By Andy May
In this post I examine the proxies used to compare CO2 to temperature from 66 million years ago (Ma) until today and comment on the quality of the comparison. In addition, we look at the Cenozoic plate tectonic events that affected global climate. Figure 1 compares Westerhold et al.’s deep-sea d18O (the Oxygen-18 isotope anomaly, a temperature proxy) to the d13C (the Carbon-13 isotope anomaly), both measurements are from the same fossils, so they can be directly compared. One of the problems with many temperature/CO2 plots is often they are from different sources and locations and due to dating errors and differing temporal resolutions, they are not directly comparable. While d13C is not a direct CO2 estimate, it is related to the CO2 concentration in the deep ocean. Atmospheric and ocean CO2 concentration estimates are compared to d13C in figure 2.
Major plate tectonic events are noted in figure 1 and a conversion from d18O to deep sea temperature is given in blue on the left. The highest temperatures in the Cenozoic are from the early Eocene (~56-48 Ma) when deep sea temperature exceeded 12°C higher than today. This was accompanied by a dramatic drop in deep-sea CO2. As already mentioned, d13C is not an estimate of CO2 concentration, but related to it. Proxy estimates of CO2 from Rae, et al. are compared to Westerhold’s d13C estimates in figure 2.
The match in figure 2 is not great and both datasets have problems, but the similarities in trends are obvious. The estimates of CO2 concentration reported by Rae, et al. are discontinuous and from a variety of proxies that are dated by many different authors with many different techniques. It is clear from the scatter that the assumption that CO2 is evenly distributed globally is not applicable at this compressed time scale. Notice the PETM (Paleocene-Eocene Thermal Maximum) carbon isotope excursion (CIE) event at ~56 Ma shows up dramatically in both records. This large divergence in the ratio of carbon-13 to carbon-12 is a prominent global rock-record phenomenon and a reliable geological time marker that occurred between 55.6 and 55.4 Ma. Possible reasons for the CIE and the PETM are discussed here. This geological event and the following warm period comprise the most dramatic climatic event in the Cenozoic.
One important event at the beginning of the PETM, between 56 and 55.6 Ma, was the North Atlantic Igneous Province or “NAIP” volcanism. This was a huge series of volcanic eruptions that accompanied the opening of the North Atlantic and placed over 5 km of lava between Greenland and northern Europe (Stokke, et al., 2020). It nearly turned the North Sea into a lake. But, regardless of the reasons for the PETM and the Early Eocene Climatic Optimum (EECO, ~56-48 Ma) period, they are very noticeable in the rock record and easily identifiable in geological sections all over the world.
After the EECO, deep-sea temperatures begin a long decline. At first CO2 increases, but at the beginning of the Oligocene it begins to decline, with the decline becoming more dramatic in the Middle Miocene.
Major Plate Tectonic Events in the Cenozoic
During the PETM and in the warm period that followed it, the continents were configured as shown in figure 3.
Notice that all the oceans are connected by a seaway in the lower and middle northern latitudes, it is marked with a white line. India is moving through the Indian Ocean and on its way to collide with Asia. The Arctic is probably isolated by land and the Southern Ocean is blocked by land masses connecting South America and Australia to Antarctica. This is the warmest planetary configuration and the EECO, is classified as a “hothouse” climate by both Christopher Scotese (Scotese, Song, Mills, & Meer, 2021) and Westerhold, et al. Hothouse climates have global average temperatures (land and ocean) above 20°C and there is no year-round ice on either pole.
Arctic sea surface temperatures (SSTs) during the EECO may have reached 24°C. Estimates of the global average SST today vary a bit, but HadSST4 estimates a global average of about 20.5°C and NOAA estimates about 19.7°C, so the EECO Arctic SST temperature was probably 4°C warmer than the global average today.
The next major event is when India collides with Asia, this occurs between 46 and 44 Ma as shown in figure 4. The collision began as early as 59 Ma, but marine fossils in Himalayan sediments don’t disappear until 45 Ma (Hu, et al., 2016).
