Claim: Volcanic carbon dioxide drove ancient global warming event

From the UNIVERSITY OF SOUTHAMPTON and the “certainty at 56 million years ago” department, comes this study. The paper had a long peer review, over a year, likely because the CO2 claim is twice removed form direct observation by two proxies, Boron isotope, and pH. They claim ocean surface pH was persistently low during the PET, and thus that implies more CO2 in the atmosphere. It’s a bit of a stretch IMHO. They also suggest the CO2 induced warming went on for 150,000 years.

The real issue in my view is this statement:

The study, published in Nature, used a combination of new geochemical measurements and novel global climate modelling.

Novelty climate modeling applied to data extracted to twice removed proxies for temperature 56 million years ago…yeah, that’s the ticket away from the “uncertainty monster”.

I’m sure the media will try to make parallels with our modest modern-day increase of atmospheric CO2, but it really doesn’t work:

The team found that the PETM was associated with a total input of more than 10,000 petagrams of carbon from a predominantly volcanic source. This is a vast amount of carbon – some 30 times larger than all the fossil fuels burned to date and equivalent to all current conventional and unconventional fossil fuel reserves.

With that much CO2 in the atmosphere, the response curve of CO2 would be in the flat saturation response area, so I’m not sure if their numbers reflect an accurate climate response. Also, there was a huge explosion of plant diversity and range during the PETM, and suggesting a CO2 residence time of 150,000 years also seems like a stretch when such an active ecosystem would be voraciously gobbling up that CO2.


Volcanic carbon dioxide drove ancient global warming event

New research, led by the University of Southampton and involving a team of international scientists, suggests that an extreme global warming event 56 million years ago was driven by massive CO2 emissions from volcanoes, during the formation of the North Atlantic Ocean.

Lava bursts from a volcano at the present-day Icelandic rift. CREDIT Morgan Jones and Henrik Svenson

The study, published in Nature, used a combination of new geochemical measurements and novel global climate modelling to show that the Palaeocene-Eocene Thermal Maximum (PETM) was associated with a geologically rapid doubling of atmospheric CO2 in less than 25 thousand years – with volcanoes squarely to blame.

The PETM is the most rapid and extreme natural global warming event of the last 66 million years. It lasted for around 150 thousand years and global temperatures increased by at least 5°C – a temperature increase comparable with projections of modern climate beyond the end of this century. While it has long been suggested that the PETM event was caused by the injection of carbon into the ocean and atmosphere; the ultimate trigger, the source of this carbon, and the total amount released, have up to now all remained elusive.

It had been known that the PETM roughly coincided with the formation of massive ‘flood basalts’ – large stretches of ocean floor coated in lava, resulting from of a series of huge eruptions. These occurred as Greenland first started separating from north-western Europe, thereby creating the North Atlantic Ocean, the vestiges of which are still continuing in miniature in Iceland today. What has been missing is evidence linking these huge volcanic outpourings to the carbon release and warming that marks the PETM.

Dr Marcus Gutjahr, who led the study while a post-doctoral fellow at the University of Southampton, and is now at the GEOMAR Helmholtz Centre for Ocean Research in Kiel Germany, explained: “In order to identify the source of carbon we first generated a new record of the change in ocean pH (a measure of its acidity) through the PETM, by measuring changes in the balance of isotopes of the element boron in ancient marine fossils called foraminifera.”

The geochemical facilities at the University of Southampton is one of few locations in the world where this kind of work can be carried out. Foraminifera are tiny marine plankton that live near the sea surface and the chemical makeup of their microscopic shells records the environmental conditions of the time when they lived, millions of years ago.

Professor Andy Ridgwell from University of California, Riverside continued

“Ocean pH tells us about the amount of carbon absorbed by ancient seawater, but we can get even more information by also considering changes in the isotopes of carbon, as these provide an indication of its source. When we force a numerical global climate model to take into account both sets of changes, the results point to the large-scale volcanism associated with the opening of the North Atlantic as the primary driver of the PETM.”

