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Hot off the projector #3: Atmospheric CO2 to 800 kyr ago

Filed under: — david @ 12 December 2007

Just a few minutes ago Chappellaz et al presented the deepest dregs of greenhouse gas concentration data from the EPICA ice core in Antarctica, extending the data back to 800,000 years ago. In Al Gore’s movie you saw what was at that time the longest record of atmospheric greenhouse gas concentrations, back to 650 kyr, and their astonishing correlation with Antarctic temperature. This iconic superstar record has probably consumed as many eyeball-hours as any in climate science, alongside other classics such as the Jones et al. global temperature trends, the Moana Loa recent CO2 record, and the hockey stick. The Antarctic CO2 record has spawned countless internet rants about the CO2 lag behind temperature, and the circle of cause and effect between CO2 and climate. And the new data say …

The first point to write home about is that the correlation between Antarctic temperatures and CO2 continues unabated. One could imagine a world in which CO2 had no impact on climate, although if you buy that Dick Lindzen has a bridge he wants to sell you. In such a world, it could be that the correlation between CO2 and temperature since 650 kyr was just a coincidence, Mother Nature playing a cruel joke, and maybe in that case a little more data would cause the spurious correlation to start to unravel. That didn’t happen. CO2 continues to be high in warm times and low in cold times. There were no gasps of astonishment from the audience at the continued striking correlation. Ho-hum, of course it still works.

That being said, there are some interesting subtleties in the latest data. The CO2 concentrations were generally lower than average between 800 and 650 kyr. The lowest CO2 value ever measured in an ice core is now 172 ppm, from 667 kyr ago. If you average over the glacials and interglacials, there appears to be a very long-term cycle in atmospheric CO2, low from 600-800, peaking around 400 kyr ago in stage 11, the 50 kyr-long “super interglacial” when the Earth’s orbit was nearly circular as it is now, and then subsiding a bit since then. Perhaps this variability is driven by variations in rock weathering, the longest-term geological carbon cycle. Interestingly, there is no corresponding million-year cycle in Antarctic temperatures, when they are averaged in a similar way. CO2 is a dominant controller of global climate, but it is not the only game in town.

There were also millennial timescale wiggles in atmospheric CO2 and methane concentration during the descent from the stage 19 interglacial to the stage 18 glacial time. There are strikingly similar to the Dansgaard-Oeschger wiggles from 30-70 kyr ago in isotope stage 3. The duration is similar, about a thousand years, and the trajectories of the events are the same, with sharp warming and associated rise in greenhouse gases, then slower recovery. As in stage 3, they occur through the slow cooling transition between extreme climates, not in the full-blown glacial or interglacial states. These abrupt climate changes appear to be business-as-usual for the global climate system.

What would be really cool is if there were enough ice to continue probing back into the deeper past. Around 800 kyr ago, the climate cycles on Earth switched from being dominated by 40 kyr cycles, to the stronger 100 kyr cycles of the more recent times. The time period from 800 – 1000 kyr ago is called the mid-Pleistocene transition, and since the rhythms of the Earth’s orbit didn’t change, it must have something to do with the way that climate on Earth operates, maybe something about the carbon cycle. What would be really cool is if we could get CO2 and methane records back to say 2 million years ago, through this crucial transition time. Alas, 800 kyr is as far back as the useful ice in this location goes. The bottom tens of meters of the ice, like the bottoms of all ice cores, are too scrambled to interpret.


123 Responses to “Hot off the projector #3: Atmospheric CO2 to 800 kyr ago”

  1. 51

    Regarding iron fertilization of the oceans, etc…

    At this point I am certainly at least willing to investigate the possibility of using iron to increase algae growth for the purpose of reducing atmospheric CO2. But there are also some fairly significant worries with regard to this. Algae produces toxins which could make its way into aquifers (something we are already worried about), and when large algae blooms die, we see them absorb a great deal of oxygen from the surrounding water, creating dead zones that last for months.

    We are already inadvertently encouraging their growth as the result of fertilizer runoff from agriculture, and coastal dead zones are expected to grow simply as the result of global warming. Land warms more rapidly than ocean, and this is changing the ocean currents as the result of changes to atmospheric circulation. This latter process is what is responsible for the growing dead zone off the coast of Oregon which has been expanding into Washington State waters recently. Then there is the issue of what dead zones encourage to grow below the oxycline.

    I would also consider the flotilla of reflective satellites or injecting aerosols into the stratosphere where they will be more long-lived since they won’t be flushed by the next rain — but each of these carries with it their own problems. The sort of global dimming which would be involved I believe results in increased drought — and due to the fact that it is dimming, it will tend to reduce agricultural production. And to counterbalance increasing levels of greenhouse gases, it must increase over time.

    Then there is the possibility of sequestering carbon by means of the production of agrichar/biochar. This is something that I am quite interested in as this will tend to increase agricultural production. However, I have heard that this also results in the production of carcinogens. Not sure how serious this is, though. Something I will want to investigate as time permits.

    Anyway, at this point, I am willing to consider anything — as long as we are willing to consider the potential implications of any “solution,” stop-gap or otherwise.

  2. 52
    David B. Benson says:

    Not sure under which topic to add this link, the story entitled Ocean’s Growing Acidity Alarms Scientists

    http://www.commondreams.org/archive/2007/12/16/5852/

    which concludes with
    Though cuts in carbon dioxide and other greenhouse-gas emissions might slow or reverse global warming, scientist say it could take thousands of years or longer to reverse the increased acidity of the oceans.

