Some Notes on Coral and the Great Barrier Reef

Guest post by Mike Jonas

I recently had a (fairly short) conversation with an acquaintance, who was stunned to discover that I did not think at all highly of the position that Professors Terry Hughes and Ove Hoegh-Guldberg at James Cook University, Queensland, have taken on coral science and the Great Barrier Reef.

“Have you seen the documentary Chasing Coral?” I was asked, “There seems to be a lot of evidence that the reef is dying.” (or words to that effect).

I agreed to watch the documentary (if I’d known it went for a whole hour I might not have agreed so readily), and to report back when we next happened to be at the local cafe at the same time – an event which occurs from time to time. A bit like coral bleaching, perhaps.

I found the documentary quite distressing, but not for the same reasons as my acquaintance. I wrote an appraisal of it (see below), but then thought .. if I’m going to get anywhere in the next conversation, I have to come prepared. So I wrote a set of notes, which follow. The question is – are these notes OK; are there major things I’ve got wrong or left out? I’ve cited a number of papers and articles, so before recommending one please see if I’ve cited it already. Each section typically consists of my notes followed by the material (in blockquote) that I used for them.

BTW, I looked for a ready-made document on coral and/or GBR, and couldn’t find one. If one exists – not too long – that might be a lot better. Otherwise, maybe these notes will be helpful to others.

My Notes on Coral and the Great Barrier Reef (GBR)

Chasing Coral (Documentary)

The documentary did look at other coral, but its major focus was on the GBR. The documentary’s video footage was necessarily anecdotal and covered only very small parts of the GBR – the reef is over 2,300 km (1,400 mi) long, with an area of ~344,400 sq km (~133,000 sq mi). The “experts” in the video were all of the one mind – that the reef is doomed by man-made climate change – and no attempt was made to find or report on any alternative view.

A very different picture can be obtained simply by reading some of the scientific evidence.

I’ll start with the long term picture …

Geological Time

The picture that emerges from the geological evidence is that corals first appeared at a time when Earth’s temperatures and CO2 levels were much higher than today’s. Or, possibly, if modern coral species did not begin until the Devonian period then they could have begun at a time when temperatures and CO2 levels were similar to today’s. But in any case they have lived through long periods (millions of years) when temperatures and CO2 levels were much higher than today’s.

“Paleozoic [~250-600mya] was the period of early life where plants, insects, fish, mollusks, corals and many more living organisms developed.”

Wikipedia puts start of corals ~240mya. [Devonian].

In the Paleozoic, CO2 levels reached ~25x today’s level. By the Devonian they were down to about today’s level, but between then and now reached ~9x today’s level. [NB. The geological data is very low resolution. There could have been large short-term variation within those periods which would not show in the long term chart.]

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“During far most of Phanerozoic the planet’s temperature was significantly higher than in modern times.”

~240mya, sea levels were similar to today’s, but in the intervening period they went much higher. [Again, NB that the long term chart is low resolution].


“Coral reefs from the Jurassic have been found on the Sakhalin Peninsula at 60 degrees northern latitude, which is 30 degrees farther north, than where today’s coral reefs are found. Coral reefs require a minimum temperature of 20 degrees in order to grow.”

“For the past 55 million years the global surface temperature has declined by more than 10°C from a “hot house” condition into an “ice house” with increasing temperature variability as depicted in Figure 1 (Mya = millions of years ago). During the Cretaceous and Early Cenozoic, glaciers and ice caps were absent from both Antarctica and Greenland. Antarctica was covered in para-tropical vegetation and Greenland was home to crocodiles. More importantly for millions of years the oceans had been storing enormous amounts of heat. In contrast to near freezing temperatures today, Antarctic bottom waters averaged about 11°C, suggesting Antarctic coastal temperatures never dropped below 11°C even during the long polar nights. Amazingly the equator to pole surface temperature difference averaged just 10°C compared to the 30°C gradient measured today. Of particular interest, changes in carbon dioxide fail to explain the greatest proportion of these ancient temperatures.”



The Holocene is the current inter-glacial period. The end of the last glacial period (“glacial maximum”) began around 20,000 years ago. Temperatures and sea levels rose rapidly at the start of the Holocene, and during the Holocene Optimum (around 6-7,000 years ago), sea levels were about 2-3m above today’s sea levels.

The Holocene itself, including the supposedly threatening and supposedly man-made climate of today, is not at all unprecedented. The Holocene is just one of an irregular series of inter-glacial periods in the current ice age. The current ice age, the Quaternary or Pleistocene, has lasted for a bit over 2.5m years. The last inter-glacial period, the Eemian, occurred a bit over 100,000 years ago. It was 2-3 degrees warmer than today, sea levels were 4-6m higher, and it had greater rates of temperature change.

“Rates and patterns of global sea level rise (SLR) following the last glacial maximum (LGM) are known from radiometric ages on coral reefs from Barbados, Tahiti, New Guinea, and the Indian Ocean, as well as sediment records from the Sunda Shelf and elsewhere. These records provide estimated global and regional rates of SLR when combined with LGM and deglacial ice sheet history and geophysical models of regionally varying glacio-isostatic adjustment (GIA) to chang- ing land ice mass. For example, Lambeck et al. (2014) estimate mean global rates during the main deglaciation phase of 16.5 to 8.2 kiloannum (ka) at 12 mm yr−1 with more rapid SLR rates (∼ 40 mm yr−1) during meltwater pulse 1A ∼ 14.5–14.0 ka and slower rates during the Younger Dryas (YD) from 12.5 to 11.5 ka.”

“We find that sea level [at Barbados] tracked the climate oscillations remarkably well. Sea-level rise was fast in the early Allerød (25 mm yr-1), but decreased smoothly into the Younger Dryas (7 mm yr-1) when the rate plateaued to <4 mm yr-1> here termed a sea-level “slow stand”. No evidence was found indicating a jump in sea level at the beginning of the Younger Dryas as proposed by some researchers. Following the “slow-stand”, the rate of sea-level rise accelerated rapidly, producing the 14 ± 2 m sea-level jump known as MWP-1B; occurred between 11.45 and 11.1 kyr BP with peak sea-level rise reaching 40 mm yr-1. Following MWP-1B, sea-level rise rapidly decreased to 8 mm yr-1.”

“The relative sea level was 2.5 ± 0.5 m above the present level during the mid Holocene between 7000 and 6000 years ago.”

