover, any risks that do exist must also be considered along with the risks that would eventuate from doing nothing , e.g., from failing to address the damages from crown-of-thorns starfish outbreaks and repeated bleaching events. Moreover, some technology-level risks are common across multiple radical options, such as difficulty in scaling (coral reef regeneration, fogging and cloud brightening, and enhanced weathering), lack of public understanding and social acceptance (fogging and cloud brightening, enhanced weathering), and lack of funding or finance (fogging and cloud brightening, reforestation, coral reef adaptation). Similarly, some benefits are common across different options, including the ability to export the technology for climate protection elsewhere (coral reef regeneration, fogging and cloud brightening) and specific protection of the Great Barrier Reef (coral reef regeneration, fogging and cloud brightening, enhanced weathering via alkalinization). To be clear, not taking action also has consequences and should be considered as part of a risk assessment, so these findings need juxtaposed with counterfactual scenarios comparing deployment vs. non-deployment.
Source: Authors, based on the qualitative data described in Section 4.
The multifaceted nature of these technology-level risks maps well onto recent examinations of risk by Lockie , who assessed the RRAP (which involves three of our four radical climate interventions). Lockie noted that some forms are closely tied to business risk–any threat to the operation of a business or project including finance and markets, regulatory issues, health and safety, reputation, and interaction with stakeholders and communities. Others pose social risks–threats to individuals and groups that arise because of social change precipitated by the decisions of external actors. Still others present biocultural risks–threats to the interplay of cultural and biological diversity generative of the full diversity of life.
Interestingly, risks do not only exist at the level of the technology. Intersecting, systems-level risks could also emerge due to deployment of all four options as part of a portfolio. As shown in Fig 13, fogging and cloud brightening could negatively impact cloud forests by changing precipitation patterns, and have negative impacts on coastal ecosystems, water tables, and weather on land (affecting agriculture as well as the processes upon which the effectiveness of enhanced weathering is incumbent). Coral reef regeneration through assisted evolution and genetic modification could adversely impact public support, not only of such activities, potentially through cross-over associations with the use of genetic engineering for food production, but of other kinds of efforts which might come to be seen as similarly “interventionist” on the Great Barrier Reef [72, 73]. Done poorly, enhanced weathering could entail the release of toxic pollution which can interfere with both reef restoration and reforestation, and if scaled up, facilitate the industrialization of agriculture with bigger machines and increased traffic, which could degrade forests. Conversely, reforestation, by demarcating certain plots of land as “off limits”, could set restrictions that preclude their use for enhanced weathering.
Source: Authors, based on the qualitative data described in Section 4.
Risks moreover have the potential to compound when radical climate interventions are combined in a portfolio. R08 hinted at this possibility, noting that “the larger the scale of intervention, the more technologies you involve, the greater the potential for positive impact, but the greater the risk.” R22 also spoke about the risk that, when you add “multiple interventions together, risks aggregate and become even more unpredictable, and perhaps insurmountable.” Condie and colleagues  noted as much in their study of multiple reef protection measures, concluding that “the effectiveness of any intervention in protecting the Great Barrier Reef will depend on many system interactions and may only become apparent over multi-decadal timescales.”
5.3 Radicality and governance
Aggregating different radical climate protection measures not only leads to technology-level and systems-level risks, it also, perhaps paradoxically, climbs up the ladder of radicality proposed by Morrison et al. . Morrison’s typology suggests that deep transitions, or those at the highest scales (i.e., 5 and 6) on the spectrum of radicality, must attempt to correct power asymmetries and restore some degree of accountability, legitimacy and effectiveness in governance in order to be deserving of being called “radical”.
We do see such degrees of radicality in our integrated portfolio of reef regeneration, fogging and cloud brightening, reforestation, and enhanced weathering, albeit often in a nascent or not fully fleshed-out form. R08 spoke about how using some of these measures could be “deeply radical and transformative”, especially when evaluated in relation to the capacities and structures of other countries, going on to note that:
“I don’t underestimate how radical it is what Australia is trying to do. And, Australia already had radical forms of governance when it came to protecting the Great Barrier Reef with multiple interconnected sociotechnical systems. I mean, the state already had a reef trust as a vehicle for multiple levels of government to invest in reef protection, research agencies basically leveraged the trust and put a joint submission to the commonwealth government. They’re funneling upwards of AUD$1 billion into reef protection over the next decade. And they are firing on all cylinders, using a mosaic of different climate interventions cutting across reefs, clouds, land-based measures, and even climate mitigation.”
R14 similarly evaluated the governance of climate interventions in this part of Australia as “best practice, best in the world, as good as it gets, with fully delegated regional agencies that are well resourced and well-staffed, with state-of-the-art monitoring and cutting-edge science.” R19 spoke about the specific involvement of Aboriginal and Indigenous groups as well, commenting that:
“We really support free prior informed consent among Traditional Owners within our climate protection efforts. Moving corals from one sea country to another is not done without extensive consultations, to ensure the science is sound, that there is enough variability and thermal tolerance, but also that everyone is respected. The community is very collaborative, on the front foot, with a proactive approach, built in all the way through, from managers to regulators and tricky areas like the involvement of Traditional Owners.”