    “For all practical purposes this is permanent,” Emerson said. “That’s not true of temperature. But with ocean acidification the time scales are long.”

    to ask to what extent this is accurate. Are they referring to the deep ocean, with millenial time scales?

    [Response: Actually, the lifetime of anthropogenic CO2 in the atmosphere is indeed measured in millennia, as is the warming to be generated by it. See my very first realclimate post on this topic. The acidification of the ocean also will last for millennia. David]

  3. 53
    William Astley says:

    In reply to Ray Ladbury’s #45.

    “William, not sure what your point is. The ice and temperature peaks are sharper than the CO2 peaks. Look at the abscissa on that graph–each of those points is at least decades. Yes, understanding CO2 uptake during cold periods is interesting, but not really relevent to the current epoch.”

    Ray, to me those graphs indicate something (not the amount of CO2 in the atmosphere) is causing the rapid temperature changes. As CO2 levels in the atmosphere follows planetary temperature, it is not clear to me how to determine what portion of the total planetary temperature change is due to the change in CO2 level as compared to other forcing functions.

    This is my problem. CO2 has been less than 500 ppm for the last 24 MM years. See “Atmospheric carbon dioxide over the past 60 million years by Pearson and Palmer. “

    http://www.nature.com/nature/journal/v406/n6797/abs/406695a0.html

    Yet as per figure 1 in the next paper, the planetary has only started to cycle 3 million years ago. What is causing the changing pattern in figure 1 in this paper? The climatic cycles seem to becoming greater, the cold glacial periods more sever and longer.

  4. 54
    William Astley says:

    CobbyWorld #50

    Re: Hanson’s “Paper Climate Change and Trace Gases:”

    CobbyWorld: I do not understand Hanson’s logic. When the planet is warmer there appears to be a strong and consistent negative feedback mechanism (clouds) that resist a change in planetary temperature (warmer or colder).

    http://pubs.giss.nasa.gov/abstracts/2007/Hansen_etal_2.html

    In a control system, a strong positive feedback makes the system unstable.

    When the planet cools to the point that ice sheets form and the ocean freezes the high albedo of the ice sheets and the ice on the ocean causes the planet to cool further (positive feedback). The feedback mechanism is only positive when the planet has cooled to the point that ice sheets form. Look at figure 1 (in the below linked paper) which shows inferred planetary temperature over the last 3 million years.

    To me the graph, figure 1, indicates that the climate was stable when the planet has warmer and became unstable when the planet cooled to the point that ice sheets formed in the Northern Hemisphere. The climatic cycle seems to becoming more extreme.

    http://www.maureenraymo.com/2003_Raymo+Nisancioglu.pdf

    What am I missing?

  5. 55
    Hank Roberts says:

    Mr. Astley, you write:

    > there appears to be a strong and consistent negative
    > feedback mechanism (clouds) that resist a change

    You appear to be citing Hansen’s paper for this. But Hansen doesn’t say that anywhere in that paper.

    And the word “cloud” doesn’t appear in the Raymo paper anywhere at all. So again where do you get this?

    Near as I can tell the IPCC is still right that the effect of clouds is still very indefinite, some reflect, some absorb depending on height and density.
    Recent work here:
    http://www.ingentaconnect.com/content/mksg/teb/2007/00000059/00000004/art00008

    What’s your source for that statement?

    Hansen writes:

    “The unusual stability of the Earth’s climate during the Holocene is probably due to the fact that the Earth has been warm enough to keep ice sheets off North America and Asia, but not warm enough to cause disintegration of the Greenland or Antarctic ice sheets
    …. indications of accelerating change on West Antarctica and Greenland (see below) indicate that the period of stability is over.”

    Hansen’s talking about albedo — ice and water, not clouds.

  6. 56
    Phil. Felton says:

    re #53

    “Yet as per figure 1 in the next paper, the planetary has only started to cycle 3 million years ago. What is causing the changing pattern in figure 1 in this paper? The climatic cycles seem to becoming greater, the cold glacial periods more sever and longer.”

    Are you sure you posted the correct paper, this doesn’t seem to refer to the fig I’m looking at?
    Regarding the changing pattern 3million years ago, that’s about when the atlantic and pacific were separated by the isthmus of panama which would have led to major changes in ocean circulation.

    “Editors’ Choice: Highlights of the recent literature
    The formation of the Isthmus of Panama about 3 million years ago (Ma), a fairly small event in terms of plate tectonics, had dramatic effects on evolution, ocean circulation, and Earth’s climate. Previously isolated North and South American land faunas mixed, and the separation of Atlantic and Pacific waters imposed changes in ocean circulation. One hypothesis is that these changes in ocean circulation triggered the ice ages; the onset of severe Northern Hemisphere glaciation was about 2.5 Ma. Long-term changes in ocean circulation can be monitored using neodynium (Nd) and lead (Pb) isotopes, which reflect the regional geology of exposed continental rocks bordering ocean basins. Thus, different waters will have different isotopic compositions, so their mixing and circulation can be resolved.
    Frank et al. and Reynolds et al. analyzed Nd and Pb isotopes from several ferromanganese crusts in the Atlantic and Pacific oceans and showed that the amount of water being exchanged through the Panama gateway waned noticeably before about 5 Ma, as the Isthmus began to form. This implies that the major effects on ocean circulation occurred considerably before glaciation increased. These records, along with new records of Nd isotopes from foraminifera preserved in sediments from near the Labrador Sea, reported by Vance and Burton, also show that formation of the ice sheets in North America and Eurasia increased erosion dramatically during the past 2 million years. — BH

    Geology 27, 1147 (1999); Earth Planet. Sci. Lett. 173, 381 (1999); Earth Planet. Sci. Lett. 173, 365 (1999).”