Coincident with this collision is some modest cooling and an increase in CO2. As the Himalayas grow after this collision, they begin to cause planetary waves (more specifically orographic gravity waves) that can dramatically affect Northern Hemispheric weather (Trenberth & Chen, 1988) and (Kuchar, et al., 2022). Planetary waves impact the northern polar vortex, which is a major determinant of Northern Hemispheric winter weather.
The next major event is the opening of the Drake Passage which connects the Southern Ocean all around Antarctica. This event is very gradual, but appears to be complete by 34 Ma, as shown in figure 5. Like most ocean passage openings or closings it is hard to pin down and estimates of when it opened vary from 49 to 17 Ma. Antarctic ice began to grow about 44 Ma, and by 34 Ma the ice cap is complete. This coincides with a dramatic decline in global temperature and a drop in CO2.
The next major event occurs around 31 Ma when the eastern Mediterranean is cut off from the Indian Ocean as shown in figure 6. The timing of the separation of the Mediterranean and the Indian Ocean is often debated and could have happened as late as 14 Ma, we prefer an earlier closing, sometime between 31 and 24 Ma. Sedimentology suggests the latest possible closure date was 24 Ma.
Next, around 17 Ma, the North Atlantic fully opens and connects to the Arctic. Panama probably begins to close at this time restricting the connection between the Atlantic and the Pacific, and the western Mediterranean closes at Spain. The western Mediterranean might have closed as late as 6 Ma, but certainly it was severely restricted by 17 Ma. These events coincide with a dramatic drop in global temperatures and deep-sea CO2. The events are circled in figure 7. The North Atlantic opening is completed by about 13 Ma, the full and permanent closing of Panama is not complete until around 3 Ma.
These very dramatic events coincide with a steep drop in temperature and CO2 that ends the Middle-Miocene Climatic Optimum. The closing of the Isthmus of Panama takes a long time, and exactly when it finally closed is the subject of much debate (Coates & Stallard, 2013), but the closure is certainly complete by 3 Ma as shown in figure 8.
Conclusions
Long-term climate changes have many causes, but one of the major factors is plate tectonics and continental drift. When the continents and oceans are oriented north-south as they are today, which restricts west-east (zonal) air flow and encourages north-south (meridional) air flow, the world is colder. The opposite is the case when west-east flow is encouraged by open ocean connections in the mid- to low-latitudes as shown in figure 3.
Another major influence on long-term climate change are the Milankovitch cycles (also see here). The influence of plate tectonics on climate change is very long-term, on the order of tens of millions of years, whereas the Milankovitch cycles work on the order of hundreds of thousands of years. Shorter periods of change are normally related to changes in the Sun itself, these work on periods shorter than a few thousand years.
In the Westerhold study where the excellent data plotted in figure 1 came from, the authors noticed a strong correlation between the astronomical Milankovitch cycles of 21, 41, 100, and 405 thousand years (kyr) length and patterns in their global deep-sea d18O and d13C data. Because the repeating Milankovitch astronomical cycles are computable and more reliable and accurate than any other dating technique, they used them to sequence and date the data plotted in figure 1. Their description of how this worked is in section 5 (“Astrochronology”) of their supplementary materials. For records older than 20 Ma only the longer eccentricity cycles could be used. The most prominent and stable cycle was the 405 kyr eccentricity cycle.
Westerhold, et al. conclude that their chronology is accurate to ±100 kyrs for the Pleistocene and Eocene, ±50 kyrs for the Oligocene, ±10 kyrs for the Miocene and Pleistocene. This sort of accuracy is remarkable if true, and it seems reasonable given their technique.