The team found that the PETM was associated with a total input of more than 10,000 petagrams of carbon from a predominantly volcanic source. This is a vast amount of carbon – some 30 times larger than all the fossil fuels burned to date and equivalent to all current conventional and unconventional fossil fuel reserves. In their computer model simulations, it resulted in the concentration of atmospheric CO2 increasing from 800 parts per million to above 2000 ppm. The Earth’s mantle contains more than enough carbon to explain this dramatic rise and it would have been released as magma, pouring from volcanic rifts at the Earth’s surface.

Professor Gavin Foster from the University of Southampton said:

“How the ancient Earth system responded to this carbon injection at the PETM can tell us a great deal about how it might respond in the future to man-made climate change. For instance, we found that Earth’s warming at the PETM was about what we would expect given the CO2 emitted and what we know about the sensitivity of the climate system based on Intergovernmental Panel on Climate Change (IPCC) reports. However, compared with today’s human-made carbon emissions, the rate of carbon addition during the PETM was much slower, by about a factor of 20.”

Dr Philip Sexton from the Open University in Milton Keynes continues:

“We found that carbon cycle feedbacks, like methane release from gas hydrates which were once the favoured explanation of the PETM, did not play a major role in driving the event. On the other hand, one unexpected result of our study was that enhanced organic matter burial was important in ultimately drawing down the released carbon out of the atmosphere and ocean and thereby accelerating the recovery of the Earth system. This shows the real value of studying these ancient warming events as they provide really valuable insights into how Earth behaves when its climate system and carbon cycle are dramatically perturbed.”

###

Source: https://www.southampton.ac.uk/news/2017/08/volcanoes-global-warming.page

Abstract:

Very large release of mostly volcanic carbon during the Palaeocene–Eocene Thermal Maximum

Nature  548,  573–577  (31 August 2017)  doi:10.1038/nature23646
Received  03 May 2016 Accepted  06 July 2017 Published online  30 August 2017

The Palaeocene–Eocene Thermal Maximum12 (PETM) was a global warming event that occurred about 56 million years ago, and is commonly thought to have been driven primarily by the destabilization of carbon from surface sedimentary reservoirs such as methane hydrates3. However, it remains controversial whether such reservoirs were indeed the source of the carbon that drove the warming1345. Resolving this issue is key to understanding the proximal cause of the warming, and to quantifying the roles of triggers versus feedbacks. Here we present boron isotope data—a proxy for seawater pH—that show that the ocean surface pH was persistently low during the PETM. We combine our pH data with a paired carbon isotope record in an Earth system model in order to reconstruct the unfolding carbon-cycle dynamics during the event67. We find strong evidence for a much larger (more than 10,000 petagrams)—and, on average, isotopically heavier—carbon source than considered previously89. This leads us to identify volcanism associated with the North Atlantic Igneous Province1011, rather than carbon from a surface reservoir, as the main driver of the PETM. This finding implies that climate-driven amplification of organic carbon feedbacks probably played only a minor part in driving the event. However, we find that enhanced burial of organic matter seems to have been important in eventually sequestering the released carbon and accelerating the recovery of the Earth system

more: http://www.nature.com/nature/journal/v548/n7669/full/nature23646.html

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53 thoughts on “Claim: Volcanic carbon dioxide drove ancient global warming event

    • Except when they cause warming. The best ‘theory’ is when it ‘predicts’ anything. Both warming and cooling from volcanoes, both ice melting and ice increasing due global warming, both less snow and more snow, both smaller animals and bigger animals, both more rain and less rain… pseudo science, crapping on the law of non contradiction as usual.

      • Adrian R., when you write “The best ‘theory’ … ” do you not mean: “The best hypothesis … ” … or, am I missing your meaning?

        Because to me, it seems that you are indeed describing a hypothesis: a scientific notion which may or may not be true; IOW, a notion unproven … one way or the other. Hmmm …

      • I used quotes because in the pseudo sciences cause, it’s not really a theory (as in scientific theory), it’s simply an idiocy that tries to imitate a scientific theory enough to fool people.

        And no, even if it would be a simple hypothesis, it’s not allowed to crap on the law of non-contradiction.