  7. 57
    David B. Benson says:

    William Astley (54) — I am but an amateur here, but I’ll opine that you are only missing what paleoclimatologists are: a sufficiently complete understanding of the drivers and responses of climate change.

    However, I believe you misrepresent figure 1 of the Ramo & Nisancioglu paper. As I read it, the figure indicates the presence of varying amounts of ice volume for the entire past 3 million years. Indeed, it suggests that the warmest interglacials have only occured in the past 475,000 years, other than perhaps at the beginning of the interval being studied.

  8. 58
    William Astley says:

    In reply to Phil. Felton #56

    The O18/O16 ratio (see figure 1, Raymo’s paper) in the paper linked to in my comment #54 is directly proportional to ice sheet temperature. Attached is a link to a Wikipedia article that has converted the O18/O16 ratio to inferred temperature on the ice sheet.

    http://en.wikipedia.org/wiki/Image:Vostok-ice-core-petit.png

    Each of those dips in temperature corresponds to a glacial cycle. That last glacial cycle is called the Wisconsin, as the North American ice sheet came down into the state of Wisconsin.

    This is map (also from Wikipedia) that shows the extent of the ice sheet, during the last glacial maximum. Note the vegetation difference in North America. Canada, no vegetation, as Canada is covered by an ice sheet. Central US the vegetation is tundra.

    http://en.wikipedia.org/wiki/Image:Last_glacial_vegetation_map.png

    In reply to Hank Robert #55

    Quote from Hanson’s paper: “The unusual stability of the Earth’s climate during the Holocene is probably due to the fact that the Earth has been warm enough to keep ice sheets off North America and Asia, but not warm enough to cause disintegration of the Greenland or Antarctic ice sheets …. indications of accelerating change on West Antarctica and Greenland (see below) indicate that the period of stability is over.” …

    ”Hanks comment, concerning what Hanson’s paper: Hansen’s talking about albedo — ice and water, not clouds.”

    Hank, the Holocene climate is stable because it is warm and Hanson does not talk about clouds. Yes I agree with that statement. I do not however agree that the Holocene climate will continue to remain stable.

    I believe some researchers have hypothesized that the trigger which brings on the glacial phase is an increase in planetary cloud cover due to a solar cycle change, which causes a drop in planetary temperature which causes snow to fall in regions that have high winter precipitation that now have rain in the winter months.

    Do you understand what my concern is?

  9. 59
    Hank Roberts says:

    > I believe some researchers have hypothesized

    I understand you believe that, but I don’t know whose work you’re talking about. Can you quote from the research, or cite to the research?

    If not, where do you get your belief that some researchers have hypothesized this? I’d like to look at where you find this stated.

  10. 60
    David B. Benson says:

    William Astley (58) — If your concern is a stade (massive ice sheets) occuring anytime ‘soon’, then there is a definite reply: Not for about 20,000 years. Orbital forcing of stade waxing and waning is firmly supported by the paleorecord; the physics of the entire process is moderately well understood. In particular, orbital forcings can be precisely calculated for millions of years into both the past and future. The earliest a stade could form is about 20,000 years from now, with a considerably better chance at about 50,000 years from now.

  11. 61
    William Astley says:

    In reply to David B. Benson’s #60.

    I do not understand your comment. I thought the paleoclimatic data shows interglacial periods ending fairly abruptly, saw tooth step down, rather than a smooth gradual reduction in temperature. (see figure 1 Raymo’s paper, comment #61.)

    Also, I believe solar insolation is currently the same as it was during the last glacial maximum.

    The earth is currently farthest from the sun in June and closest to the sun in December. Due to orbital eccentricity the summers are colder and winters are warmer, because of orbital eccentricity. This is opposite to the condition at the termination of the last glacial cycle.

    Orbital precission (the axis of the earth moves in a circle like a top, with a period of about 20kyr.) changes the timing of the year where the earth is at apogee and perigee of its orbit around the sun. 20,000 years ago when the ice sheets melted the earth was closest to the sun in June and farthest in December. 20kry years ago, the summers where warmer and winters colder, than they are currently.

    The earth’s tilt is now 23.5 degree, as opposed to its maximum tilt of 24.5 degrees.(Minimum is 22 degrees. I believe the orbital tilt was around 24 degrees when the ice sheets melted. The obliquity cycle is 41kyr.).

    I believe colder summers and warmer winters in the critical latitude of 65N, is the condition for the start of a glacial period.

  12. 62

    William Astley, thinking a new ice age imminent, posts:

    [[I believe colder summers and warmer winters in the critical latitude of 65N, is the condition for the start of a glacial period.]]

    Why don’t you actually work out the matrix math which interprets the Milankovic cycles and see when the next ice age should start? Everybody who has gets 20-50,000 years from now.