Comparing the known Cenozoic climate changes with Scotese’s plate tectonic reconstruction shows a coincidence of major climate changes with large geological events on a scale of many millions of years. Thus, it is easy, and logical, to conclude that the geological events caused the longer-term changes. I found it very encouraging that Westerhold, et al. could “see” the Milankovitch astronomical cycles in their deep-sea fossil records so clearly that they could be used for dating them. One of the biggest problems with comparing CO2 records to temperature records is that the CO2 records are made using different samples that must be dated separately from the temperature proxy samples. This gives me a lot more confidence in the d13C data in figures 1 and 2 than in the Rae, et al. data shown in figure 2. Further the prominent gaps in the Rae et al. CO2 data leaves too much to the imagination.
Westerhold’s deep-sea d13C proxy is not a direct CO2 proxy, but it can be paired directly with the d18O temperature proxy, and it is continuous. These characteristics make it superior to other CO2 proxies in my opinion.
I should note that the exact timing of the major plate tectonic events discussed in this post is the subject of furious debate in the geological community (Hu, et al., 2016; Torfstein & Steinberg, 2020, Coates & Stallard, 2013). The precise dates when India collided with Asia, the Isthmus of Panama closed, or the North Atlantic opened to the Arctic are not known. They occured over millions of years and different geological studies can reasonably provide different dates depending upon the data used. Thus, the dates given in this study are just based on my best judgement and are open for debate.
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Panama partially resubmerged c. 1.8 Ma, but only shallowly, at the former Pliocene-Pleistocene boundary.
Very interesting! I can see it happening, but I didn’t know about it. Do you have a link?
I’m sorry I don’t. A geologist working on the Canal expansion project told me this in 2014. At that time there was a controversy on whether the Isthmus had closed in the Miocene rather than at the Pliocene-Pleistocene boundary. He favored the later c. 2.7 Ma date, except for a brief resubmergence of a section of the Panama Isthmus. It might not have been enough to rearrange oceanic circulation and affect climate.
Formation of the Isthmus was also initially a two step process, apparently, before the 2.7 Ma closure.
Thanks, I’ll continue to look for a reference. Personally, I think it was many more than a 2-step process, a multistep process that involved multiple closures, followed by re-openings. See this article, it is not paywalled:
https://www.sciencedirect.com/science/article/pii/S0012821X05004048
Thanks!
One other important paper. This one proposes a closing as early as 15 Ma. The early closing may have happened, but the isthmus then reopened.
https://www.ingentaconnect.com/content/umrsmas/bullmar/2013/00000089/00000004/art00004
That hypothesis was current when I talked to the geologist in Panama. I’m not sure how well accepted it is now.
the geologist pointed to a megalodon nursery in Panama at that time. Land sharks!
I hope you don’t spend a lot of time trying to track down a paper on the Pleistocene reopening of the Central American (or Interamerican) Seaway.
Makes sense to me and in addition I wonder at the possible extra terrestrial influences, not only in terms of millions of years orbiting the galaxy, but also the influence of cosmic rays – and the Sun over relatively shorter periods of time..
I agree. Nir Shaviv and Henrik Svensmark have presented a lot of evidence that variations in cosmic rays make a large difference in the climate. Very interesting stuff, but still controversial.
I have recently come across a hypothesis that cosmic rays might vary according to whether the solar system is travelling through a galactic arm. So many variables.
That is Nir Shaviv’s idea and he makes a good case. I write about it here:
https://andymaypetrophysicist.com/2020/01/03/earths-ice-ages/
Great post, AM. I knew the generalities but not the specifics you have laid out.
No less than Prof. Duffies of Princeton wrote that he was certain the current ice age onset was caused by closing the Panama Isthmus.
And we know the Mediterranean was once closed because of the massive salt evaporite layer underneath it caused by the ‘Messinian Salt Crisis’ that occurred while it was closed.
Correct. The Mediterranean nearly completely dried up around 5.96 Ma. This is why some say the Strait of Gibraltar closed 6 Ma, but that seems awfully quick. I suspect it first closed around 17 Ma, then periodically opened and closed until a fairly long-term hard close nearer to 6 Ma. None of these plate tectonic closings or openings happen like the flick of a switch.
