Claim: Future global warming could be even warmer

From the UNIVERSITY OF COPENHAGEN – NIELS BOHR INSTITUTE and the “worse than we thought” department comes this claim by one researcher looking at the past climate events, specifically the PETM, and using it to predict the future. It is unclear what caused the PETM, scientists can only speculate with ideas like the methane burp hypothesis. He’s right about future warming depending on “the sensitivity of the climate system and response to feedback mechanisms”, but so far climate sensitivity seems to be lower than predicted, and positive feedbacks don’t seem to be manifesting themselves in the atmosphere.


Warning from the past: Future global warming could be even warmer

paleo-climate-sensitivity

Climate sensitivity at different global temperatures in the atmosphere is shown. The figure shows from the right estimates for the past warm period, the PETM 56 million years ago, the period before the PETM and for the present. On the left the figure shows estimates for the Last Glacial Maximum. (Credit: Gary Shaffer/ Roberto Rondanelli)

Future global warming will not only depend on the amount of emissions from man-made greenhouse gasses, but will also depend on the sensitivity of the climate system and response to feedback mechanisms. By reconstructing past global warming and the carbon cycle on Earth 56 million years ago, researchers from the Niels Bohr Institute among others have used computer modelling to estimate the potential perspective for future global warming, which could be even warmer than previously thought. The results are published in the scientific journal,Geophysical Research Letters.

Global warming from greenhouse gas emissions depends not only on the size of the emissions, but also on the warming effect that the extra amount of gas has on the atmosphere. This effect, called climate sensitivity, is usually defined as the warming caused by the doubling of the amount of CO2 in the atmosphere. Climate sensitivity depends on a number of properties of the earth’s climate system, such as the composition of clouds and cloud cover.

“The research shows that climate sensitivity was higher during the past global, warm climate than in the current climate. This is bad news for humanity as greater climate sensitivity from warming will further amplify the warming,” says Professor Gary Shaffer, University of Magallanes, Chile, and the Niels Bohr Institute, University of Copenhagen.

The past tells about the future

The study was based on reconstructions and climate modelling of a period of global warming 56 million years ago. The period known as the Palaeocene-Eocene Thermal Maximum (PETM) was triggered by massive releases of carbon into the atmosphere and climate researchers have long identified it as a time that could in some ways be analogous to today’s global warming.

Reconstructions of past temperatures show that even before the PETM the Earth was about 10 degrees warmer than today and then warmed an additional 5 degrees during the PETM. In addition, they combined data about minerals, isotopes and the carbon cycle with climate models to estimate the concentration of CO2 in the atmosphere – both before and during the period. From this, they could estimate the climate sensitivity and the result was that where it was about 4.5 degrees C before the PETM, the temperature rose to about 5.1 degrees during the PETM. Climate sensitivity is currently around 3 degrees.

“Our results show that the amount of carbon that drove the PETM warming was about the same amount as the current ‘easily accessible’ fossil fuel reserves of about 4,000 billion tons. But the warming that would result from adding such large amounts of carbon to the climate system would be much greater today than during the PETM and could reach up to 10 degrees. This is partly due to the current atmosphere containing much less CO2 – approximately 400 ppm (parts per million) – compared to before the PETM, where the concentration was about 1,000 ppm and partly because we emit carbon into the atmosphere at a much faster rate than during the PETM. If we then also take into account the fact that climate sensitivity increases with the temperature, it means that it is all the more urgent to limit global warming as soon as possible by reducing the man-made emissions of greenhouse gases,” explains Professor Gary Shaffer, who conducted the study in collaboration with researchers from Purdue University, USA, the University of Chile and the Technical University of Denmark.

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81 thoughts on “Claim: Future global warming could be even warmer

  1. What would happen if a major oilfield was breached by the sea? Hundreds of years of oil slicks/oil sheen would have an effect on various mechanisms which cool the planets, albedo change, aerosol production etc.
    JF

    • JF, nope. The Macando blowout in GoM was such a breach. Rapidly multiplying Methanotrophs ate the methane before it ever reached the atmosphere. BP did pay for oil slick surface cleanup. But micro-organisms would have done the same in just a few years. Even in much colder Alaska, there are almost no significant traces of the Exxon Valdez mishap left. Maybe some very hard bitumens. Off Cancun, there are shallow water bitumen deposits left from natural oil leaks. These are sufficiently biologically inert to host corals and sponges.