  1. “the concentration of atmospheric CO2 increasing from 800 parts per million to above 2000 ppm”

    So Co2 concentrations were twice what they are today before the PETM event.
    Hum.

  2. The seem not to provide any evidence that the warming was driven by CO2. They assume so, and conclude that volcanos must be responsible.

    And this is science?

    • DHR – ““How the ancient Earth system responded to this carbon injection at the PETM can tell us a great deal about how it might respond in the future to man-made climate change.”

      CO2 or Lava Rock? Also might one of the processes have been When a continent breaks apart, as Greenland and Northwest Europe did 55 million years ago, it is sometimes accompanied by a massive outburst of volcanic activity due to a ‘hot spot’ in the mantle that lies beneath the 55 mile thick outer skin of the earth. 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). – See more at: http://www.cam.ac.uk/research/news/under-the-sea#sthash.LLR1IIV5.dpuf

      Molten rock can vary between 700 and 1,200 degrees C (1,300 to 2,200 F). So 8,000,000 Km^3 of 1,000 C rock in one of the most important ocean circulation areas or back-radiation of CO2? Which might have the most affect?

      And what other lava flows were going on at the PETM? How many candals should be on the Mt. Denali/McKinley birthday cake this year?

      Over tens of millions of years, 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, giving it plenty of time to be uplifted and eroded to it’s present lofty condition.
      https://www.nps.gov/dena/upload/Brief%20Geology%20of%20Mt.pdf

      How many KM^3 in the Alaska Range, which was ocean floor at the time?

  3. In what form do that propose all the Carbon existed, within the magma underlying the volcanoes. Or was it all in the organic matter at the bottom of the ocean and simply “burned up”. Either way it seems like more carbon than is reasonable, given that much of it must have been in inorganic forms that would not “burn” or nor turn into CO2 gas.

  4. The instant problem as I see is that of volcanic ash,….. The only way you’re going to get those massive rises in volcanic emitted CO2 is if you have corresponding massive amounts of ash to go with it,….. & you can kiss goodbye your “Volcanic CO2 led global warming” at that point.

    • No Ian. These were mostly flood basalts, not much ash at all.

      That said, we’ve seen this sort of thing many times before,and it always starts with the assumption that CO2 and only CO2 can cause warming. And then validates itself by correlating a warm period with high CO2.

      If you started from the assumption that orbital cycles and ocean circulations caused warming and warmer oceans released a lot of CO2, you would validate that by similar circular reasoning. Have they heard that the oceans contain 60 or 70 times as much CO2 as the atmosphere, and that a 1°C rise in average ocean temperature would release 2±1 shedloads of CO2? Inconvenient facts for the warmists.

  5. According to largeigneousprovinces.org, the North Atlantic event, predominantly 62-58mya was a large event. It was right on the heels of and roughly on a par with the Deccan event at 66mya.

    There was a bit of a break before the roughly equivalent Afar event at 31 to 29mya.

    The temperatures during the Deccan and Afar events were several degrees cooler than during the PETM, even though these events were equal in magnitude to the North Atlantic.

  6. The PETM was warm. A volcanic source of CO2 seems more likely than methane clathrates to me. We also have the huge areas of flood basalts and we know volcanoes can produce huge amounts of CO2, so the whole thing seems at least plausible.

    • TonyL

      You state “and we know volcanoes can produce huge amounts of CO2”

      Please provide a link to this statement.

      The VEI7 eruption of Mount Pinatubo did not show any blip in the closely monitored CO2 emissions at that time, nor were there any indications of CO2 emissions during the Little Ice Age (only cooling).

      Most volcanic eruptions produce large amounts of Sulfur Dioxide aerosols, which cause cooling, but also warming as they quickly settle out of the atmosphere after the eruptions cease..

      .

      • Please provide a link to this statement.

        Oh Please!
        Check a textbook.
        The Mauna Loa Observatory often comes in for some humorous criticism for measuring CO2 while being sited on a volcano which belches CO2.
        You need a link? Remember: “Google is your friend”
        How about the United States Geological Survey?
        https://volcanoes.usgs.gov/vhp/gas.html
        And the Money Shot:

        Carbon dioxide (CO2) trapped in low-lying areas can be lethal to people and animals.

