By Kenneth Richard on 19. August 2025
New research from Indonesia indicates that from about 10,000 to 6000 years ago, when the ocean was warmer than today, coral reef growth was rapid, averaging ~6 mm per year.
Sea levels rose rapidly from the Early to Mid Holocene in this region, as they were up to 2 m higher than today 6000 years ago. The higher sea levels meant there was more room for coral reef growth.
As the ocean cooled and sea levels fell ~2 meters from the Mid-Holocene highstand, coral growth slowed to ~2-3 mm per year.
Today corals are only growing at rates of ~1 mm per year, as the water depths are too low to accommodate reef expansion. In fact, coral coverage “has declined on the flats over the last few decades,” as the “accommodation space is less than a meter at points.”
Image Source: Hynes et al., 2025
Research from the Great Barrier Reef region (e.g., Leonard et al., 2020) also indicates coral growth experienced “turn-off” periods during cold centuries (such as the Little Ice Age) with falling sea levels. When the ocean was “~1-2°C warmer than present” and sea levels were “~1.0 m higher than present,” this “allowed reefs to accrete uninhibited.”
Image Source: Leonard et al., 2020
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It’s almost as if Sea Level and Coral growth have a symbiotic relationship. Imagine that!
Corals did even better far longer ago, before our present ice age even started 34 million years ago.
Seas were much warmer than now during the PETM and for most of the Mesozoic Era, ie for more than 200 million years following the Permian-Triassic mass extinction event. Modern stony corals evolved after this Great Dying. They like it hot!
They also survived the 400+ foot sea level rise just 10-15,000 years ago, and the comet which killed the dinos. I kinda doubt puny humans can clobber them. Heck, we already tried with all those oceanic nuclear bomb tests, and they’re still around.
‘New research’?? Learned in 1965 in the first university palaeontology course: Solubility of CaCO3 in sea water decreases with increasing temperature, making it less energy intensive for calcareous sea creatures to extract calcite in warmer water; and most calcareous sea creatures like corals have an ‘infinite capacity for reproduction’, and populations are limited only by the availability of space to affix to the ocean floor. I never felt that had to be rediscovered.
1961 for me.
Pull up a map on the internet showing the distribution of corals around the
world and you will see that they occur in warm tropical seas here
Do a google search on corals and climate change and you find this sort of thing:
Climate change is the greatest global threat to coral reef ecosystems.
Scientific evidence now clearly indicates that the Earth’s atmosphere
and ocean are warming, and that these changes are primarily due to
greenhouse gases derived from human activities. As temperatures rise,
mass coral bleaching events and infectious disease outbreaks are
becoming more frequent. NOAA
Is it necessary to point out the disconnect between the above two facts?
I should point out that the evidence to support this “warming” is weak at best. The claimed warming is well below the accuracy levels of the instruments being used to measure it. Not to mention there aren’t enough sensors to create an accurate map in the first place.
Besides that there’s this:
Voyager: Is there a limit to how much sea temperatures can rise? LINK
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At the ocean surface, the ocean and atmosphere place a natural cap on water temperature thanks to convection, the force that causes strong vertical movement in the atmosphere and makes towering thunderstorms.
As ocean temperature rises in a given region, convection pulls moisture upward into the atmosphere and builds clouds. Those clouds limit the sunlight that reaches the ocean surface and thus cool it. This process begins to take place when ocean surface temperatures reach 26° C (79° F) or so.
Very small areas of water can get very hot for short periods of time but that doesn’t say much about the overall warmth of the ocean so let’s consider regional or larger scales and monthly averages. At the present time, the limit to which ocean surface temperatures can rise at those scales is estimated to be about 30° C (86° F), though monthly maximums in a few areas in the tropics have reached 31° C (88° F). Around the world, the temperature of the sea surface and overall average temperature of the ocean are rising because there is slightly more incoming solar radiation globally than there is outgoing heat radiation.
___________________________________________________________________
Are reefs in the “Very small areas of water” category?
There’s a need to point out the disconnect; there is also the need to point out that only *two* of those *THREE* things, “coral grows in warm tropical seas,” and “the Earth’s atmosphere and oceans are warming,” are facts. The other, “these changes are primarily due to greenhouse gases derived from human activities,” is hypothetical bullshit.
It seems odd NOAA can forecast the following from higher temps:
The two things don’t match.
