The Great Barrier Reef

Interview with Dr Jennifer Marohasy

Jun 29, 2024

A vibrant underwater scene of the Great Barrier Reef showing a variety of colorful corals and marine life. The reef is teeming with fish of different shapes and sizes, with bright corals in shades of pink, green, and blue. In the background, a deep blue ocean contrasts with the lively foreground, showing the diversity and beauty of the ecosystem. The image should capture the dynamic and diverse nature of the reef, with intricate details of the coral structures and the vibrant colors of the marine life.

I’ve struggled to get interviews with truth telling subject matter experts to shed light on Climate Change™. I’m not sure why.

I’m not exactly sure how I first came across Jennifer’s work, but I’m very glad she agreed to do this interview with me.

Australia’s Great Barrier Reef is one of the most iconic places on earth.

It’s also one of the most heavily politicized Climate Change™ subjects in Australia.

As you will see from this interview, it’s basically impossible for the public to make heads or tails of the subject, as all parties are swimming in unreliable data and the narratives they spawn.

With thanks to Dr Jennifer Marohasy.

Jennifer Marohasy - Scientist, Author and Speaker

Denying Even a Cyclone – Absurd Reef Statistics

1. Jennifer, you've had a fascinating career at the intersection of biology, climate science, and the Great Barrier Reef. Can you share a bit about your background and what drew you to focus on this iconic ecosystem?

It was assumed I would go to university, neither of my parents had, but my older brother was already studying law at the University of Queensland, and it was assumed that I would follow him to that same university.

A lot of money had been spent on sending me to private boarding schools, both my parents who were from working class backgrounds believed that the way to get ahead was to get a tertiary education. I wanted to study marine biology, but my parents thought that a bit frivolous and so in the end I wrote on the QTAC form: 1. Agricultural Science, 2. Batchelor of Business, and 3. Marine Biology.

I was not unhappy when I got into Agricultural Science, my first choice according to the form, but I only lasted one semester before I changed over to a Bachelor of Science degree, with the plan to major in Botany. Then in third year my father suggested I do some entomology as that was more practical than botany – more likely to land me a job, so he suggested. I ended up completing a BSc in both botany and entomology, a double major.

I did work for a good decade as an entomologist, including running a field station in Madagascar. My PhD is in insect ecology. I don’t think I would have got such a good grounding in ecology if I had become a marine biologist. I am very pleased with the education that I got as an entomologist, in the most important disciplines within the biological sciences including statistics.

Of course, all these years later, 44 years later, I am circling back to marine science but with a relatively long career of experience and learning in related areas, including more recently the application of big data and artificial intelligence to understanding how the natural world works.

2. In recent years, coral bleaching has become a huge concern at the Great Barrier Reef. Based on your research, how do you see the bleaching issue - is it an unprecedented crisis or part of a natural cycle?

Bleaching is part of a natural cycle. This last year bleaching has been particularly bad just across the bay from where I live in Yeppoon, it has been particularly bad at the reefs fringing Great Keppel Island that are part of the southern Great Barrier Reef.

The last time the bleaching was this bad at the Keppel islands was back in 2006, 18 years ago, corresponding with the last Major Lunar Standstill, that links to the El Nino Southern Oscillation. During these cycles water sloshes from the western Pacific, including from the Great Barrier Reef, across to the other side of the Pacific.

This is associated with a weakening or reversal of the dominant south eastern wind pattern, known as the trade winds.

With the lower sea levels, and calmer conditions, it is not surprising that there is bleaching at those reefs that are inherently more susceptible, including the coral reefs fringing the Keppel Islands.

The bleaching has been remarkably bad at the Keppel Islands. But because scientists have been falsely calling it every year, this important fact is likely to be lost to our collective memory. It is also a problem when my colleagues deny this bleaching. If we deny when there is bleaching and claim bleaching when there is none – it is impossible to know the cycles and their causes.

This last year not only did my local coral reefs bleach very badly, but my favourite coral reef John Brewer reef that is a mid-shelf reef offshore from Townsville, it was absolutely pummelled by a cyclone.

3. Many are quick to point to climate change as the culprit behind coral bleaching. Do you think this is an oversimplification? What other factors might be at play?