      • “TonyL on August 31, 2017 at 2:05 pm

        Carbon dioxide (CO2) trapped in low-lying areas can be lethal to people and animals”

        Say what? How is CO2 “trapped”? CO2 does nothing but displaces lighter gases, trapps nothing, not even “heat”.

  7. I don’t supposed there was any ash released with the CO2 that might have altered the pH of the ocean?

  8. “They claim ocean surface pH was persistently low during the PET, and thus that implies more CO2 in the atmosphere..”

    Have they figured out that volcanoes emit SO2 (and NOx) that causes acid rain? To attribute all of a pH depression to CO2 is a bridge too far.

  9. Since we’re all here talking about it the event must not have amounted to much. Our gene pool even survived ice ages since. And it was surely a good time to be an herbivore, termite, or bark beetle.

    • “On the other hand, one unexpected result of our study was that enhanced organic matter burial was important in ultimately drawing down the released carbon out of the atmosphere and ocean and thereby accelerating the recovery of the Earth system”
      They seem to agree with you. That enhanced organic matter came from somewhere.

    • Since we’re all here talking about it the event must not have amounted to much.

      If it hadn’t happened we probably wouldn’t have been here. The PETM opened high latitude dispersal corridors to tropical animals (like primates) allowing them to disperse over most of the World.

  10. If sea floor spreading was responsible it should have left a magnetic signature from which its timing and duration could be estimated. As the sea floor spreads away from the mid oceanic ridge a symmetrical pattern of magnetic polarity “stripes” is created on each side of the spreading centre. The stripe withdths between magnetic reversals are roughly proportional to the rate of spreading. Identification of these stripes was what provided the evidence for sea floor spreading and showed that all present day Atlantic Ocean sea floor is Cretaceous or younger. A massive spreading event like this should be evidenced by an extremely wide polarity stripe – or stripe pair if there was a magnetic reversal during its creation. The PETM occurred about 10my after initiation of Atlantic sea floor spreading so it might be possible to pin down the timing fairly closely.

    [The mods request that you pick a single username and stick with it while commenting here at WUWT. Thank you. -mod]

  11. The carbon isotope changes due to biochemical events are not constant today. Making assumptions about such things 56 million years ago is even more perilous. This is another case where the uncertainties are so large that many explanations can all be fitted to the very poor data, and the imagination of the “climate scientist” can run riot, which it usually does.

  12. The abstract states, “This finding implies that climate-driven amplification of organic carbon feedbacks probably played only a minor part in driving the event. However, we find that enhanced burial of organic matter seems to have been important in eventually sequestering the released carbon and accelerating the recovery of the Earth system.”

    Something that seems to have been overlooked by the researchers is that extensive laterization of rocks occurred during the Eocene. Laterization is associated with chemical weathering in the tropics, with alternating wet and dry seasons. Acidic rain is helpful, but that means the carbonic acid is removed as carbonates and probably end up in the oceans. So, they overlooked the role of chemical weathering in “… the recovery of the Earth system.”

    Note to Nick Stokes: Even ‘acidic’ rocks like granite are dissolved and chemically partitioned by carbonic acid.

    • “extensive laterization of rocks occurred during the Eocene.”

      However PETM only comprises about 100,000 years at the Paleocene-Eocene border so any laterization directly connected to it was already over practically before the Eocene had even begun.

      • TTY,
        Laterization is taking place today in the tropics. It isn’t a phenomena that is restricted to peak PETM temperatures. In the foothills of what are now the Sierra Nevada (CA) the Eocene laterization was apparently ended by the volcanic eruptions during the Oligocene, which apparently also brought down the temperatures while burying the Eocene landscape in lava and ash. It was probably the abundant ash thrown out for a long period that caused the decrease in temperature. Of course, if the entire globe cooled, then outgassing of CO2 from the oceans would have dropped off. It seems to me that studies of this sort are so focused on trying to reinforce the ‘Greenhouse’ effect that they often lose sight of the bigger picture, or purposely cherry pick the things that best support the consensus.