There’s this on tectonics and climate, and carbon dioxide, and the fact that the planet has generally been much warmer than now:
https://news.berkeley.edu/2019/04/11/ice-ages-triggered-when-tropical-islands-and-continents-collide/
I had some correspondence with the researcher mentioned – Nicholas Swanson-Hysell in 2019. I wonder if he is still a carbon dioxide fan.
I find it amazing how many knots these otherwise intelligent researchers will tie themselves into in order to blame CO2 for climate changes that are clearly due to other factors.
It is amazing! Whatever happened to subduction and volcanic activity?
Separate comment about natural variation on much shorter time scales than in this post. The warming from ~1920-1945 is both visually and statistically indistinguishable from the warming ~1975-2000. (MIT’s Prof Lindzen first made this observation in 2011.) Yet even AR4 WG1 SMP said only the latter was CO2 induced—reason being not enough CO2 change in the former period to have induced sufficient ‘forcing’. So the IPCC has been scientifically inconsistent with itself for a long time.
Great plate tectonics and climate review article, Andy. The other plate tectonics and climate factor is the continuous movement of continental plates, land mases, moving closer to a pole or further away, where they accumulate more “permanent” ice (glacial ice) or lose it, with sea level going down or up. The question for CAGW fanatics, is “how do you isolate a signal that justifies your global warming/CO2 theories, against such a normally variable background?”. Can’t do it.
Andy, thank you for presenting the Westerhold and Scotese together at this time – together, they provide powerful evidence, along with the ice cores, that CO2 is NOT the ‘control knob’ of the Earth’s climate system.
Very much worth looking at are Willis Eschenbach’s chronological analysis of Westerhold, here;
https://wattsupwiththat.com/2020/09/15/cooling-the-hothouse/
and a nice video by Tom Gallagher & Roger Palmer that combines Willis’ work with that of Chris Scotese, here:
Thanks Frank!
Oddly, I saw Tom Gallagher’s series on Paleoclimate and noticed Willis’ graph in it. That took me a little while, but I tracked down Willis’ post and was intrigued. I had asked Willis about it, but he had forgotten it and I found it on my own. Originally, I was going to write about his cool graph and Gallagher’s series, but along the way I changed to the topic above. So, while I did not use anything from Gallagher or Eschenbach in this post, it was their work that stimulated me to write it. Funny how it works.
Indeed, Willis’ CO2 vs. T graph annotated for geological time is very ‘cool’ – lots of doublings and halvings on the CO2 axis with little movement in T, compared with big changes on the T axis independent of CO2 whenever plate movements result in meaningful changes in ocean circulation. It also shows that over geological time there are many occurrences when the same level of CO2 can give rise to multiple temperature regimes. For me, this one graphic is a dagger through the heart of CO2 alarmism.
Thanks for the link to Gallagher’s video…very interesting with lots of good graphs.
Good video! While I watched Gallagher’s three-part series on paleoclimatology, I had not seen this video before. Worth watching.
Very nice Andy.
As Feynman said “It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong.” Of course, presenting as fact something that cannot be proven wrong by experiment, is stock-in-trade for “climate scientists”.
The Earth is a big ball of mostly glowing rock. It’s cooling slowly, losing energy at about 44 TW. It doesn’t just get “colder” or “hotter”. Climate is just the statistics of weather observations, so long-past “climate” is unknown.
Looking into the far past is completely pointless. The history of a chaotic system provides no clue to its future. Nothing does.
I suppose if people can get some fool to pay them a heap of money to indulge their hobby, why not? I’d rather see money spent on things that might be of benefit to humanity, but that’s obviously not a widely held view.
Sorry Andy, but I can’t see the point of your article. Assuming the crust is in constant chaotic motion, and that the atmosphere and aquasphere are also chaotic in nature, neither the past nor the future states of any can be usefully determined. Some people want to live in the past, obviously, but they’re a bit late. The past is gone.
