The Great Barrier Reef is not fine and nor is it dying; truth is inbetween
Paul Hardisty, AIMS CEO
In 2019, the Australian Institute of Marine Science issued its annual long-term monitoring report on the state of the Great Barrier Reef, entitled Mixed Bill of Health for the Reef, reflecting the fact that while some parts of the reef were still in very poor condition in the aftermath of the 2016 and 2017 mass bleaching events, some showed good signs of recovery and others – such as many of the southern reefs – remained in excellent condition.
Predictably, this report was translated by many commentators into two diametrically opposed and equally false messages: one, that the reef was near death; and the other, that the reef was absolutely fine, and as good as it had ever been. These extreme views were typically bolstered by anecdotes of personal visits to specific parts of the reef, confirming the polar opposite interpretations, and the exhortation to “see for yourself”.
But for an ecosystem as huge and majestic as the GBR – the whole system includes over 3000 individual reefs along 2300km of Queensland’s coastline – visiting a single reef can never give a complete picture. That is why every year since 1985, AIMS scientists visit reefs across the length and breadth of the GBR, conducting detailed surveys of coral health and fish abundance. Every year we spend more than 200 days at sea with our two state-of-the-art ocean-going research vessels, collecting hundreds of thousands of observations, and adding to our store of literally millions of images, to provide the most complete and enduring monitoring record of any major reef system in the world. As a result, our annual long-term monitoring program reports (and the detailed explanatory analysis they contain) are the definitive source of information on the state of health of the GBR.
And, despite another widespread bleaching event in 2020, our monitoring report for 2021 shows that from north to south, corals are starting to recover. This welcome news reflects the relatively benign conditions the reef experienced last summer. But even though the GBR is unquestionably the best-managed reef system in the world – thanks to significant government investment over the years, and the substantial efforts of farmers, tourism operators, regulators and the public – the longer-term picture is not so positive. Our 40 years of data clearly show the largest and most diverse reef system in the world is under growing pressure from the combined effects of coral bleaching, outbreaks of coral-eating crown-of-thorns starfish, cyclones and poor water quality. Today, there are still many parts of the reef that remain in excellent condition – the ecosystem has huge in-built resilience that allows coral to recover when given the chance – but the number of such reefs has been declining over time. And the number of reefs in poor condition is increasing.
In the past 20 years, climate change has emerged as the single biggest threat to the future of the GBR and reefs worldwide. The evidence is clear and unequivocal. Corals are highly susceptible to small changes in water temperature. Warming of as little as 1C maintained for eight weeks is enough to cause coral bleaching – which can lead to death. Mass bleaching, unheard of before the 1990s, is now becoming a regular occurrence, with major events in 1998, 2002, 2010, 2016, 2017 and 2020. We now know coral reefs take about a decade to recover after serious damage. Mounting evidence suggests that as reefs recover, they are changing in composition and diversity. And as marine heatwaves become more frequent, there is less and less time for recovery. It’s a vicious spiral.
Despite this year’s good news, the trend is clear, and the next major bleaching event is only ever a summer away. All the planet’s coral reefs face the same threat. If global emissions are not brought under control, and quickly, the vast majority of reefs around the world will disappear by mid-century, and those that remain will look very different to those we enjoy today. Reducing emissions alone will no longer be enough. There is already so much warming locked into the global system we also need to do everything we can to bolster reef resilience now.
And this is where Australia is leading the world. Significant efforts are being made to improve water quality and combat coral-eating pests that weaken the reef’s overall resilience. Importantly, AIMS and partner organisations, including the Great Barrier Reef Marine Park Authority, James Cook University, Queensland University of Technology, CSIRO, University of Queensland, Southern Cross University, and the Great Barrier Reef Foundation have come together to deliver the Reef Restoration and Adaptation Program. Funded by the federal government through the Reef Trust Partnership, this world-leading research effort seeks to develop the tools to help reefs recover from, and adapt to, the effects of climate change. At the National Sea Simulator, AIMS’s state-of-the-art research aquarium facility in Townsville, experiments are already under way to test methods that could be deployed at large scale to help build up the reef’s resilience. These include identifying heat-tolerant corals in nature and safely deploying them to enhance recovery, methods to temporarily cool and shade large areas where marine heatwaves are imminent, and ways to accelerate the natural evolution of corals. Our early work suggests a combination of methods may be able to keep more reefs in good condition for longer while the world acts decisively on reducing emissions.
It’s a huge effort that will take a decade or more. But we won’t know what we can accomplish unless we do the research. And, while it’s tempting to reduce such a complex issue to simple statements such as “the reef is fine” or “the reef is dead”, the truth is that while the trend is worrying, there remains much to be hopeful about. In the end, it is up to all of us. If we want to save the world’s reefs, we can, by working together. The place to start, as with most things, is with a firm basis in fact.