Scientists trial cloud brightening to protect coral reefs

Following the third mass bleaching event of the Great Barrier Reef in five years, scientists have trialled a world-first ‘cloud-brightening’ technique to protect valuable reef systems from further such events.

The Great Barrier Reef is experiencing mass coral bleaching for the third time. (Image credit: Greg Torda)

A research team led by the Sydney Institute of Marine Science and Southern Cross University has successfully trialled world-first ‘cloud brightening’ technology off the Townsville coast to protect valuable reef systems from future bleaching events.

Cloud brightening is a process in which microscopic sea water droplets are sprayed into the air. As they evaporate, they leave nano-sized sea salt crystals that act as seeds for cloud droplets, brightening existing cloud and deflecting solar energy away from the reef waters.

“In the future this technology might be able to be applied over the Great Barrier Reef to reduce the severity of coral bleaching during marine heat waves, cooling and shading the corals below,” explained project leader Dr Daniel Harrison in a statement.

Cost-effective protection from climate change

Dr Harrison continued that cloud brightening could potentially protect the entire Great Barrier Reef from coral bleaching in a relatively cost-effective way, buying precious time for longer-term climate change mitigation to lower the stress on this irreplaceable ecosystem.

To conduct their trial, the team set up on two large vessels near Broadhurst Reef, 100km off the coast of Townsville in Far North Queensland. The prototype cloud brightening machine along with its ancillary equipment and accommodation for the scientists was on an ocean barge.

“We tested the hypothesis at one-tenth of the scale we’re aiming for, using a drone in the atmosphere and a sampling vessel 5km away on the sea surface and showed how we can successfully create hundreds of trillion of these sea salt crystals per second which float up into the atmosphere to bolster the reflectivity of the existing clouds,” Dr Harrison said.

Upping the scale

Next year the team plans to test the technology at three times the size, ready for a ten-fold increase a year later, which the researchers say should be able to brighten clouds across a 20-by-20-kilometre area, according to the statement.

Over the next four years researchers from multiple institutions will explore all aspects of the technology including considering environmental risks such as whether the technology could alter rainfall patterns over the ocean or land.

Recently, the Federal Government launched the $150m research and development phase of the world-leading Reef Restoration and Adaptation science Program (RRAP) to help preserve and restore the Great Barrier Reef, which includes larger trials of Dr Harrison’s Cloud Brightening technique, concluded the statement.

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