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A specific story about record coral cover at the Great Barrier Reef has been loudly trumpeted in the skeptosphere.
Bjorn Lomborg tweeted about it multiple times.
I personally wrote a post about it.
However, the following post from Jennifer Marohasy casts serious dount on the above stories, with a credible first hand account and observations. It would be remiss of us to not correct the record.
Jennifer Marohasy
If you believe Bjorn Lomborg, we have record high coral cover and we can fix climate change. Both are nonsense propositions. In fact, this last year has been devastating for many reef ecosystems because of weather events that are part of natural climate cycles.
In the central Great Barrier Reef, we had the double whammy of coral bleaching and Tropical Cyclone Kirrily. Three reefs (Davis, Chicken and John Brewer) that were included in the recent AIMS’ Long-Term Monitoring Program surveys bore the brunt of Kirrily’s fury that hit as a severe category three before making landfall as a category one.
The basis of most Great Barrier Reef statistics is the survey. Get that wrong and add in an extraordinary amount of hubris – the type often found amongst academics who concern themselves with climate change – and we end-up with more lying headlines.
There are some major problems with the AIMS’ LTMP as a measure of total coral cover at the Great Barrier Reef:
- It does not consider how the distribution and abundance of corals varies with different reef habitats,
- It is a perimeter survey unlikely to include habitats with higher percentage coral cover,
- In not surveying shallower reef habitats, including the reef crest, it cannot measure the true impacts of cyclones or bleaching.
Meanwhile, Peter Ridd has gone to some effort over the last few years to suggest that the health of the Great Barrier Reef can be reduced to a single number representing coral cover based on these LTMP perimeter surveys.
And his political interest is not actually in this number but in the trend.
Yet even after John Brewer Reef took a direct hit from Tropical Cyclone Kirrily on 25th January 2024 pummelling much of the crest clean of coral and strewing coral around the reef perimeter, the LTMP registered no significant change in coral cover at this reef.
The latest number for total coral cover at the Great Barrier Reef, as extracted and calculated first by Ridd, and following his lead by Lomborg, include recent surveys of three large reefs in the central regions of the Great Barrier Reef – Chicken, Davies and John Brewer.
Until TC Kirrily these were exceptionally beautiful reefs in warm crystal-clear waters, with the most magnificent corals – reaching their climax as ecosystems with more than 100 percent coral cover in some places.
I write more than 100 percent, because these reef crests can be of densely packed corals, competing for space and especially light; corals growing over each other with so many fishes – crowded, colourful and bustling like little metropolises on top of platforms rising from the sea floor.
Then these bustling metropolises were obliterated – by Tropical Cyclone Kirrily. And they came to look more like Gaza.
When I visited these reefs soon after that cyclone, I found that many of the very largest of the plate and branching corals had been picked-up, turned-over and dropped-off the edge of sections of these reefs that rise from the sea floor, sometimes as platforms. There was coral strewn about their perimeters.
Indeed, the entire wall of coral that featured in the short film I made last November about the ‘Café Latte Coral’ at John Brewer Reef that entire wall of coral has collapsed. It has broken off from the reef crest proper and has fallen seven meters to the perimeter.
As absurd as it might seem, only now is their opportunity for these broken corals to be part of the AIMS’ surveys used by Lomborg and Ridd to claim record cover coral at the Great Barrier Reef.
The LTMP data that these academics rely on is from surveys that are only ever of the perimeter and at a depth of between 6-9 meters – where so much broken coral landed after TC Kirrily.