  2. “Reconstructions of past temperatures show that even before the PETM the Earth was about 10 degrees warmer than today “.
    I thought Mann proved that the earth had never been warmer than today. There was also supposed to be a “tipping point” that we were dangerously close to reaching and beyond which there was no rescue.
    Why is everything “bad news for humanity”?
    And if humans are the problem shouldn’t we cheer the bad news for humanity?
    Sorry, I am confused.

    • The study was based on reconstructions and climate modelling of a period of global warming 56 million years ago. The period known as the Palaeocene-Eocene Thermal Maximum (PETM) was triggered by massive releases of carbon into the atmosphere and climate researchers have long identified it as a time that could in some ways be analogous to today’s global warming.

      But according to a chart included in Jim Steele’s recent paper (Figure 1, p 7), CO2 levels were declining steadily from the end of the Jurassic (146 Mya) through the PETM and did not start to rise again until the beginning of the Miocene (23.5 Mya), by which time temperatures had dropped approximately 6°C from the PETM peak 22.5 million years earlier.
      The chart in Steele’s paper comes from Nasif Nahle. 2007. Cycles of Global Climate Change. Biology Cabinet Journal Online. Article no. 295..
      I cannot reconcile the claim quoted above with the data presented by Nahle.

      • Data? We don’t need no stinkin’ data! (to butcher Blazing Saddles)
        Of course one needs no inconvenient data when one has a political agenda to pursue!

      • It was anything but funny when first spoken, in ‘The Treasure of the Sierra Madres’ . . which was most certainly not a comedy . .
        Badges? Badges? We don’ need no steenkeen badges . . (Bang!)

      • The actual line was “Badges? We ain’t got no badges! We don’t need no badges!
        I don’t have to show you any stinking badges!”

      • “Our results show that the amount of carbon that drove the PETM warming was about the same amount as the current ‘easily accessible’ fossil fuel reserves of about 4,000 billion tons. or lava at densities of about 3000 – 3500 kg per cubic meter.
        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^2 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 flows were going on at the PETM? How many candles 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?

    • Let me help straighten you out then.
      It was Gore who proved the earth has never been warmer but his research has been sequestered under the National Security Act. The ‘tipping point’ was reached when he got rid of his aging wife Tipper.
      It was Mann who revolutionized dendrochronology through an advanced new proxy technique and in the process proved beyond debate that the Vikings never existed in Greenland.
      It works something like this but since it’s a proprietary technique he’s not legally allowed to explain it >
      https://climateaudit.org/2009/10/14/upside-side-down-mann-and-the-peerreviewedliterature/
      As for your questions:
      1) “Why is everything “bad news for humanity”?” > Because “bad news” = ridiculous amounts of grant money
      2) “And if humans are the problem shouldn’t we cheer the bad news for humanity?” > Sorry we don’t cheer bad news over here. We leave that to the professional ‘climate scientists’. See 1) for explanation.

    • Because the amount of money they get shows others are stupider: therefore they are smart.

    • On a stupid scale of 1 to 10 this study is a solid 3 and was likely paid out accordingly.
      The big money goes to the 10’s like the Acid Oceans study, where they proved beyond debate that coral reefs, shelled mollusks and crustaceans are dissolving in today’s acid oceans.
      They must have been on acid when they wrote it because all three life forms evolved ~500 million years ago during the Paleozoic era when CO2 levels were 10 to 20 times higher than today.