I don’t know about a simple north/south alignment of landmass mattering much by itself, but obviously geography has a huge influence on the climate. If most of the continental landmass is located in low latitudes, then it’s obviously going to make ice accumulation on land more difficult, and open water around the poles will discourage sea ice accumulation.
Michael, this statement makes no sense at all:
It is denying the basis for all natural sciences, Geology, Geophysics, petrophysics, biology, paleontology, etc. All these sciences use the same basic principle that “The past is the key to the present and future.”
Andy, you wrote –
I’m not denying anything. You are just making an unfounded accusation, based on nothing at all.
“Climate science” is an oxymoron. Climate is the statistics of weather, no more and no less. Presumably billions and billions of dollars have been wasted, on the basis that “climate scientists” claim that they can usefully foresee the future. This makes them fools or frauds. Future states of a chaotic system are unpredictable. The best anyone can do is guess and hope.
The past is not the key to the present the future at all, unless you are a “climate scientist” studiously adjusting the past to further your funding. Your rather unsubtle attempt to equate “climate science” with sciences such as geophysics and biology is a wee bit lame.
For example geophysicists and geologists have performed measurements which indicate that the Earth itself (the rocky mass) is losing some 44 TW (joules per second). A knowledgeable scientist would call this cooling. “Climate scientists” pretend to measure air temperatures, and claim that the Earth is “warming”, because it is “cooling more slowly.”! Delusional.
The past is the past. Some people find it interesting – historians for example. I find it interesting, because if the surface was molten in the past, and it is not at present, then the surface has cooled. This assumption is supported by geologists and geophysicists, apparently.
So no, I’m not denying that “climate science” is not a science like physics, geology, chemistry etc., or that you are free to waste your time any way you see fit.
I still can’t see the point to your article – and neither can you, it would appear. If you did, I assume you would have told me what it was.
44 TW, divided over the entire surface of the planet, is an amount that is so small that it is meaningless.
The fact that you seem to feel that this is the only number that matters, just shows how unscientific your views are.
44 TW, divided over the entire surface of the planet, is an amount that is so small that it is meaningless.
If you say so, but it indicates that the Earth is cooling, doesn’t it?
Not meaningless at all. No “energy balance”, no “warming”.
Unscientific views? Who cares what my “views” are? You?
True, I don’t believe in the existence of phlogiston, or the luminiferous ether. My view on Sir Isaac Newton’s alchemical studies is that I will not bother pursuing alchemy.
As to “smallness”, a single Ebola virus is both required and sufficient to kill you in a particularly nasty manner. Treat individual Ebola viruses as being so small as to be meaningless, and you will have joined a vast number of ignorant people around the world.
Only if the sum of solar insolation, heat from radioactive decay, and residual heat in the core and mantle being conducted to the surface is less than 44 TW +/- the variance. That is, the actual net value of both the incoming heat to the surface and the heat leaving Earth will oscillate around the nominal net value over short time periods.
Your appeal to the analogy of Ebola is flawed. It deals with a terminal event, whereas the heat flux is continuous, open-ended, and varies in magnitude over time. To arrive at the net effect, one integrates the flux rate over some arbitrary start and and an equally arbitrary end. Even small effects can have cumulative results, whereas Ebola terminates a person if a threshold of the strength of the immune system is exceeded.
Well, that’s meaningless word salad, isn’t it? “Nominal net value”, which is . . . ?
With respect to Ebola, it wasn’t an analogy. My comment was an example of the futility of saying something was so small as to be meaningless. If you prefer, I can point out that there is no minimum value at all, which applied to initial conditions, may lead to completely unpredictable outcomes of a chaotic systems.
You have flown off at a tangent, producing more meaningless word salad.
The Earth has demonstrably cooled, and will continue to do so, as long as it remains beyond its isothermal equilibrium point. Outer space is quite “cold”, and the Sun is a long way away.
I’m assuming all your waffling word salad is an endeavour to show the existence of some mythical effect which has no consistent unambiguous description at all.
