“Back to the future of climate change”

Syracuse University professor uses ancient marine sediment as benchmark for present, future climate models

SYRACUSE, N.Y. – Researchers at Syracuse University are looking to the geologic past to make future projections about climate change.

Christopher K. Junium, assistant professor of Earth sciences in the College of Arts and Sciences (A&S), is the lead author of a study that uses the nitrogen isotopic composition of sediments to understand changes in marine conditions during the Paleocene-Eocene Thermal Maximum (PETM)–a brief period of rapid global warming approximately 56 million years ago.

Junium’s team–which includes Benjamin T. Uveges G’17, a Ph.D. candidate in A&S, and Alexander J. Dickson, a lecturer in geochemistry at Royal Holloway at the University of London–has published an article on the subject in Nature Communications (Springer Nature, 2018).

Their research focuses on the ancient Tethys Ocean (site of the present-day Mediterranean Sea) and provides a benchmark for present and future climate and ocean models.

“The nitrogen isotope record demonstrates that oxygen-free [anoxic] conditions initiated rapidly at the onset of the PETM, changing the way important nutrients, such as nitrogen, were recycled,” says Junium, a sedimentary and organic geochemist. “The magnitude of this nitrogen isotopic shift is similar to those observed during rapid warming intervals in the Mesozoic Era [252 million to 66 million years ago], when broad areas of the Tethys and Atlantic oceans became depleted in oxygen, below the surface.

Such depletion, known as deoxygenation, triggered Oceanic Anoxic Events (OAEs) in the Eastern Tethys during the Mesozoic Era. Scientists believe OAEs coincided with rapid changes in the ancient Earth’s climate and ocean circulation–changes marked by an influx of carbon dioxide from periods of intense volcanism.

“While the exact cause of the PETM is an area of active debate, we are certain that potent greenhouse gases, including carbon dioxide and methane, contributed to overall warming,” Junium says.

The fate of the Tethys Ocean and areas surrounding it during the PETM has been the subject of much speculation by paleoclimatologists, notably Dickson, who has written extensively about it. He and Junium are convinced that a panoply of factors–including ocean acidification, intense rainfall and weathering on land, and an influx of nutrients (e.g., nitrogen, phosphorous and sulfur) from river discharge–set the stage for deoxygenation. Similar to what is happening today.

“Coastal marine systems may be more vulnerable to OAE-like conditions than previously thought,” Junium says. “This is particularly so in enclosed basins, such as the Baltic Sea, or near large river systems, including the Mississippi, which are seeing major influences from anthropogenic activity. … The expansion of anoxic waters, particularly during summer months, impacts marine communities, as well as those relying on coastal areas for food sources, commercial fishing or recreation.”

Drawing on data from the ancient Kheu River system in southern Russia, Junium and his colleagues have confirmed that the nitrogen cycle of the Eastern Tethys underwent a “major reorganization” during the PETM. “Pertubations to the nitrogen cycle can have widespread consequences,” says Junium, referring to the process in which nitrogen changes from one form to another, while circulating throughout the atmosphere, the terrestrial and marine ecosystems. “Nitrogen is critical for life on Earth.”

The group’s research goes a step further. Variations in nitrogen isotope data from the Kheu suggest episodes in which anoxic conditions relaxed, causing oxygen to mix into the water column.

“The transition between oxygen-free and low-oxygen conditions in the Tethys Ocean during the PETM may have created conditions that favored increased production of nitrous oxide, a potent greenhouse gas made by microbes at very low oxygen concentrations,” Junium says. “Studying conditions that fostered nitrous oxide production [during the PETM] enables us to calibrate current and future Earth system models. There is more to warming than just increased concentrations of carbon dioxide.”

Nitrous oxide provides an interesting, albeit speculative twist to the group’s research because the gas cannot be measured directly in ancient rock. “I think we can make a case for finding out whether or not conditions during the PETM favored increased production,” Junium says.

Dickson agrees, adding that the mere suggestion of nitrous oxide contributing to global warming during the PETM is “fascinating.”

“Events such as the PETM are some of the best geological analogues we have for a warmer world. And yet, for years, a satisfactory explanation of how the climatic drivers of these ancient events interacted to produce the level of observed warming has eluded climate modelers,” Dickson says. “The suggestion of a nitrous oxide feedback on climate warming adds a new layer of intrigue to this discussion and highlights the role a changing nitrogen cycle might have on our future Earth.”