  3. Ridiculous paper. No matter what caused/happened in the ~56mya PETM temperature excursion, it can teach nothing about today’s climate sensitivity/ CO2 response. The continents were in different positions. The isthmus of panama had not even begun to form; a wide open large ocean gap between N and S America that did not close until ~2mya. The Drake passage was closed; Antarctica was suffiently ‘north’ that its ice sheet would not begin to form for another 30 million years after it drifted suffiently ‘south’. Colorado/wyoming/Utah was covered by a large inland sea; proof is in the Green River marine kerogen shales and their fish fossils.
    Sensitivity depends on a lot of Earth factors simply too dissimilar, in addition to the ocean and albedo differences just noted.
    How can such scientific garbage get through common sense review, let alone peer review at GRL?
    The comparison figure in the post is cartoon science, not real science.

    • FYI:The Green River Formation and its fish fossils were deposited in a large freshwater lake, not a sea.

    • One other difference. Why do they assume that the PETM was caused by CO2 in the first place. To find a climate sensitivity to CO2 you have to demonstrate (or in this case assume) that the temperature change was caused directly or indirectly by the CO2 increase. That is something for which no evidence has been, or indeed can be, presented. At best they can say that they can see no other cause. However, proof by exhaustion is appropriate for rigorous mathematics and closed circle mysteries, not for identifying the responses of a 50 million year old climate change. In this case it is merely a case of argumentum ad ignorantiam

      • BoH, looked at that briefly while reading up on PETM before commenting. There is a lot of geological evidence for either CO2 or CH4 or both releases. Has to do with the 12C/13C isotope ratios found in the sedimentary carbonate rocks of that era. Speculation more about sources than that the fact that it happened. The temperature inferences are from delta18O, changes in Mg/Ca ratios in benthic foraminifera, and related proxies. With both GHG and delta T there is obviously a lot of uncertainty.
        I doubt the post’s figured PETM uncertainty bar is wide enough, but did not bother to read the silly paper itself to find out how it was estimated. For sure the modern day green bar (1.5-4.5, mode 3) is just AR4 gospel, and also just wrong based on all the newer energy budget studies like Lewis and Curry 2014.

      • Technically, they said “carbon” not CO2, but I am picking a well-worn nit on that one.

      • THANK YOU! How do they come up with the ridiculous notion that CO2 was the “cause” of the temperature rise in the first place?! When they can’t show CO2 “causing” temperature rise in any other part of the Earth’s climate history, and can’t show MUCH HIGHER (and INCREASING) CO2 levels to be able to stop temperature from plummeting from similar levels into a full blown glaciation (about 450 mya). This is nothing but more hypothetical BS, like the entire AGW house of cards. CO2 does NOT drive the f-ing climate – never has, isn’t now, and never will.

      • Ristvan. Perhaps I was unclear. I understand that there is a lot of evidence for the increase of CO2 as well as for an increase in temperature. However, there’s a further assumption that’s implicit in this determination.
        “The CO2 is the sole cause of the temperature increase. Anything else that caused an increase in temperature is due indirectly to the CO2 increase”
        That’s the requirement of calculating climate sensitivity. It’s a mandatory prerequisite. However, that’s a dubious assumption in the 20th century with all of its recordkeeping, it’s a ludicrous assumption when assigned to paleological evidence.

  4. This made absolutely no sense..They admit that the CO2 was at 1,000 ppm during the PETM and we are only at 400 ppm, so, we have 600 more ppm to go BEFORE we have to start worrying !

    • Yes, but the global temperature was 10 C warmer than it is today, BEFORE PETM, and everything was doing rather well and here they are saying a 2 C increase in global warming would be dangerous. I don’t think they even know what they are talking about 100% of the time.

      • Agreed 100%. Like the entirety of the AGW house of cards, they try to invoke the spirit of all-powerful CO2 from those periods that “appear” to present the possibility (which they of course interpret as “certainty”) of CO2 inducing temperature change, while willfully turning a blind eye towards alternate portions of Earth’s climate history that directly refute such a thing.

    • Reminded me of Pooh’s poem, The More it Warms;
      The more it warms (Tiddely pom),
      The more it goes (Tiddely pom),
      The more it goes (Tiddely pom),
      On warming.
      And nobody knows (Tiddely pom),
      How long my nose (Tiddely pom),
      How lomg my nose (Tiddely pom),
      Is growing.