  13. You can see this as a last effort to save the theory that CO2 caused the PETM. The trouble with this is that the temperature rise was quite large (4-5 degrees C) but the simultaneous carbon isotope change (d13C) was fairly modest. To explain the temperature rise without an absurdly high climate sensitivity a really massive amount of CO2 is needed which means that the coal must be isotopically heavy, so all the politically correct CO2 sources (methane clathrates, melting permafrost, vast wildfires etc) are out. It has to be volcanoes or nothing. And volcanoes can’t even cook off to much organic material which is the favored explanation to squeeze large amounts of CO2 out of volcanic activity.
    So by postulating a volcanic source they can up the amount of carbon to 10,000 Pg, which allows about 1,25 doublings of CO2 from 870 to 2200 ppm. So, by using the politically correct climate sensitivity of 3 degrees per doubling (well known to be much too high) they can squeeze out 3,6 degrees of warming which they call “close” to the 4-5 degrees known to have happened.
    So, yes it works, sort of.
    However there is another problem. The PETM was short, geologically speaking, on the order of 100,000 years. So all those 10,000 Pg Carbon must be absorbed by weathering, by the biosphere or as sediments on the sea bottom in less than 100,000 years. The only mechanism that might be fast enough is deposition on the seafloor, but the problem is that there was no Ocean Anoxic Event and there are no large deposits of organics-rich slates of the right age, so all that carbon just disappeared without trace.
    And then there is this:

    Temperatures on Earth had been rising for about five million years when PETM happened, supposedly because the amount of CO2 in the atmosphere was gradually increasing (“the master knob”, remember?). At the end of the PETM the temperature returned to the same level as before, and then went on rising just as before, at the same rate for another 5 million years, until reaching about the same level as during PETM. Now if there are mechanisms that can absorb 10 000 Pg Carbon in short order, why did these apparently just switch off and allow this vastly slower rise to continue for another 5 million years?

  14. I don’t think expressing mass units in grams, so that rather minor rates of release have to be given in “petagrams”, isn’t scary enough. We should switch from grams to atomic mass units (amu), Thus the 10,000 petagrams of “carbon” (dioxide?) becomes a staggering 6.02E+42 amu instead! That’s MUCH scarier!

    As an aside, 10,000 Pg “carbon” released over 25,000 years would be equivalent to burning 441 million short tons of coal per year. That’s assuming they really mean “carbon,” and not carbon dioxide. The US by itself consumes over 700 million short tons of coal per year. That’s what I mean by “minor rates of release.”

  15. These are the dark ages of natural sciences. When natural sciences have a renaissance, thousands of factoid based papers will go straight to the dust bin.

  16. A supplement to this story has been published in The Conversation today: https://theconversation.com/volcanic-emissions-caused-the-warmest-period-in-past-56m-years-new-study-82354

    Note who funded the study:

    This article was originally published on The Conversation. Read the original article.
    This study was funded by a UK Ocean Acidification Research Program NERC/DEFRA/DECC grant (NE/H017518/1).
    Gavin Foster receives funding from the Natural Environment Research Council (NERC).
    Philip Sexton receives funding from the Natural Environment Research Council (NERC).

  17. Apparently, invalid preconceived notions can lead to misinterpretation of observation and if you can find like-thinkers to peer review your work (confirmation bias), you can even get it published.

    As to ‘peer review’ there is this quote, available in Wikipedia, by Richard Horten, editor of the Lancet “But we know that the system of peer review is biased, unjust, unaccountable, incomplete, easily fixed, often insulting, usually ignorant, occasionally foolish, and frequently wrong.”