… and lots more …

Kobashi and Alley GISP2 Central Greenland Temperature Reconstructions

“The Eemian interglacial period [..] began 127,000 years ago and extended to 106,000 years ago. [..] It is estimated that the Eemian temperatures were 1–2° higher than the current ones (Kaspar, 2005). In England, the fossil studies show tropical fauna such as hippopotami, and this period has been called Ipswichian. In addition, the study of corals and foraminifera shows that the seas were 2–3° degrees warmer than the current temperature (Lea et al., 2000; Pelejero et al., 2010; Martrat et al., 2004). The Eemian sea level was 4–6 m higher than the current coastline, which probably was due to the melting of the Greenland ice sheet (Cuffey and Marshall, 2000). During this period the earth’s orbit around the sun was more eccentric and its perihelion coincided with summer in the Northern Hemisphere (today it corresponds to the aphelion). The inclination of the earth was also greater than the current 23°27′. This led to a seasonality and the heat was greater, with colder winters, than at present, corroborated by the study of the former coral reefs (Felis et al., 2004).”


The GBR has existed for about 20m years. But it has not survived in its current form over that period. On the contrary, it has essentially died many times, when sea levels dropped below the continental shelf, and recovered each time the sea level rose again. By “died” I mean that the reef as we know it died, because it was left high and dry. Graphs of the last 400,000 years of temperature suggest that the GBR as we know it would have died several times in that period. And there could have been many other such occasions over the last 20m years.

In spite of these large changes in sea level, some corals must have survived where there was still sea – presumably the outer edge of the continental shelf would have been one of those places. There are still corals in those (now very) deep places, but the mix of coral species in deep and shallow waters is quite different. So it seems likely that the reef changes its mix of coral species to deal with changing conditions – in other words, some species can die out from some areas and be replaced by others.

“The Great Barrier Reef is an extremely ancient, enormous host of living things, composed of living coral growing on dead coral dating back perhaps as much as twenty million years.”

“For large parts of that time, during periods of glacial activity, the area of the Great Barrier Reef was dry with large flat coastal plains. This area is at a depth of less than one hundred metres below sea level today.”

“Global sea level rose by about 120 m during the several millenia that followed the end of the last Ice Age (approximately 21,000 years ago) …”


[NB. Chart is in feet not metres]

“Even four times as deep as most scuba divers venture, the Great Barrier Reef blooms. A new exploration by a remote-operated submersible has found the reef’s deepest coral yet.

The coral Leptoseris is living 410 feet (125 meters) below the ocean’s surface, a discovery that expedition leader Pim Bongaerts of the University of Queensland called “mind-blowing.””

“The 410-foot distance is surprising for the Great Barrier Reef, where scuba divers find stunning coral displays at depths down to 100 feet. But corals are known to live deep elsewhere. In the Gulf of Mexico, researchers have found the coral Lophelia pertusa thriving 2,620 feet (799 m) down. Lophelia doesn’t need sunlight to survive. In Puerto Rico, light-dependent corals survive as far down as 500 feet (150 m).”

Leptoseris and Lophelia do not appear in the Australian Geographic list of coral species that “… are all found in the outer reef at Heron Island, at about 1–3m depth, as well as in other shallow reef zones of the Great Barrier Reef.”.

Coral Resilience

Although some scientists and others are very ready to forecast the end of the GBR, all of those forecasts are based on quite mild changes in conditions – mild relative to the changes that the reef has gone through in its past. One thing that is very clear is that these scientists and others are underestimating coral’s resilience. They are also overstating the importance of coral bleaching. Bleaching is one of coral’s defence mechanisms, and there is a world of difference between a bleached coral and a dead coral.

“Despite increasing confirmation of the Adaptive Bleaching Hypothesis and its ability to explain coral resilience, most people are unaware of its debate within the scientific community. The ability to rapidly adjust to changing environments by modifying their symbiotic partnerships has been the key to their success for millions of years. As one expert wrote, the “flexibility in coral–algal symbiosis is likely to be a principal factor underlying the evolutionary success of these organisms”.”

“… when a reef is reported as ‘bleached’ in the media, that often leaves out a critical detail on how severe that bleaching is, at what depth the bleaching has occurred and if it’s going to cause permanent damage to the coral at that site.”

“Reefs around the world experienced bleaching in 2016 and 2017, and while the northern part of the Great Barrier Reef did experience some severe bleaching, this condition did not affect the entire Reef and there are currently encouraging signs of recovery at a variety of key tourism sites. Recent photos taken in June and July 2018 show healthy, vibrant coral at numerous locations that suffered during the back-to back coral bleaching events in 2016 and 2017 including Fitzroy Island, Moore Reef and Saxon Reef near Cairns, among other locations.”

Great Barrier Reef starts to recover after severe coral bleaching, survey of sites between Cairns and Townsville shows

[..] The [Australian Institute of Marine Science]’s Neil Cantin said they were surprised to find the coral had already started to reproduce.” (Sep 2017)

“An amazing example of coral resilience has been found in the Gulf of Aqaba, west of the Arabian mainland. Specimens of the coral there have been placed into tanks where they are exposed to rising temperatures and sub-optimal pH levels. Scientists reported that most of the variables measured, such as energy metabolism or the building of a skeleton were actually improved. One explanation for these surprising results where such corals are observed in the stress tests to be not only surviving, but thriving, is that coral in the Gulf of Aqaba is highly evolved due to historical extreme changes in the climate of the region. The ramifications of such discoveries may be significant. Associate Professor David Suggett suggests that events such as these teach us that corals are surviving in waters that are really hot, very acidic and have very little oxygen. He reminded his 40 person audience that these are the same conditions that have been predicted under climate change.”

[From the report on a lecture by Associate Professor David Suggett M.Sc., Ph.D.

Marine Biologist, University of Technology, Sydney, at the NSW Southern Highlands branch of the Royal Society, Jun 2018]

2016-7 Bleaching

Some scientists are very ready to ascribe the 2016-7 severe bleaching of the GBR to rising water temperatures. But perhaps the main cause was a fall in sea level. A fall in sea level is prima facie a greater danger to coral than a rise in temperature.

CO2 levels and pH also appear unlikely to be the cause. As shown above, corals evolved in, and/or survived through, a period of much greater CO2 concentration than today’s. They have also survived through a period of much lower sea surface pH than today’s.

“CLIMATE change sceptic and geophysicist Professor Peter Ridd has questioned research that blames global warming for devastating coral bleaching on the Great Barrier Reef.

