Paul Hardisty, Australian Institute of Marine Science ; Christian Roth,CSIRO ; Damien Burrows, James Cook University ; David Mead, AustralianInstitute of Marine Science ; Ken Anthony, Australian Institute of MarineScience ; Line K Bay, Australian Institute of Marine Science ; Mark Gibbs,Queensland University of Technology , and Peter J Mumby, The University ofQueensland

Scientists recently confirmed the Great Barrier Reef suffered another seriousbleaching event last summer – the third in five years. Dramatic interventionto save the natural wonder is clearly needed.

First and foremost, this requires global greenhouse gas emissions to beslashed. But the right combination of technological and biologicalinterventions, deployed with care at the right time and scale, are alsocritical to securing the reef’s future.

This could include methods designed to shade and cool the reef, techniques tohelp corals adapt to warmer temperatures, ways to help damaged reefs recover,and smart systems that target interventions to the most strategicallybeneficial locations.

Implementing such measures across the breadth of the reef – the world’sbiggest reef ecosystem – will not be easy, or cheap. In fact, we believe thescale of the task is greater than the Apollo 11 Moon landing mission in 1969 –but not impossible.

That mission was a success, not because a few elements worked to plan, butbecause of the integration, coordination and alignment of every element of themission’s goal: be the first to land and walk on the Moon, and then fly homesafely.

Half a century later, facing the ongoing decline of the Great Barrier Reef, wecan draw important lessons from that historic human achievement.

Intervening to save the reef

The recently released Reef Restoration and Adaptation Program conceptfeasibility study shows Australia could feasibly, and with reasonableprobability of success, intervene to help the reef adapt to and recover fromthe effects of climate change.

The study, of which we were a part, involved more than 100 leading coral reefscientists, modellers, economists, engineers, business strategists, socialscientists, decision scientists and reef managers.

It shows how new and existing interventions, supported by the best availableresearch and development, could help secure a future for the reef.

We must emphasise that interventions to help the reef adapt to and recoverfrom climate change will not, alone, save it. Success also depends on reducingglobal greenhouse emissions as quickly as possible. But the hands-on measureswe’re proposing could help buy time for the reef.

Cloud brightening to heat-tolerant corals

Our study identified 160 possible interventions that could help revive thereef, and build on its natural resilience. We’ve whittled it down to the 43most effective and realistic.

Possible interventions for further research and development includebrightening clouds with salt crystals to shade and cool corals; ways toincrease the abundance of naturally heat-tolerant corals in local populations,such as through aquarium-based selective breeding and release; and methods topromote faster recovery on damaged reefs, such as deploying structuresdesigned to stabilise reef rubble.

But there will be no single silver bullet solution. The feasibility studyshowed that methods working in combination, along with water qualityimprovement and crown-of-thorns starfish control, will provide the bestresults.

Harder than landing on the Moon

There are four reasons why saving the Great Barrier Reef in coming decadescould be more challenging than the 1969 Moon mission.

First, warming events have already driven the reef into decline with back-to-back bleaching events in 2016 and 2017, and now again in 2020. The next majorevent is now only just around the corner.

Second, current emission reduction pledges would see the world warm by2.3-3.5℃ relative to pre-industrial levels. This climate scenario, which isnot the worst case, would be beyond the range that allows today’s coral reefecosystems to function.

Without swift action, the prospect for the world’s coral reefs is bleak, withmost expected to become seriously degraded before mid-century.

Third, we still have work to do to control local pressures, including waterquality and marine pests crown-of-thorns starfish.

And fourth, the inherent complexity of natural systems, particularly ones asdiverse as coral reefs, provides an additional challenge not faced by NASAengineers 50 years ago.

So keeping the Great Barrier Reef, let alone the rest of the world’s reefs,safe from climate change will dwarf the challenge of any space mission. Butthere is hope.

We must start now

The federal government recently re-announced A$100 million from the Reef TrustPartnership towards a major research and development effort for this program.This will be augmented by contributions of A$50m from research institutions,and additional funding from international philanthropists.

Our study shows that under a wide range of future emission scenarios, theprogram is very likely to be worth the effort, more so if the world meets theParis target and rapidly cuts greenhouse gas emissions.

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