The climate is always changing, and there are different components to this climate change, some that affect sea level more than temperature.

Bleaching at my local reef Keppel Island reefs this last summer was probably as much to do with a drop in sea level as a rise in temperature.

During an El Nino a lot of water sloshes from the western Pacific across to the eastern Pacific. We can see this in the sea level data. The lower sea tides and weaker tides, together with some cloudless skies likely caused the recent catastrophic coral bleaching at Great Keppel Island.

Climate change is more usually defined as a shift in weather patterns; according to what is known as ‘the consensus’ it is claimed to be caused by increases in concentrations of greenhouse gases and associated with a continual, a linear, increase in global temperatures.

I see cycles, and cycles within cycles, rather than any generally increase in temperatures. If we consider the temperature data before it is remodelled by the IPCC-linked institutions, there was cooling of more than 1.5 degree Celsius, in the higher latitudes of the northern hemisphere from 1940 to 1970, and there has been warming of more than 2 degrees Celsius since. I reference this region as there is so much temperature data for Europe going back more than 200 years.

The idea that we can keep temperatures within 1.5 degrees Celsius is a complete invention. It is very political, but inconsistent with what the temperature data actually says. And by temperature data I mean location specific data, unaffected by ‘urban heat island’ (UHI) affects. It is the case the cities hold heat from each day in asphalt and concrete that is released at night, this is one component of the UHI effect. Minimum temperatures that are overnight temperatures are more likely to be affected by the UHI effect, so best to consider maximum temperatures when considering climate as opposed to weather.

Long maximum temperature series from rural areas unaffected by UHI will give a much better indication of actual climate change temperatures.

There has been a lot in the press about the recent spike in global temperatures, and claims have followed about how this has caused the oceans to warm and the corals to bleach.

There has been a spike in global temperatures as measured by the satellites since April last year.

This satellite record is relatively short, only beginning in 1979, there remains much regional and seasonal variability in this data. Furthermore, the same satellite data very clearly shows that the warmth is coming from a particular part of the ocean, not from the greenhouse gases in the atmosphere.

The warmth is from the equatorial Pacific with a two- month lag before we see the same extent of warming in the atmosphere.

4. You've mentioned there is a lack of understanding about the dynamics of coral bleaching. What are some of the key misconceptions you encounter?

Most people don’t realise that the most common colour of healthy corals is beige. This is the most common colour of the symbiote algae, the zooxanthellae. Really healthy coral will be a darker brown, replete with zooxanthellae.

When temperatures become too hot or too cold, the zooxanthellae can become toxic to the corals and so they are expelled. When this happens corals can appear more colourful. For example, the most colourful reef that I have ever visited was John Brewer Reef in April 2022 when it was being reported around the world as the centre of a sixth mass coral bleaching.

Many of the corals had lost their zooxanthellae and so the natural pink colour from a florescent protein in the corals at this reef was showing through. There were some corals that had gone completely white, which is the next stage of bleaching.

There was a very white coral from this reef that featured in an article in The Guardian. I noted where the coral was and monitored it for the next two years. I observed that it had taken back its zooxanthellae within three months. When I next visited with my daughter in July 2022 that coral was beige again.

I made a short film about this coral with Sky News personality Rowan Dean, if you Google ‘Café Latte Coral’ you can watch it. I explain how corals change colour naturally, even with the seasons – and how quickly they can recover from bleaching.

Unfortunately, this same coral was smashed by Tropical Cyclone Kirrily that pummelled John Brewer reef on the Thursday afternoon of 25^th January. When I visited this reef three weeks later my ‘Guardian coral’ (as it had become known) was in little pieces 7 metres below the reef crest, at the perimeter of this reef in pieces. It has not recovered.

The media seemed interested when some of the corals bleached, mostly uninterested when the same corals recovered from the bleaching, and in absolute denial when that entire section of reef was smashed by TC Kirrily.

5. How has our ability to monitor and measure the health of the Great Barrier Reef evolved over the years? What are the strengths and limitations of the current methods?

