Cooling and Shading

Shading by cloud brightening

Field trial of cloud brightening. Photo courtesy of Southern Cross University

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.

Field trial of cloud brightening

Field trial of cloud brightening. Photo courtesy of Southern Cross University

Scope and expected outcomes

The Cooling and Shading R&D Subprogram aims to progress both categories of cooling and shading interventions in parallel:

  • those that can potentially be deployed at large scale, hundreds of square kilometres up to the entire Great Barrier Reef
  • those that are likely only achievable at smaller scale, such as an individual reef or tens of square kilometres.

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. 

Testing surface films in the National Sea Simulator, AIMS

Field trial of cloud brightening

Field trial of cloud brightening. Photo courtesy of Southern Cross University.

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.

Subprogram lead:

Southern Cross University

Subprogram team:

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

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

Partner Institutions

Queensland University of Technology


Hebrew University of Jerusalem (Israel)

Sydney Institute of Marine Science

University of Sydney

University of Melbourne

Monash University

Bureau of Meteorology

Quaternium (Spain)

Airborne Research Australia

EmiControls (Italy)

Ron Allum Deep Sea Services

Palo Alto Research Center (USA)