Junium thinks his team is on the right track. As carbon dioxide concentrations dangerously approach 400 parts per million (levels not experienced in three million years), they are aware that warming will continue to increase. The ecological and societal implications could be huge.

Navigating such terrain, Junium says, requires better model-based forecasts for global warming.

“Indeed, there are gaps in our understanding between the model worlds and the fossil worlds. The past enables us to test and hone models on which future projections are based. It also helps us determine what processes are missing from our current Earth system models,” he says. “These things combined help us understand and prepare for what is on the horizon.


88 thoughts on ““Back to the future of climate change”

  1. There is a great amount of pure speculation in that ‘study’ and in the words of the authors quoted above.
    ‘Speculative hypothesis’ – yes.
    Fact based science – No.

      • The extent to which a mono-culture of political thought has infected and spread through universities stifling freedom of speech and thought, what hope has any student studying science have at a university that also offers the arts.

      • I agree, George, one can have a department that studies Art, & one that studies Science, but both? In my experience Arty types have enormous imaginations & little or no knowledge of matters scientific!

        • I’m an “arty type”, and, well, look, I’m here critiquing stupid alarmism right along with the rest of you engineerie types. (^_^)

          No offense taken, … just messing with you.

        • For what it’s worth, I was a physics major when I took off in search of fame, artistic fulfillment and, oh yeah, the wild dollar sign. Me and Barney, my faithful B-3, have been through a lot since then, including ending up as an operating engineer.

  2. “…we are certain that potent greenhouse gases, including carbon dioxide and methane, contributed to overall warming,” Junium says.
    Of course you are. That is the whole “purpose” of your “study”. Confirmation bias much?

  3. Lithologic scare tactics won’t work. But we do need more research on the coral record of the AMO to quantify the variability of that long cycle as it relates to climate.

  4. this 300ppm to 400ppm change in co2 responsible for everything is exhausting. more fires, more floods, more drought, crop damage, famine, heat stroke deaths, sea level rise, civil war in syria…yikes. probably responsible for the long lines at the dmv and why the cost of amazon prime went up. at 500 or 600 ppm the devastation on earth will be unbelievable!

    • Certainly…It has already caused grievous harm to the Internet with Google Search Engine Bias and now Youtube labeling certain content as “Undesirable” with links to other severely biased data sources (GOOGLE, WIKI) for proposed reeducation

      • Bryan, I’m all for reeducation. Where do I sign up?

        It presupposes education in the first place… and I like the sound of it!

    • justadumbengineer

      You forgot to mention the typhoons in your living room when CO2 reaches 2,000ppm on a winter’s evening!

      Just what kind of engineer are you?


  5. It has always puzzled me. These scientists can predict into the future with all such sophisticated modelling tools. If it was me, I would rather use these tools to play the stock market.

    But hey, grants are assured profits are not.

    • Problem with that is (and the likely reason they don’t do just that) the models would be as incapable of picking stock winners as they have so far proven to be able to forecast climate

      • Well, the Climate Models actually do work as Stock predictors too, but just like with Climate it only works over long time periods.

        I mean, I’m sure they’ll be right about how Renewables, Electric Vehicles, and such will surge ahead while Fossil Fuels die off, eventually. And surely ocean front property will become valueless once all those Meters of sea level rise finally arrive.

        Remember, it’s a Settled Science. It’s predictions CAN’T be wrong. But they may take a century or two longer then first made to actually be proven. So don’t give up on that Solar City stock just yet.


      • Was it not Lieberman Brothers in NY who commissioned a couple of climate reports prediciting the Earth’s climate a 100 years from 2010, yet they were unable to predict their own sudden demise 12 months later?

  6. When they’re looking at rocks they should be careful it isn’t the ones that are falling out of their heads.

  7. Using low resolution proxies to make statements about small temperature deviations is like telling us all about Mars as seen through a microscope on Earth.

  8. So the Earth got through the PETM without any help from electric cars, no single-use plastic bags, or any of the other current ideas, and here we are on a beautiful, living, balanced Earth and everything is fine. I say balanced because there is ice in polar regions and deserts in the middle.