  18. Physics and thermodynamics establish that the 2 major factors in the temperature of the atmosphere are (1) the energy input, known as total solar irradiance, and (2) the mass of the atmosphere, usually measured as pressure since the total surface area of the planet is nearly a constant, as is the acceleration due to gravity. The Gas Laws relate the temperature of the gas to its density and pressure for any given amount of energy per unit mass, but not to its composition. The energy per unit mass is unchanging for a gas in equilibrium with its surroundings, and the stirring of the atmosphere by convection and black-body radiation law continually maintain thermodynamic equilibrium.
    Warmists are fond of comparing earth’s temperature to that of Venus, which they (erroneously) attribute to a ‘runaway greenhouse effect’ due to the fact it is mostly carbon dioxide.
    To make an honest comparison of the temperatures one must compare the earth’s average temperature at the surface (the 1 atmosphere isobar) with the temperature of Venus’ atmosphere AT THE SAME PRESSURE. The respective numbers are 288 Kelvins for earth and 328 Kelvins for Venus, where the 1 atmosphere isobar is found at 50-55 km altitude.

  19. The genesis of RGHE theory is the incorrect notion that the atmosphere warms the surface. Explaining the mechanism behind this erroneous notion demands RGHE theory and some truly contorted physics, thermo and heat transfer, energy out of nowhere, cold to hot w/o work, perpetual motion.

    Is space cold or hot? There are no molecules in space so our common definitions of hot/cold/heat/energy don’t apply.

    The temperatures of objects in space, e.g. the earth, moon, space station, mars, Venus, etc. are determined by the radiation flowing past them. In the case of the earth, the solar irradiance of 1,368 W/m^2 has a Stefan Boltzmann black body equivalent temperature of 394 K. That’s hot. Sort of.

    But an object’s albedo reflects away some of that energy and reduces that temperature.

    The earth’s albedo reflects away 30% of the sun’s 1,368 W/m^2 energy leaving 70% or 958 W/m^2 to “warm” the earth and at an S-B BB equivalent temperature of 361 K, 33 C cooler than the earth with no atmosphere or albedo.

    The earth’s albedo/atmosphere doesn’t keep the earth warm, it keeps the earth cool.

    https://springerplus.springeropen.com/articles/10.1186/2193-1801-3-723

    • Nicholas Schroeder August 31, 2017 at 1:54 pm:
      “The genesis of RGHE theory is the incorrect notion that the atmosphere warms the surface.”
      and:
      “The earth’s albedo/atmosphere doesn’t keep the earth warm, it keeps the earth cool.”

      WR: My guess: the oceans warm the surface/atmosphere with a lot of degrees by collecting effectively the energy of sun rays and by transferring that energy to the atmosphere.

      And indeed, clouds keep the atmosphere cool.

      Scotese estimates that global average temperatures vary during geological periods within a range of + 28 and + 13 degrees. https://www.youtube.com/watch?v=DGf5pZMkjA0 The production of warm or cold deep water by the configuration of continents and oceans could explain most of the difference between minimum and maximum average global temperatures.

      Oceans (H2O) could be the big temperature stabilizer, the big storage facility and the cause of the warmer than expected SB temperatures. They have the potential to be the main factor in the in the above link mentioned “Atmospheric Thermal Enhancement (ATE)”

      • It has been my experience that rocks, sand, and pavement get much hotter than the air around my head. I think it is obvious that the surface CAN warm the atmosphere in the daytime. Also, at night, in the absence of sunlight, those same materials give back their heat to the cooling atmosphere.

        In a similar manner, bodies of water can give back their heat to moderate coastal climates. However, I’ve never experienced water hotter than the air in the daytime, except maybe in shallow ponds heated by the sand or rocks under them.

      • Clyde Spencer August 31, 2017 at 4:03 pm: “It has been my experience that rocks, sand, and pavement get much hotter than the air around my head.”

        WR: Agree. And much hotter than the sea. And that is exactly the reason why on the average (!) ‘land’ is cooler than ‘sea’. Radiation during daytime is that much higher by land, that the average temperature of land will be lower – as explained by Willis Eschenbach in The Moon is a Cold Mistress: https://wattsupwiththat.com/2012/01/08/the-moon-is-a-cold-mistress/

        Clyde Spencer August 31, 2017 at 4:03 pm: “In a similar manner, bodies of water can give back their heat to moderate coastal climates.

