What Corals Can Tell Us About Climate Change

From The Institute of Public Affairs

Written by John Abbot

A new paper from Dr John Abbot, Senior Fellow at the Institute of Public Affairs, reveals that records from living and fossilised corals show natural variations in temperature stretching back thousands of years.

Dr Abbot urged Australia’s Government-funded research institutions to resume the program of coring corals and publication of trend data that appeared to cease in the early 2000’s, as detailed in the recent IPA documentary, Finding Porities.

The research report, What Corals Can Tell Us About Climate Change: Temperature Variability Over Millennia, was released today by the IPA, to coincide with this week’s hearing in the High Court of the case of Dr Peter Ridd, dismissed by James Cook University for his criticisms of quality of the reef science being undertaken by some of his colleagues.

“We are constantly being informed that the world is in the midst of a climate crisis and that current atmospheric temperatures are unprecedented, but this should be viewed in the context of what has occurred in the past,” Dr Abbot said.

“The public and politicians have been conditioned to associate ‘climate change’ with the destructive behaviour of generations of humans since the onset of the industrial revolution about 130 years ago. However, the scientific literature informs us that climate change is a natural phenomenon that has occurred over thousands of years and there is no reason to believe that this process is not ongoing.

“Studies of corals can contribute to our knowledge and understanding of these natural processes that are contributing to current climate change and also enable us to quantify the contribution from human activities,” he said.

Dr Abbot applies the evidence in the coral record gathered in his research to critique the famous “hockey-stick” of Dr Michael Mann, which had the effect of flattening the temperature record of the last millennium and implying a rapid increase in recent times. By contrast, the studies of corals cited by Dr Abbot show that sea surface temperatures have been increasing since about 1790 AD after a period of decline of at least several centuries.

Source: IPA, Ljungqvist, F. C., (2010) A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia.

This fits with temperature profiles that show evidence for the Little Ice Age, approximately during the period of 1600-1800 AD, following a relatively warm period called the Medieval Warm Period around 1000 AD, which had maximum temperatures similar to the present.

Dr Abbot has a BSc in chemistry from Imperial College, London, an MSc from the University of British Columbia, Canada, a Master of Biotechnology from the University of Queensland and a PhD in chemistry from McGill University, Canada. He has has published more than 100 papers in the peer-reviewed scientific literature. He also obtained a Juris Doctor degree from the University of Queensland and was admitted as a solicitor in Queensland, and later obtained an LLM from the University of Queensland.

Download the report here.

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June 28, 2021 2:37 pm

Both corals and fish appeared first during the Cambrian, about 535 million years ago.
When atmospheric CO2 was 6000-7000 ppm.
Jawed fish appeared later in the Ordovician when CO2 was at 4000-4500 ppm.

Fish and corals living happily with atmospheric CO2 of many thousands ppm.

Can someone please remind me how it is possible that a present day increase from 300 to 400-500 ppm is meant to pose a threat of “acidification”? One that didn’t happen during the Cambrian or Ordovician?

history temp CO2 phanaerozoic.png
John Tillman
Reply to  Hatter Eggburn
June 28, 2021 3:06 pm

Also with oceanic temperatures much higher than now. Even modern stony corals thrived during the hot seas and high CO2 of the Mesozoic Era and Paleocene and Eocene Epochs.

Cambrian Chinese proto-fish Haikouichthyes, one inch long in life:
comment image

Considered a basal chordate or possibly even craniate, descended from sea squirts, aka ascidians or tunicates, whose larvae they resemble.

I feel a haiku coming on.

Reply to  John Tillman
June 28, 2021 3:18 pm

Thanks – was this a descendant of Pikaea?

John Tillman
Reply to  Hatter Eggburn
June 28, 2021 3:37 pm

It’s smaller and quite a bit older, so possibly an ancestor, or related to Pikaia‘s forebears. The Burgess Shale is Middle Cambrian, c. 508 Ma. The Maotianshan Shales are Early Cambrian, c. 518 Ma, but possibly older. Like the Burgess, they contain Lagerstätten with exceptional preservation.

Cambrian tabulate coral fossils are rare but become more common in the Ordovician and Silurian.

Reply to  Hatter Eggburn
June 29, 2021 4:06 am

Yes my undergraduate “Form and Function” is coming back to me.
So we are in fact all descended (chordates) from sea squirts?

John Tillman
Reply to  Hatter Eggburn
June 29, 2021 6:18 pm


Reply to  John Tillman
June 29, 2021 7:28 am

Yea the larvae of sea squirts could have been the prototype chordates with notochord and brain and fish like swimming. In this creature the larva is chordate-like and free-swimming; but on becoming adult it settles head first on a rock or something, the head turns into a root structure and the brain is digested. It is rooted to that spot for the rest of its life.