    • Procedure is evidently “choose a period when CO2 increased before temperature (or not – where did they get this? – I see CO2 falling prior to the 56 mya temperature spike, and smell more “revisionist history”), assume CO2 was the sole cause of the change in temperature, and then calculate a “sensitivity” based on the aforementioned assumptions.” Disregard the complete lack of any evidence that CO2 actually drives the Earth’s temperature, the presence of other inconvenient portions of Earth’s climate history that refute that CO2 has any such power, and the lack of any actual knowledge about the actual causes of the temperature change in the carefully selected period, of course. Seems entirely scientific, no? LMFAO.

  5. The current carbon cycle is not understood at all, it is a theory, an assumption without foundation. Allocataions without any emperical support. I wonder if this fellow drives to work in reverse looking in the rear view mirror.
    The basic knowledge and interpretation of CO2 in our immediate atmosphere, its movements, where it ends up and what the individual sampling sites are actually recording is very poor. To build further theories on a poorly established base is futile.

    • Have faith Kiwikid
      If the current Empirical Data doesn’t support the modeled outcome, they will simply Twerk the data until it does

    • Couldn’t have said it better – it’s nothing but a house of cards. One poorly supported hypothesis and a stack of assumptions and extrapolations based on that poorly supported hypothesis piled atop one another, all of which doesn’t amount to a hill of beans.

  6. So…
    It is going to worse… and I bet it will be faster to onset….
    There must be a climate conference coming..again so the hype has to be rolled out.

  7. I was under the impression that the climate sensitivity of carbon dioxide was on the order of 1degree C or less. Using bogus figures in a bogus model is typical for “climate science”.

    • TH, about 1.2C for no feedbacks. The observational energy budget studies are suggesting effective climate sensitivity maybe 1.7-1.8C per doubling. That includes all feedbacks over about a 135 year period 1880-present.

      • We’re nearly half way to a doubling of CO2 now. We should have seen .5C of warming from CO2 alone all ready. So where is it? Unless we’re willing to say that all the warming since the LIA is anthropogenic, then the expected warming from CO2 just isn’t there…

      • Nonsense – more than half of the SUPPOSED (and probably inflated) amount of warming can be directly attributed to solar influences. The climate feedbacks are negative, not positive, which can easily and quickly be inferred by the Earth’s lengthy periods of relative climate stability which wouldn’t exist in a system dominated by positive feedbacks, and have been measured by others in a way that confirms the “greenhouse effect” in TOTAL (including the influences of both so-called “greenhouse gases” AND clouds) has DECLINED, not increased, despite rising CO2 levels. The real word continues to show the hypothetical climate crisis is BS.

        • I agree. Ristvan is attributing all warming to CO2, and essentially none to solar or unknown effects. A straightforward effect of CO2 should track temperature better, without those embarassing 18 year pauses.

  8. “Global warming from greenhouse gas emissions depends not only on the size of the emissions, but also on the warming effect that the extra amount of gas has on the atmosphere. This effect, called climate sensitivity, is usually defined as the warming caused by the doubling of the amount of CO2 in the atmosphere.”
    ======================================
    Bait and switch
    ” Global warming from greenhouse gas emissions’
    All GREENHOUSE GASses
    “doubling of the amount of CO2”
    Just the … CO2 … boogyman
    ===========================================
    Then there is
    ——————————————————————–
    ““The research shows that climate sensitivity was higher during the past global, warm climate than in the current climate. This is bad news for humanity as greater climate sensitivity from warming will further amplify the warming,” says Professor Gary Shaffer, University of Magallanes, Chile, and the Niels Bohr Institute, University of Copenhagen.”
    =======================================
    Which when added to this tidbit a little later
    =======================================
    ” Reconstructions of past temperatures show that even before the PETM the Earth was about 10 degrees warmer than today and then warmed an additional 5 degrees during the PETM”
    =======================================
    Looks like a kind of double speak
    “Climate sensitivity was higher during the past” says that Climate sensitivity is lower now and this is “bad news” because the lower sensitivity we have is really a “Greater climate sensitivity from warming” and will cause further amplification.
    How can the current Lower sensitivity (if climate sensitivity was HIGHER in the past) actually equate with “Greater climate sensitivity from (current?) warming will further amplify>>>?
    So if the Earth was 10 degrees warmer prior to the PETM and warmed an additional 5 degrees
    How can a 10 degree cooler climate with a lower CO2 (current 400ppm vs 1000ppm prior to the PETM) possibly make things worse today than then?
    Does a lower CO2 concentration equate with Higher Climate Sensitivity?