Prof Ridd also says the work of a US schoolteacher, who claims a drop in sea level caused by the El Nino phenomenon might have caused bleaching, should not be discounted.

Prof Ridd, of James Cook University’s Centre for Tropical Water and Aquatic Ecosystem Research, has re-entered the fray in a simmering climate war.


“I think the sea level (issue) could account for some of the bleaching but I’d be surprised if it accounts for all of it,” Prof Ridd said.

He said wind died off during El Nino events, causing sea levels to drop.”

“It is puzzling why the recent 2017 publication in Nature, Global Warming And Recurrent Mass Bleaching Of Corals by Hughes et al. ignored the most critical factor affecting the 2016 severe bleaching along the northern Great Barrier Reef – the regional fall in sea level amplified by El Niño. Instead Hughes 2017 suggested the extensive bleaching was due to increased water temperatures induced by CO2 warming.

In contrast in Coral Mortality Induced by the 2015–2016 El-Niño in Indonesia: The Effect Of Rapid Sea Level Fall by Ampou 2017, Indonesian biologists had reported that a drop in sea level had bleached the upper 15 cm of the reefs before temperatures had reached NOAA’ Coral Reef Watch’s bleaching thresholds. As discussed by Ampou 2017, the drop in sea level had likely been experienced throughout much of the Coral Triangle including the northern Great Barrier Reef (GBR), and then accelerated during the El Niño. They speculated sea level fall also contributed to the bleaching during the 1998 El Niño. Consistent with the effects of sea level fall, other researchers reported bleaching in the GBR was greatest near the surface then declined rapidly with depth. Indeed if falling sea level was the main [driver] in 2016’s reef mortalities, and this can be tested, then most catastrophic assertions made by Hughes 2017 would be invalid.

Indeed the Great Barrier Reef had also experienced falling sea levels similar to those experienced by Indonesian reefs. Visitors to Lizard Island had reported more extreme low tides and more exposed reefs as revealed in the photograph above, which is consistent with the extremely high mortality in the Lizard Island region during the 2016 El Niño. Of course reefs are often exposed to the air at low tide, but manage to survive if the exposure is short or during the night. However as seen in tide gauge data from Cairns just south of Lizard Island, since 2010 the average low tide had dropped by ~10 to 15 cm. After previous decades of increasing sea level had permitted vertical coral growth and colonization of newly submerged coastline, that new growth was now being left high and dry during low tide. As a result shallow coral were increasingly vulnerable to deadly desiccation during more extreme sea level drops when warm waters slosh toward the Americas during an El Niño.”

[The whole article is worth reading]

“Although some researchers have raised concerns about possible negative effects of rising CO2 on ocean surface pH, there are several lines of evidence demonstrating marine ecosystems are far more sensitive to fluxes of carbon dioxide from ocean depths and the biosphere’s response than from invasions of atmospheric CO2. There is also ample evidence that lower pH does not inhibit photosynthesis or lower ocean productivity (Mackey 2015). On the contrary, rising CO2 makes photosynthesis less costly.

Furthermore in contrast to researchers arguing rising atmospheric CO2 will inhibit calcification, increased photosynthesis not only increases calcification, paradoxically the process of calcification produces CO2 and drops pH to levels lower than predicted by climate change models. A combination of warmer tropical waters and coral reef biology results in out-gassing of CO2 from the ocean to the atmosphere, making coral reefs relatively insensitive to the effects of atmospheric CO2 on ocean pH.

Sixty million years ago proxy evidence indicates ocean surface pH hovered around 7.4. If surface pH was in equilibrium with the atmosphere, then CO2 concentrations would have hovered around 2000 ppm, but there is no consensus that CO2 reached those levels. However as will be discussed, there are biological processes that do lower surface pH to that extent, despite much lower atmospheric CO2 concentrations.”

Rate of Change

All of the above indicates that corals have survived much more extreme conditions than are expected to occur because of man-made climate change. But much of the alarmism has pointed to the rate of change, claiming that it will be too fast for corals to adapt. A typical statement would be “These corals aren’t going to adapt at an unlimited rate”.

But are things really changing that fast now, compared to times past? That’s often difficult to assess because we can measure things today with high precision and high resolution, whereas data from the distant past tends to be of low precision and low resolution.

There is a clue in the rate of sea level rise. The sea level has been rising at something like 2mm per annum since the Little Ice Age ended about 350 years ago. Scary charts of global mean sea level like this …

… are produced to try to make us believe that something frighteningly different is happening now.

But if you look carefully, you will see that (a) the sea level rise highlighted in the chart began in 1890, long before mankind started putting serious quantities of CO2 into the atmosphere, (b) the average rate of sea level rise is only 1.8mm pa, and (c) there is little recent acceleration. It is also worth noting that high-resolution recent data has been spliced onto low-resolution older data – a definite no-no in proper science.

Compare the sea level rise rate in that chart with some of the sea level rates from times past, as cited above. eg: 12mm pa from 16.5 to 8.2 ka (that’s 6 times today’s rate for more than 8,000 years), ~40mm pa during a meltwater pulse ~14.5-14.0 ka, 25mm pa in the early Allerød and a “plateau” of 4mm pa (still double today’s rate) in the Younger Dryas.

So some things at least must have happened a lot faster in the not-so-distant past than they are happening today, without wiping out the coral.

And finally …

… if you want a really cynical view of reef alarmism, read Jo Nova:

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John Tillman
September 26, 2019 2:15 pm

The Devonian wasn’t 240 Ma. That was the Triassic, when scleractinian or stony corals replaced earlier forms wiped out by the end Permian extinction. Corals first evolved in the Cambrian, some 535 Ma.

The Devonian laster from about 419.2 to 358.9 Ma.

James Bull
Reply to  John Tillman
September 29, 2019 12:25 am

I must say that my first thought was that I would have told the story of what happened to someone who questioned what his colleagues were saying about the reefs and the data and the response from JCU when it’s been shown the be wrong in it’s response and behaviour both publicly and privately.

If that doesn’t make your friend question what the film shows I not sure what would.

James Bull

John Tillman
September 26, 2019 2:29 pm

Cambrian CO2 ranged from 7000 to 4500 ppm. The Triassic averaged 1750 ppm.

Even the mid-Cretaceous thermal maximum, with average tropical SSTs of 35 degrees C or higher, didn’t kill off corals. They like it hot.

Plus they can migrate if one region should get warmer than a particular species prefers.