An extraordinary amount of time and money is being spent purportedly monitoring and measuring the health of the Great Barrier Reef. The monitoring has historically been of coral growth rates, coral cover, and water quality. More recently there have been aerial surveys purportedly to report on the extent of coral bleaching.

Obviously, it would be expected that the results from an aerial survey undertaken at the same time as an in-water survey of coral cover would be consistent. This is not the case at all, and no one seems to care.

For example, John Brewer reef was reported as the epicentre of a sixth mass coral bleaching in March 2022, when my ‘The Guardian’ coral bleached, before it was smashed-up by the cyclone.

A special aerial survey was undertaken by The Australian Institute of Marine Science (AIMS) at that time, in March 2022, that made media headlines reported bleaching at John Brewer Reef to be in the order of 31 to 60%, while not including photographs or other evidence to support this claim.

By coincidence, a routine underwater survey by manta tow also by AIMS was undertaken of John Brewer Reef on 6th March 2022. The underwater survey was reported sometime later in a routine report, that received no media attention, and reported no bleaching.

There is no supporting information available for either survey method. I have argued that neither are scientific.

I have shown using aerial drone photography that it is impossible to know the state of the corals from a 150 metres altitude out the window of an aeroplane. By the same token, the in-water surveys by manta tows are subjective assessments, and results are not credible.

There was another in water survey of John Brewer reef just recently, in June. It found little difference in coral cover at John Brewer reef before and after TC Kirrily pummelled the reef crest. That is because these in water surveys are only of the reef perimeter where there is relatively little coral anyway.

Peter Ridd has gone to some effort over the last two years to promote these AIMS in-water coral cover surveys, to claim they show record high coral cover at the Great Barrier Reef. This may be what they show. But science is a method, it is not the truth. The truth exists independently of what might be reported.

In all the promotions, it is ever acknowledged that these AIMS coral cover surveys are only of the reef perimeter, these surveys do not include the habitat with arguably the most coral cover that is the reef crest. The reef crest is not surveyed because this habitat can be difficult to survey at low tide in water.

I have a more fundamental problem with the method, particularly Ridd’s claim that the surveys provide a high-level of certainty specifically over the last year he has added an error bar of 0.04 to the chart of ‘record high coral cover’ that he promotes ad nauseam. Yet, this value sometimes shown as +/- 4% is an invention.

When considering this ‘uncertainty value’ as Ridd describes it, it is worth considering the method used by the Australian Institute of Marine Science that has undertaken these surveys since 1984. AIMS records coral cover according to the following categories very low (0-10%), low (10-30%), medium (30-50%), high (50-75%) and very high (75-100%). To be clear, the data is categorical. It is collected not as a continuous number, but rather it is noted that coral cover for a particular section of reef fits in a particular category.

It is impossible to calculate a standard error, by which I mean an uncertainty value of any sort, let alone one of 0.04 from data collected in the way AIMS collects their coral cover data. In order to calculate an ‘uncertainty value’ such as 0.04 it is necessary to know the sample mean.

Just think for a moment. If one of the categories is 75 to 100%. This is a rather large range of 25%, yet we have a purported confidence interval of +/- 0.04 (8%).

In fact, it doesn’t matter how many samples AIMS collect. If they only ever record that coral cover is within such broad bands as 0-10%, 75-100% etcetera no one can ever logically conclude accuracy to be any better than this.

To be clear, it is not credible to add an uncertainty value to categorical data, let alone a value of 0.04 as Ridd does.

6. In the blog post, you suggest there has been some "mischief making" and questionable claims made about the state of the reef, even by some in the scientific community. What's your take on this?

In my answer to your first question, I indicated that I am glad my original training was in entomology rather than marine science. One of my first jobs as an entomologist was working on the Darling Downs, an agricultural region in southern Queensland. I worked from sunrise to sunset over the summer of 1981-82 counting insects according to a particular survey method, counting different types of insects but especially numbers of eggs of the major pest of cotton, which at that time was a grub called Heliothis. This was before the advent of genetically modified cotton varieties.