  9. “As carbon dioxide concentrations dangerously approach 400 parts per million (levels not experienced in three million years)”

    It never occurs to these morons that something keeps using it up making it drop……..
    …and without it, we’re all dead

    • And the data points represents a multimillennial sample. Let’s average today’s CO2 with levels over a millennium or two and compare that to the proxies (they will be, what, 250ppm?), they won’t differ much from their Paleo CO2. I guess the hockeystick “Nature Trick” made it okay to graft on modern annual GHG with the much smoothed down paleo stuff. At least Mann was only going back a thousand years. These grafters are going back 56,000 times as far. This is a worthless study with built in findings.

        • It’s always best to read and critique the original article in the peer reviewed journal. As well as provide the direct link. Then any comments to your comment will be better informed.

          • Pamela,



            Please show how you derived your estimate of a PETM rate of carbon increase, from whatever source, just 1/20 or the rate since AD 1850 or 1750, whenever you deem the industrial age to have begun.


            The paper you cite says that the ocean pH excursion lasted some 50,000 years, but the flood basalt volcanic eruptions might have lasted more or less time, anything from centuries to a million years.

            The paper says:

            “In response to carbon emissions, atmospheric pCO2 in the model increases from ~866 to a peak PETM value of 2176 +1904/-669 μatm, consistent with independent atmospheric pCO2 constraints based on variable terrestrial and marine δ13C gradients over the PETM.”

            Taking the central value, CO2 ppm gained 1310 vs. the ~125 ppm since AD 1850, ie the past 168 years. So if the eruptions lasted only 1761 years, then the rate of increase was the same as now.

            In any case, we’re now in an Icehouse world, not Hothouse. No way will we even get to 866 ppm, let alone 2176. Burning all recoverable fossil fuel over the next few centuries won’t even get us to 600 ppm. Unfortunately for land plants and all those who rely upon them.

        • RyanS,
          How do you reach the conclusion, “… today we’re dumping CO2 in at 20 times the PETM rate.” from the Nature article you linked?

        • The PETM rate is an estimated guess.
          The total PETM CO2 total release was estimated as several orders of magnitude more than is possible in the worst case anthropogenic scenario.

      • Yes. Exactly right. Compressed ice layers for dust are far more accurate than compressed ice layers of gas. A child blowing up a balloon with holes in it can figure this out.

      • Those that are not geologists seem to lack an appreciation for the fact that the temporal resolution decreases as one goes back in time. That is one reason that claims of “unprecedented warming” are unsupportable.

    • It’s over 400 ppm/v now… it’s 410 ppm/v… so … think about the horror that is going through some brainwashed head… closer to braindead, must be too much co2.

    • I find it interesting that these kinds of analysis of paleo-carbon-cycle don’t mention the fact that CO2 becomes less soluble as the surface waters warm. What is missing in the analysis is any consideration of the comparable rates of decreasing solubility with the rate of partial pressure increase of CO2. They don’t seem to be looking at the whole picture.

  10. Ocean circulation was completely different during hothouse conditions. The deep ocean was about 15 C warmer and the deep water originated from warm, very salty and oxygen poor areas of the Tethys.

    Today deep water originates around Antarctica and off Greenland. It is salty, very cold and oxygen-rich.

    Ocean Anoxic Events can’t happen until Antarctica moves away from the pole (though local anoxia is possible, The Black Sea is anoxic, and the Eastern Mediterranean was anoxic during the previous interglacial).

    PETM is an interesting interval (not least because the extreme warming had virtually no negative effects whatsoever on biota), but is irrelevant to current climate and geography.

    This is just a gimmick to get globull warming money for their research.

        • I think we can safely exclude 200,000 and two millions on geological evidence. 200 and 2,000 years are quite possible and 2 or 20 while unlikely cannot be excluded on current evidence.

          • I first wrote 200 and 2000, but decided to double down on the unknowns. The paper itself mentions a million years as the upper bound for the effects it found.

            I agree that the flood basalt episode could have been as brief as two or 20 days, but if the amount of carbon be in the ball park, it would have had to have been a big eruption.

            If the carbon were volcanic in origin, the release should also have included SO2, which ought to have cooled the planet.

  11. Duhh! Make an argument relying on something one cannot measure, so your hypothesis cannot be tested? I think it was caused by unicorn farts.