Driving this point home, R01 sketched out the kinds of changes in terms of decision-making processes and regulatory approaches which would be necessary for ongoing efforts to be successful. In particular, they noted the broad need to engage with and create space for Traditional Owners and their understanding of ecosystems, specifically asserting that “self-determination and indigenous knowledge are two sides of the same coin”. The limitations and challenges observed by some interviewees with regard to the inclusion of indigenous communities remind us that putting those principles and ideals in practice requires engagement with diverse values and assumptions of actions, as well as acknowledgement that also engagement processes and participatory schemes can be imbued by power relations .
R20 added that even though “the restoration regulation space is very nascent, what’s going on in the Great Barrier Reef is super-duper compared to everywhere else, it has a restoration policy, adapting fisheries policies to accommodate for restoration, strong educational and outreach programs, and a platform that facilitates the respectful inclusion of 72 Traditional Owner Groups in the region that have a claim to owning sea country or forest territory.”
Other respondents spoke about the ability for climate interventions to lead to new forms of ethics and ways of valuing nature, thereby promoting a deeper re-valuation in society at large. R08 specifically stated that:
“As wonky as the technology is for some of these interventions, I don’t think it’s really about the technology. It’s about something deeper. It’s about changing the way we relate to seascapes and landscapes that are important to us, technology is just a set of tools that might help us. The critical step is that we’re willing to interact with seascapes in a different way, to see them as something different. This leads to a profoundly different way of thinking about ecosystems.”
R06 added that Australia is leading a vanguard of “different ethics and climate priorities here; we’re very much a coastal society, very much a society used to living with natural resources, it’s creating an opportunity space for experiments and trials that doesn’t exist anywhere else on earth.” Both statements imply that Australian efforts have elements approaching Morrison’s final two levels of strategic and deeply radical actions, for they to change the fundamental values and drivers contributing to climate change.
Radical climate interventions are often separated into categories that avoid any overlap in peer-reviewed research. For example, studies convened by the National Academies of Science of carbon removal are increasingly split from solar geoengineering [74–76], and interventions on land (such as reforestation) are treated as distinct from efforts to protect coral reefs in the sea or preserve ocean biodiversity. Within the scientific literature, this neglects synergies, both positive and negative, and justice tradeoffs among the different climate-intervention options (e.g., ).
Yet, studies on such interventions in the Australian [29–31] and marine contexts  continue to buck this trend–perhaps because concrete national or issue-based agendas bring together options that are technically dissimilar but share a common purpose or impact a common environment or polity. Our study builds on these literatures and draws from expert interviews and extensive site visits to reveal the integrated drivers and dynamics of deploying reef regeneration, fogging and cloud brightening, community reforestation, and enhanced weathering as a portfolio for tackling an urgent problem, namely, the damage and destruction of the Great Barrier Reef. While acknowledging important distinguishing features of individual approaches, systemic perspectives are needed that account for the multiple interrelations between a variety of potential climate interventions. Treating such options as a portfolio reveals previously unidentified technology-level benefits and prospectively positive couplings, but also technology-level and systems-level risks.
But a portfolio approach also creates opportunity for more transformative forms of change, particularly in combination with existing management approaches. Whereas some options such as solar geoengineering, engineered carbon removal or forestry may not be deeply radical in isolation, they become closer to representing the deeper forms of radicality when put into a portfolio. What is more, such a portfolio, if coupled with appropriate levels of governance, has the potential to improve the performance and effectiveness of more conventional approaches. The whole becomes greater than the sums of its parts—and the potential for compounded risks are juxtaposed with the chance of equally important rewards.
Finally, by focusing on one of the only places where a portfolio of radical climate interventions is being assessed and employed, the current study scopes novel subjects and issues which might become increasingly important in the future. In particular, we elucidate the importance of considering land-sea interactions. Such interactions are germane both to a fuller range of potential risks (and benefits), especially considering the unique “biocultural”  importance of the ecosystems involved. In a similar vein, the lessons to be learned from the trials on the Great Barrier Reef establish it as a test laboratory, conceptually and practically, with relevance for other future efforts. Indeed, a number of experts underscored the intention and desire for those efforts that are successful to be translated to other contexts, e.g., threatened coral reefs in develop countries, where similar challenges are being confronted.
In sum, we build upon Morrison et al.  to show that radicality might also emerge as a consequence of a range of climate interventions being undertaken together. When it comes to engendering public awareness of the extent of the threat to cherished ecosystems such as the Great Barrier Reef, perhaps the willingness to explore such radical options instills a sense that the problem is more severe than realized. The language of R22, is instructive here, to give the Reef a “fighting chance”. Expanding alongside the severity of the climate crisis, it could well be that the kinds of solutions considered send a message of their own.
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