The RRAP Cooling and Shading R&D Subprogram aims to investigate technologies to prevent or reduce bleaching stress on coral reefs by reducing the amount of solar radiation reaching the Reef.
This includes the concepts of creating shade through clouds, mist, fog or surface films to reduce solar radiation during high-risk periods for coral bleaching.
The interventions being investigated range from the scale of an individual reef to protecting the entire Great Barrier Reef Marine Park.
Cooling and shading interventions aim to maintain existing biodiversity, cultural values, and ecosystem services, rather than supplementing or replacing them.
Providing they can be successfully deployed at large scales, cooling and shading interventions have amongst the highest potential of the interventions being examined by RRAP. At smaller scales, targeted cooling and shading may protect high-value sites.
Modelling has shown cooling and shading interventions to be strongly synergistic with other novel interventions being investigated by RRAP as well as with traditional management techniques such as crown-of-thorns starfish control.
Despite their promise, these interventions are as-yet unproven and technically challenging to develop.
This subprogram prioritises rapid technology development and field testing to determine the technical feasibility. In parallel, a large effort will be devoted to atmospheric sampling, monitoring and modelling to inform assessment of efficacy and risk.
Cooling and shading techniques represent a deliberate attempt to temporarily alter the environment of coral reef ecosystems to relieve stress. While eco-engineering approaches are commonly used in land conservation, their application for marine conservation, as well as the proposed large spatial scales have scarce precedent. Accordingly, engagement with Traditional Owners, stakeholders and the public, along with robust governance, are as critical to achieving successful implementation as the technical and engineering development.
The Cooling and Shading R&D Subprogram aims to progress both categories of cooling and shading interventions in parallel:
Cooling and shading interventions represents a temporary disturbance of the dynamic physical environment. Efficacy and risk are therefore dependent on the prevailing conditions at the location and future time of implementation.
Modelling (across multiple scales, resolutions, domains and approaches) will be required to estimate efficacy, design and interpret field experiments, optimise deployment strategies, and quantifying risk.
This subprogram also aims to address the significant knowledge gaps in atmospheric and meteorological conditions over the Reef, with an early foundational science component in the atmospheric survey, atmospheric monitoring and modelling projects.
It includes identification and scientific investigation of risks of unintended impacts and will closely integrate with an independent effort (facilitated by the Eco-RRAP Subprogram) to enable their quantification and assessment.
Funding of development pathways for individual intervention methods is stage-gated in anticipation that not all technologies will prove viable. The timeline for reef scale interventions aims for technology transfer to industry commencing from Year Four, and for regional-scale interventions, from Year Eight to 10.
Testing surface films in the National Sea Simulator, AIMS
This project is focused on understanding the atmosphere and cloud physics over the Great Barrier Reef. The project collects and analyses highly detailed information over a specific area of the reef, characterising the interaction of meteorological, aerosol, and cloud microphysical processes that influence the radiative transfer of energy from sun to surface waters and corals.
This project extends the atmospheric survey in space and time, providing data for northern, central and southern regions of the Great Barrier Reef and across seasons, creating a data set that will inform GBR-wide assessment of atmospheric conditions.
The objective of this project is to develop, calibrate, and verify the models required to underpin design, proof of concept, field testing and permitting activities for cooling and shading interventions.
This project provides leadership, program management, sub-contractor management and field support services across the Cooling and Shading Subprogram. The management team will also foster collaboration, innovation and integration among projects, partners and stakeholders.
This cross-cutting project will develop engineering systems necessary to deliver the cooling and shading interventions, as well as review and update the ongoing engineering feasibility of each intervention.
This project will progress fogging technology and undertake on-reef proof of concept experiments to demonstrate a seawater fogging system aimed at localised cooling and shading of reef environments.
This project progresses cloud and sky brightening technology to on-reef proof on concept experiments, demonstrating sea salt aerosol cloud condensation nuclei generating technology at scale.