    • Well, yes, as I understand it, if we are speaking of additional parts per mil . . but not, if we are (as usual) speaking of doubling whatever parts per mil . . Thing is, I don’t trust these CAGW guys to hold to a single definition within a single sentence . .

  9. GRASSHOPPER: Is it going to be bad, Sensei?
    SENSEI: It is going to be really bad, Grasshopper.
    GRASSHOPPER: Really bad?
    SENSEI: Really, really bad.

  10. We see here time and time again, that to get funded for research in any field, one must pay homage to the god CO2 at the altar of CAGW.
    On the other hand, if one’s purpose is to worship the god CO2, then no paper is so bad, so stinky that it can not pass peer review. even the worst stinky messes are rewarded with publication in major journals.
    Doing good science is *hard*. It may just not be worth the effort anymore.

    • It is worse than you think , apparently the UN climate fund is failing to find sufficient projects , according to a link via DieKalteSonne and Climatechangenews:
      -“By Ed King
      The UN’s flagship climate fund says it will miss a target to approve $ 2.5 trillion of new projects in 2016 unless more countries submit proposals.In an email sent to media and national delegations Zaheer Fakir, co-chair of the Green Climate Fund board, urged Governments and banks linked to accelerate their applications for financing.
      So far 41 proposals worth $ 2.4 trillion havebeen submitted, but not all of these will be approved this year, Said the email.
      Developing countries, “Get Up Stand Up” – do not wait, do not hold back in terms of the number or ambition of proposals for the #GCFund
      – Zaheer Fakir (@zaheer_fakir) May 25, 2016
      “GCF’s ability to deliver against the USD 2.5 trillion target will depend on the Fund’s capacity to approve proposals, and on the volume and quality of proposals it receives,” Fakir said.
      “We need countries, Accredited Entities, and National Designated Authorities not to wait, and not to hold back in terms of the number or ambition of proposals They submit to the Fund.”
      More than $ 10 bn pledged to the #GCFund and it now faces the challenging task of moving from resource mobilization to implementation
      – Zaheer Fakir (@zaheer_fakir) May 25, 2016
      The GCF officially launched last year and so far has started work on 8 projects worth $ 168 million.
      Under the Paris Agreement on climate change, the Seoul-based fund which designated one of two main funding mechanisms to help developing countries invest in green energy and prepare for extreme weather events.The US, UK, France, Germany and other developed countries pledged just over $ 10 trillion to the GCF in its first funding window. “-
      I had no idea that the UK had so many trillion dollars to dispense – difficult to receive this news calmly on a day when Greater Manchester Fire Authority announce massive redundancies to save £15million , almost certainly triggering a strike which will kill people and destroy homes .
      Apologies to all for the parochial rant , but surely elsewhere in the US and UK local problems are being starved of money to pay for this GCF, without necessarily the support of the relevant voters

  11. I used this preserved redwood from 300m down in a diamond pipe (Ekati) about 100km from the Arctic Circle in an earlier post but was too late for anyone to have seen it. It was from the Paleocene-Eocene 53 million years ago and found by miners recently:
    http://www.livescience.com/23374-fossil-forest-redwood-diamond-mine.html
    A 1000 ppm CO2 gets gobbled up in creating an unbelievable forest cover. Imagine a California climate with redwood forests over over Canada. The wood of the specimens is wood, even with seams of sugary amber, not truly a fossil in the usual sense that silica and calcium carbonate replaces the actual biological material. Apparently wood chunks at Ekati are abundant. How much carbon would be sequestered in a forest like that covering at least 2/3 of North America. Similarly, logs have been found at depth in South African mines and others.