John Tillman
Reply to  John Tillman
September 26, 2019 2:42 pm

Stony corals use the form of calcium carbonate called aragonite, while their Paleozoic relatives, the tabulate and rugose corals, used calcite.

Rising sea levels during the Devonian did adversely affect tabulate corals, which went extinct with the rugose corals in the Permian-Triassic mass extinction event, aka “Great Dying”. Calcite-shelled ammonite cephalopods were wiped out then, too, but aragonitic nautiloids survived.

John Tillman
Reply to  John Tillman
September 26, 2019 3:07 pm

The calcite-aragonite survival discrepancy in the Permian MEE suggests changes in ocean chemistry far more profound than a slightly less basic shift in pH.

Reply to  John Tillman
September 26, 2019 3:46 pm

Growing corals turn water more acidic without suffering damage

Phytoplankton calcification in a high-CO2 world.

Here, we present laboratory evidence that calcification and net primary production in the coccolithophore species Emiliania huxleyi are significantly increased by high CO2 partial pressures

John Tillman
Reply to  Latitude
September 26, 2019 8:49 pm

Why let stubborn facts get in the way of an hypothesis so lucrative?

Reply to  Latitude
September 27, 2019 4:02 pm

Hugh underwater coral reef system at the mouth of the Amazon, whose waters have a pH of around 6.

They should have learned from its discovery that they have a poor understanding of the environments in which corals can thrive.

Reply to  John Tillman
September 26, 2019 3:10 pm

Ammonites only became extinct during the K-Pg extinction 66 million years ago. They almost became extinct during the P-T extinction (and during every major extinction – they were an extreme “boom-and-bust” group, but the Chicxulub impact finally finished them off)

John Tillman
Reply to  tty
September 26, 2019 3:53 pm

You’re right. How could I forget the Jurassic Coast, where Mary Anning sold ammonite seashells by the sea shore?

Anyway, the calcite-aragonite divergence happened in both cases.

Loren Wilson
Reply to  tty
September 26, 2019 6:27 pm

A pity. Just think what a great pet an ammonite would make.

John Tillman
Reply to  Loren Wilson
September 26, 2019 8:53 pm

Your aquarium would have to be extra special to accomodate ammonites.

Reply to  John Tillman
September 26, 2019 3:20 pm

Most of the ocean apparently became anoxic at the time. This has happened from time to time, but is only possible in a hothouse climate when there is no production of cold well-oxygenated deep water near the poles.

John Tillman
Reply to  tty
September 26, 2019 3:56 pm

In our present Icehouse climate (34 million years and still getting colder), little risk of anoxic oceans. Lots of deep, cold oxygenated water at the North Pole and around the South Pole.

Mike McHenry
September 26, 2019 2:32 pm

I don’t get the assertion of significant change in ocean temperatures I hear all the time. The NOAA argo floats don’t show this nor ships cooling water intake dating to the 1950’s. Thermodynamic properties of air vs water tell you that air has a puny amount of heat compared to water. Wheres the data?

September 26, 2019 2:46 pm

Greenland doesn’t have 5 m of sea level rise on it. Not least because it has a mahoosive lake in the middle. Must have been the unstable West Antartic ice shelf, probably due to volcanic activity beneath it.

Reply to  Chaswarnertoo
September 26, 2019 3:03 pm

Actually Greenland does have about 7 m of sea level rise on it. The central lake would be quite shallow. West Antarctica on the other hand only has about 3 m of sea level rise on it. Because most of the ice there is below sea-level most of the meltwater would be used up to fill out the same volume with seawater (which is about 10% denser than glacier ice).

Not that the Greenland ice is likely to melt anytime soon, 10,000 years of 5-8 degrees warmer temperatures during the last interglacial didn’t melt it, nor did 30,000 years of higher temperature than today during the fourth interglacial back (MIS 11)

September 26, 2019 2:55 pm

240 million years ago is Early Triassic, not Devonian, and it is true that modern (scleractinian) corals shows up then. Earlier corals belonged to other groups, perhaps not closely related.

The GBR isn’t anything like 20 million years old. More like 1 million years, or less:

Very few really large reefs anywhere seems to be more than c. 800,000 years old. The 41,000 year glacial cycles before that were probably too short for major reef building. And yes, it has died at least 8 times in the last 800,000 years, during each glaciation. As a matter of fact it has been dead, and turned into a low limestone range for about 90% of that time.

And so has every coral reef anywhere in the World.

The corals have to move up and down the continental slopes continuously as sea-levels change. However sea-levels have stayed relatively stable, and at about the same level for 10,000-30,000 years during each of the last 7-8 interglacials, so that level is where the big reefs and atolls build up.

If you want to see how it works, visit the Huon Peninsula in PNG. It has been rising rapidly during the Pleistocene, so there the old dead reefs form a “staircase” rather than building up in the same place:

comment image

And by the way barrier reefs are much older than (scleractinian) corals, and don’t even have to be built by corals. There is a beatifully preserved Devonian barrier reef going around much of Kimberley, the Napier Range. That was largely built by bacteria and algae:

Rud Istvan
September 26, 2019 3:00 pm

Two suggested resources.
1. Jim Steele’s posts here on coral biology and bleaching.
2. My essay Shell Games in ebook Blowing Smoke, the relevant first half covering the scientific misconduct behind the first main coral/CO2 paper by Aussie ‘scientist’ Fabricius in Nature Climate Change 2011. H2S, NOT CO2, was the culprit—and her SI water samples prove she knew it.

September 26, 2019 3:00 pm

Deliberate confusion of bleaching with dying.
Bleaching corals are not dying, they are in the process exchanging one symbiot for another that is better adapted to the new temperature.

Reply to  MarkW
September 26, 2019 3:30 pm

No Mark, there has been extensive dying.
Mike ‘not thinking highly’ of the reef scientists doesn’t go far in science, and like Jonova,he needs to actually present his evidence for review instead of hiding it in confirmation bubbles.

Richard S Courtney
Reply to  Greta2
September 27, 2019 1:01 am


No Greta2, there has been no extensive dying.
You ‘not thinking highly’ of the Mike doesn’t go far in science, and you need to actually present your evidence for review (as Jo Nova does) instead of hiding it behind pseudonyms attached to anonymous comments.


Reply to  Richard S Courtney
September 27, 2019 2:32 pm

Wow, a complete 180 accusation, you’ve won !.
Which alt science sites have you been glued to ?.
I’m not the one pretending to be a scientist.