This process has been likened to the attainment of tenure by a university academic. (Probably an old joke.)

Bill Parsons
Reply to  John Tillman
June 29, 2021 12:03 pm

“I feel a haiku coming on.”

Better yet a song…

A fish-like thing appeared among the annelids one day.
It hadn’t any parapods nor setae to display.
It hadn’t any eyes nor jaws, nor ventral nervous cord,
But it had a lot of gill slits and it had a notochord.

    It’s a long way from Amphioxus. It’s a long way to us.
    It’s a long way from Amphioxus to the meanest human cuss.
    Well, it’s goodbye to fins and gill slits, and it’s welcome lungs and hair!
    It’s a long, long way from Amphioxus, but we all came from there.

It wasn’t much to look at and it scarce knew how to swim,
And Nereis was very sure it hadn’t come from him.
The mollusks wouldn’t own it and the arthropods got sore,
So the poor thing had to burrow in the sand along the shore.

“The Amphioxus Song”


John Tillman
Reply to  Bill Parsons
June 29, 2021 6:19 pm

Thank God I didn’t have to attempt my own haiku!

Rich Davis
Reply to  Hatter Eggburn
June 28, 2021 3:08 pm

Stop with your “facts” and “logic” already!

We feel it’s a problem. And the solution to every problem is “stop burning fossil fuels”.

Abolition Man
Reply to  Rich Davis
June 28, 2021 6:42 pm

It’s not the fossil fuels so much, it’s the horrible capitalist system that has used those energy stores to increase health, wealth and liberty for millions!
The ruling elite has decreed that capitalism must die because they’re tired of upstarts wanting a share of their treasure, and they fear a new revolutionary era that could end their reign!

Rich Davis
Reply to  Abolition Man
June 29, 2021 6:59 am

Shhhh! Of course the reason why we always suggest getting rid of fossil fuels is to destroy capitalism. And once capitalism is well and truly destroyed we will use fossil fuels like demons without the slightest concern for the environment (cf Soviet Union). But you can’t go letting that cat out if the bag! We have to destroy capitalism and get the deniers into gulags first.

Charles Higley
Reply to  Rich Davis
June 28, 2021 6:47 pm

So, if I stop burning fossil fuels, the libtards will be gone, because they are the problem? Worth the effort? Hmmm.

John Phillips
Reply to  Hatter Eggburn
June 28, 2021 3:59 pm

Can someone please remind me how it is possible that a present day increase from 300 to 400-500 ppm is meant to pose a threat of “acidification”? One that didn’t happen during the Cambrian or Ordovician?

 ” Even modern stony corals thrived during the hot seas and high CO2 of the Mesozoic Era and Paleocene and Eocene Epochs.”

Untrue. Corals have experienced numerous extinction events in the intervening eras, modern species are very different to those that thrived then. In fact stony corals filled the vacant niche left empty when the rugose and tabulate species of the Cambrian and Ordovician, before disappearing mid-Eocene. According to the Global Reef Project:

 The climate of the globe is currently undergoing a rapid PETM-like event, driven by greenhouse gases as in the PETM. Evidence now suggests that coral reefs will pass a point of no-return around 2040, and go into terminal decline, eventually disappearing at the end of this century. If so, based on past evidence, it is likely that many millions of years will pass before they return.


John Tillman
Reply to  John Phillips
June 28, 2021 4:59 pm

My statement is true. Stony corals took over from the tabulate corals wiped out in the Permian extinction. That’s why I said “Mesozoic”, because tabulate corals dominated the Paleozoic until their demise at the end of it.

John Phillips
Reply to  John Tillman
June 29, 2021 1:18 am

So the relevance to today’s conditions: zilch.

Rich Davis
Reply to  John Phillips
June 29, 2021 5:42 am

That is absurd. See my comment above. The question is not whether the DNA of modern corals is exactly the same as predecessor species. The relevant question is whether animals in the ocean will no longer be able to maintain shells and exoskeletons if CO2 conditions rise slightly from their very low levels today (relative to geological timeframes when CO2 was 10x as high or more).

Reply to  John Phillips
June 28, 2021 6:45 pm

Corals have experienced numerous extinction events in the intervening eras

You mean like the complete obliteration of the Bikini Atoll reef by atom bomb testing in the 1950s, and which then completely regenerated themselves to their former size and health in just 60 years?

Corals are like (beautiful) weeds – you can’t ever completely get rid of them, they just get trimmed back for a bit.

Dave Andrews
Reply to  Mr.
June 29, 2021 8:44 am

In total the US detonated 23 nuclear weapons, including one H Bomb at Bikini.

The H Bomb, ‘Castle Bravo’ was detonated on March 1st 1954 and was the most powerful weapon ever detonated by the US, at 15 megatons 1000 times more powerful than the Hiroshima bomb. The mushroom cloud contaminated more than 7000sq miles (18000 sq kms).