    • I also meant to say, it also tells us that the climate would appear to have been lovely- a forested California- and hey, the Caribbean would about the same as it is now.

      • It was also a period of time when there was deep lateritic weathering, at least in California, preserved in many road cuts in the Foothills of the Sierra Nevada. There were large, meandering rivers. It might have been analogous to the Amazon Basin of today.

  12. At that time it was believed the Earth was 15K higher in temperature than today. How would the world survive that, all must have tipped to a cataclysmic catastrophy.
    And how could the temperature drop 15K when no peoble was around to stop burning fossil fuels.
    The greens were not even invented at that time.

  13. “From this, they could estimate the climate sensitivity and the result was that where it was about 4.5 degrees C …”.
    =============================
    The CO2 concentration ~1700 was about 275 ppm and according to IPCC projections (business as usual) ought to reach double that (550 ppm) around 2045 – 2050.
    With a climate sensitivity of ~4.5C and assuming the pause lasts another two years or so due to La Niña, the GAT would have to shoot up ~4C in the following 20 – 30 years.
    I hope I live long enough to see that, it should be quite spectacular.

  14. ““Our results show that the amount of carbon that drove the PETM warming was about the same amount as the current ‘easily accessible’ fossil fuel reserves of about 4,000 billion tons. ”
    Of course, this is clearly ignoring the fact that CO2 partitions 50 to 1 into the oceans and even 4000 billion tons will have little effect, probably undetectable.
    And, the same clowns ignore the fact that the half-life of CO2 in the atmosphere is about 5 years and not the 200–1000 years dishonestly claimed by NASA and the IPCC.
    Between these two huge errors, the result is that CO2 is plant food and any effect it will have on climate is picayune compared to the advantages to life on Earth.

    • Yup! But hey – their BS story makes for great headlines! And browbeating the minions into obedience is the goal here, not real scientific inquiry.

  15. The news release above has all the earmarks of a fairytale.
    Once upon a time, before mankind…
    Complete with the mystical magical ‘greater sensitivity’.
    They’ve yet to learn how to write a good fairytale ending, though.
    Must because they had bad childhoods, horrible role models and villains for heroes.

  16. The past tells about the future

    Funny because most of the time, the same advocacy peddlers are telling us this is unprecedented and the past is no measure of what could happen… LOL

    • Hey, this is the same talking-out-of-both-sides-of-their-mouths Eco-Naz!s that brought you “winters with little snow = AGW” AND “winters with lots of snow = AGW” – did you really expect consistency in their BS?! They start with the preconceived conclusion and work backwards into the supposed support for it, no matter how many contradictions that entails.

  17. One factor is where the continents are, because that affects presence and distribution of snow and ice cover. A significant reason for the cooler temperatures of the past few millions of years, Antarctica has been located where it can get glaciated.
    As for climate sensitivity during the past few million years:. It seems higher when there is more snow and ice (and variability thereof) in sunnier latitudes. So as the earth warms and gets cleared of ice, climate sensitivity will generally decrease. Also, the lapse rate feedback (which is negative) becomes greater as greenhouse gases increase and the surface warms.

    • Yeah, shuffle Antartica a few thousand kilometers northward, unslam the Indian sub-continent and unfold the Himalyan rocks that pushed land masses near-into the tropopause… then close the Atlantic a few 1000 km, and open Panama as a straight.
      That should just about get the continents back to the PETM config.
      After that, devolve C4 plants and grasses.