Richard S Courtney
Reply to  Greta2
September 28, 2019 1:34 am


I commend for your education the information in this thread addressed to you from Bob Fernley-Jones. Also, you need to refer to the works of Peter Ridd who has completely refuted the scsremongering assertions you have parroted here.

Your personal comments are misplaced because anybody can check that I made an entire career as a research scientist while the only information about you is that you are an anonymous internet troll who has parroted nonsense.


Reply to  Greta2
September 27, 2019 1:45 am

There is indeed a big distinction between bleaching and dying that is apparently not understood by the media and hence the general public.
Are you aware of how little of the GBR has actually been surveyed for mortality?
Go to GBRMPA final report and lookup transects.
The standard of reporting is really quite inadequate and is all highly subjective of course, and reported second hand.
I’ve yet to discover an estimate of mortality divided between the flats, crests and slopes, which all have potentially different causes for thermal bleaching.
I note that in the aerial bleaching survey videos there was plenty of bleaching on the slopes and mortality surveys were done in deeper waters but what the demography outcomes were are a mystery to me.

Reply to  Greta2
September 27, 2019 4:08 pm

According to the ‘models’ of reef scientists, coral reefs could not exist at the mouth of the Amazon. But there is one. Never put too much faith is what scientists say can be, can’t be, will be, won’t be. The are basing their opinions on their current understanding of the science, but the science is NEVER settled.

michael hart
September 26, 2019 3:06 pm

Not sure why you would describe Jo Nova as “really cynical”. She is usually spot on. One of the most clued up skeptic sites on the interwebs. Most of what she comments on in the kingdom of global warming really is as worse as she describes it.

Dr. Deanster
September 26, 2019 3:07 pm

Good read .. but you are wasting your time if you expect it to have any impact on your buddies who are apparently “believers”. Any time belief enters the picture, you can forget having any influence at all.

You hit a lot of obvious points I would bring up …. as recently as 20k years ago … ALL the coral you see today was on dry land. Then the El Nino effect of lowering water levels. …. all that makes sense to me. … but like I said, it won’t phase your buddies.

John in Oz
September 26, 2019 3:07 pm

You are making a mistake in thinking that data and facts are important and the basis for making decisions.

Mo matter how much reality you produce, the eyes will glaze over and you will be told that ‘all of the authorities agree’ and ‘97% of scientists agree’.

“Facts! We don’t need your stinking facts. We are woke and unicorns have as much right to be rainbow-coloured as are teenagers to a clean, peaceful, happy-happy nirvana with fast internet speeds and free mobiles”

Gordon Dressler
Reply to  John in Oz
September 27, 2019 10:05 am

. . . and you overlooked “the science is settled” refrain.

September 26, 2019 3:12 pm

Many thanks for the constructive comments to date. I’ll adjust my notes accordingly, before going for coffee.

A happy little debunker
September 26, 2019 3:13 pm

For some reason? Coral is both abundant and healthy near Indonesia, in much warmer waters.

Where they have recorded coral bleaching, it has been because of lowering sea levels rather than rising sea levels.

So, in a warming ocean with rising sea levels – the GBR is under little threat.

September 26, 2019 3:27 pm

Haven’t seen the Chasing Coral video, but I suspect the creators probably plied the same deceptive-manipulative tricks as used by the “Gas Land” video creators. Which of course are the same manipulative Al Gore tricks used in his original IT video in 2005. Each builds on the deceptions of the last one — Ever higher piles of junk on top of previous piles of junk science.

The trick:
– Pick a environmental narrative and build cherry-picked images and video clips around it.
– Use frequent simple uncontroversial science and then wrap ever larger exaggerations around them to create the desired deception in order to call any skeptics “deniers of science.”
– Don’t allow alternative explanations into the video.
– Play to gullible people’s beliefs in urban legends and lack of basic science knowledge as most people would be hard pressed to describe the difference between CO2, CO, and methane for example.

Peter D
September 26, 2019 3:28 pm

The current GBR is less than 10,000 years old. Sea level rose a few hundred meters at that time. Doubtless there was an outer reef, long submerged. This is recent enough to remain in oral Aboriginal history. There is scientific evidence. Even JCU accepts the dates.
The reef is highly adaptive almost plastic over short periods.

John Tillman
Reply to  Peter D
September 26, 2019 3:46 pm

From the Last Glacial Maximum low to Holocene highstand, sea level rose 120 meters, but it’s now perhaps two meters lower than during the Holocene Climate Optimum. Maybe more in Oz.

John Tillman
Reply to  Peter D
September 26, 2019 3:50 pm

Recent paper on Holocene highstand in Oz says 1.0 to 1.5 m higher than present mean sea level in Queensland, but 1.84 m higher 80 km. south of Sydney:

Crispin in Waterloo
Reply to  John Tillman
September 27, 2019 5:07 am

Australia’s Prof Fairbridge documented old shorelines on the eastern shores and said there were visible lines 2m above present high tide marks.

He felt the change over the past 10,000 years included levels 2 m above present but not much below.

He was a strong supporter of the idea of a solar origin of temperature and weather changes.

Reply to  Peter D
September 26, 2019 4:08 pm

“The current GBR is less than 10,000 years old. Sea level rose a few hundred meters at that time. ”
What? Where is your proof for that?

comment image

Reply to  Simon
September 27, 2019 1:39 am

Correct. The sea level has not been more than about 140 meters lower than now for the last few million years since the Bab el Mandeb has never been dry during the Pleistocene.

Reply to  Peter D
September 26, 2019 4:36 pm

Do you have evidence that Aborigines were able to travel to the outer reef, that they knew what the outer reef meant in the context of your comment, evidence that reliability can be assumed for several thousand years of oral transmission of events, evidence that modern interpretation of alleged dream time material is accurate and untainted and finally that any such material actually was handed down through generations and not, like other material familiar to me, invented by academics around the middle of the 20 the Century? Geoff S

Rod Evans
Reply to  Geoff Sherrington
September 27, 2019 1:22 am

Quite. +100
It would be fascinating to hear how a “believer” would set about proving the dream words handed down was actually handed down, as opposed to merely imagined, it was handed down.
It might all be just a dream….

Reply to  Geoff Sherrington
September 27, 2019 1:24 am

Good point Geoff!

Reply to  Geoff Sherrington
September 27, 2019 1:24 am

Good point Geoff!