Please correct me if I’m wrong – a few facts rather than the contents of your imagination might help.
I completely disagree with you `Assuming the crust is in constant chaotic motion’ where did you get that idea, have you studied geology or the history of tectonics?
The Earth has a very long history of aggregation, cooling, evolution and differentiation of elements and rocks into the core, mantle, crust oceans and atmosphere. These processes took place over billions of years, but we understand the Phanerozoic best from about 560my ago when biological life exploded into a variety of phyla that have evolved to live in many environments. Like climate we understand many of the processes involved in Earth evolution as it continues today, but we do not have much detail on core-mantle interactions and apparent periodic expansions of the lithosphere that drives plate tectonics- the modern version of continental drift.
However, the opening up and closing of oceans is real and has a major effect in distributing solar heat from the equatorial regions towards the poles via ocean currents and wind patterns. Blocking E-W heat flow from the equator via continents and mountain ranges, or island arcs changes climate patterns. Ever since the Drake passage opened between S America and the Antarctic, we have had an unimpeded circling Southern Ocean that has maintained a frozen Antarctic for 35M yrs and helped slowly cool the rest of the oceans creating the Ice ages over the past 3m yrs with Milankovitch orbital cycles determining warmer or cooler periods.
We are in the process of cooling back into the next Ice Age in 1500-3500yrs, so we should enjoy our current Modern warm period, instead of bitching about as the environmental nutters and AGW alarmists tell us to. Climate appears chaotic because we don’t understand it well enough and can’t model it well because of the complex variables involved. However, we will never get anywhere with climate using the now discredited CO2 related global warming hypothesis. So, all you climate worriers out there, get over it, we don’t have the technology yet to change climate, let nature be!
From theory, and observations. Early proponents of continental drift, for example were regarded as crackpots for several decades – by geologists. You are free to think as you wish, but you cannot even usefully predict where the North magnetic pole will be tomorrow, nor say where it was 1,000 years ago. A chaotic track, by the look of it .
I’ll point out again that climate is mere the statistics of weather observations. No science there. I agree that it is presently impossible to change weather outcomes, and that adding CO2 to air does not make it hotter.
The Siberian Traps – Radiometric Dating Published 40Ar/39Ar ages (whole-rock, biotite and plagioclase separates) exist for basalts and gabbros from Noril’sk, Putorana, Maymecha-Kotuy, West Siberian Basin, Taimyr, Kuznetsk Basin and the polar Urals. Normalised to a common standard, they all lie within error of each other, and indicate a magmatic crystallization ages of between 248-250 Ma.
Milanovskiy (1976) concluded that the original volume of the Traps and related rocks exceeded 2 x10^6 km3, and Masaitis (1983) estimated their volume to be ~ 4 x 10^6 km3. Reichow et al. (2002) estimated the present-day volumes to be around 2.3 x 10^6 km3, but their estimate did not take into account any igneous rocks in the Yenesei-Khatanga Trough, Taimyr Peninsula, or beneath the Kara Sea. Any ‘working estimate’ for the total volume of erupted magmatic products is likely to be at least 3 x10^6 km3, and possibly as much as 5 x10^6 km3.
None of these estimates consider the volume of deeply-seated intrusions (e.g. magmatic underplate at the base of the crust, and frozen magma bodies in the lower and middle crust). If the Siberian Traps are analogous to the North Atlantic Igneous Province, it is likely that many million cubic kilometers of material lie buried at depth in the crust or uppermost mantle.
When the North Atlantic broke open, it produced 1-2 million cubic miles (5-10 million cubic kilometres) of molten rock which extended across 300,000 square miles (one million square kilometres).
Mt. McKinley has been uplifted by tectonic pressure (collision of the Pacific plate with the North American plate) while at the same time, erosion has stripped away the mostly sedimentary material above and around it. (Portions of slightly older sea floor rock (flysch) are found near the 20,320′ true, or south summit, and they completely cap the 19,470′ north summit of Mt. McKinley.) The crystallization age of the Mt. McKinley granites is around 56 million years ago.
