Coral tells own tale about El Niño’s past

Rice, Georgia Tech study in Science reveals Pacific temperatures over a millennium

Rice University

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Georgia Tech climate scientist Kim Cobb samples an ancient coral for radiometric dating. She is part of a team of Rice University and Georgia Tech scientists using data from coral fossils to build a record of temperatures in the tropical Pacific Ocean over the last millennium.

Credit: Cobb Lab

HOUSTON – (March 26, 2020) – There is no longer a need to guess what ocean temperatures were like in the remote tropical Pacific hundreds of years ago. The ancient coral that lived there know all.

A study in Science led by Rice University and Georgia Tech researchers parses the record archived by ancient tropical Pacific coral over the past millennium. That record could help scientists refine their models of how changing conditions in the Pacific, particularly from volcanic eruptions, influence the occurrence of El Niño events, which are major drivers of global climate.

They found the ratio of oxygen isotopes sequestered in coral, an accurate measure of historic ocean temperatures, shows no correlation between estimates of sulfate particles ejected into the atmosphere by tropical volcanic eruptions and El Niño events.

That result could be of particular interest to scientists who suggest seeding the atmosphere with sun-blocking particles may help reverse global warming.

According to Rice climate scientist and primary author Sylvia Dee, previous climate model studies often tie volcanic eruptions, which increase sulfate aerosols in the atmosphere, to increased chances for an El Niño event. But the ability to analyze climate conditions based on oxygen isotopes trapped in fossil corals extends the climatological record in this key region across more than 20 ancient eruptions. Dee said this allows for a more rigorous test of the connection.

“A lot of climate modeling studies show a dynamical connection where volcanic eruptions can initiate El Niño events,” Dee said. “We can run climate models many centuries into the past, simulating volcanic eruptions for the last millennium.

“But the models are just that — models — and the coral record captures reality.”

Coral data that Georgia Tech climate scientist Kim Cobb and her team arduously collected on trips to the Pacific show little connection between known volcanoes and El Niño events over that time. Like tree rings, these paleoclimate archives hold chemical indicators, the oxygen isotopes, of oceanic conditions at the time they formed.

The coral data yields a high-fidelity record with a resolution of less than a month, tracking the El Niño-Southern Oscillation (ENSO) in the heart of the central tropical Pacific.

The eight time-overlapped corals Cobb and her colleagues recently studied held an unambiguous record of conditions over 319 years, from 1146-1465. This and data from other corals spans more than 500 years of the last millennium and, they wrote, “presents a window into the effects of large volcanic eruptions on tropical Pacific climate.”

That span of time includes the 1257 eruption of Mt. Samalas, the largest and most sulfurous of the last millennium.

Cobb said her lab has been developing techniques and expanding the coral record for years. “My first expedition to the islands was in 1997, and it has been my sole focus pretty much since then to extract the best records that we can from these regions,” she said, noting the lab has issued many papers on the topic, including a groundbreaking 2003 study on ENSO in Nature.

Cobb said dating the ancient coral samples depends on precise uranium-thorium dating, followed by thousands of mass spectrometric analyses of coral oxygen isotopes from powders drilled every 1 millimeter across the coral’s growth axis. “That speaks to the temperature reconstruction,” she said. “We’re borrowing on 70 years of work with this particular chemistry to establish a robust temperature proxy in corals.”

The oxygen-16 to oxygen-18 isotopes revealed by spectrometry show the temperature of the water at the time the coral formed, Cobb said. “The ratio of those two isotopes in carbonates is a function of the temperature,” she said. “That’s the magic: It’s based on pure thermodynamics.”

“This beautiful coral record is highly sensitive to El Niño and La Niña events based on its location,” Dee added. “My collaborators worked to extend this coral record to span a period where we know there were a lot of explosive volcanic eruptions, especially in the first half of the millennium.

“Scientists have reconstructed the timing of those volcanic eruptions from ice-core records,” she said. “We compared the timing of the largest eruptions to the coral record to see if volcanic cooling events had any impact on tropical Pacific climate.”

Only some volcanoes launch particulate matter — particularly sulfate particles, leading to a phenomenon called sulfate aerosol forcing — into the stratosphere, where the particles reflect incoming sunlight and cool the planet over the short term, Dee said. “But that cooling’s impact on the tropical Pacific is uncertain, and might be regionally heterogeneous,” she said.