  13. 63
    Hank Roberts says:

    Mr. Astley, you write:

    > I thought the paleoclimatic data shows interglacial periods
    > ending fairly abruptly, saw tooth step down

    You see a ‘saw tooth step’ down, but the ‘up’ side of the event looks like a vertical line, on that very compressed chart.

    Look at a more expanded picture — just the most recent 450kyears — of that same ice age time sequence: http://www.globalwarmingart.com/images/f/f8/Ice_Age_Temperature.png

    You can see that the ‘saw tooth step down’ is the slow cooling over many more tens of thousands of years than the much faster warming event, each time.

  14. 64
    William Astley says:

    In reply to Barton Paul Leveson #61 & Hank Roberts #63

    Hank & B.P.L. I do not understand your comments. Look at Raymo’s paper’s figure 1 at say zoom 400. Where are the long, stable interglacial periods in that record? What is causing that sharp pattern?

    http://www.agu.org/pubs/sample_articles/cr/2002PA000791/2002PA000791.pdf

    I believe most climatic researchers believe the saw tooth abrupt changes in the climatic record are real. For example, from this review paper:

    Sudden climate transitions during the Quaternary

    http://www.esd.ornl.gov/projects/qen/transit.html

    “Until a few decades ago it was generally thought that all large-scale global and regional climate changes occurred gradually over a timescale of many centuries or millennia, scarcely perceptible during a human lifetime. The tendency of climate to change relatively suddenly has been one of the most surprising outcomes of the study of earth history, specifically the last 150,000 years (e.g., Taylor et al., 1993). Some and possibly most large climate changes (involving, for example, a regional change in mean annual temperature of several degrees Celsius) occurred at most on a timescale of a few centuries, sometimes decades, and perhaps even just a few years.”
    “According to the marine records, the Eemian interglacial ended with a rapid cooling event about 110,000 years ago (e.g., Imbrie et al., 1984; Martinson et al., 1987), which also shows up in ice cores and pollen records from across Eurasia. From a relatively high resolution core in the North Atlantic. Adkins et al. (1997) suggested that the final cooling event took less than 400 years, and it might have been much more rapid.”
    I thought there was series of abrupt cooling events throughout the climatic record. (i.e. The Eemian cooling is not an isolated event.) For example, I believe the Younger Dryas

  15. 65
    Ray Ladbury says:

    William Astley, if figure 1 in Raymo’s paper is 4 inches long on your screen, then every mm is 3000 years. The “rapid” changes discussed by Adams et al. in your ORNL reference are taking place on a timescale ~10x that of the current warming epoch. Rapid paleoclimatic change epochs are important. They may not provide much guidance for the current epoch.

  16. 66
    David B. Benson says:

    William Astley (various posts) — The Eemian interglacial ended rather abruptly. The climactic optimum was 134,000 years ago and it was over by 131,000 years ago. (Do note that the ‘autumal’ phase lasted 3000 years! Abrupt, as I said.)

    The Holocene, on the other hand, is one of the long interglacials, lasting about 28,000 years from so-called Holocene Climatic Optimimum until the next possible stade.

    The interactions of the two main periods of the orbital forcing just happen to be that way just now. But if you look back aways in the paleorecord, you’ll see there was a previous long interglacial. (It might be Termination 4, I don’t recall with certainty.)

  17. 67
    David B. Benson says:

    William Astley (64) — The ORNL review paper you provided a link to appears to have be written in 1998. Since then, more has been learned.

    In my opinion, that paper over-emphasies the similarities of the Holocene to the Eem. For example, in the Petite et al. work on the Vostok ice core, there is a period of about 330 years during the ‘spring’ of the Eem, before the climatic optimum, when the temperature measured by the ice core proxy dropped about 2 degrees Celcius and then recovered. I, at least, know of nothing comperable in the Antarctic ice core records for the Holocene.

    Since that review paper, other data has been collected and interpreted. A recent example is the discovery that (almost surely) the Younger Dryas was caused by a comet striking North America (and also some of Europe and Siberia). Others question the extent to which Greenland ‘sudden warming’ applies to regions other than perhaps northern Europe.

    Still, thank you for the link. The paper was interesting even if now a bit dated.

    [Response: The ORNL paper is indeed dated, but I think you have a mistaken impression of the likelihood of the comet hypothesis being correct. The evidence is very shakey for an impact and the chain of inference linking an impact to climate change is even shakier. There's been some serious science done on this subject but still I'd give it no more than a 10% chance of being correct, and that's generous --raypierre]

  18. 68
    David B. Benson says:

    Raypierre (reponse to 67) — Thank you. My (amateur) reading of the evidence for a comet impact is that it is fairly good. Linking this to climate change is merely good agreements on the dates. I’ll refrain from writing about this connection until well established, if ever.

    And I certainly wish you, and the other contributors here on Real Science, best of the season! :-)

  19. 69
    William Astley says:

    In reply to David Benson’s #66

    “The Holocene, on the other hand, is one of the long interglacials, lasting about 28,000 years from so-called Holocene Climatic Optimimum until the next possible stade.”

    I could not find any papers that support an extended interglacial period. The analysis and data, I could find supports the statement that the duration of the interglacial period has in the past been around 12kyr.

    Does anyone have more information concerning the duration of interglacials? How long is the Holocene interglacial expected to last?

    This paper states that the length of the interglacial period is determined by what ever is causing the millennial variability in the climatic record. (Rapid increases and decreases, of planetary temperature.)