But the asteroid impact off the Yucatán Peninsula in Mexico that killed off the dinosaurs 66 million years ago and sent just about everything into the grave, would have still been having an effect.
Molten rock can vary between 700 and 1,200 degrees C (1,300 to 2,200 F). So a couple million Km^3 of 1,000 C rock might have a longish term effect on climate.
As a matter of curiosity, I have seen estimates of the duration of this “killing off” ranging between 100,000 and 1,000,000 years.
I am not disputing your assertion, but it seems to me that a catastrophic meteor impact affecting the entire globe might take less than 100,000 years to exterminate dinosaurs.
I haven’t come across a reasonable explanation, but I haven’t looked all that hard. If you have, what did you find?
“The Earth is a big ball of mostly glowing rock. It’s cooling slowly, losing energy at about 44 TW. It doesn’t just get “colder” or “hotter”.”
That’s not what the science shows. The temperature of the interior of the earth makes close enough to zero difference in the temperature of the surface, that the difference isn’t worth talking about.
If you want to attack the science by which proxies are used to estimate past temperatures and climate, go ahead.
If you want to simply declare that it is impossible and leave it at that, then you make yourself look like another know nothing crank.
Anybody who says “That’s not what the science shows . . .”, is misusing the term, in Richard Feynman’s view, and I agree.
The temperature of the interior of the earth makes close enough to zero difference in the temperature of the surface, that the difference isn’t worth talking about.
Well, yes, it does. About 35 K or so, according to my calculations, but if you imply the Earth was created at absolute zero, like Sagan, Hansen, and others, be my guest.
The Earth is cooling – always has, always will. Currently losing 44 TW or so, more in the past, less in the future.
Adding CO2 to air does not make it hotter. Climate is the statistics of past weather observations. Disagree all you want.
“ this occurs between 46 and 44 Ma as shown in figure 4.”
I believe it was a Tuesday, ’round tea time.
A couple of thoughts, why is such a big deal made about the brief blip known as the PETM, while a good chunk of the Eocene was just as warm, and for a lot longer?
Also, while geography via continental drift has a major influence on climate, what about the fact that we get very big changes in coastal geography over much shorter periods thanks to post-glacial rebound? After an interglacial gets long in the tooth, seas start to shrink or disappear, and new land bridges reappear. I would argue that that’s more significant than relatively small insulation changes from mild orbital variations.
Very large changes in climate do occur at the end of glacial periods and very quickly, geologically speaking. Especially changes in high latitude temperature and precipitation. Changes going into a glacial period are slower, but just as dramatic.
However, changes due to plate tectonics determine whether glacials appear at all and they add or remove year-round glacial ice at the poles. Remember glacial periods are unusual in Earth’s history and usually there are no ice caps on either pole.
Yes, very good point. Everyone assumes we’ve always had ice at the poles but as you point out we’re living in a very unusual period in the Earth’s history.
Also at a totally unique time in the solar system history. We will no longer be able to see total eclipses of the Sun (in a few million years) as the Moon is rapidly moving away from us and will then no longer cover the Sun…we will just have annular eclipses for the rest of humanity’s time on the Earth! Total eclipses are not visible from any other planet in our solar system. So, Enjoy, as they say!
The PETM is very important to geologists for several reasons. First the associated “CIE” or an abrupt change in the carbon-13 to carbon-12 ratio at the time is a worldwide time marker that is widely used. It occurred between 55.6 and 55.4 Ma, so it is helpful for geologists.
It also marks the beginning of the EECO, the warmest period in the Holocene, which is oddly (to some) associated with a drop in CO2.