I worked for an agronomist who ran a private business advising farmers when to spray with pesticides. Back then, the financial success, or otherwise, of a cotton farm depended on controlling infestations of Heliothis with aerial sprays of pesticide but it was important these sprays be in response to actual infestations and timed accordingly. Because each application was very expensive. It was important we accurately calculated standard errors, by which I mean uncertainty values. Farmers in consultation with Bernie Caffery, based on my counts, continually assessed the cost to benefit of an aerial spray. So, it was important that my surveys, that my counts, and the method were reliable.

There is not the same accountability when it comes to assessing the state of the corals at the Great Barrier Reef. The livelihood of some of the researchers is more dependent on them announcing catastrophe than on any accurate assessment.

I am reminded of a story Shaun Fricette told me. I spent a week at sea with Shaun a few years ago. Shaun came on the trip at short notice, wanting to know first-hand the state of the Great Barrier Reef; he had heard it was dying. He was working as a volunteer at a turtle rehabilitation centre on Fitzroy Island, which is just to the south-east of Cairns and part of the Great Barrier Reef Marine Park. Ten years earlier, he worked as a deep-sea diver in the Gulf of Mexico.

He got into deep sea diving in his late twenties because he had developed a passion for environmental issues especially marine conservation. At the time, he figured if an oil pipe was leaking on the sea floor it took a diver to go down and fix it, so he trained as a commercial diver and went to Louisiana. He did lots of diving on the oil rigs as well as working topside on saturation systems and diver tending. His goal at the time was to become a saturation diver and live life ‘like an astronaut’ except on the sea floor. To achieve that goal, Shaun knew he would have to put in years of hard work proving himself in the industry, but he never realized that the industry would meanwhile prove to care so little for life under-the-sea. For example, the oil companies, trained him to cut through steel with torches that burn at over 10 thousand degrees so that spent oil rigs could be dismantled safely – but instead they sent him down to the bottom of the ocean to plant explosives because it was faster to decommission a rig that way.

Shaun remembers:

The oil companies would send ‘turtle girls’ up in a helicopter to scout dolphins and sea turtles and if they gave the ‘all clear’ charges would go off and we would return to location. The problem was those oil rig platforms become like coral reefs after years of being submerged and the sea life around them is so biodiverse and special.

The turtle girls could only see 5 meters underwater on a good day so what I witnessed was horrific. Turtles cut in half, wounded dolphins and thousands of floating fish stunned from the explosions.

Something changed inside of me after seeing that and it’s altered my life path ever since.

The turtle girls were put in a position where they couldn’t see what they were being asked to report on, and it seems like much of the reporting of the state of the corals at the Great Barrier Reef is of an equally dubious quality.

The correct term to describe at least some of this is perhaps ‘premeditated ignorance’.

7. Jennifer, in a recent blog post, you called out the work of three prominent reef researchers - Peter Ridd, Neil Cantin, and Mike Emslie. You suggest they have been misrepresenting the state of the Great Barrier Reef, particularly at John Brewer Reef, either due to flawed methodology or a desire to push a particular narrative about climate change. Can you walk us through, in layman's terms, how their assessments differ from what you've personally observed at John Brewer Reef?

I’ve just now explained that it is difficult to know the state of something under the water from some distance in the air – be that from a helicopter or airplane. If it is difficult to see a turtle, it is also going to be difficult to see a coral. Yet this is essentially what Neil Cantin has been championing with the GBRMPA and AIMS aerial surveys of corals at an altitude of 150 metres.

I have already explained that aerial surveys undertaken in March 2022 lead by Neil Cantin made international media and according to the maps published at that time reported bleaching at John Brewer reef to be severe in the order of 31% to 60% (that was the category) yet an underwater survey by a different division of the same organization, Mike Emslie’s group, reported no bleaching (placed in the category 0-10%).

When I have written to AIM and GBRMPA asking about these discrepancies, when there is a reply, I am told that the aerial surveys will be subject to ground truthing. But I have never been able to get access to any of this data.

I’ve also already made mention of the proposition by Peter Ridd in my answer to one of your previous questions: specifically, that total coral cover at the Great Barrier Reef is 32.7% and that he knows this with an accurately of within 8% – so, he knows for sure that coral cover is between 29 and 37% at the Great Barrier Reef. To repeat, over the last year Ridd has been adding an ‘uncertainty value ca. +/- 0.04’ to his chart of ‘record high coral’. It is endlessly promoted, this chart of record coral cover, not just by Ridd, but it has been republished and promoted by big names including at Jordon Peterson’s ARC conference in London and by Benny Peiser’s Global Warming Policy Institute. There are a lot of people who should know better than to republish and promote this error in how we do statistics.