“Our study suggests that linkage (between volcanoes and ENSO) doesn’t exist or, if it does, it is obscured by the large natural variability in the climate system,” Dee said. “In general, El Niño is a natural oscillator in the climate system. It’s a product of chaos, like a Slinky going back and forth. It is so strong that the system might be immune to big climate perturbations like short-term volcanic cooling.

“Incidentally, our scientific community uses the same climate models that we evaluated to estimate the climate’s response to geoengineering and solar radiation management schemes that employ sulfate aerosols,” Dee said. Cobb and Dee characterized the study as a cautionary tale for those who study geoengineering. “There is no doubt whatsoever that if we inject stratospheric aerosols, we will cool the planet,” Cobb said. “That’s been shown and modelled. What we’re trying to ask is, what else happens? And how well can we predict that? Our work really motivates further study to flesh out the full scope of climate impacts from sulfate aerosols.”

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Co-authors of the paper are Julien Emile-Geay, an associate professor of Earth sciences at the University of Southern California; Toby Ault, an associate professor of Earth and atmospheric sciences at Cornell University; Lawrence Edwards, the Regents & Distinguished McKnight University Professor at the University of Minnesota; research scientist Hai Cheng of Minnesota and Xi’an Jiaotong University, China; and Christopher Charles, a professor at the Scripps Institution of Oceanography at the University of California, San Diego.

The research was supported by the National Science Foundation, Brown University and the University of Texas at Austin.

Read the abstract at https://science.sciencemag.org/lookup/doi/10.1126/science.aax2000

This news release can be found online at https://news.rice.edu/2020/03/26/coral-tells-own-tale-about-el-ninos-past/

Follow Rice News and Media Relations via Twitter @RiceUNews. Related materials:

Ice-age climate clues unearthed: http://news.rice.edu/2018/10/24/ice-age-climate-clues-unearthed-2/

El Niño/Southern Oscillation and tropical Pacific climate during the last millennium: https://www.nature.com/articles/nature01779

Highly variable El Niño-Southern Oscillation throughout the Holocene: https://science.sciencemag.org/content/339/6115/67

The (Paleo) Climate Group at Rice (Dee lab): https://sylviadeeclimate.org

Kim Cobb Lab: http://shadow.eas.gatech.edu/~kcobb/people/people.html

Rice Earth, Environmental and Planetary Sciences: https://earthscience.rice.edu

Wiess School of Natural Sciences: https://naturalsciences.rice.edu

Images for download:

https://news-network.rice.edu/news/files/2020/03/0330_EL-NINO-4-web.jpg Georgia Tech climate scientist Kim Cobb samples an ancient coral for radiometric dating. She is part of a team of Rice University and Georgia Tech scientists using data from coral fossils to build a record of temperatures in the tropical Pacific Ocean over the last millennium. (Credit: Cobb Lab)

https://news-network.rice.edu/news/files/2020/03/0330_EL-NINO-3-RN.jpg CAPTION: Sylvia Dee. (Credit: Rice University)

https://news-network.rice.edu/news/files/2020/03/0330_EL-NINO-5-web.jpg CAPTION: Kim Cobb. (Credit: Cobb Lab)

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,962 undergraduates and 3,027 graduate students, Rice’s undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 4 for quality of life by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance.

From EurekAlert!

59 thoughts on “Coral tells own tale about El Niño’s past

    • The record does not show anything since we dont’ get to see it. We do get a few holiday pics of here posing with a hammer.

      If anyone finds the hidden data file that would be worth looking at.

      • Doesn’t matter, they’ll come up with a “novel statistical method” to get the desired result. And then will dismiss any expert opinion as coming from industry shills. Pretty boilerplate.

        • Oh, and the raw data will have been “signed in triplicate, sent in, sent back, queried, lost, found, subjected to public inquiry, lost again, and finally buried in soft peat for three months and recycled as firelighters” (h/t Douglas Adams)

      • Hidden?
        its cited at the end of the paper along with the code’

        Julien Emile-Geay is an Open source open data guy.
        don’t you follow the science he does???
        heck when I see his name on a study I know there has to be code and data
        and if its not there, just ask him.
        Psst, he will eat you alive, he’s wicked smart

        https://science.sciencemag.org/content/suppl/2020/03/25/367.6485.1477.DC1

        And data will end up here over time

        Again cited in the paper. duh
        https://www.ncdc.noaa.gov/paleo/study/27490.