  12. “helps us determine what processes are missing from our current Earth system models”
    – very revealing… not only do they acknowledge that they are working off system models (not actual facts) but while presenting the various results of their modelling, to fit with their agenda, they have been aware that their models are missing essential processes.
    Funny, I’ve never read/heard any reports based on climate modelling, presented as fact, that has ever stated, “processes are still missing from our current Earth models”

    “climate modelers”
    – I think this is a more accurate name for their ilk, I like it!

  13. ‘As carbon dioxide concentrations dangerously approach 400 parts per million’

    It is exhilarating to live in such dangerous times.

    • Dangerously? Sez who? I guess 99% of the Earths history was flat out dangerous since it was above 400 ppm.

      • Earths history was full of dangers. the ppm of one trace gas had little to nothing to do with those dangers.

  14. so much certainty about how the climate system operated 100-200 million years ago! Yet a tiny change in cloud cover, precipitation efficiency, etc., would also change the average state of the climate system, which could have been different from land/ocean effects (Pangea) changing wind shear and prevailing wind patterns, unknown solar flux, etc, etc. Yet CO2 is supposed to dominate since we know SO much about it. It’s embarrassing that scientists behave like this.

  15. Interesting that this period of rapid warming appears to have happened during a similar period of intense volcanism; or so the article says. Rather spoils the plot methinks.

    • If there was a period of intense volcanic activity the world would have cooled. Most of volcanic activity isn’t co2, it’s so2. SO2 when it reaches the stratosphere reflects incoming light and heat.

  16. Never mind that Earth had been a Hothouse state for tens of millions of years before the PETM, and remained so long after it. And that the continents were arranged differently, to include land connections with or shallow seas between Australia, South America and Antarctica and deep oceanic channels clear around the globe in the tropics.

  17. “As carbon dioxide concentrations dangerously approach 400 parts per million (levels not experienced in three million years), they are aware that warming will continue to increase. The ecological and societal implications could be huge”.
    Yikes, plant life will take over and strangle the planet triffid-style?

    “The Paleocene–Eocene Thermal Maximum (PETM)period with more than 8 °C warmer global average temperature than today” (Wiki).
    The PETM temperature ‘spike’ is dramatised by comparing it with the current global average, but not so dramatic when seen in its geological context:
    It occurred concurrently with an injection into the atmosphere of 2000 GT – 7000 GT of carbon compared with the current net annual increase of human-caused carbon in the atmosphere of ~6 GT.

      • Nobody knows how long it took. Such short intervals aren’t measurable that far back.

        This is from your own link a few posts back:

        “estimates of the duration of carbon release, which range from less than a year to tens of thousands of years. “

  18. “As carbon dioxide concentrations dangerously approach 400 parts per million ”

    I thought we broke through that barrier several years ago.

    Shouldn’t the catastrophes have started already?

    • Shouldn’t the catastrophes have started already?
      Yes they have. Expect to drown or get heat stroke soon.

      See: Mauna Loa

      Monthly average for July 2018 is 408.71.

      400 was reached on a monthly basis about March 2014. Then went down. Note the seasonal cycle.

      Late 2015 was the last time the monthly mean went below 400.

      [Just sight reading]

  19. Ok a few little questions about the climate 56 million years ago…

    1. Were the Hadley, Ferrel, and Polar cells still in the same position?
    2. Given that the air chemistry was different then, were the atmospheric layers in the same places?
    3. How active was the jet-stream back then?
    4. What were the air pressure variations at all atmospheric layers?
    5. What were the humidity/cloud cover variations at all atmospheric layers?
    And given that the Earth’s topography was markedly different from today,
    6. What were the wind speed variation at all atmospheric layers?

    Certainly the oceanic circulation were vastly different from today (see comment from tty August 10, 2018 2:06 pm above), IMO so too was the atmospheric variability, so how did you model it?
    If all, or some, of the above were markedly different from today how can anyone assess the climate processes that occurred then to be a good, or even fair, analog for what might happen now or in the future?

  20. “….or near large river systems, including the Mississippi,… ” I have read a lot (and studied some of it) about the Louisiana situation but this nitrous oxide confuses me. While the nitrogen cycle is as complicated as you can get, I would think a reduced environment would select against it. He does cite papers about how it’s produced but I was not impressed with his references, only two general that might have had something about the modern sediment diagenesis producing hypoxia. Lots of bubbles do come out of mud there, but I would think that there would be lots of competition for oxygen and other work has shown how complicated it is.

