BBC Panorama cloud brightening - Southern Cross University

Published: 20 December 2024

Mechanical trees that absorb carbon, a solar reactor that makes fuel from fresh air, and Southern Cross University’s ‘machines that brighten clouds’. In a world where the climate is changing, these technologies have made the leap from ‘blue sky thinking’ to reality.

Audiences in the UK met the scientists and innovators behind these and other projects in ‘Can Scientists Save the World?’, a BBC Panorama worldwide investigation of technologies underway, or being trialled, to lessen the impacts of anthropogenic climate change.

Southern Cross University was showcased alongside universities and non-profit organisations working to either remove and store atmospheric carbon dioxide, or reflect sunlight to reduce global temperatures.

In the introduction to the hour-long news program (the equivalent of Australia’s ABC Four Corners), BBC journalist and episode host Richard Bilton says: “Our climate is changing. We’re seeing more extremes. We need to cut our use of fossil fuels, but other solutions will be needed. So can scientists help save the world?"

A scientist outside the National Marine Science Centre

The BBC Panorama team travelled to Heron Island on Great Barrier Reef to see the damage from last summer’s high sea temperatures which caused corals to bleach, even in the usually cooler waters around Heron, off Gladstone, in the Reef’s southern section.

Then at Southern Cross University’s National Marine Science Centre in Coffs Harbour, they met Associate Professor Daniel Harrison who leads the marine cloud brightening project, part of the Reef Restoration and Adaptation Program.

On a windy day, as journalist and marine scientist walked the beach at Charlesworth Bay, Associate Professor Harrison explained the idea behind the marine cloud brightening trials on the Great Barrier Reef: to replicate natural processes.

“Tiny little droplets of sea water are blowing off and evaporating and drifting up to the clouds and you can see the sea spray blowing across behind us there,” said Professor Harrison.

“So it’s exactly that we’re replicating. We want the clouds to be brighter and to hang around longer so they’re reflecting more sunlight into space.

“The only ingredients are energy and seawater.”

The seawater is concentrated through nozzles and sprayed into the air to create a plume. The nozzles create nano-sized droplets of seawater which air currents lift into existing low-lying clouds. The salt particles alter the cloud’s structure and serve as nuclei for water droplets to condense around, creating more and smaller droplets, which make the cloud whiter and more reflective of sunlight, thereby reducing ocean temperatures.

Nozzles concentrating seawater — Close-up of the nozzles in action: seawater is concentrated through nozzles and sprayed into the air to create a plume.

Professor Harrison showed the BBC Panorama team a range of nozzles at the nearby nozzle testing facility.

“The nozzle already works,” said Professor Harrison. “But we want to do two things: we want to improve its energy efficiency, so we want to put out more droplets for the same amount of energy; and we also want to narrow the size distribution of those droplets.”

Reflecting on Southern Cross University’s marine cloud brightening trial and the other innovations, Richard Bilton said: “Science created our problems. Many believe science will be part of the solution.”

‘Can Scientist Save the World? aired as Southern Cross University’s marine cloud brightening team was making preparations for the next marine cloud brightening field trial on the Great Barrier Reef in February/March 2025.

Learn more about BBC Panorama’s ‘Can Scientists Save the World?’

No broadcast date is yet available for Australia.

A group of men in a research facility — Associate Professor Daniel Harrison (2nd from right) and Richard Bilton (centre) at the nozzle testing facility with (left to right) Marine Cloud Brightening team member ____, camera operator Seamas McCracken, producer Maurice May and Marine Cloud Brightening team member Chris Medcraft.

Reef Restoration and Adaptation Program

Marine cloud brightening on Australia's Great Barrier Reef is led by Southern Cross University as part of the Reef Restoration and Adaptation Program (RRAP).

RRAP’s Cooling and Shading subprogram aims to investigate technologies, including marine cloud brightening, 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 Reef Restoration and Adaptation Program is funded by the partnership between the Great Barrier Reef Foundation and the Australian Government’s Reef Trust. It is delivered by a collaboration between the Australian Institute of Marine Science, the Great Barrier Reef Foundation, CSIRO, The University of Queensland, QUT, Southern Cross University and James Cook University.

About the Reefs and Oceans Cluster

Associate Professor Daniel Harrison leads the Reefs and Oceans Research Impact Cluster at Southern Cross University. The Reefs and Oceans cluster works with industry, government and communities to leverage the ecological, environmental, economic, and cultural value of our precious marine environments.