Baird, M. E., Green, R., Lowe, R., Mongin, M., & Bougeot, E. (2020a). Optimising cool-water injections to reduce thermal stress on coral reefs of the Great Barrier Reef. PLoS ONE, 15, e0239978. https://doi.org/10.1371/journal.pone.0239978
Baird, M. E., Wild-Allen, K. A., Parslow, J., Mongin, M., Robson, B., Skerratt, J., Rizwi, F., Soja-Woźniak, M., Jones, E., Herzfeld, M., Margvelashvili, N., Andrewartha, J., Langlais, C., Adams, M. P., Cherukuru, N., Gustafsson, M., Hadley, S., Ralph, P. J., Rosebrock, U., … Steven, A. D. L. (2020). CSIRO Environmental Modelling Suite (EMS): Scientific description of the optical and biogeochemical models (vB3p0). Geoscientific Model Development, 13, 4503–4553. https://doi.org/10.5194/gmd-13-4503-2020
Condie, S. A., Anthony, K. R. N., Babcock, R. C., Baird, M. E., Beeden, R., Fletcher, C. S., Gorton, R., Harrison, D., Hobday, A. J., Plagányi, É. E., & Westcott, D. A. (2021). Large-scale interventions may delay decline of the Great Barrier Reef. Royal Society Open Science, 8, 201296. https://doi.org/10.1098/rsos.201296
Tagliafico, A., Baker, P., Kelaher, B., Ellis, S., & Harrison, D. (2022). The effects of shade and light on corals in the context of coral bleaching and shading technologies. Frontiers in Marine Science, 9. https://doi.org/10.3389/fmars.2022.919382
Butcherine, P., Tagliafico, A., Ellis, S. L., Kelaher, B. P., Hendrickson, C., & Harrison, D. (2023). Intermittent shading can moderate coral bleaching on shallow reefs. Frontiers in Marine Science, 10. https://doi.org/10.3389/fmars.2023.1162896
Eckert, C., Monteforte, K. I., Harrison, D. P., & Kelaher, B. P. (2023). Exploring meteorological conditions and microscale temperature inversions above the Great Barrier Reef through drone-based measurements. Drones, 7, 695. https://doi.org/10.3390/drones7120695
Hernandez-Jaramillo, D. C., Harrison, L., Kelaher, B., Ristovski, Z., & Harrison, D. P. (2023). Evaporative cooling does not prevent vertical dispersion of effervescent seawater aerosol for brightening clouds. Environmental Science & Technology, 57, 20559–20570. https://doi.org/10.1021/acs.est.3c04793
Eckert, C., Hernandez-Jaramillo, D. C., Medcraft, C., Harrison, D. P., & Kelaher, B. P. (2024). Drone-based measurement of the size distribution and concentration of marine aerosols above the Great Barrier Reef. Drones, 8, 292. https://doi.org/10.3390/drones8070292
Ellis, S. L., Butcherine, P., Tagliafico, A., Hendrickson, C., Kelaher, B. P., Schulz, K. G., & Harrison, D. P. (2024). Shading responses are species-specific in thermally stressed corals. Frontiers in Marine Science, 11. https://doi.org/10.3389/fmars.2024.1333806
Hendrickson, C., Butcherine, P., Tagliafico, A., Ellis, S. L., Harrison, D. P., & Kelaher, B. P. (2024). Combining shading and lipid-enriched diets as an adaption tool to reduce coral bleaching. Journal of Experimental Marine Biology and Ecology, 572, 151988. https://doi.org/10.1016/j.jembe.2024.151988
Hernandez-Jaramillo, D. C., Medcraft, C., Braga, R. C., Butcherine, P., Doss, A., Kelaher, B., Rosenfeld, D., & Harrison, D. P. (2024). New airborne research facility observes sensitivity of cumulus cloud microphysical properties to aerosol regime over the Great Barrier Reef. Environmental Science: Atmospheres. https://doi.org/10.1039/D4EA00009A