I have swum over a few coral reefs in my time, and I know that the variability intrinsic to any one reef is greater than this, that there is significant variability between habitats at any one Great Barrier Reef coral reef. So, 0.04 would seem to be an unrealistically low number, intuitively.

What Ridd rarely explains is that this number of 32.7% is not actually a direct measure of total coral cover but derived from perimeter surveys – that the counting is only of coral around the edge of each coral reef. This is somewhat like counting the number of houses around the perimeter of one of our cities and from this determining the population of that city.

To know the population of a city, it is necessary to sample areas with different dwelling densities – it is necessary to know how many people are living in the central business district (CBD) as well as on acreage. Furthermore, I would argue that the reef perimeter is not a habitat as such, and so should not be a survey category as such.

And as I have already explained when the survey method does not involve the determination of the actual area of hard coral, but rather the estimation of coral cover according to broad categories (each of which is greater than 8%), it is not possible to calculate a sample mean and so it is not possible to calculate an uncertainty value.

To calculate the standard error/variance/uncertainty it is necessary to first calculate the sample mean. This is not possible with categorical data, yet this is the only type of data that AIMS collects as part of its ‘Long Term Monitoring Program’ from which Ridd generates the nonsense ‘32.7 +/- 0.04’. You see he doesn’t actually add up the individual values to come up with 0.04 – I’ve asked him how he gets this number and he apparently found it in a report from some time ago.

To summarise, the basis of most statistics is the survey and how the data is collected will affect what can finally be concluded. In the case of coral cover two fundamental errors are made by Ridd: how the problem is formulated (ignoring the high-density areas/the reef crest) and how the data is collected (according to categories rather than as numbers). So, his analysis and interpretation are a nonsense because it is not consistent with how the data was collected.

If AIMS as part of their Long Term Monitoring Program never sample any of the reef habitats with high-densities of coral, Ridd in all honesty, cannot comment on total coral cover; and 2. if this data is collected by AIMS according to broad categories (0-10%, 30-50%, 50-70%, and 75-100%) it is not possible to calculate a sample mean with a corresponding uncertainty value. Uncertainty, calculated as the standard deviation/standard error/variance depends on knowing the sample mean and this requires continuous variables to measure actual coral cover not categories of coral cover.

As regards Mike Emslie, he heads the ‘Long Term Monitoring Program’ that just recently reported on the state of John Brewer Reef.

John Brewer Reef as an ecosystem was approaching climax, in all its beauty when it was smashed in January this year by Tropical Cyclone Kirrily.

This category three cyclone sat over the top of John Brewer reef, one of the most spectacular of all the Great Barrier Reef’s mid-shelf reefs, for two long hours, unleashing such destruction and yet Emslie’s monitoring program has no record of it?

That is correct, this event is not recorded as a significant change in hard coral cover, or anything else in their newly released ‘reef-wide hard coral cover’.

Hard coral cover at John Brewer Reef was recorded as just 23% before TC Kirrily, which is a complete misrepresentation, and just 17% in this latest survey – and so much coral was destroyed in between. At the crest for sure, coral cover went from more than 70% to perhaps less than 20% in one afternoon.

I watched satellite imagery of the cyclone in real time as it passed directly overhead John Brewer as a category three on Thursday 25th January 2024.

Then at the first opportunity, I visited – that was three weeks later, on 15th February 2024.

I saw first-hand how massive plate corals in shades of pink, green and chocolate brown, once beautifully arranged such that they over-lapped, and over-hung a wide and deep crevasse – these corals had been picked-up, flipped-over and smashed-up by the cyclone. The extent of the destruction was gut wrenching.