September 26, 2019 3:41 pm

POST: “the little ice age ended about 350 years ago

I believe the Little Ice Age ended mid 1800’s or about 150 years ago.

John Tillman
Reply to  PmhinSC
September 26, 2019 5:20 pm

The depth of the LIA was during the Maunder Minimum, c. AD 1695, hence some 325 years ago. But it didn’t end until the middle of the 19th century.

Richard S Courtney
Reply to  John Tillman
September 27, 2019 1:23 am


John Tillman is right. Although the LIA did not end until ~150 years ago, recovery from the LIA began more than 300 years ago.

In his above article Mike Jonas says,
“The sea level has been rising at something like 2mm per annum since the Little Ice Age ended about 350 years ago.”
As you rightly say, that can be challenged.
Jonas would have done better to have used the phrase “the depths of the Little Ice age ended” instead of the phrase “the Little Ice age ended”.

However, pointing that out is ‘nit picking’ because – for the reason stated by Tillman – in context the meaning of Jonas’ words is true.


Reply to  Richard S Courtney
September 28, 2019 10:38 am

Thank you for the reply and the information.

It does need to be clarified as someone not familiar with the LIA will go to Wikipedia which says “about 1850.” To the layperson not receptive to the authors message, they could easily focus on that “discrepancy(?)” and wonder what other discrepancies exist.

September 26, 2019 3:57 pm

The death of the Great Barrier Reef is an Icon for the Global Warmists propaganda machine.
Other icons are starving polar bears ,caving glaciers , sinking coral islands and hurricanes .
The average person is to busy getting on with living and take little notice of the constant propaganda .
When you engage in conversation they generally know very little but they will say “but the great barrier reef is stuffed “or “the polar bears are heading for extinction “or sea levels are going to flood low level islands and our shores ”
The alarmists have to push the death of the Great Barrier Reef even if it costs millions to defame Petr Ridd or any one else who is strong enough to stand up and tel the truth .
The Great Barrier Reef is an Icon and if it becomes proven beyond any doubt that it is flourishing and that is widely there goes one of the main pillars of the temple of Climate Change .
Just look at the lies and abuse that Susan Crockford has had to endure when telling the truth that polar bears are doing just fine .
We had a news item last night of a coral island in the Solomon’s about a woman’s house that had washed away, complete with a tree laying in the tide .
Always propaganda and never any counter view .
Graham NZ

Rod Evans
Reply to  Gwan
September 27, 2019 1:45 am

We had that same image propaganda here in the UK too, The link up between the media outlets across the globe is very concerning. Our images were provided by the ITV network. They have been running a mass propaganda push for the past few weeks. They even included (after the drowned atoll clip) Emma Thompson being allowed to claim her trip from LA to London in first class was simply a flight home, and immediately attending the climate demonstration to demand people should fly less, was not related. Rageh Omaar allowed that pathetic cop out to pass, without any challenge. She also went on to say we should avoid flying where it isn’t necessary. She gave an example, “don’t fly to NY for a hen party bash if you are in the UK, it would be more environmentally sensible to celebrate locally”…
Now I don’t think many girls in Liverpool, Manchester or any other major city were planning to fly their hen party guests to NY, but hey if you were, just go to Estonia like normal people….
Oh, he also asked her if she would stop flying? She was emphatic and clear “No that would be too draconian”, her words.!!
So there you have it, Thompson thinks the climate crisis is so bad everyone should contribute to saving the world by stopping flying, except her!
I should also point out for clarity, she claims she is not a hypocrite.

It doesn't add up...
Reply to  Rod Evans
September 27, 2019 2:18 am

The hen party being referred to obliquely was Megan Markle’s. You’d have to look at her guest list to see whether it made more sense to hold it in London or NY. However, she flew by private jet and the whole bash cost several hundred thousand dollars. How many of her guests also flew in by private jet should also be a factor.

She now has a planeload of journalists following her antics in Southern Africa. Definitely a high carbon footprint woman and a hypocrite, along with her husband.

Ron Long
September 26, 2019 4:05 pm

Great posting, Mike J. and great comments. As a mining exploration geologist I have worked extensively in limestones, which are the sedimentary rock produced at the carbonate factory (Dr. Jon Thorsen) which is a reef. Coral seems to be a part of the reef since Cambrian times, and is always accompanied by a great variety of aragonite/calcite based critters. Sometimes the entire reef complex is buried by muds/silts/sands and preserved in entirety, usually called a bioherm in the stratigraphic record. The environments these limestones and bioherms exist in is quite variable, excepting that they are formed in shallow water (fine-grained limestones are downslope debris and can move a long ways from origin). I saw many patch reefs, marked by Trigonia sp. throughout the Early Cretaceous Vaca Muerta (famous because it is loaded with some of that black gold that D. M. likes) and the environment was a very muddy bay. Reefs are not fragile, they persist by moving into a somewhat more friendly environment, and return as conditions allow.

John Tillman
Reply to  Ron Long
September 26, 2019 5:28 pm

I’m guessing that Argentina welcomes fracking in the Dead Cow Formation.

September 26, 2019 4:34 pm

I remember reading on WUWT about a study of 19 uninhabited Pacific islands with coral reefs that had suffered no damage, contrasting with fairly nearby and inhabited ones that were damaged. This suggested that the damage in the latter was attributable to manmade actions, like hunting for parrot fish, pollution runoff, sunscreen wash-off, etc. I think this is strong ammo. I hope someone else knows where to find it.

One can search for “coral reefs” in WUWT’s “Category” search box, cunningly concealed nine page-downs below page one. Or click here:

Stephen Skinner
September 26, 2019 4:37 pm

As corals first appear around 240 million years ago before the current ice age they would have formed on a world with completely different shaped continents and no Atlantic Ocean. Corals survived CO2 hitting 3,000 ppm and temperatures up to 10C warmer than now so it does seem an exaggeration to say the earth will hit ‘tipping points’ with CO2 and temps only slightly above what they were 100 years ago.
Incidentally, about the time Antarctica began to freeze was right about the time India collided with Eurasia and formed the Himalayas and the Tibetan Plateau. The Atlantic Ocean had opened fully from Antarctica to the North Pole and Antarctica became surrounded by open ocean, the newly formed Southern Ocean.
At 5 million years the Mediterranean fills for the last time. This would remove the heating affect of a depression that was at it’s deepest 5,267m below sea level, or 17,280ft below sea level!
Are these changes inconsequential compared to changes in atmospheric CO2 concentrations ?