    “The Duration of Forest Stages in Southern Europe and Interglacial Climate Variability” by Tzedakis et al.

    http://www.sciencemag.org/cgi/content/abstract/sci;1102398v1

    “What emerges is that, although the broad timing of interglacials is consistent with orbital theory, their specific duration may be dictated by millennial variability. This complicates the prediction of the natural duration of interglacials, at least until the origin of this climate variability is understood.”

    Comment:
    1. Where the interglacial duration is asserted to be longer than 12kyr, the interglacial temperature appears to have not reached typical maximum. (Cycle amplitude is capped, as if the millennial forcing function straddled an orbital cycle.)
    2. The following is a link to Adam’s paper that discussions sudden temperature changes in the Quaternary.

    http://ethomas.web.wesleyan.edu/adamsetal99.pdf

    [Response: I wrote a paper about the onset of the next ice age, and the impact of fossil fuel CO2 on that prospect. You can find it here. We basically concluded that the solar insolation forcing in the NH summer is just grazing the trigger insolation that historically has been correlated with descent into glaciation, so it's too close to call for the natural world this time around. The next such cold snap in the orbital forcing is about 50,000 years from now. Fossil fuel CO2, because it hangs around in the atmosphere for so long, has to potential to keep the Earth from glaciating, we concluded, for hundreds of thousands of years. The last time the Earth's orbit was as circular as it becoming now was isotope stage 11, about 400 kyr ago. That was a long interglacial interval, 30 or 50 kyr I think. David]

  20. 70
    David B. Benson says:

    William Astley (69) — Here is a link wherein one can find that some of the interglacials were quite long:

    http://en.wikipedia.org/wiki/Timeline_of_glaciation

    but further study (on your part) of MIS 11 and 13 is probably warrented.

    The Archer & Ganopolski paper which David provided a link in his reply is very clear and I recommend it. It is from that paper that I estimated that the Holocene would last about 28,000 years, baring AGW.

    The Adams et al. paper appears to be another over-emphazising the similarity of the Eem and the Holocene, IMO. Nonetheless I’ll attempt to find time to read the two links you provided.

  21. 71
    David B. Benson says:

    Re: #67 #68 — Here is a link to the PNAS paper regarding a North American ET impact 12,900 years ago:

    http://www.pnas.org/cgi/content/abstract/0706977104v1

    pdf file of full paper:

    http://www.pnas.org/cgi/reprint/0706977104v1

  22. 72
    Al Tekhasski says:

    David, you said:
    “One could imagine a world in which CO2 had no impact on climate, although if you buy that Dick Lindzen has a bridge he wants to sell you. In such a world, it could be that the correlation between CO2 and temperature since 650 kyr was just a coincidence, Mother Nature playing a cruel joke, and maybe in that case a little more data would cause the spurious correlation to start to unravel. That didn’t happen. CO2 continues to be high in warm times and low in cold times.”

    It looks like one simple logical possibility continues to escape your attention: there is no need for T to depend on CO2 for the correlation to take place. It is sufficient that CO2(t) is a time-delayed function of temperature. Therefore, there is no need to invoke “Nature jokes” or “spurious coincidence” to deal with T->CO2 correlation.

    Regards,
    – Al Tekhasski

  23. 73
    Ray Ladbury says:

    Al Tekhasski,
    Well, except there are some paleoclimatic warming events where CO2 seems to actually coincide with the warming. And then there’s all that pesky physics that says increasing CO2 in the atmosphere of a body that radiates in the IR will increase temperature. And there’s all the evidence that CO2 now going into the atmosphere is from a fossil source. But, hypothetically, if you wanted to ignore all the evidence, sure.

  24. 74
    Al Tekhasski says:

    Well, there certainly should be SOME exceptions in an inherently chaotic signal. However, there are plenty of quasi-regular events such as deglaciations. After EACH deglaciation, and when global temperatures are already on decline for a good thousand years, the CO2 concentrations “seems” to continue rising according to ice proxies. Every time. This “seems” to defy the whole CO2-induced catastrophic warming theory. It does seem to me that this is the evidence that you wanted to ignore, sure.

    About that pesky physics… Any PhD in physical sciences seems to know that the whole physics is based on ability to make a distinction between a main effect, and secondary-order effects, which can be estimated and neglected. Obviously, one can find some physics and study an effect of moonlight on growth of telegraph poles. So what?

    Speaking about main effects, you probably know that the OLR curve matches absorbed radiation at the height of approximately 0.6 bar, according to Ray Pierrehumbert book. Interestingly, this is about half way up to tropopause. But wouldn’t you find it coincidental that this is exactly the height of an atmospheric layer that carries about 95% of water vapor?

    Merry X-mas,
    – Alexei

  25. 75
    Ray Ladbury says:

    Well, Al, this PhD in physical sciences learned that one has to consider all of the contributing factors that are significant in the problem. And yes, water vapor is one of them, but would you really expect a factor that varies on a timescale of days to produce >20 years of warming? And in most past warming epochs, CO2 wasn’t the initiator, but rather kicked in after some warming had occurred. This epoch is different from most in a lot of ways. Did you have some specific question or point you wanted to make, or are elliptic references all we can expect. Have a happy holiday, Ray

  26. 76
    Ron Taylor says:

    Uh, Al, where did you get “Any PhD in physical sciences seems to know that the whole physics [??] is based on ability to make a distinction between a main effect, and secondary-order effects, which can be estimated and neglected.” That seems really oversimplified.