Then on June 24, 2024, I received an email: ‘the AIMS Long-Term Monitoring Program have recently completed the final survey trip of the 2023-24 reporting year’, there is mention of John Brewer reef, I click across, there is comment: ‘In June 2024 reef-wide cover of hard corals was 17.3 %, having remained similar since the impact of crown-of-thorns starfish in 2019. In 2019 Crown-of-thorns starfish were at below outbreak levels.’

And with those two sentences all that destruction and coral loss is denied. It is as though ‘the tree never fell in the forest’, to invoke George Berkeley and the associated arguments about human knowledge and how it exists.

In the case of the AIMS Long-Term Monitoring Program and this most recent absurd reporting of the unchanged state of John Brewer Reef is it simply gross incompetence that dates to the inception of the program nearly 40 years ago? Could it be that they simply have no idea how to sample a structurally diverse ecosystem to meaningfully quantify change? Is it the case that Ridd, who does not collect his own data, that he just repeats the errors intrinsic to the design of the original AIMS Long-Term Monitoring Program?

8. For concerned citizens who want to support the health and resilience of the Great Barrier Reef, what are the most impactful ways they can take action? What should our priorities be?

Get out into nature and start appreciating its beauty and the natural cycles – try and go somewhere that gives you the opportunity to see to the horizon.

Various studies have shown that just being in nature is good for our health, it can be a cure for depression – something that can be an issue for me if I don’t get enough exercise and enough nature.

Take a walk in your local park, visit the seaside and turn over a rock and see what creatures are underneath? You may not have the time or resources to get on a boat, and visit John Brewer reef, but you should be able to nevertheless experience some nature. Soak it up, that is the beginning of caring about the Great Barrier Reef – it is staring to see nature, to see different life forms.

The more you observe the more you will come to realise that there are cycles, that rarely is change linear. It doesn’t ever keep getting hotter and hotter. Rather, for example, a summer day may get hotter and hotter as the Sun rises in the sky, but by mid-afternoon it will usually begin to cool off, and it will get even cooler after the Sun sets. Begin to notice these things – and you will begin to notice other cycles, nature is cycles. Think about what may be causes the changes that you observe.

At your local park there will be periods when the grass perhaps is frosted over, and then it regrows; when the trees lose their leaves and then with spring there may be flowers – even flowers emerging from bare ground. Perhaps not every spring, sometimes there are variations even to seasonal cycles. But if you never get out into nature you can’t know even how these things change.

I’m not sure whether immersing yourself in the Great Barrier Reef will help the corals but it will be good for your soul.

Before TC Kirrily I used to spend all my time exploring the crevasses overlaid with large pink plate corals just beyond the boat where you jump off into the lagoon at John Brewer reef, and so I never made it around to the reef front proper – at least not down the sandy front to a depth of 22 metres. I was there, after TC Kirrily the second time I visited in May. I was encouraged to go a bit further, down the reef front and I was mesmerised. So many soft corals, especially Gorgonian fans in shades of purple and gold, feather stars, and fish, and more fish – so many little fishes in every shape and colour. The corals below about 10 metres were mostly unaffected by the cyclones, and I had never seen them before.

I was recently over at Great Keppel Island, the reef flat that we were diving was to my eye ‘ordinary’ and clearly suffering from the recent bleaching, but the American I was diving with, my buddy for that dive was an airline pilot from Colorado and he was in awe of this reef: the colourful fish and colourful corals. It was the first time he had dived at the Great Barrier Reef. When I explained, after the dive, that this reef was suffering from the recent bleaching, he explained to me that it was the best dive he had ever done. He explained that ‘the best’ he ever gets to see on scuba back home in a nearby freshwater lake is a bit of moss growing on a wreck, a plane sunk into that same lake.

It is the case that not all environments are equally inspiring and rejuvenating.

Whether coral cover at John Brewer Reef is 20% or 80% just getting in the water at that reef will be good for you – I know that. The Great Barrier Reef is still one of the seven natural wonders of the world because there is still so much coral that it is still visible from outer space – even at John Brewer Reef and even after Tropical Cyclone Kirrily.

Dr Jennifer Marohasy blogs at JenniferMarohasy.com, with a recent post about deficiencies in AIMS monitoring complete with photographs and charts (link).

She also often cross posts at her official Facebook page and she encourages you to like that page, Facebook.

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