John Tillman
Reply to  Stephen Skinner
September 26, 2019 5:44 pm

Yes, stony corals have survived and thrived since Pangaea was intact, the world much warmer and CO2 much higher. They have experienced titanic tectonic shifts and rifts. Pangaea started breaking up at the Triassic-Jurassic boundary, with the CAMP, volcanic rifting leading to the formation of the central Atlantic between Africa-Europe and North America some 200 Ma.

The then Indo-Australian Plate, after setting a tectonic speed record in crossing the Indian Ocean from Antarctica, had closed the Tethys Sea by about 50 Ma, after which its collision with the Eurasian Plate began lifting the Himalayas and associated mountain ranges. The associated mass extinction event led to dominance of the dinos in most terrestrial environments.

But Gondwana kept splitting up. By the Eocene-Oligocene boundary some 34 Ma both South America and Oz had separated from Antarctica with deep oceanic channels between the continents, creating the Southern Ocean. This set off dramatic cooling into the Cenozoic Icehouse, which has just gotten colder and colder since then. Our present realtively less chilly interglacial won’t last. Unless fusion-powered blow driers can melt the NH ice sheets sure to start forming again some thousands to tens of thousands of years hence.

Mark Broderick
September 26, 2019 5:08 pm

John MacDonald
September 26, 2019 5:56 pm

Most people today seem to think reefs are only creatures of the current surface ocean. The reality, as mentioned here, is that corals have been producing reefs since the Devonian, and the early creations are still quite useful. In my early careers I built facilities to produce Nisku pinnacle reef structures in the West Pembina area of Alberta. These small, mushroom shaped reefs made wonderful oil and gas traps with excellent permeability. Here’s an abstract from Andre Chow of Chevron that describes them nicely:

ABSTRACT: Dolomitization and Reservoir Quality in Upper Devonian Nisku Pinnacle Reefs, West Pembina Area, Alberta, Canada

CHOW, ANDRE M. C., Chevron Canada Resources, Calgary, Alberta, Canada

The Upper Devonian Nisku pinnacle reef trend in the West Pembina area is located in south-central Alberta (T47-52, R8-13W5M) roughly 250 km northwest of Calgary. Since their discovery in the late 1970s, these reefs have been prolific hydrocarbon producers. Approximately 50 pinnacle reefs have been discovered to date in the northeast-southwest-trending West Pembina area, which covers a fairway about 50 km in length and 10 km in width. These pinnacle reefs are small in size (average 1 km in diameter) and grew up to 100 m in height. They are usually circular in plan view and mushroom-shaped in cross section.

The Nisku pinnacle reefs are different from other Upper Devonian reefs of the Western Canada sedimentary basin. (1) They were initiated in deep water (roughly 50 m). (2) Their fauna is dominated by corals rather than stromatoporoids. (3) They exhibit a vertical facies zonation that is different from the typical lateral facies zonation exhibited in the larger Upper Devonian Swan Hills and Leduc reefs of Alberta.

There are several petrographically recognized dolomite types in the Nisku. The three most important types are a fine-grained matrix dolomite, a coarse-grained matrix dolomite, and saddle dolomite. All of the Nisku pinnacle reefs contain fine-grained matrix dolomite in varying amounts. Reefs with only this type of dolomite present are poor reservoirs as this type of dolomite does not enhance porosity or permeability. Reefs that contain the coarse-grained matrix dolomite are generally excellent reservoir rocks. This type of dolomite, along with the associated dissolution of limestone, greatly enhances the porosity and permeability. Saddle dolomite commonly occurs as a pore-filling cement in reefs that contain coarse-grained matrix dolomite. It reduces the porosity but generally does not adversely affect the permeability.

Fine-grained matrix dolomite and coarse-grained matrix dolomite are formed during intermediate burial diagenesis. Saddle dolomite is formed during the late stage diagenesis.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)

September 26, 2019 6:08 pm

I read somewhere that Jennifer Maharosey is photographing the GBR.

“I’m leaving Noosa tomorrow for the Great Barrier Reef. If you would like to be updated on my work there — with a drone pilot and underwater photographer — considering subscribing for my irregular email updates:

In Mike Jonas’ excellent information within the article:

“It is estimated that the Eemian temperatures were 1–2° higher than the current ones (Kaspar, 2005). In England, the fossil studies show tropical fauna such as hippopotami, and this period has been called Ipswichian.”

I vote we bring hippopotami back to their natural environment in England!
Though, with temperatures only 1° – 2° higher than today; the hippopotami likely only lived in Southern England.

John Tillman
Reply to  ATheoK
September 26, 2019 6:40 pm

Peak Eemian warmth was a lot hotter than that. The Eemian last some 5000 years longer than the Holocene so far, and globally was at least 2-4 degrees C balmier than now, yet the Greenland Ice Sheet didn’t melt.

The Southern Dome lost perhaps 25% more than now. The Northern Dome was essentially unaffected.

Reply to  John Tillman
September 27, 2019 1:51 am

The Eemian proper, MIS 5e, was only about 10,000 years. However the end was time-transgressive, the cooling started in the north while the Mediterranean area had interglacial conditions for a few thousand years longer even as ice built in Scandinavia and Siberia.

It is difficult to derive a global temperature for the Eemian, but it wasn’t as much as 4 degrees warmer globally, though it was as much as 8-10 degrees in some arctic areas. The tropics were only 1-3 degrees warmer.
The 8 degrees warming the NEEM ice-core found for northern Greenland has been disputed, but has recently been confirmed by a lake deposit in northwestern Greenland:

John Tillman
Reply to  tty
September 27, 2019 9:35 am

I thought that the Eemian lasted about 16,000 years, ~130 to 114 Ka, but I guess it’s hard to date interglacials with much precision.

Reply to  ATheoK
September 26, 2019 6:42 pm

I messed up the link to Jennifer Marohasy’s web page:

And I mistyped her last name within my messed up link..

Michael Ozanne
September 26, 2019 7:17 pm

“I recently had a (fairly short) conversation with an acquaintance, who was stunned to discover that I did not think at all highly of the position that Professors Terry Hughes and Ove Hoegh-Guldberg at James Cook University”

disagreeing with the university of east Wankerton… how dare you….. 😛

September 26, 2019 8:51 pm

Self important arrogant a-holes are the people who 1, think the reef cannot stand a couple of degrees of warming after surviving so long that to many of them the timescale is beyond their imagination and 2, that it needs their help to do it. We live in an age where everything is in trouble and all we need to do is get out the sonic screwdriver and fix it. These are the same people who take regular tissue sample from whales by stabbing them with a corer. Because you see, by doing this they will be able to play with microscopes and take DNA analysis which of course is going to save them.

