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CO2 Residence Times, Ocean Levels What Next?

  1. Sep 25, 2009 #1
    I have been reading through some of the older papers concerning CO2 levels in the 20th and century, CO2 residence times, and the carbon cycle. (The papers this linked to article and paper are referencing. Another source is the 2300 papers Ian Plimer references in his book Heaven and Earth.) What I found is interesting.

    CO2 Residence Time, Source of 20th Century CO2, Could CO2 levels start to drop? Why did the Ocean level increase in the 20th century? Could ocean levels drop?

    If the residence time for CO2 in the atmosphere is short, then the majority of the 20th century CO2 increase does not have to be anthropomorphic. Did anything changed in the 20th century that could have increase CO2 in the atmosphere? If that hypothesis were correct, then if the forcing function that increased CO2 in the 20th century diminished, CO2 levels could drop or at least stop rising. i.e. The CO2 levels in the atmosphere could be delinked from anthropomorphic emissions.


    Because of the argument going on about global warming people are caught up with arguing one side or the other, which makes it difficult to see or discuss the problem situation.

    There are multiple paradoxes associated with the paleo climatic data, the geological data, and the current observations that appear logically connected.

    One of the puzzles to explain is why in the past have CO2 levels increased and decreased. Another is why ocean levels have increased in decreased in the past.

    A basic analysis shows the Himalayan/Tibet plateau hypothesis does not explain the reduction in CO2 in the Cenozoic. There is obviously something that resupplies a form of carbon to the atmosphere. The question is what stabilizes the amount of CO2 in the atmosphere. A short residence time for CO2 allows the 80 times atmosphere CO2 in the oceans to buffer changes to help regulate the amount of CO2 in the atmosphere so it does not fall to dangerously low levels.

    Something else is regulating the amount of CO2 in the atmosphere. Something else is controlling amount of carbon that is released into the atmosphere. As noted in the Sloan Deep Carbon there is evidence immense inputs of C12 rich carbon into the planet.

    If you look at paleo data for the last 500 million years. The planet cools, ice sheets form and then after the ice sheets form the CO2 level drops.
  2. jcsd
  3. Sep 25, 2009 #2
    Saul you need to provide a credible reliable source for discussion.

    Blogs are not credible sources for this forum.
  4. Sep 25, 2009 #3
    This paper supports the blog. If do not have a scientific comment, please make no comment.

    What Caused the Glacial/interglacial atmospheric pCO2 cycles?

    http://www.cgd.ucar.edu/tss/staff/mahowald/papers/archer2000.pdf [Broken]

    Last edited by a moderator: May 4, 2017
  5. Sep 25, 2009 #4
    That paper does not support a short atmospheric residency for CO2.

    You are attempting to put forth a specious argument picked up on a denier blog.

    And that is against forum rules.
  6. Sep 25, 2009 #5
    Stop posting and either read the paper or stop commenting. The blog specifically reference papers that show a short resident time. A short residence time is not controversial.

    You are not thinking about the problem situation. The paper I quoted above shows there is no explanation for the drop in CO2 levels during the glacial phase.

    The additional CO2 that cold water can hold cannot possible explain the drop of CO2 during the glacial phase. Vast areas of the ocean are covered with ice so that water cannot exchange CO2. During the glacial phase the biosphere shrinks. Vast areas are covered with ice and hence cannot support life.

    When the planet is colder it is also drier. Deserts increase in size. Almost a 1/2 of the Amazon forest becomes grassland which is as we are aware of, not a good CO2 sink. CO2 should have increased not decreased during the glacial phase.
    Last edited: Sep 25, 2009
  7. Sep 25, 2009 #6
    If David Archers paper supports a short residency for CO2, then please point it out.

    As for short residency being non-controversial???


    BTW, the chart above is within the parameters of http://geosci.uchicago.edu/~archer/reprints/archer.2005.fate_co2.pdf" [Broken]

    Actually their conclusions are that none of the explanations fit the data well, not that there is no explanation. They never made any such claim that CO2 must have a short atmospheric residence. In fact, five years later David Archer published another paper that reached the exact opposite conclusion.
    Last edited by a moderator: May 4, 2017
  8. Sep 25, 2009 #7

    You do understand the problem situation. Archer and others are arguing for a resident time of a 1000 years, while the previous papers argued for a residence time of 5 to 7 years. That is an astonishing large change in residence time.

    It is controversial to argue for a 1000 year residence time because a 1000 year residence time cannot explain how the planet has responded to the high C14 created by atomic testing or to CO2 spikes produced by super volcanoes. (i.e. The glacial phase was not interrupted when there is a CO2 spike.)

    The CO2 spikes are smoothed in the past as the ocean CO2 sink is 80 times the size of the amount of CO2 in the atmosphere. 80 times atmosphere is a very large number. If the residence time is not a 1000 years, but rather 5 to 7 years it becomes very difficult for a spike in CO2 to change the 80 times atmosphere reservoir.

    The "blog" is written by the author of the published paper. Of course do not listen to the logical arguments that author presents. As I stated you appear to be not interested scientific discussion. You just appear to want to interrupt this thread.