Coral is highly mobile … Every year spawning releases trillions of gametes into the ocean which float in the current until they find a suitable spot. Along the GBR the prevailing major ocean current is southward to cooler water.
Fun fact: Moreton Bay off Brisbane Australia has corals growing in it and it has evidence of vast coral plantations from hundreds of years ago.
10,000 to 6,000 years ago. Sounds like the heart of the Holocene Optimum.
It isn’t called “Optimum” for nothing.
One thing that would have made things even better would have been more atmospheric CO2.
Wouldn’t warmer oceans be out gassing more CO2 ?
Corals Thrived In Warmer-Than-Today Temps
Unlike Englishmen.
Story tip: Green jobs
Oil and gas trade association Offshore Energies UK has written to Starmer warning that Labour’s net zero drive will lead to nearly 1,000 direct and indirect industry job losses a month between now and 2030. That’s around 52,000 jobs up in smoke…
https://order-order.com/2025/08/20/starmer-warned-net-zero-will-slash-1000-jobs-a-month-between-now-and-2030/
The gap between the British political class and the mass of the population is probably wider now than its ever been in a century or more. Miliband trying to make Britain lead the world in getting to Net Zero is one example.
But a couple of recent court decisions have also illustrated that its not just a gap with the population, its also a gap with the law. There was the Supreme Court decision that there are two sexes, and that ‘man’ and ‘woman’ in the Equalities Act refers to their biology, not what they claim to be. That overturns a mass of civil service and government policies
Then there is the latest High Court decision about migrant hotels, finding in favor of a local council who wanted to close such a hotel. The nominal legal reason was that it was a change of use without planning consent, but in fact the matter at issue is local opposition and demonstrations on grounds of safety. That will open the floodgates and make the current migration policy unsustainable.
Its extraordinary. A political class that wants to have open borders, to distinguish between men and women not by biology but by what anyone claims to feel they are, and that wants to move the country to being powered by wind and solar – in these latitudes! And a population that is increasingly in open revolt on all three of those issues, and indeed many more ‘woke’ issues.
The extent of the revolt is shown in the latest Reform Poll numbers. 347 seats in a 650 seat Parliament? Or it could be even larger by the time the next election happens.
https://www.electoralcalculus.co.uk/prediction_home.html
“The gap between the British political class and the mass of the population”
Even Moses would be impressed.
The judiciary and the civil service are unelected and wholly unaccountable to the public; they know best…
“Acting Reform Warwickshire [Council] leader George Finch wrote to the council’s chief executive asking for the flag, which includes the colours of the trans rights movement and traditional rainbow colours, to be removed.
But the chief executive refused the request, stating in an email response to Finch that she was responsible for such decisions.”
https://www.bbc.co.uk/news/articles/c4gee4w7djzo
If you combine all those rainbow colours you get white. But somehow trans are not human because they need different rights than human rights.
The only flags government takes down are the Union Jack and the English . They can’t fix potholes but can over paint flags on the road overnight.
I read the other day that someone had asked if public bathrooms would need litter boxes and hydrants for those who identify as cats and dogs.
How does the Monarchy feel about this?
A massive underestimate to be sure.
So, warmer temps and higher sea level. Got it! CO2 to the rescue! 😉
Corals are said to have evolved around the middle Triassic period…
I am just in awe of the Godlike power of CO2! There is nothing it can’t do. 😉
I wish it could knock some sense into politicians.
Want get a good idea of just how resilient corals are?
Look no further than the Bikini Atoll.
Reefs there were totally obliterated in the 1950s by 23 atomic bomb tests.
To the surprise of marine scientists, just 50 years later (2002), the reefs there had re-established themselves to ~ 70% of previously-observed 1950s states.
https://www.sciencedirect.com/science/article/abs/pii/S0025326X07004523
Corals are the weeds of the sea, I reckon.
Like land weeds, there are numerous varieties of them, they grow where they’re not supposed to, many are colorful and attractive, and once established, you can’t get rid of the buggers.
Mangroves are the true weeds of the ocean 🙂
Acropora sp. corals can grow at significant rates given water to grow into … I’ve personally grown acro +100mm in 12 months. In one of my displays, I simulated a tidal range of 50mm and the coral stood out of the water at “low tide”.
Exactly, coral loves warm water. This has been known for decades. So do I.