Richards, L. S., Siems, S. T., Huang, Y., Zhao, W., Harrison, D. P., Manton, M. J., & Reeder, M. J. (2024). The meteorological drivers of mass coral bleaching on the central Great Barrier Reef during the 2022 La Niña. Scientific Reports, 14, 23867. https://doi.org/10.1038/s41598-024-74181-2
Ryan, R. G., Eckert, C., Kelaher, B. P., Harrison, D. P., & Schofield, R. (2024). Boundary layer height above the Great Barrier Reef studied using drone and Mini-Micropulse LiDAR measurements. Journal of Southern Hemisphere Earth Systems Science, 74. https://doi.org/10.1071/ES24008
Scofield, J. M. P., Prime, E. L., Flores, F., Severati, A., Mongin, M., Bougeot, E., Baird, M. E., Negri, A. P., & Qiao, G. G. (2024). The development of a floating mono-particle “Sun Shield” to protect corals from high irradiance during bleaching conditions. Journal of Marine Science and Engineering, 12, 1809. https://doi.org/10.3390/jmse12101809
Harrison DP (2024) An Overview of Environmental Engineering Methods for Reducing Coral Bleaching Stress. In: Wolanski E, Kingsford M (eds) Oceanographic Processes of Coral Reefs. CRC Press, pp484
Foster, R., Shumway, N., Harrison, D., & Fidelman, P. (2025). Governing marine cloud brightening for ecosystem conservation under a warming climate. Earth System Governance, 23, 100240. https://doi.org/10.1016/j.esg.2025.100240
Baresi, U., Baum, C. M., Fischer, T. B., Lockie, S., Piggott-McKellar, A., Graham, V., Bohensky, E., Fritz, L. B., Shumway, N., Harrison, D. P., Foster, R., Sovacool, B. K., Vella, K., & Ristovski, Z. (2025). A call for strategic assessments of regional applications of solar radiation management: Exploring the challenges and opportunities from marine cloud brightening and albedo surface modification. Environmental Impact Assessment Review, 110, 107701. https://doi.org/10.1016/j.eiar.2024.107701
Braga, R. C., Rosenfeld, D., Hernandez, D., Medcraft, C., Efraim, A., Moser, M., Lucke, J., Doss, A., & Harrison, D. (2025). Cloud processing dominates the vertical profiles of aerosols in marine air masses over the Great Barrier Reef. Atmospheric Research, 107928. https://doi.org/10.1016/j.atmosres.2025.107928
Deschaseaux, E. S. M., Dunne, E., Schulz, K. G., Eyre, B. D., & Harrison, D. P. (2025). The Central Great Barrier Reef as a net source of climatically relevant biogenic volatile organic compounds. Journal of Geophysical Research: Oceans, 130, e2024JC021192. https://doi.org/10.1029/2024JC021192
Hernandez-Jaramillo, D. C., Kelaher, B., & Harrison, D. P. (2025a). A review of plume dispersion and measurement techniques applicable to marine cloud brightening. Frontiers in Marine Science, 12. https://doi.org/10.3389/fmars.2025.1450175
Hernandez-Jaramillo, D. C., Harrison, L., Gunner, G., McGrath, A., Junkermann, W., Lieff, W., Hacker, J., Rosenfeld, D., Kelaher, B., & Harrison, D. P. (2025). First generation outdoor marine cloud brightening trial increases aerosol concentration at cloud base height. Environmental Research Letters, 20, 054065. https://doi.org/10.1088/1748-9326/adccd7
Virah-Sawmy, D., Beck, F. J., & Sturmberg, B. (2025). The synergy between battery and hydrogen storage in stand-alone hybrid systems: A parameterised load approach. International Journal of Hydrogen Energy, 141, 266–282. https://doi.org/10.1016/j.ijhydene.2025.05.324