    I am of course interested in the practical implications of the two hypotheses.

    If the residence time for CO2 is short say 5 to 7 years, then the CO2 rise in the atmosphere must be due to some other mechanism.

    Did anyone have a look at the Sloan Deep Carbon seminar information?
  9. Sep 25, 2009 #8


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    If you could find a peer reviewed science article that has determined a shorter residence time for CO2, then that would be a good starting point. Otherwise, we are left with what the IPCC has concluded is the state of the science regarding the subject; namely that the residence time for CO2 is long enough to be a concern.

    On the other hand, we know that CO2 levels have not been constant throughtout earth's history. Some of the mechanisms (besides volcanonism and weathering of rocks) that are thought to be a factor in the past (but not now) are methane calthrates and anoxic conditions in the artic ocean.

    Methane calthrates are thought to have caused the significant rise in CO2 that led to the Eocene optimum. They are deep in the ocean and only come into play when ocean temperatures rise significantly. Right now, they are stable.

    An anoxic arctic ocean is thought to have caused the significant decrease in CO2 that led to the glaciation of antarctica. Ordinarily, the oceans does not sequester carbon efficiently since it is oxidized into CO2 so easily. However, if enough freshwater covered the arctic ocean, then it there could be an oxygen poor layer along the bottom that could allow carbon to be sequestered.

    I believe the 2 mechanims desribed above are not normally thought to be part of the carbon cycle, but have come into play in the past and could in the future as well.

  10. Sep 25, 2009 #9
    Ian Plimer has a number of papers referenced in his book. I will see what I can find.
  11. Sep 25, 2009 #10
    The atomic testing produced C14 supports a retention time of around 4 years. There is suggestion in IPCC literature of a retention time of 4 years to 200 years. There is a recent published paper that is suggesting retention time of 1000 years. These long retention times seem physically impossible based on the C14 retention time which is in accordance with basic physical principles of equilibrium of gas in a liquid. (CO2 is absorbed and released in the ocean. So the ocean equalizes the ratio of CO2 in the atmosphere and the ocean.)


    Atmospheric Residence Time of Man-Made CO2
    Potential Dependence of Global Warming on the Residence Time (RT) in the Atmosphere of Anthropogenically Sourced Carbon Dioxide

    Comment: There appear to be a new paper that is proposing a CO2 retention time of 1000 years.

    IPCC 2001 estimates the CO2 retention time in the atmosphere to be 5 year to 200 years.

    That is a very wide range, a factor of 40.

  12. Sep 25, 2009 #11


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    Here are some excerpts from the IPCC technical summary
    document concerning carbon residence.
    • Positive feedback
    • Significant uncertainty
    • More acidic oceans
    • 30,000+ years to equilibrium
    • 1000+ years committed climate change

    TS.5.4: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-ts.pdf

  13. Sep 25, 2009 #12


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    "Retention time" derived from atomic weapons testing is physically not the same thing.
    Weapons testing released relatively small amounts of radioactive carbon into the atmosphere. It takes only a few years for these radioactive components to diffuse thru the biosphere and reach equilibrium. The amount of carbon released is so small that it has negligible impact on the pH of the oceans or the climate. So, the only thing being measured by tracking radioactive carbon is the diffusion time.

    With climate change, we are concerned with the release of gigatons of CO2. Over the long term, these emission result in a warmer and more acidic ocean, which in turn is less able to absorb CO2. Likewise, warmer land temperature influence the carbon cycle due to biological changes of the soil.

    So, with respect to the impact of the climate, the concern is how long it takes to reach biological and chemical equilibrium with the emission. The IPCC is currently looking at 30,000+ years for CO2 to reach chemical equilibrium and 1000+ years of committed climate change. These values are large due primarily to the depth of the oceans.
  14. Sep 26, 2009 #13

    This is a list of the papers that discuss retention time.


    I think the discussion has moved from CO2 absorption times in the ocean which we agree is around 5 years to the ocean's ability to regulate CO2 in the atmosphere.

    Another approach to understanding the CO2 regulation problem situation is to examine all of the unexplained CO2 regulation and CO2 levels in the atmosphere problems together.

    Look for a solution that solves all puzzles. Akin to suggesting tectonic plates move to provide a solution to the set of geological surface puzzles.

    Puzzle 1
    During the glacial phase detailed carbon balance calculations show that CO2 levels in the atmosphere should stay the same or slightly rise, rather than falling from 280 ppm to 180 ppm. Higher solubility of CO2 in colder water is off-set by less water surface area and the contraction of the biosphere and biosphere's effectiveness to absorb CO2 during the glacial phase. The biosphere contracts as the planet is drier which converts vast areas of tropical forests to savana.

    Puzzle 2
    Missing CO2 sink in current times.

    Puzzle 3
    Evidence that in 19th and early 20th century that CO2 levels have fluctuated, with peaks as high as 400 ppm.

    Puzzle 4
    Explanation for rising and falling CO2 levels on geological time periods.