Finally, our distant ancestors, the first primates, evolved at the time and rapidly spread around the world. There was a minor extinction event where some deep-water forams went extinct, but shallow–water forams and most plants and animals thrived. More here:
https://andymaypetrophysicist.com/2021/08/18/the-paleocene-eocene-thermal-maximum-or-petm/
In your article. I couldn’t help but notice the changes to the CO2 in oceans and atmosphere affect greatly also bottom dwelling ocean animals. The events warming and cooling were coupled with a large change to ocean circulation.
the CO2 cult will never be convinced that its not the control knob … this is an exercise in futility …
I’m sure I’m biased, but I believe the wheels are falling off of the ‘CO2 cult’s’ cart. Whether it takes an economic calamity to drive the point home or the scientific method somehow just reasserts itself, there’s nothing futile about keeping up the good work of putting the truth in front of the public.
Great point Frank, given the overt politics and huge economic costs involved in climate mitigation policies that are impoverishing many western and third world countries, the public are becoming aware they have been had royally. Once they know they are paying for these policies from their own pockets they will reflect and reject them- this is now happening globally. Only the ideological pure alarmists are unaffected, but they will also change when their funding and jobs and prestige disappear.
The thing that is paramount and isn’t talked about is ocean heat transport. It’s by far the biggest factor in climate, then atmospheric changes. As the continents roam around and collide with each other it changes how oceans transport heat around the world.
And one of the bigger factors is the fight for the bottom of the ocean, highly salinity is far more a factor than temperatures. Rivers of high salinity cold water from Antartica is going to the bottom of the ocean and some arctic places, there is very little places where highly saline warm waters is going to the bottom of the oceans.
Much of the tropical sunlight energy is getting used to evaporate the oceans and not transferred around the oceans, it’s more stratification. This makes today’s cold very cold oceans, average of 90% of the oceans is between 0-4 degrees. It’s very very cold oceans geologically. If one adds waters pushing down very warm waters and the oceans would warm and the world would warm. Europe isn’t warm because of CO2, Siberia isn’t cold because of a lack of CO2 but how close to the oceans they are.
One can see it in the beginning of the interglacial with Arctic water temperatures up to seven degrees warmer than today and many warm water molluscs that live there then. And the cooling and neoglaciation of the islands like iceland about 4.2k years ago. The steady changes as oceans transport changes. The ocean transport changes made the Sahara wet then dried them out, denoting a change in ocean transport as a stronger Hadley Cell made and strengthened deserts in the mid latitudes over time isolating again energy of the tropics.
From this I would have to guess that they can prove when earth was an ice ball there were no plate tectonics, no earthquakes.
Clarification: The alarmists and doom sayers.
How did Man’s CO2 cause plate tectonic “change”?
More money needed.
The Earthbyte Group from the School of Geosciences at Australia’s Sydney University have been producing great data on ocean floor age reconstructions through time. They even estimate heat flows from spreading ridges which may help to explain some ocean heat content variations through time. Check out the Earthbyte YTube channel.
Their paper on Seawater Chemistry has summaries of key seafloor spreading parameters through time, the data being available from their website. The image below is from the paper – note the young crustal age of the eastern pacific which translates to a higher heat flow regime. Also note the triple point and crustal age near the Nino development area.
An excellent article with a couple of observations.
I don’t think the Antarctic Ice is all that permanent. The oldest ice recorded is the ‘Blue Ice’ at 3.2 million years BP. (Paul Voosen Science News Aug. 15, 2017, 12:15 PM). This coincides approximately with the closing of the Panama Isthmus. Ice, younger at about 2 million years has also been recorded at similar elevations. The 5-year hole project currently being drilled by ANARE should, as with the deep cores from Greenland intercept a temperate climate with a timing of about 1 million years BP. Depth of hole about 3,000 metres. It is also being drilled in a highly stable ice regime.
Certainly didn’t exist before the first liquid water formed as the crustal temperature fell, and for quite a long time after that.
My assumption is that Antarctic ice is here to stay, as long as Antarctica remains high, dry, and sitting over the South Pole.
Notwithstanding unforeseen circumstances, of course.