    Do you understand coupled variables? Does it make sense to you that the climate system is such that an increase in temperature might lead to an increase in CO2, or an increase in CO2 might cause an increase in temperature? And, in fact whichever one is increased by an external driver, the other will follow, with positive feedbacks then playing out? You are one of several who keep positing mysteries that any first-year student of differential equations should undertand. The idea that between any two variable in a physical system, only one can be the cause and the oather the effect is plainly simplistic.

  27. 77

    Alexei posts:

    [[After EACH deglaciation, and when global temperatures are already on decline for a good thousand years, the CO2 concentrations “seems” to continue rising according to ice proxies. Every time. This “seems” to defy the whole CO2-induced catastrophic warming theory]]

    It does nothing of the kind. Yes, in a natural deglaciation, temperature rises before CO2 does, although the added CO2 then amplifies the warming. But that is not what’s happening now. For 200 years carbon dioxide has led temperature.

    In a natural deglaciation, the carbon dioxide comes from warming oceans. In the present global warming, carbon dioxide is coming from fossil fuels. We know by the isotope signal.

    Your argument is like saying, “People have died naturally for thousands of years, so this guy with his body on the guillotine and his head in the basket must have died naturally.”

  28. 78

    RE #72 & “there is no need for T to depend on CO2 for the correlation to take place. It is sufficient that CO2(t) is a time-delayed function of temperature.”

    I, for one, am very concerned that warming increases CO2, since we are in a state of warming now. But T increasing CO2 doesn’t prove in any way at all that C02 doesn’t increase T. And that is the real issue with which people living in the world should be concerned, that given the evidence(and physics)-based hypothesis that C02 increases T, can we prove at the 99% level that it does not increase T. If not, then we need to reduce GHG emissions like crazy, esp since we all agree T increases CO2. I.e., we need to avoid the false negative on this most dangerous situation.

    One problem with Western analytic, linear thinking is that we often fail to see all the interconnections, or the whole picture. It’s like my relative who could take the clock apart, but couldn’t put it back together again.

  29. 79
    David B. Benson says:

    Al Tekhasski (764) wrote: After EACH deglaciation, and when global temperatures are already on decline for a good thousand years, the CO2 concentrations “seems” to continue rising according to ice proxies. Every time.

    Not so. I copied the Petite et al. Vostock temperature and CO2 data from the NOAA Paleoclimate web site for the dates around the climatic optimum of the Eemial interglacial (termination 2). I sorted the two data sets together by date. This makes it completely plain that the maximum of the CO2 measurements is during the 150 years or so of maximum temperature.

  30. 80
    Al Tekhasski says:

    Ray asks: “would you really expect a factor that varies on a timescale of days to produce >20 years of warming?”

    It is a very confused question. First, water vapor persisted in the Earth atmosphere for billion of years. Second, no matter how fast it varies, it always persists here or there, and therefore maintains the GHE on average. Third, maybe the 20-year part of your question is exactly a hint that greenhouse gases are hardly the cause of any warming (if any at all)?

  31. 81
    Al Tekhasski says:

    David, we must be looking at different data. Look again:

    http://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/vostok/deutnat.txt
    http://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/vostok/co2nat.txt

    Dump all into Excel, make charts with proper scaling, and please inspect, say, the period of 250 to 200 kyBP. Keep in mind that the time resolution of CO2 is 1500 years on average in this data set, so it would be hard to nail peaks if they are less than a millennium apart. The counter-trends are all over the place.

  32. 82
  33. 83
    Ray Ladbury says:

    Alexei says: “Keep in mind that the time resolution of CO2 is 1500 years on average in this data set, so it would be hard to nail peaks if they are less than a millennium apart.”

    Yup, Alexei, that would be a good thing to keep in mind. Why don’t you do that? And again, without a consistent trend in H20 vapor, how does it produce a sustained 20 year rise? OTOH, CO2 persists for hundreds to thousands of years.

    So, Alexei, which is it? On the one hand you’re trying to blame the warming on water vapor. On the other hand you’re saying that it can’t be greenhouse gasses. You know, you’re not going to convince many people if you keep changing your story like that.

    How about you posit a cause for the sustained >20 year warming trend we’re experiencing, ‘kay? But keep in mind that it has to warm the poles more than the tropics. It has to warm things at night more than during the day. And so on. Sure sounds like a greenhouse mechanism to me?

  34. 84

    RE #80 & “water vapor persisted in the Earth atmosphere for billion of years”

    From what I understand WV molecules only stay in the atmosphere a few days, so there is a constant infusion of new water molecules (it’s a feedback of other forcings). It’s sort of like seeing that the rate suicide remains fairly constant year to year, but it’s obviously not the same people committing suicide each year.

    As for CO2 molecules — whether they be released into the atmosphere due to the warming melting permafrost and ocean hydrates, or people driving cars, etc. — they stay in the atmosphere a lot longer, a portion staying up even up to 100,000. See http://www.realclimate.org/index.php/archives/2005/03/how-long-will-global-warming-last

    So, though CO2 is certainly a feedback from the warming, it has the longevity in the atmosphere to be a forcing, whereas WV does not.

    I hope this helps.