  18. According to Sluijs, et al., Nature (December 2007) [1]:
    “We show that the onsets of environmental change (as recorded by the abundant occurrence (‘acme’) of the dinoflagellate cyst Apectodinium) and of surface-ocean warming (as evidenced by the palaeothermometer TEX86) preceded the light carbon injection by several thousand years.”
    English translation:
    During PETM, temperature rose 3,000 years before CO2 rose!
    Thus, PETM could not have been caused by the CO2 greenhouse effect.
    1-“Environmental precursors to rapid light carbon injection at the Palaeocene/Eocene boundary”
    – Sluijs, et al., Nature 450, 1218-1221 (20 December 2007)
    http://www.nature.com/nature/journal/v450/n7173/full/nature06400.html

  19. Oh right. We can tell exactly how/why the climate changed 56 million yrs ago. Of course CO2 was the cause. /sarc

    • They’ve never been able to show CO2 was the cause of ANY temperature change. It’s pure hypothetical BS. Reality shows that if there IS a relationship, it’s temperature driving CO2 levels (based on solubility of CO2 in water), not the other way around.

  20. The problem with this paper is that there is no way to measure the CO2 concentration during the PETM with any precision. What can be measured precisely is the change of carbon isotope ratios, from which the change in the amount of CO2 in the atmosphere can be estimated provided you know the isotope ratio of the CO2 added to the atmosphere.
    Unfortunately this is not known, since the isotope ratio depends on the source of the carbon. At least the following six sources have been suggested for the PETM:
    1. Impact of a volatile-rich asteroid (or more likely a comet)
    2. Release of methane from deep-sea methane hydrates
    3. Very large scale peat fires
    4. Oxidation of organics-rich marine deposits in desiccated former shallow seas
    5. Oxidation of organics by large scale volcanic eruptions through carbon-rich sedimentary rocks
    6. Large-scale melting of permafrost in interior East Antarctica
    All of these will give different results, and to complicate things further, combinations of two or more of these mechanisms are quite possible.
    Also the best PETM profiles show pretty conclusively that the climate warming started slightly before the isotope ratio change, which suggests that the change in the carbon cycle was a consequence rather than a cause of the warming.

  21. They are dreaming if they rthink that carbon dioxide caused the PETM. It was ten times higher in the Cambrian and Ordovician while temperature then stayed at the Cretaceous level which precedes PETM. What they need is to understand that carbon dioxide is not warming the world now and has not done so in historic times. The most direct observation of this comes from the existence of the twenty-first century hiatus. It so upset the warmists that they sent NOAA out in the hope of unearthing global warming that could prove absence of the hiatus. They did find some questionable data which Karl et al. then blew up and claimed that it proved the non-existence of the hiatus. What happens during a hiatus is that atmospheric carbon dioxide keeps increasing as it has since measurements exist, but temperature does not. If you shorten the global temperature observation period to a segment between 2002 and 2012 you are leaving out the super El Nino of 1998 that is usually included in the hiatus. What you have now is a ten year long temperature segment that is no longer just horizontal but actually slopes down. No way can this be turned into warming as Karl would have it. The Arrhenius greenhouse theory they use requires that if carbon dioxide goes up, temperature also must go up. Existence of a horizontal temperature curve, or even better, one that slopes down, is totally impossible according to their own greenhouse theory. Their theory has made a wrong prediction here and a scientific theory that makes a wrong prediction belongs in the trash can of history. The only greenhouse theory that correctly predicts the hiatus temperature is MGT, the Miskolczi greenhouse theory. According to MGT, carbon dioxide and water vapor in the atmosphere form an optimal absorption window in the infrared whose optical thickness is 1.87. If you now add carbon dioxide to the atmosphere this has the effect of increasing the optical thickness. The added carbon dioxide also causes additional absorption, just as Arrhenius says. But as soon as this happens, water vapor will start to diminish, rain out, and the original optical thickness is restored. The added CO2 will of course keep absorbing beyond that point but by now the removal of water vapor has reduced total absorptivity to background level and no greenhouse warming predicted by the Arrhenius theory is possible. An observer looking from the side sees carbon dioxide increasing but no change in temperature. That is exactly what is happening during the hiatus. But even better, it is not necessary to have a hiatus to stop warming. This process works any time you add carbon dioxide to the atmosphere, hiatus or no hiatus. Hence, greenhouse warming is simply impossible.

  22. Of course they can’t be sure yet they say increased co2 in the atmosphere was what caused the PETM . What else could have caused it other than a trace gas which is present in the atmosphere at 400 parts per million, or less than .05 of one percent.

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