        WR: Bodies of water are giving back their energy (! I prefer ‘energy’ to ‘heat’) to air every moment they evaporate. That energy is transported upwards and horizontally in enormous quantities and is warming everything. Thanks to this transport a lot of degrees of latitude radiate more energy than they receive by the sun. See:

        Clyde Spencer August 31, 2017 at 4:03 pm: “However, I’ve never experienced water hotter than the air in the daytime, except maybe in shallow ponds heated by the sand or rocks under them.”

        WR: On the average, oceans are much warmer than land. And they have a much higher heat content than land. It seems logical that ‘oceans’ are warming ‘land’. And the atmosphere.

        Global Mean Annual Temperature, 1880-2005
        Land Surface Mean Temperature: 8.5 °C
        Sea Surface Mean Temperature: 16.1°C
        Combined Mean Surface Temperature 13.9 °C

        Source: table E17.9.2, http://wps.prenhall.com/wps/media/objects/2513/2574258/pdfs/E17.9.pdf

      • Wim,

        If you look at the frequency distribution of temperatures for Earth,

        https://wattsupwiththat.com/2017/04/23/the-meaning-and-utility-of-averages-as-it-applies-to-climate/

        there is apparently a long tail on the cold side, largely a result of the lows reached in the polar regions, which is responsible for the 8 deg difference in land and water temperatures. That is, there is no ocean to average in Antarctica so the land temperatures weight the average lower than for water.

  20. CO2 releases were 30 times what we are likely to experience in the modern era and temperature rise was only 5C.

    More proof that CO2 is nothing to worry about.

  21. All the evidence suggests that the Eocene was a time when all flora and fauna flourished on land and in the oceans. Only when there was cooling at the end of the Eocene was there a mass extinction. If (big IF) the warming was caused by CO2 then we’ve nothing to fear an a lot to look forward too. (Especially Pen Hadow who’ll be able to holiday at the North Pole every summer).

  22. TonyL:

    Re your reply Aug.31, 2:05 pm.

    Thank you for your suggestions.

    Never having seen any evidence of any warming from any historical volcanic eruptions, I wrongly assumed that that volcanoes were not actually emitting any CO2..

    The answer, of course, is that, although copious amounts of CO2 are emitted, they do nothing to warm the environment (as I have proven in my on-line post “Climate Change Deciphered”

    The PETM warming could only have been due to reduced volcanic activity injecting fewer dimming SO2 aerosols into the atmosphere. (SO2 emissions from underwater sea-floor spreading eruptions would have largely dissolved in the water and not entered the atmosphere to cause cooling)

  23. Ah, volcanic eruptions…they cause global cooling, except for when they cause immense global warming.

  24. In my view the real issue has been further obfuscated by this study. I wrote to Gutjahr commending him on his recognition that PETM basaltic volcanism was largely responsible for the dramatic temperature rise at the time, but offering an alternative explanation for the actual mechanism of warming. So far, I haven’t heard back from him.

    I’ve presented that mechanism in this forum previously (https://wattsupwiththat.com/2016/10/10/interesting-climate-sensitivity-analysis-do-variations-in-co2-actually-cause-global-significant-warming/). The basic idea, developed by my friend and colleague Peter Ward, is that HCl and HBr emitted by non-explosive rift basalts in subaerial settings like that between Greenland and North America during the PETM, can act like CFCs, being photodissociated on polar stratospheric clouds to release monatomic halogens that thin the ozone layer, allowing increased irradiation of Earth’s surface by solar UV-B, which then causes global warming.

    Ward’s ozone depletion model does a far better job of explaining the actual behavior of Earth’s atmospheric temperature behavior over the past 50 years than steadily increasing CO2 concentration does, which I pointed out to Gutjahr as well. Since monatomic chlorine destroys ozone catalytically and has a long residence time in the atmosphere, and since the ozone layer is stlll depleted, it makes perfect sense that we should still have the so-called “global warming hiatus,” with its elevated temperatures punctuated by an occasional spike from a large, subaerial basaltic eruption such as Iceland’s Bardarbunga in 2014-15.

    Frankly, I have difficulty in understanding why there is such resistance to considering this model amid both “warmists” and “deniers.” I know of no hard evidence that militates against the model as opposed to multiple problems that pervade the CO2/warming model.

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