Yet, as you say, in 2008, 54 years later, scientists found that 70% of the atoll’s previous coral reef species had resettled the lagoon

Charles Higley
Reply to  John Phillips
June 28, 2021 6:49 pm

No such thing as greenhouses gases and CO2, a trace gas cannot do so even it it was. This is a joke when one claims CO2 is a problem. Learn, please learn. The Global Reef Project is another joke.

Reply to  John Phillips
June 28, 2021 7:00 pm

John, “will pass a point of no-return around 2040” It amazes me that the dates are so accurate. I am wondering if it will still be 2040 in 2035? I don’t know and I am sure you don’t either.

Reply to  Ardy
June 28, 2021 8:34 pm

We pass a point of no return every year. After 2040, it will never be 2040 again. Beyond that, the phrase has no meaning.

Reply to  John Phillips
June 29, 2021 4:37 am

Your argument about this family or that family of corals is irrelevant.
We are talking about the fundamental inorganic chemistry of life in oceans with a certain concentration of CO2 in the atmosphere. Finessing smoke and mirror arguments – so characteristic of the alarmist position – are not scientifically plausible.
The fundamental biochemistry and metabolism within a Phylum does not change so much that an organism tolerating 5000 ppm CO2 is then going to have a problem with 500 ppm CO2.

The reality is that the whole ocean acidification argument and alarm story was concocted with no awareness or consideration whatsoever of the context of the evolution of these phyla during periods of high CO2 and the implications of that. The inventors of the acidification meme quite likely were ignorant of these facts.

Now – as always – rearguard actions are being fought with smoke and mirror arguments that “everything was different way back then”. No – it was not different. Chemistry was just the same and the phyla were more or less the same as well.

All 20 or so of the phyla of multicellular animals appeared during or shortly after the Cambrian explosion. This is the amazing reality about that event and why it is called the “explosion”. Those phyla have lived successfully over the ages with CO2 concentration s varying over a wide range from 200-10,000, making a nonsense of dystopian stories of acidification with the recent tiny changes in CO2 levels.

Rich Davis
Reply to  John Phillips
June 29, 2021 5:34 am

So I guess that homo habilis, homo erectus, et al would be proof that man has gone extinct several times as well?

I am not an expert on coral by any means, but you are saying that modern corals arose independently of the species that we apparently inaccurately refer to as corals, going back over half a billion years?

Sounds a lot like the “extinction” of the western spotted owl to me. (An excuse to stop logging because it might harm a particular habitat of a bird that can live elsewhere).

Maybe you can prove my guess wrong, John. My guess is that different species evolved over time and the best adapted predominated for a time until conditions shifted. And many species disappeared when their preferred habitats disappeared. But I’ll wager, today’s coral is related to Cambrian corals nevertheless.

Isn’t it actually the case that your claim is a sophist argument to wiggle out of the inconvenient fact that corals (and many other ocean-dwelling species) were perfectly able to build structures out of calcium carbonate even when CO2 levels were ten times higher than today and more?

Reply to  John Phillips
June 29, 2021 12:42 pm

“Corals have experienced numerous extinction events”

Yet we still have corals. Imagine that.

Reply to  Hatter Eggburn
June 28, 2021 6:27 pm

There is something very very wrong about that temp/CO2 chart….seems no correlation…at all. I have been suffering some indigestion today…from climate change…I’m sure.

Charles Higley
Reply to  Anti_griff
June 28, 2021 6:52 pm

That is the point of the chart. Temperature and CO2 ARE NOT CONNECTED. If you look at the overall CO2 trend, reef processes and CaCO3 deposition has been working steadily to precipitate all of the CO2. This could kill the planet. It is mainly volcanic processes that introduce enough CO2 and the ocean which store it that keep this planet alive. The cliffs of Dover and the reefs of Coralville, Iowa clearly show that CO2 has been removed in mass quantities over time.

It would be nice to have the clown ecologists understand that their wonderful life-filled planet is trying to kill them and they are helping.

Charles Higley
Reply to  Hatter Eggburn
June 28, 2021 6:45 pm

Water moving into and through a coral reef is acidified by the waste from the many organisms living there. However, photosynthesis is an alkalizing process such that the 8.4 pH can reach 10-11 on a sunny day in an estuary or bay. Hmm, don’t see that killing anything.

Again, the clown ecologists do not recognize the power of cell physiology that makes organisms very adaptable and tolerant to pH changes, particularly over a day.

Clyde Spencer
June 28, 2021 3:09 pm

The public and politicians have been conditioned to associate ‘climate change’ with the destructive behaviour of generations of humans since the onset of the industrial revolution about 130 years ago.