  35. 85

    Speaking about forcings v feebacks & responses, I’m thinking there should be some calcuation of how many people we are killing via GW (deaths per xxx tons of GHG emissions), and I think we should include farmer suicides due to GW-enhanced drought as well, and other less direct deaths at the end of GW causal chains. It should also include all the deaths over the entire lifetime of the GHGs emitted today (not just over the next 100 years). We need some ballpark figures on this. It could be done in a multiple “scenario” fashion.

    Also, the GHGs emitted for products produced in, say, China, but consumed by someone in another country should be attributed to the consumer, not the manufacturer.

  36. 86
    James says:

    Re #85: [Also, the GHGs emitted for products produced in, say, China, but consumed by someone in another country should be attributed to the consumer, not the manufacturer.]

    Not entirely. They should be shared: the consumer has a choice whether or not to buy a product, while the manufacturer has choices about the manufacturing process and energy sources.

    It seems as though implementing a carbon tax would do a pretty good job of apportioning the blame fairly.

  37. 87

    RE #86, that sounds right, James. It would only be the products actually purchased by the person. Of course, it’s often a dilemma without good choices re the carbon footprint of the product. So the carbon tax would help, or…..it would be great if each product had a carbon footprint code (overseen by some trustworthy group or agency). That way we could choose the more expensive, but less carbon-intensive produce. Although Confucius say, “how can greater carbon emissions decrease product cost?”

  38. 88
    David B. Benson says:

    Al Tekhasski (81) — Same data. But I stated the Eemian interglacial. About 128400 ya in the Petit et al. time reckoning. When the CO2 samples are about 300 years apart.

    It only takes the one to disprove your mistaken claim.

  39. 89
    Dan says:

    The beauty of the carbon tax is that it internalizes the societal cost of carbon emissions in the price of every product, so there is no need for complex calculations regarding carbon footprints. See the Carbon Tax Center web site, http://www.carbontax.org, and note that we recommend a revenue-neutral carbon tax, gradually phased in, to provide time for energy consumers to adjust. At least initially, the societal cost of carbon will not be fully internalized in the price of energy products and in the cost of manufacturing and transporting most all products.

  40. 90
    Al Tekhasski says:

    David, as I mentioned, the CO2 time resolution is too coarse to compare peaks; the actual peak can be missed due to a lost sample. You’d better look at times from 127445 ybp down to 114082 ybp, where CO2 stayed straight flat while T was dropping like a rock, for a good 14000 years. Or if you prefer shorter time scale, look at the period between 126809 and 124571 – when the CO2 rose by 18ppm over 2200 years, while temperatures dropped by 2C.

    And again, like I said before, noise-contaminated (or chaotic) signals exhibit all sorts of behavior when taken over short periods of time, that’s why a mathematically correct technique called “cross-correlation” should be used. And it says that the two signals are shifted by 800 years, and CO2 is lagging. If you apply sufficient smoothing of each data set, you will clearly see counter-trends after each deglaciaion, precisely for those 800 years.

  41. 91
    Al Tekhasski says:

    Ray Ladbury says: “without a consistent trend in H20 vapor, how does it produce a sustained 20 year rise? OTOH, CO2 persists for hundreds to thousands of years.”

    You are drawing far-fetched conclusions from what I said. I didn’t say that water vapor causes (or “produces”) warming. What I tried to communicate is that water vapor, being in abundance, acts as a greenhouse gas and provides quick and effective balancing of incident solar flux (at the surface) and outgoing long-wave radiation (at the altitude of effective radiating level of atmosphere) by quickly developing corresponding moist lapse rate. The point I am trying to convey is that small addition to this dominating mechanism would not change much of a thing. It seems that you are completely fixated on the idea that 0.01% change in concentration of a minor greenhouse gas could be the only reason for climate variation. What happened to your PhD’s philosophy that “one has to consider all of the contributing factors that are significant in the problem”. Could it be possible that you misjudged significance of some other factors, fro example, those “poorly understood cloud formation” mechanisms?

    And why do you keep insisting on the nonsense that CO2 persists for “hundreds to thousands of years” while the half-life of CO2 seems to be close to 5-10 years, kinetically speaking? If you mean statistics of individual molecules, I am sure you could find one or two water molecules that have been in the atmosphere for a million years, if you trust the classical statistical mechanics.

    I am also not sure about poles or night selective warming. So far the surface (and satellite) data are indistinguishable from noise, so any conditional averages can produce any desirable results.

  42. 92
    Ray Ladbury says:

    Alexei, the effect you mention is included in the models. I suggest you familiarize yourself with the physics of absorption, relaxation, radiation, etc. by greenhouse gasses. I suggest you take a look at the “Saturated Gassy Argument” series on this site, and at Spencer Weart’s AIP History of Climate Change. Spencer in particular has a section on why CO2 persists in the atmosphere rather than completely dissolving in the oceans. Every indication is that so far the oceans have taken up only about half of the CO2 emitted by humans–or do you dispute that CO2 is rising as well?
    I would point out that the physics has been verified by both experts in climate science as well as independent panels and organizatins such as the National Academy of Sciences, AAAS, APS, AGU, ACS. Even the American Association of Petroleum Geologists has withdrawn its opposition.

  43. 93
    David B. Benson says:

    Al Tekhasski (90) said David, as I mentioned, the CO2 time resolution is too coarse to compare peaks; the actual peak can be missed due to a lost sample.