        • Well hidden, yes. When I clicked on doi link give Urea Alert it get a preview of the abstract and attempts to get the pdf or the data what me to subscribe and login to myASSS.org .

          At that point I concluded it was the usual paywalled science and I could spend the next hour trying to dig out pre-print or pirate copy of the pdf and decided I had more pressing engagements.

          In any case many thanks for the links . I just popped back to see whether anyone replied and you’ve come up with the goods. I don’t see much value in their conclusions derived by comparison to defective climate models but I’m always interested in new datasets.

          Much appreciated.

  1. “There is no doubt whatsoever that if we inject stratospheric aerosols we will cool the planet, Cobb said.That’s been shown and modelled.” Shown how? I hate to think that Dr. Strangelove Wannabees are injecting aerosols into the stratosphere, and they probably aren’t, so how is this shown? Modelled? Is Cobb taking a modelling exercise as “shown”? Is Cobb referring to documented large (explosive) volcanic eruptions as having shown this effect? Beautiful sunsets in San Francisco, due to Krakatoa are one thing, but “shown” is something else.

    • Sagan et al “showed” that oil fires in the Middle East would cause a nuclear winter. Their proof? Their rep, their models, and because they said so.

  2. ““Our study suggests that linkage (between volcanoes and ENSO) doesn’t exist or, if it does, it is obscured by the large natural variability in the climate system,” Dee said.”

    “There is no doubt whatsoever that if we inject stratospheric aerosols, we will cool the planet,” Cobb said.”

    If anything this study only emboldens the geoengineering lunatics, as there may not be any expected ENSO response to such an anthropogenic aerosol forcing.

    Someone needs to sit them down though with some basic engineering calculations on how many megatons of sulfate aerosols would have to be continuously injected into the stratosphere to even come close to one big eruption like Pinatubo did in a short time. The stuff does eventually wash out, so it would have to be done continuously. And getting volcanic aerosols into the stratosphere requires the very forceful energy of a superhot volcanic plume driving megatons of ash and sulfate 10-12 km vertically to punch through the tropopause into the stratosphere.

    • Willis’ work has convinced me that aerosol effects from volcanic activity is grossly overstated, and often times non existent in the temperature record.

    • Reasonable thought Joel. However, I’m by no means sure that “atmospheric science” is up to the job of modelling aerosols/particulates well enough to be useful. When Richard Feynman looked at “nuclear winter” theories in the 1980s, his assessment was “I don’t think these people know what they are talking about” And indeed, when Saddam Hussein torched the Kuwait oilfields in 1991, the impacts were in the right direction. But nowhere near as severe as predicted. Probably things are better today. But how much better?

    • Kim Cobb is a climate scientist. Corals are undoubtedly almost as good a proxy of atmospheric(?) temperature as tree rings, except their dating may be a little uncertain 🙂

  3. Once again the sniff test raises a question mark or two.
    Where was the photo taken? I thought all the atolls were sinking so old coral would not be available to look at or knock bits off like that.
    Models, models, models. See Joel and Ron bove.
    1146 – 1465 . Very precise dating Why not 1155 – 1477?
    Not convinced.

  4. What did they find? So much blah blah blah and no data. That’s where affirmative action gets you.

  5. Almost off topic
    I’m surprised to see the researcher using a framing or carpenter’s hammer to collect samples. Using a carpenter’s hammer to strike a chisel is a dangerous practice. When I researched the safety of using various types of hammers for breaking rocks or driving a chisel, every case I ran across where someone had gotten a sliver of steel in their eye or skin was while using a carpenter’s hammer. They are hardened differently than the high quality Estwing line of hammers, notably having a very hard, and brittle, striking face. She should be using a hammer with a much larger and softer striking face. I’m left with the impression that this person has very little field experience.

    • I wasn’t very old when my father taught us that Claw hammers were for soft iron nails and ball peen hammers were for chisel and hard steel.

    • It looks to me like she is using the hammer to shoot an anchor into the rock/coral. The orange handle and long dark steel tube is a standard tool for shooting steel nails into concrete and other hard objects. I have one for work around the house, nailing studs to concrete, etc. Looks just like what she is using.

      • BobM
        If you look closely I think that you will see that the International Orange thing she is holding with her left hand is a standard hand protector that chisels have been sold with for the last few years. However, there is no question that she is using a claw hammer, and not some kind of nail gun.

      • That was my first thought as well, but on second look it appears that she has a chisel or star drill with a hand guard.