2021 – 130 = 1891

In the period 1760 to 1830 the Industrial Revolution was largely confined to Britain. … Two Englishmen, William and John Cockerill, brought the Industrial Revolution to Belgium by developing machine shops at Liège (c. 1807), …


Reply to  Clyde Spencer
June 28, 2021 3:18 pm

I was thinking that was a bit off.

John Tillman
Reply to  Clyde Spencer
June 28, 2021 3:42 pm

The Industrial Revolution got started earlier, relying on water power, but Watts’ improved steam engine was produced from 1776, after some 13 years in development. So 230 years might have been what he meant, although 260 is defensible.

Smart Rock
Reply to  Clyde Spencer
June 28, 2021 5:03 pm

I’d put the start of the industrial revolution at 1712, when the Newcomen steam engine was developed. Those early steam engines were so staggeringly inefficient that their only real use was in pumping water out of coal mines, where the fuel was in ready supply. But it did allow practical underground coal mining, and coal was the only fossil fuel until oil entered the picture around 1860.

The industrial revolution took off slowly, but began to accelerate with the James Watt steam engine in the 1770s, which allowed stationary steam engines to power factories, then in 1802 Trevithick built the first high pressure steam engine, efficient enough to power a self-propelled locomotive. And on and on and on.

But to be fair to Dr. Abbot, his date of 1890 marks the development of the Benz internal combustion engine, and the rapid development of electrical generation and distribution started at about that time. And the gas mantle was invented in the 1880s, making household and street gas lighting much more efficient, practical and widespread. World coal production was about 300 million tonnes a year, doubling every 15 years (until about WWI when oil really embarked on its momentous journey). So yes, 1890 would be about the time that humans started adding CO2 to the atmosphere in a serious way. And that was what he was really talking about.

John Tillman
Reply to  Smart Rock
June 28, 2021 6:09 pm

The start of the Industrial Revolution is traditionally dated from Hargreaves’ spinning jenny in 1764-5. But a progressive process in cottage textile industry from c. 1720 preceeded that development

I’m OK with Newcomen, but the first steam engines were put to work or at least described in the 17th century, ie Ayaz y Beaumont’s in 1606, Somerset’s of 1662 and most importantly, Savery’s “miners’ friend” of 1698.

June 28, 2021 4:31 pm

Since the oceans have risen some 100 meters after the great ice sheets melted then any coral core samples from the near surface corals would only date back a short while in absolute years. Are there any studys of cores from deeper deposited more ancient corals which would inform us about conditions from antique times?

Rory Forbes
Reply to  RMoore
June 28, 2021 5:26 pm

Corals have an egg and larval stage in which they are planktonic. This would explain how the same species might be found at every depth in a rising sea, especially if they’re from an earlier era.

John Tillman
Reply to  RMoore
June 28, 2021 6:10 pm

Yes. Fossil coral reefs abound.

Christopher Hanley
June 28, 2021 4:48 pm

The PDF says the Saenger et al. Bahamas proxy reconstruction was related to the NOAA instrumental record, does that imply a screening process was used, what Steve McIntyre calls ‘ex post’ screening?
The fact that suitable coral samples are “difficult to locate” unlike trees etc. I’m guessing that the researches use all available samples in their reconstructions avoiding the ‘ex post’ bias that bedevils many reconstructions.

Charles Higley
June 28, 2021 6:42 pm

What the clown ecologists do not understand is that coral reefs and rainforests are the two most stable ecosystems in the world. They are always hot regardless for glacial stage we are in. They are hugely resilient not because of their specialization by their very deep gene pool of many species.

It’s the polar and subpolar ecosystems that are the weakest because of low species diversity and the fact that we and they die when buried under a mile of ice. Duh.

One can do whatever they want in Canada because the next glacial period is going to clean its clock down to bare rock.It’s a glacial flush.

Robert of Texas
June 28, 2021 7:17 pm

Don’t worry…by the time the “scientists” get done drilling cores out of corals and then painting entire reefs with antibiotics they will be in massive decline!

Just like all the small populations of unique amphibians the “scientists” tracked fungus all over in order to try to determine how the “ozone hole” was affecting them.

Or how scientists tracked a fungus into difficult to access caves trying to study the bat population declines. (The fungus is thought to have been brought to North America by European cave tourists – soon they discovered the spores were being spread on the mud of cavers’ boots).

Leave the coral be, clean up the pollution in the rivers near them, and they will be fine.

Tombstone Gabby
June 28, 2021 8:35 pm

“…and also enable us to quantify the contribution from human activities,” he said.”

Now why do I hear the unspoken “… if any” at the end of that sentence.

June 29, 2021 4:37 am

What corals tell us is that climate changes constantly, it always has and always will. The real question is how we get our tax money back from these manipulative scumbags who keep stealing it?

June 30, 2021 2:38 am

That climate changes, has always changed even before man existed and will continue to change even after man no longer exists.

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