    There are no lost samples. For the Eem the coincidence of peaks is clear from just the Petit et al. data. When I have the time I’ll also check this occurs for the Eem in the work on the Vostock ice core of the other two groups also on the MOAA Paleoclimatology site.

    However, your use of cross-correlation is deficient. A highly readable recent paper by Hansen et al., Climate change and trace gasses, will enlighten you.

    However, my point remains that you claim that CO2 always lags temperature during deglaciations is false, due to the example of just the Eem. I am sure there are many, many other examples.

  44. 94
    Al Tekhasski says:

    David says: “my point remains that you claim that CO2 always lags temperature during deglaciations is false, due to the example of just the Eem.”

    I already told you twice, noisy data could have accidental spikes that coincide. It disproves nothing. Comparing raw noisy data using transparencies is a very deficient technique of 18-th century. Advanced technique in computerized 21-th century is cross-correlation.

    About the paper, it looks as a collection of unsubstantiated statements of faith. To start with introductory sentence:
    “Trace atmospheric gases have played a leading role in climate change throughout Earth’s history.” Cross-correlation of Co2 to T from ice cores with CO2 lag of 700 years clearly disproves this opening presumption.

    Or look at the opening in discussion:
    “Earth’s climate is remarkably sensitive to forcings, i.e. imposed changes of the planet’s energy balance.” For the last 100M years I am sure there were many “imposed changes”. Yet abundance of biological species, all having a pretty narrow range of conditions to exist, have successfully survived, procreated, and evolved into rather high forms, even if the CO2 concentrations have been many times higher than today. This clearly defies the scary “remarkable sensitivity” of climate to various “forcings”, and to trace GH gases in particular.

    [edit]

    [Response: The length of time it takes for the ocean carbon pool to respond to climate changes has no bearing on the radiative forcing of GHGs. And the 'remarkable sensitivity' comes directly from the fact that orbital forcings make tiny changes to the net heat balance of the planet (on an annual cycle), and yet drive huge changes in climate. I agree with Hansen here, that is pretty remarkable. If you want to criticise his papers, you need to raise your game. - gavin]

  45. 95
    David B. Benson says:

    Al Tekhasski (94) — Part 4 of the linked lectures will explain better than I why your approach is insufficient:

    http://ocw.mit.edu/OcwWeb/Earth–Atmospheric–and-Planetary-Sciences/12-301Fall-2006/LectureNotes/index.htm

    But in particular, analysis by cross-correlation assumes a particularly simple relationship between the two data sets. In your comment #90 you have already given examples which demonstrate that such a simple relationship does not exist.

    While an amateur student of climatology, I know enough by now not to be overly enthralled by such simplicities and misunderstandings such as Cross-correlation of Co2 to T from ice cores with CO2 lag of 700 years clearly disproves this opening presumption. In particular, in the Hansen et al. paper, leading role is to be read as most important.

    In Carl Wunsch’s lectures, Part 4 of the above link, we see

    Because of this tendency for similarity to be perceived, statisticians have developed objective techniques, such as coherence analysis — ­e.g. Priestley, 1982­ to measure the true similarity of records

    Try that with your lag.

  46. 96
    James says:

    Re #94: [For the last 100M years I am sure there were many “imposed changes”. Yet abundance of biological species, all having a pretty narrow range of conditions to exist, have successfully survived, procreated, and evolved into rather high forms, even if the CO2 concentrations have been many times higher than today.]

    Something you miss here is the timescale of the changes. Perhaps this is a perspective effect: long-ago times seem compressed, so that a thousand years, or a million, might get squeezed into a single pixel on a graph.

    Life can adapt to any reasonable change if it has time: time either to move to a more suitable environment, or to evolve to better suit the new conditions. We have many, many instances of such adaptations in the fossil record. The problem facing us is that the time available is too short for adaptation. We have examples of similar situations in the fossil record, too: they’re called extinction events.

  47. 97
    Al Tekhasski says:

    David, analysis “by cross-correlation” does not assume any particular relationship, it is just one of methods of data analysis. It is just a function of relative shift of two time series, and it gives you an information. The cross-correlation could be a sharp function of timeshift, or could be a broad (or more complex) function, which would suggests more complex relationship between the two functions, that’s it. There are many more ways to analyze relationship between two time series. You have to agree that peak matching is the least sophisticated method of analysis, and cross-correlation is the next level, and so on. Shift of the peak in cross-correlation function means that the “leading term” of CO2 time series is shifted relative to T time series. Where the additional noise comes from, nobody knows so far.
    In any case, this observed shift is sufficient to conclude that on 1000-years time scale the CO2 follows changes in temperature, and therefore cannot play “leading role” in climate changes. The rest is noise, and you are arguing about noise and second-order effects.

  48. 98
  49. 99
    Rod B says:

    I don’t understand the water vapor variances answers; nay, even the question. What does an infrared photon care if a H2O molecule has been there for a long time or just showed up after a different vapor molecule vanished into a liquid? How does the photon even know the history? It seems water vapor maintains a fairly consistent concentration — variable a little by location with minor ups and downs over a day’s/week’s/month’s period. Why is the fact that vapor molecules are replaced with other vapor molecules over a week or two such an AHA! moment for AGW?? What am I missing?

  50. 100
    Rod B says:

    Lynn (85) Slap! Slap! Lynn, get a grip.. [;>)


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