    • And by the looks of it, just a pair of sunglasses. At least she has a hat on, that’ll save her from skin cancer never mind going blind (I know what eye injury is all about fortunately temporary and not involving hammers and chisels. But the opticians can still see tiny glittering fragments in that eye).

    • Hammers are just tools : to be used as a tool to achieve a specific outcome,
      there is only a `correct` way for a very `specific` condition, conditions change then the method changes irrespective of what that is so would suggest your knowledge of `useage` overrides that of most others.

      life dictates how one uses a hammer, how one was trained, how one was brought up as a kid, what tools one has at the time, what one is trying to achieve, how skilfull one is, how angry one is.

      Unfortunately my hammer collection runs from the V headed rock maul right down to the lightest finger hammers, to break rock, to work steel, through smoothing out the dent in the trumpet and down even futher than that.
      Each one has a different requirement in how to use and each one specifically engineered for the intended task, and each one with its one impact time signature, which can be used to advantage, but that does not stop them being used for anything else (such as upside down in the vice for fine plannishing work)
      In 50 years I have dressed lots of chisels and polished hammers faces, and had lots of granite and stone in the eye and damaged skin, but I wouldnt dream of challenging the use of a claw hammer and chisel (?) for a specific type of coral until I have spent some time working with the stuff.

      • jono
        It isn’t the issue of the coral. It is the issue of hitting a piece of steel with a hardened steel hammer, not a great deal larger in diameter that the chisel. Did you bother to read the link I provided before commenting?

  6. This is really great hands-on research with a wonderful outcome. It was an open question to me whether volcanic aerosols affected the ocean temperature, as Pinatubo aerosols didn’t so much compared to irradiance, and now to see that confirmed with coral research and ENSO reconstructions to boot is pretty cool. They worked a long time for their achievement.

    https://i.postimg.cc/C55TwXGp/Solar-vs-Volcanic-Cooling.jpg

    … El Niño events, which are major drivers of global climate.

    Taking the idea to its logical conclusion, since aerosols don’t affect ENSO, then neither do clouds, so clouds aren’t the ENSO climate forcing linchpin as is often said and besides, El Ninos and clouds are synonymous.

  7. “ a high-fidelity record with a resolution of less than a month”….that seems to be unbelievable accuracy.

  8. Here’s the abstract. It would be nice if these postings included at least the abstract
    The data is behind a paywall. Probably because it’s not hockey-stickish enough, and points to internal ENSO variability as the dominant factor. Bad scientist – no cookie.

    El Niño/Southern Oscillation and tropical Pacific climate during the last millennium
    Kim M. Cobb, Christopher D. Charles, Hai Cheng & R. Lawrence Edwards
    Nature volume 424, pages271–276(2003)

    Abstract
    Any assessment of future climate change requires knowledge of the full range of natural variability in the El Niño/Southern Oscillation (ENSO) phenomenon. Here we splice together fossil-coral oxygen isotopic records from Palmyra Island in the tropical Pacific Ocean to provide 30–150-year windows of tropical Pacific climate variability within the last 1,100 years. The records indicate mean climate conditions in the central tropical Pacific ranging from relatively cool and dry during the tenth century to increasingly warmer and wetter climate in the twentieth century. But the corals also document a broad range of ENSO behaviour that correlates poorly with these estimates of mean climate. The most intense ENSO activity within the reconstruction occurred during the mid-seventeenth century. Taken together, the coral data imply that the majority of ENSO variability over the last millennium may have arisen from dynamics internal to the ENSO system itself.

    • Taken together, the coral data imply that the majority of ENSO variability over the last millennium may have arisen from dynamics internal to the ENSO system itself.

      The coral data don’t imply climate is forced internally; this is the old ‘weather causes weather’ argument which comes about because someone again missed the solar influence.

      • Weather sometimes does cause weather. Internal chaotic-nonlinear forcing does cause internally generated oscillations in complex systems. Not all systems – such as climate – are passive, forced only form outside.

        Take the example of Cepheid variable stars. They oscillate in brightness, turning regularly brighter and dimmer with a constant periodicity of days to months.

        How does this happen. I’m psychic – I can read your thoughts. Right now, you’re saying to yourself – “it must be solar forcing”. But there’s a problem here. A cepheid variable star … already is a star. So – I guess there must be another star nearby that is varying, and causing the cepheid star to vary by external forcing. It must be so. Because nothing oscillates all by itself right?