A C Osborn
September 27, 2019 1:50 am

Mike, forget the history data, it is too much for them to take in.
Just quote the good lady Australian Environment Minister Sussan Ley who actually went there and LOOKED FOR HERSELF and said the Reef is doing fine and not dead.

September 27, 2019 2:56 am

That’s not a bad bit of collation you’ve done there. I think most biologists who have been around long enough to understand some of the basics of how natural systems respond to change – climate or otherwise (Darwin knew it 190 years ago, better than many today) – must be very suspicious of the current alarmist stance on the GBR. Just think of the astounding fecundity of corals – you’ve maybe seen the videos? – and the distances and speeds over which they may disperse, and you’ll realise how rapidly adaptable they are. The species mix may change, sure, but the GBR will still be there, and will still be a stupendous tourist attraction.

Some of the comments on this thread are very smart, and very pertinent. Amazing knowledge base some of the denizens have. You might consider giving your friends a link to it, if that would help. Though (my experience too) you may find your friends just dissemble, or go quiet on you, rather than make an effective counter, let alone change their minds.

September 27, 2019 3:49 am

I read in WUWT a couple of years ago that global warming, the air in contact with the ocean UV, long wave radiation, did not penetrate water. The ocean is warmed by direct sunlight down to 100 metres. Its got nothing to do with carbon dioxide. Warming happens during El Ninos when there is less cloud cover.

September 27, 2019 5:25 am


Additional facts and research results are always helpful to a difference of opinion. But step back and consider the motivation for a documentary. These things are not intended to be encyclopedic. They’re opinion pieces motivated by a point of view. That doesn’t make them bad, but it does make them incomplete. Approach the next conversation with your acquaintance by discussing the context of the documentary. Why did the producers choose corals as a topic? Why did they select only certain information to present? Why was it resricted mostly to the GBR? Once it’s established that the documentary isn’t the last word, you have an avenue for discussion of all of the research information.

Don K
September 27, 2019 6:03 am

Interesting article and excellent comments. Two things that I don’t see discussed.

1. If the GBR were in trouble due to climate change (i.e. global warming), my expectation would be that the Northern (more tropical) part of the reef might be in trouble, but the Southernmost part would be thriving and expanding Southward. That’s not at all what is (alleged) to be happening. NOTE: I could, I think, be convinced by much better evidence than I’ve seen, that the GBR is in trouble. But the cause would probably be disease, chemical pollutants, silt from agriculture or something else other than simple warming.

2. Assuming that the GBR were dying, how would one tell? The reef is about the size of California or Italy. And it’s under water. A biological survey of the entire state of California performed by a few observers on foot would be utterly impractical. The results would likely be pretty poor. Trying to survey a similar area with swimmers would seem to me to be orders of magnitude more difficult. How about aerial surveys? Well, yes, I think that’s what would have to be done. Trouble is that identifying bleached/dead coral at any depth at all in an aerial photo is likely to be next to impossible. I’m pretty sure I couldn’t do it. I wouldn’t be at all surprised that no one can.

John Weistroffer
September 27, 2019 8:12 am

Here’s another problem with the Chasing Coral movie that irked me. The movie insinuates (but never states explicitly) that the Caribbean reefs are in bad shape also due to Global Warming. This isn’t true.

The Caribbean reefs are indeed in very bad shape (for the most part, there are certain spots that are fantastically healthy). But there are completely separate reasons for the decline of Caribbean reefs:

– Diadema urchin die-off (epizootic)
– White band disease (caused by human fecal bacteria – inadequate septic treatment)
– Black band disease and other coral diseases (likely caused by eutrophication and phosphorus limitation)

These issues have worked synergistically over the last 30+ years to prevent recovery of the Caribbean reefs. It’s really a sad situation but there are some fantastic people out there working to truly restore these reefs – particularly in the Florida Keys.

While there have been bleaching events in the Caribbean they are NOT the main cause of the problems there. And here’s the main takeaway: There are many different issues that can and do cause coral mortality. Extreme water temperature is merely one issue. To focus solely on that and to ignore the others is a disgrace.

September 27, 2019 6:17 pm

In spite of these large changes in sea level, some corals must have survived where there was still sea – presumably the outer edge of the continental shelf would have been one of those places. There are still corals in those (now very) deep places, but the mix of coral species in deep and shallow waters is quite different.

Its all too easy to think these changes are quick. Today “normal” sea level and tomorrow 10s of meters lower but the reality is that coral lives just below the surface (and deeper) and as the sea level dropped, the coral stayed exactly the same relative to the surface with imperceptible changes in its location from day to day. The same applies as sea level increases.

The key to this whole “sea level” issue is to realize that in terms of life on earth, the changes are utterly imperceptible, pose no threat, and at worst will mean that human structures today will possibly be lost in the future…which would have happened anyway because our structures (like your average home) on the whole last a blink of an eye.

September 28, 2019 9:11 am

“So some things at least must have happened a lot faster in the not-so-distant past than they are happening today, without wiping out the coral.”

The coral alarmists don’t have much sense of history of the GBR but perhaps we’ll help them with the homework-
Been a bit of sea level movement over the years eh chaps?

Johann Wundersamer
October 9, 2019 2:21 am

Amazingly the equator to pole surface temperature difference averaged just 10°C compared to the 30°C gradient measured today. Of particular interest, changes in carbon dioxide fail to explain the greatest proportion of these ancient temperatures. –>

Amazingly the equator to pole surface temperature difference averaged just 10°C compared to the 30°C gradient measured today. Of particular interest, changes in carbon dioxide concentrations fail to explain the greatest proportion of these ancient temperatures.

Johann Wundersamer
October 9, 2019 2:22 am

Amazingly the equator to pole surface temperature difference averaged just 10°C compared to the 30°C gradient measured today. Of particular interest, changes in carbon dioxide fail to explain the greatest proportion of these ancient temperatures. –>

Amazingly the equator to pole surface temperature difference averaged just 10°C compared to the 30°C gradient measured today. Of particular interest, changes in carbon dioxide concentrations in the Earth’s atmosphere fail to explain the greatest proportion of these ancient temperatures.

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