Ellis, S. L., Baird, M. E., Harrison, L. P., Schulz, K. G., & Harrison, D. P. (2025). A photophysiological model of coral bleaching under light and temperature stress: Experimental assessment. Conservation Physiology, 13. https://doi.org/10.1093/conphys/coaf020
Harrison, L. P., Medcraft, C., & Harrison, D. P. (2025). Effervescent nozzle design to enable outdoor marine cloud brightening experimentation. Environmental Science: Atmospheres, 5, 1071–1080. https://doi.org/10.1039/D5EA00073D
Ryan, R. G., Toms-Hardman, L., Smirnov, A., Harrison, D. P., & Schofield, R. (2025). Aerosol vertical profiling over the Southern Great Barrier Reef using lidar and MAX-DOAS measurements. Atmospheric Chemistry and Physics, 25, 11183–11197. https://doi.org/10.5194/acp-25-11183-2025
Horchler, E. J., Alroe, J., Harrison, L., Cravigan, L., Harrison, D. P., & Ristovski, Z. D. (2025). Measurement report: Aerosol and cloud nuclei properties along the Central and Northern Great Barrier Reef — impact of continental emissions. Atmospheric Chemistry and Physics, 25, 10075–10087. https://doi.org/10.5194/acp-25-10075-2025
Yu, J., et al (2025). A coupled Eulerian–Lagrangian approach with explicit volume diffusion subgrid modeling in turbulent jet breakup and spray dispersion. Applications in Energy and Combustion Science, 24, Article 100350. https://doi.org/10.1016/j.jaecs.2025.100350
Khan, S. B., Alroe, J., Medcraft, C., Sauret, E., Harrison, D., & Ristovski, Z. (2025). Secondary droplet breakup of impaction-pin nozzle: Comparison between experimental and CFD-DPM modelling. Journal of Aerosol Science, 190, Article 106664. https://doi.org/10.1016/j.jaerosci.2025.106664
Wu, L., Horchler, E. J., Ristovski, Z., Liu, J., Yu, F., Han, S., Zhao, W., Richards, L., Harrison, D., Zheng, J., & Miljevic, B. (2025). Ammonia emissions from an avian-rich island in the Great Barrier Reef: Environmental drivers and observational insights. Atmospheric Environment, 361, Article 121525. https://doi.org/10.1016/j.atmosenv.2025.121525
Medcraft, C., et al. (2025). Flash atomisation of saltwater through convergent-divergent nozzles: Implications for marine cloud brightening. Journal of Aerosol Science, 191, Article 106677. https://doi.org/10.1016/j.jaerosci.2025.106677
Li, Z., Harrison, L., Alroe, J., Scoble, H., Chen, C., Medcraft, C., Holloway, C., Brown, R., Baker, P., Harrison, D. P., & Ristovski, Z. (2025). Characterizing the crosswind structure of artificial seawater droplet plumes during a sea trial on the Great Barrier Reef. Environmental Science & Technology, 59(50), 27222–27229. https://doi.org/10.1021/acs.est.5c10024
Virah-Sawmy, D., Beck, F. J., & Sturmberg, B. (2025). Uncertainty ahead: Should stand-alone energy systems bet on hydrogen backup? Energy Reports, 14, 3481–3494. https://doi.org/10.1016/j.egyr.2025.10.026
Zoram Ristovski
Ceylena Holloway
Brendan Kelaher, SCU
Peter Wilson, SCU
Bradley Eyre, SCU
Mark Baird, CSIRO
Matthew Woodhouse, CSIRO
Daniel Rosenfeld, HUJ
Matthew Cleary, USYD
Ian Jones, USYD / SIMS
Robyn Schofield, UMELB
Peter Marshall
Yi Huang, UMELB
Stephen Siems, Monash
Alain Protat, BOM
Jorg Hacker, ARA
Wolfgang Junkermann, ARA
Ron Allum, RADSS
Alverman Soster, EmiControls
Philipp Mayr, EmiControls
Gregorio Centurion, Quaternium