        But then, that star nearby that is forcing the variation in the cepheid star by it’s variation – how does that variation happen?

        Easy – there’s a third star nearby that is also varying. It is forcing the variation in the second star, and so on to the first star.

        “So you think you’re smart? But it’s stars all the way down…”

        • There’s a limit to how much weather can force weather, thanks to entropy. The neglect of the solar variation, the assumption that its variability is in the range of not-to-weakly related to climate, continually keeps people looking elsewhere. A steady-state sun rarely happens, really only during GSMs with many nearly zero sunspot activity cycles, periods which are historically noted for colder declining temperatures and more ice. My work indicates such a long-term low state of solar activity leads to a dry hot summer land climate with lower CO2 ocean outgassing and poorer growing conditions, dust bowls.

          Opposite to a GSM such as the Maunder Minimum was the solar modern maximum with notably higher solar activity and the opposite climate: warmer, wetter, and greener from more CO2 ocean outgassing.

          Internal variability then reduces down to being a variable response to variable solar activity, therefore climate variability is reducible to solar variability, stars all the way down or not.

        • Bob
          Thanks for replying and the nice video.
          BTW the twinkling of stars is just atmospheric refraction, not the Cepheid type oscillation.
          But the more important thing is that spontaneous nonlinear pattern formation is as real as gravity. The ocean drives climate. The ocean and thus climate are not passive. Those that believe only CO2 influences climate are as wrong as those who believe that only the sun influences climate. The climate influences itself. It is active, not passive. The technical term is that the ocean is an excitable medium subject to positive feedbacks that lower the dimensionality of chaotic-turbulent systems to lower order chaos with emergent pattern and oscillation. The ocean is not a passive puddle only forced from outside.

          I do not exclude solar forcing. If you read the literature of classic chaotic-nonlinear pattern forming systems, such as the Belousov-Zhabotinsky thin film reaction, exist in both internally driven and externally periodically forced versions. Both are internally driven oscillations, but they can be entrained from outside. This internal dynamics give the energy for change, the eternal forcing just entrains it to the forcing frequency (or some complex function of it if the forcing is weak).

          https://www.youtube.com/watch?v=o72GGxQqWt8

          Going back to the Cepheid stars, they oscillate in brightness due to a positive feedback involving two types of helium ion (+1 and +2) which – like the ocean – make the star’s outer layer an excitable medium. Like the BZ reaction also. Such chaotic pattern phenomena link many otherwise very different systems.

          And finally – if climate is driven by external forcing by variable solar irradiation – what drives the sun to oscillate in activity? It can’t be only Jupiter.

          • “Phil Salmon March 28, 2020 at 1:38 pm

            BTW the twinkling of stars is just atmospheric refraction…”

            Or atmospheric scintillation as I discovered it to be called when I studied planetary science. Has been known about for a long time and all ground based optics need to be adjusted for it. If the atmosphere was truly warming at an accelerated rate those optics would need constant adjustments to compensate. That does not happen at ever increasing rates.

          • I first saw the volcano video with the twinkling stars the day before yesterday and recognized the twinkling was due to the atmosphere but couldn’t resist the analogy after your cosmic comment.

            Certainly, the weather “can” influence the weather. Cold arctic polar air masses move south and affect the weather of lower latitudes, or warm air masses from the tropics moving north(in NH) but does that really cause climate change by itself? No, because something else is actually causing the climate to change, which makes the arctic and tropics get colder or warmer over time, variable insolation from sun-earth distance changes in the long term, and solar variability in the short term.

            Thanks for the info on chaotic systems, it sounds like solar climate forcing as I see it.

  9. “Coral data that Georgia Tech climate scientist Kim Cobb and her team arduously collected”. I’d like that gig. Who wouldn’t want to go to the Pacific islands and visit several beautiful islands. I’m sure therre was a little time to swim and surf.

  10. How can there be an article about proxy work without showing at least one curve?
    Throw us a bone here.
    OK it’s behind a paywall, but just one would be nice.
    How are we supposed to indulge in wiggle-matching and hold forth on our geothermal-astrological theories, with no curve to look at?

  11. So, it seems that corals could give us accurate ocean temperatures. This is much more important than simply correlating El Nino with volcanoes. We have never had anything like an accurate record for ocean temperatures.

    Are the researchers reluctant to simply publish an accurate record of ocean temps at depth and year? Wow….

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