Air Quality Current and PETM rates of atmospheric carbonization over time (wunderground.com)

Published on March 22nd, 2016 | by Sandy Dechert

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Atmosphere Absorbing CO2 Faster Than PETM, When Dinosaurs Perished

March 22nd, 2016 by  

Conchs (Strombus alatus) kept in seawater under different levels of atmospheric carbon dioxide to effects of increased ocean acidity (whoi.edu/oceanus/Tom Kleindinst)

Conchs (Strombus alatus) kept in seawater under different levels of atmospheric carbon dioxide to effects of increased ocean acidity (whoi.edu/oceanus/Tom Kleindinst)

A new study in Nature Geoscience, led by Richard Zeebe of the University of Hawaii, looked at an anomalous time period called the Palaeocene-Eocene Thermal Maximum, or PETM. This phenomenon occurred about 56 million years ago, about ten million years following the beginning of the Cenozoic era (Age of Mammals), just about when the dinosaurs became extinct.

During the PETM, concentrations of carbon dioxide in the atmosphere spiked by 5 degrees Celsius, far higher than they have risen since human preindustrial levels 200 years ago. Climate scientists and world policy makers agree that 2 degrees more is all humans can probably take—or maybe 1.5, as more cautious voices are warning.

Zeebe’s expert team of researchers used a new technique to extract rates of change in a deep sedimentary record from the New Jersey shelf. They based their analysis on the relative timing of climate and carbon cycle changes. An age model was not necessary.

Cenozoic pCO2 and stacked deep-sea benthic foraminifer oxygen isotope curve for 0 to 65 Ma. Updated from Zachos et al. and converted to the Gradstein timescale (publications.iodp.org)They applied the new method to stable carbon and oxygen isotope records using time-series analysis and carbon cycle–climate modeling. By doing so, they determined the ratios between different isotopes of carbon and oxygen found in PETM sediments.

The investigation indicates that earth’s population now is emitting carbon into the atmosphere faster than carbonization at any other time in earth’s history since the PETM. Zeebe explains:

Current and PETM rates of atmospheric carbonization over time (wunderground.com)“If you look over the entire Cenozoic, the last 66 million years, the only event that we know of at the moment, that has a massive carbon release, and happens over a relatively short period of time, is the PETM. We actually have to go back to relatively old periods, because in the more recent past, we don’t see anything comparable to what humans are currently doing.”

In fact, our current rate of anthropogenic carbon release is at least an order of magnitude (10x) higher than what the world experienced during the PETM. The study concludes that “given that the current rate of carbon release is unprecedented throughout the Cenozoic, we have effectively entered an era of a no-analogue state.” In other words, earth has apparently never seen a situation like today’s for at least 66 million years, if ever. At that time, the hothouse world lasted over 1,000 centuries.

Atmospheric CO2 and ice-free periods on the geologic time scale (wunderground.com)

Weather Underground scientists provide the following description of the PETM:

“There are a lot of uncertainties surrounding the PETM—this extremely warm geologic period has been notoriously difficult to recreate, but recent advancements in understanding the warming have been made. Uncertainties should not be interpreted as misunderstanding. Instead, they should be treated a testament to how sensitive the climate system could be, and how influential humans are on the delicate global energy balance. It is clear that the earth dumped almost all of its stored carbon into the atmosphere, and now we are doing the same by pulling fossil fuels out of the ground and burning them. Just like the previous great global warming did, we are likely catapulting ourselves into a new geologic era: the Anthropocene.”

The abstract for the Nature Geoscience paper concludes:

“Given currently available records, the present anthropogenic carbon release rate is unprecedented during the past 66 million years. We suggest that such a ‘no-analogue’ state represents a fundamental challenge in constraining future climate projections. Also, future ecosystem disruptions are likely to exceed the relatively limited extinctions observed at the PETM.”

Zeebe says the two main conclusions are that ocean acidification will be more severe this time around, and that existing ecosystems may be hit harder because of the higher rate of carbon release.

 
 
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About the Author

covers environmental, health, renewable and conventional energy, and climate change news. She's currently on the climate beat for Important Media, having attended last year's COP20 in Lima Peru. Sandy has also worked for groundbreaking environmental consultants and a Fortune 100 health care firm. She writes for several weblogs and attributes her modest success to an "indelible habit of poking around to satisfy my own curiosity."



  • john

    For a very good look at PETM go to this site
    https://www.wunderground.com/climate/PETM.asp?MR=1

  • Larry

    “During the PETM, concentrations of carbon dioxide in the atmosphere spiked by 5 degrees Celsius,” I hope there is a printing mistake here. The concentration of CO2 does not increase by degrees of temperature. It can CAUSE an increase in atmospheric temperatures, but that isn’t what was printed.

  • Jan Galkowski

    To nitpick a bit: The extinction related to the PETM was *not* that of the dinosaurs. They were extinct at the Cretaceous-Tertiary boundary, 65 million years ago, not 56 million years ago. The title of this post should be corrected.

    • onesecond

      Also, maybe it’s me, but I really don’t like the wording of the headline. “Absorbing” sounds like “neutralizing” which is not at all what is meant. This word is used a lot in the context of carbon sinks, so while it is technically correct, I wouldn’t use it here.