    The four puzzles could be explained by a mechanism that modulates a carbon source to the planet's atmosphere. The upper ocean is currently saturated with CH4 which would indicate there is an input of CH4 into the ocean.

    There is evidence that the biosphere constantly removes carbon from the atmosphere so there needs to be a steady input of carbon into the biosphere. One possible source (See Sloan Deep Carbon) is deep core carbon that is resident in the liquid core. As the liquid core solidifies the CH4 comes out of the liquid and moves up through the mantel.

    So what is required is a mechanism that has increased the amount of CH4 that is released during the later half of the 20th century and that is cyclically suppressed during the glacial phase and then returns to the current normal during the interglacial phase.

    The point is now one is looking for a changing CH4 input. To explain all observations.

    Now assuming that the CO2 level increase in the 20th century was partly due to the increase in CH4 in the 20th century it then becomes possible for CO2 levels to fall if whatever has forcing the CH4 abates.

    If that were the mechanism one should look at this time for a reduction in the rise of CO2 in the atmosphere. If there was a significant reduction in the rate of rise of CO2 or even falling CO2 levels that observation support a mechanism that has a modulated CH4 source.
    Last edited: Sep 26, 2009
  15. Sep 27, 2009 #14


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    Your link was to some type of denialist blog; not a reputable source.

    Anyhow, concerning puzzle 1: I don't understand what the puzzle is. Please detail the calculations that you are referring to. If it's from a denialist; then consider that it's probably just a mis-representation of the science.

    Puzzle 2: The Oceans are our current CO2 sink; why would anybody consider them missing? True, they are being over whelmed, but eventually thru increased precipitation and weathering, CO2 levels will stabilize. It's just going to take a 1000 years or so.

    Puzzle 3: Really? Please show us.

    Puzzle 4: Clearly there is more than 1 mechanism at work; and sorting them all out is a puzzling challenge. Besides the interplay between ocean temperatures and CO2 solubility, global precipitation and weathering, we have to consider Methane Clathrates,plate tectonics, volcanoes and implications of anoxic ocean conditions.
  16. Sep 27, 2009 #15


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    What is the molecular form of that C14 from atomic tests? Straight carbon particles (i.e. charcoal) or CO2? It needs to be CO2 to compare.
  17. Sep 28, 2009 #16
    Puzzle 1
    During the glacial phase detailed carbon balance calculations show that CO2 levels in the atmosphere should stay the same or slightly rise, rather than falling from 280 ppm to 180 ppm. Higher solubility of CO2 in colder water is off-set by less water surface area and the contraction of the biosphere and biosphere's effectiveness to absorb CO2 during the glacial phase. The biosphere contracts as the planet is drier which converts vast areas of tropical forests to savana.

    The estimate of -8.5 ppm during the glacial phase is at the limit of the mechanisms. As noted in the paper an estimate of no change is also within the range of the carbon cycle mechanisms.

    The hypothesis that the ocean pump is more efficient at removing CO2 begs the question how the ocean pump kept the CO2 levels low for 100 kyrs.

    What is the time delay before CO2 rises after the planet warms?


    Glacial/interglacial variations in atmospheric carbon dioxide

  18. Sep 28, 2009 #17
    This is an interesting graph.

    Try to explain the shape of the graph assuming temperature is driving CO2 or CO2 is driving temperature.

    Remember in the interglacial phase ice melting leads the CO2 rise by up to 1000 years.

    http://www.jennifermarohasy.com/blog/archives/Siegenthaler,%20Nov%2005.html [Broken]

    http://www.realclimate.org/epica.jpg [Broken]
    Last edited by a moderator: May 4, 2017
  19. Sep 29, 2009 #18


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    The point is that the situation now is maybe different, and the mechanism doesn't need to be the same. Even if in the past, it was temperature that was driving CO2, say, that doesn't mean that if you *add by hand* CO2, this is not having any influence.

    Even if in the past, due to an other initial drive (say, solar), there was a temperature increase, and that was then the cause of a CO2 rise, this doesn't say anything about what happens when you influence directly the CO2 level.

    In other words, the "input function" is different. Now we have good indications that the input function is human CO2 exhaust. If you look at a different input function into a complex system, the response is going to be different too.

    This is why correlations, without a causal understanding, don't learn us much by themselves.

    I might be wrong, but I think that there's something unique to the current situation, which is massive CO2 exhaust mostly independent of any other climate drive. I don't think that such a thing happened in the past in a similar situation. So there are no past data which describe exactly what we are living now. The only thing we can do is to try to *model* it and calculate.

    We can use past data in order to *check* the general validity of the models. But we cannot predict what will happen now just based upon past data, because those past data don't contain anything similar to the current situation.
  20. Sep 29, 2009 #19
    But those graphs are not depicting global temperature and concentration of CO2 in the atmosphere of the last several 100,000 years.

    What they do show is isotope ratios and CO2 concetration of the ice in Antarctic ice cores and it is only an educated guess that these accurately represent climate of the past.

    However with stunning corellations like that, one should be deeply suspicous, especially when other things in the explanations don't add up.
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