    Would a fair guess be that the window necessary to produce it would be small? One of their references concluded this–“In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments.” Watch out for those other critters and chemicals.

    “This argument underscores the sensitivity of modern coastal ecosystems to the consequences of rapid climate change.” This last sentence suggests they are experts in isotopes/sediment diagenesis/climate change/ocean ecosystems past and present!!!! This is a very interesting area of research, hate to see it biased.

  21. Three million years? It’s too bad they accept speculations from rock hounds, but not chemists using chemical methods to determine the CO2 content of the atmosphere over the past 150 years.

    The Mauna Loa CO2 series was started using early NDIR technology. And how did they calibrate it? Using the same chemical methods they reject for showing CO2 used to be higher than it is now. Fascinating. How far as they willing to push this?

    • Crispin in Waterloo

      Probably a stupid question, but why do they reject the calibration standards they use for one but not the other?

  22. Oh look, it’s all so much balderdash. Today’s scientists have little clue how to interpret Earth’s resilience to past climate conditions, in particular to the microbes active at that time and what they could process. What we do know is that the climate was resilient, and that past conditions (including times of high CO2) didn’t lead to runaway greenhouse anythings. How today’s scientists are not being held accountable to Earth’s known climate resilience is a sad parody.

  23. If researchers don’t understand the processes of upwelling and downwelling in the ocean, they will never understand the cause of anoxic deep oceans.

    And they will not understand climate neither.

    • Right on. Research on Sea Surface Temperature is low hanging fruit. The real goodies are in the complex internal ocean columns at every location and for every continental drift position.

  24. “As carbon dioxide concentrations dangerously approach 400 parts per million (levels not experienced in three million years), they are aware that warming will continue to increase.”

    What happened to the claims that there ismore C02 in the atmosphere today than there has been for 650,000/ 750,000/850,000 years, (pick a number!) 😉

  25. If someone hands you a ticket for a sedimental journey, you don’t have to get on the bus.

  26. “While the exact cause of the PETM is an area of active debate, we are certain that potent greenhouse gases, including carbon dioxide and methane, contributed to overall warming,”

    AAAAAAAAAAAAAAAAnd we would know this because?????????????????

  27. Eocene amber is fairly abundant throughout the world. Would air bubbles in the amber help resolve the questions of CO2 and nitrous oxides? Then they wouldn’t have to speculate with models!

    • Good point. Dunno if there is any from the PETM, but Early Eocene, yes.

      A Russian specimen even had a gecko in it, instead of the usual insects. Must have been some air bubbles in a chunk of amber that large.

      Off topic, but geckos have even been found in Cretaceous amber, already with their foot adaptations for walking across ceilings. Except that there were as yet no ceilings of course.

      If you’ve ever lived in the tropics, you’ll know how appealing geckos are, and appreciate their appetite for bugs.

  28. “While the exact cause of the PETM is an area of active debate, we are certain that potent greenhouse gases, including carbon dioxide and methane, contributed to overall warming”

    Translation: We don’t know what caused the warming back then so we will just assume that it was the greenhouse effect of CO2 & CH4 because we don’t know how to say “we don’t know”.

  29. I agree with these researchers. These “geologic time frame resolution” incidents indicate that we only have another 5 to 20 thousand years to decipher exactly what’s happening and respond to it. I’m all for studying the climate another millennium so that we aren’t too surprised when miles high sheets of ice suddenly overwhelm us.

    Oh, wait….as we all now know, CO2 effects have no negative feedbacks…so increasing CO2 as oceans warm means nearly unending increasing atmospheric CO2 concentrations (until oceans run outa CO2)….so NO MORE ICE AGES.

    Very comforting, now that we know all there is to know about CO2 and climate.

  30. Their research focuses on the ancient Tethys Ocean (site of the present-day Mediterranean Sea) –> Their research focuses on the ancient Tethys Ocean (site of the present-day rivers Danube and Rhein)

  31. “Indeed, there are gaps in our understanding between the model worlds and the fossil worlds.”

    But despite this knowledge, these “scientists” hold to the idea that in the foreseeable future they could depict the real world in their models.

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