    • Dallin Paul Jensen

      I don’t think that’s nitpicking. An 11 million year difference is the difference between modern humans and our shared ancestor with orangutan. Falsely likening the PETM to being “about the same time as when the dinosaurs died” is the same kind of alarmism anthropogenic climate change deniers routinely accuse environmental activists of. Either the author did not take the time to really understand the science, or she is willfully misrepresenting it. As a stable isotope geochemist it is dismaying to see this type of media coverage of good science.

  • Omega Centauri

    “carbon dioxide in the atmosphere spiked by 5 degrees Celsius”
    This is wrong. CO2 is not measured in temperature, although it effects temperature. It should have been something like CO2 (maybe helped by methane) spiked enough to raise the temperature by 5C. Too much of a mouthful for a sound bite, unfortunately.

    Also of note, we know enough about stellar evolution to say the sun was roughly .5% dimmer during the PETM, so the planet at that time would have needed a more CO2 to reach the same temperature. Thats not the case anymore, we now need a low atmospheric CO2 concentration to keep from overheating, because the sun has gotten brighter.

  • Ivor O’Connor

    So in summary is it safe to say we our raising CO2 faster ever, the temperatures are warming faster than ever, and we will absolutely have higher temperatures than ever before on this planet?

    • vensonata

      It is safe to say it, dangerous to do it.

    • Frank

      I don’t think so. I think when the last protoplanet hit the earth, and created the moon, the earth was still really hot. Of course the earth wasn’t habitable then either.

    • Larmion

      – Raising CO2 faster than ever: yes, as far as we can go back in the geological record at least.
      – Temperatures are warming faster than ever: yes, as far as we can go back in the geological record at least.
      – Temperatures will become higher than ever before on this planet? No.

      Earth is still relatively cool at the moment, and will be far from peak temperatures even after the worst case climate changes predictions come to pass.

      It is not the magnitude of global warming that is unprecedented, it’s the pace at which it happens. And that makes adaptation difficult for species that adapt slowly, a category that includes most higher animals and quite a few plants.

      • onesecond

        Well, actually the worst climate prediction I have read is actually all water evaporating in 300 years. Granted, the paper said it is only a rough earth model and we would have to raise the CO2 level to 1500 ppm, but then the increasing amount of water vapor that acts as a climate gas as well would start a vicious cycle with an ever increasing rate of heating which would lead to no fluid water on earth in 200 years. So basically we could end all life on earth in 300 years. Good news is that we would have to burn all fossil fuels. Bad news is, that at 2 degrees of Celsius higher temperatures, the methane hydrates could become unstable, and whith methane being a 20 times more potent climate gas, that alone could push us over the edge. On the other hand, that obviously didn’t happen before, so there could be a stabilizing mechanisms. My guess would be algae that start to bloom and deposit huge amounts of carbon (that we so happily burn again today). On the other other hand, as the rate of temperature increase will probably be much, much faster today, maybe algae can’t do their trick this time because of the lack of time and we in fact will end all life in 300 years. I guess only time will tell.

        • neroden

          That’s the Venus scenario. And yes, it probably doesn’t happen.

          There seems to be some sort of massive ocean algae bloom which starts sucking CO2 out of the air before that happens. (Humans will all be dead dead dead dead dead if the algae bloom happens, since both the ocean and land food chains will have collapsed much earlier. So the extinction of humans will help with the problem: once humans go extinct, no more fossil fuel burning!)

    • onesecond

      Well, yes, higher temperature since life started seem to be a possibilty. Please read my other post on that in this thread.

    • Nolan Thiessen

      https://upload.wikimedia.org/wikipedia/commons/f/f5/All_palaeotemps.png

      Not nearly the warmest ever seen on Earth, but certainly the warmest ever seen by any species of homo.

      • neroden

        Most worrisome is that the situation we’re seeing now — the temperature spike and CO2 spike and methane spike — is most similar to the geological record of the P-Tr extinction. Which was the BIG one.

  • Nolan Thiessen

    I have always used the PETM as my ‘real world’ analogy when people say “the Earth has gone through these cycle before”.
    The fastest warming period we know of took 20,000 years to raise 5C. Our current worst case (keep increasing fossil fuel use at current rates) has us reaching the 5C mark in 100 years.

    • Lon

      When I hear the argument, “the planet warming and cooling has happened naturally in the past, so this is just natural fluctuation” I try to explain:
      1) We only know this because scientists have told us so
      2) These same scientists now tell us the current changes are not natural
      3) So this would be the same as you noticing that darkness now consumes 23 hours of each 24 hour period and when you point out that it is not natural, someone argues, “yes, but day light hours have always varied depending on the time of year.”

    • Lon

      When I hear the argument, “the planet warming and cooling has happened naturally in the past, so this is just natural fluctuation” I try to explain:
      1) We only know this because scientists have told us so
      2) These same scientists now tell us the current changes are not natural
      3) So this would be the same as you noticing that darkness now consumes 23 hours of each 24 hour period and when you point out that it is not natural, someone argues, “yes, but day light hours have always varied depending on the time of year.”

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