Pouring Cold Water On It

One might expect the Annual Summary Report of Coral Reef Condition 2021/2022 to be widely reported in the mainstream media as a good news story, given that its main conclusion is that “Continued coral recovery leads to 36-year highs across two-thirds of the Great Barrier Reef”. One might expect that, but one would be wrong.

Both the BBC and the Guardian have reported on this news with what seems to be the inevitable heavy caveat we have come to expect. In the case of the BBC the relevant article is headed “Great Barrier Reef sees record coral cover, but it is highly vulnerable”. Meanwhile the Guardian report is headed “Record coral cover on parts of Great Barrier Reef, but global heating could jeopardise recovery”.

In fairness, although you have to read beyond the report summary and trouble yourself with the detail of the report itself to find any caveats, they are indeed there to be found if you look. That said, the overwhelming message from the annual survey is good news, and it is my belief that the media headlines (just like the headline to the Report itself) really should have reflected that. After all, the bullet points from the survey summary (save the final one) are pretty much relentlessly positive:

Over the past 36 years of monitoring by the Australian Institute of Marine Science (AIMS), coral reefs in the GBR have shown an ability to begin recovery after disturbances.

In 2022, widespread recovery has led to the highest coral cover recorded by the LTMP in the Northern and Central GBR, largely due to increases in the fast-growing Acroporacorals, which are the dominant group of corals on the GBR and have been largely responsible [for] previous changes in hard coral cover.

Above-average water temperatures led to a mass coral bleaching event over the austral summer of 2021/22, the fourth event since 2016 and the first recorded during a La Niña year. The peak of this bleaching event was in March, and accumulated heat stress measured as Degree Heating Weeks (DHW) for most of the GBR reached levels expected to result in widespread bleaching but not extensive mortality.

Survey reefs experienced low levels of other acute stress over the past 12 months, with no severe cyclones impacting the Marine Park. The number of crown-of-thorns starfish outbreaks on survey reefs has generally decreased; however, there remain ongoing outbreaks on some reefs in the Southern GBR.

The combination of few acute stresses and lower accumulated heat stress in 2020 and 2022 compared to 2016 and 2017 has resulted in low coral mortality and has allowed coral cover to continue to increase in the Northern and Central GBR.

Nearly half of the surveyed reefs (39 out of 87) had hard coral cover levels between 10% and 30%, while almost a third of the surveyed reefs (28 out of 87) had hard coral cover levels between 30% and 50%.

On the Central and Northern GBR, region-wide hard coral cover reached 33% and 36%, respectively; the highest level recorded in the past 36 years of monitoring.

Region-wide hard coral cover on reefs in the Southern GBR was 34% and had decreased from 38% in 2021, largely due to ongoing crown-of-thorns starfish outbreaks.

In periods free from intense acute disturbances, most GBR coral reefs demonstrate resilience through the ability to begin recovery. However, the reefs of the GBR continue to be exposed to cumulative stressors. The prognosis for the future disturbance regime suggests increasing and longer-lasting marine heatwaves, as well as the ongoing risk of outbreaks of crown-of-thorns starfish and tropical cyclones. Therefore, while the observed recovery offers good news for the overall state of the GBR, there is increasing concern for its ability to maintain this state.

Meanwhile, the first two paragraphs of the BBC report faithfully record the good news (recovery; highest amount of cover in the 36 years of surveying) before devoting the rest of the article to doom and gloom about the Great Barrier Reef’s prospects, and almost inevitably concluding:

The Great Barrier Reef Marine Park Authority, which manages the reef, says the outlook for the icon is “very poor” due to climate change.

Unesco, the UN’s scientific and cultural body, says not enough is being done to protect the reef.

The Guardian, not to be outdone, managed only one positive half sentence before launching into the doom narrative:

…but warned any recovery could be quickly overturned by global heating.

The Australian Institute of Marine Science’s annual long-term monitoring report says the fast-growing corals that have driven coral cover upwards are also those most at risk from marine heatwaves, storms and the voracious crown-of-thorns (COTS) starfish.

Global heating is accepted by scientists as the reef’s biggest long-term threat.

Earlier this year, unusually hot ocean temperatures caused the first ever mass bleaching during a La Nina year – a natural climate phase that should have given corals a respite.

The first ever mass bleaching on the reef was recorded in 1998, but since then corals were hit in 2002, 2016, 2017, 2020 and again earlier this year.

The prognosis for the reef’s future under climate change, the report said, was one of increasingly frequent and longer-lasting marine heatwaves, with the ongoing risk of COTS outbreaks and tropical cyclones.

Mitigation of these climatic threats requires immediate global action on climate change,” the report said.

The irony of the fact that the part of the Reef that has recovered most slowly is in the colder southern waters seems to have been completely overlooked.

Alternative Narrative

I shall leave the last words to Peter Ridd, who has rapidly produced for the GWPF a rebuttal (headed “The Good News on Coral Reefs”). As his Report reminds us:

Peter Ridd is a physicist. He has researched the Great Barrier Reef since 1984, and has published over 100 scientific publications. A former head of the Marine Geophysical Laboratory at James Cook University, Townsville, Australia, he was fired in 2018 for pointing out quality assurance deficiencies in reef-science institutions.

His Report is relatively short, readily accessible and well worth a read. I will simply end with his upbeat conclusion, expressed in his own Final Comment:

The latest data on the GBR indicates it is in good shape. It happens to have a great deal of coral in 2022 because there have been few major mortality events over the last five to ten years. The three or four bleaching events since 2016, which have been widely reported in the media, could not have killed much coral, otherwise the 2022 statistics would not be so good. The data since 1986 shows that every region, every sector and most reefs have had occasionally had [sic] periods of very low coral cover for one reason or another. This is entirely natural. The media makes much of occasional setbacks to coral cover, but a measure of the health of an ecosystem is the ability to recover from a major stress. Frail systems will not recover, robust systems recover well, just as healthy people recover quickly from disease. The GBR has proven to be a vibrant and healthy ecosystem. This should not be a surprise; there are few human pressures on the reef, and it is well protected. It is also unreasonable to expect that the small temperature rise over the last century (1°C) will have caused much impact, especially as it is well known that most corals grow faster in warmer water. The data collected by AIMS shows that the GBR is a robust system with rapidly fluctuating coral cover. We must expect that, sometime in the future, a sequence of events will cause the coral cover to fall sharply, as it did in 2011. We must then remember that this is almost certainly natural, and not allow the merchants of doom to depress the children.

Not allowing the merchants of doom to depress the children is good advice indeed.

via Climate Scepticism


August 4, 2022 at 02:33PM

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