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Comments 51 to 56 out of 56:

51. scaddenp at 05:57 AM on 6 November, 2011
    Actually I can. Try Severinghaus & Battle 2006. You can find other interesting papers (eg look for MA Headly) by looking for papers that cite it in google scholar.
52. John Marshall at 22:31 PM on 25 February, 2012
    The problem with the graph showing the atmospheric CO2 content, with the rapid increase in the 20th century is that it is wrong. CO2 has never followed a level of 250ppmv over the past 10,000 years. That claim is a lie. In 1850's CO2 measurements showed atmospheric CO2 content to be 490ppmv, well above today's level and according to alarmists well over the 'tipping point' level.
53. Tom Curtis at 23:39 PM on 25 February, 2012
    John Marshall @52, if you run your car in a closed garage and measure the CO2 concentration in the garage, it will be well above 390 ppmv. It would be obviously foolish to conclude from that that global CO2 concentrations are greater than 390 ppmv. You have a nearby source of CO2 that is contaminating the measurement. As it happens, there are many sources of CO2 contamination. Not only are there cars, factories and people in abundance in cities, all busily emitting CO2 in abundance, and consequently contaminating any measurement. Not only that, but trees and grass are net CO2 sinks in daylight, but net emitters of CO2 at night. Consequently measurements in a forest on a still night will show elevated CO2 levels, again the result of contamination. In the 1850s, and indeed, even in the 1930s this was not well known, and many measurements of CO2 concentrations were made in areas where contamination would be expected. What is worse, Beck, who should have known better compiled a list of measurements without compensating for local contamination beyond the crudest measure, and simply took an average of measurements to determine the CO2 concentration. Given that CO2 concentrations can vary by 100 ppmv or more on a daily basis due to local contamination, the result significantly overestimates background CO2 levels. To determine genuine background levels of CO2, you need to get away from local sources of CO2 emission by getting either very far away from their source vertically, as with these measurements over Colorado: Note that near ground concentrations shown can be as high as much as 50 ppmv above the upper altitude levels even at 500 meters altitude (let alone the 2 meter altitude used by Beck), but with gain in altitude, CO2 concentrations drop to background levels. Alternatively you can rely on strong winds to dilute the contamination to determine the background by plotting CO2 levels against wind speed: Again, notice when wind velocities are low, local contamination (mostly from forests in this case) can result in CO2 concentrations as high as 600 ppmv, but that the background level is clearly around 390 ppmv. Or you can get as far away geographically from any contamination as you can, by going to the South Pole: Citing measurements that do not take these precautions to ensure they are measuring the genuine background concentrations, rather than a contaminated sample are, of course of no interest.
54. Bob Lacatena at 00:27 AM on 26 February, 2012
    52, John Marshall, Please note how easily and completely you fell for what is actually a well understood "lie". You read at a denial site about how CO₂ levels were way higher in the 1800s and there's a paper to prove it. Except it turns out that everyone who cares to actually be skeptical and look at the science knows that's nonsense. Scientists go to great lengths to properly, accurately measure CO₂, and they aren't stupid about it. At the same time, the paper cited by deniers to trumpet this issue was literally stupid about it. They know this. This information is readily available, and it's pretty obvious if you take just a little while to think about it. So why do denial sites keep feeding people this nonsense? The point is that you were tricked, and you came in here all full of anger because you thought the ones who tricked you were the scientists. But it wasn't, it was the deniers. [Fortunately, this site exists exactly because of those sorts of situations. Every time you have one of these "ah ha, got them" moments by reading something at a nonsense denier site, come here to SkS, use the search button, read and learn. After you've done it enough, you'll start to realize that there is no science or truth to the denial arguments. None.] So how do you feel now? Is your anger redirected at a more appropriate target? Or are you instead simply more firmly invested in finding something to justify your anger at "alarmists?" And if the latter is the case... doesn't that say something even more important about the "debate."
55. Bernard J. at 01:33 AM on 26 February, 2012
    John Marshall. Take the hint from Tom Curtis and Sphaerica - you are, to put it nicely, profoundly in error. If the conversation here is too technical for you, there was a more colloquial one on Deltoid, that should make you blush with embarrassment once you've read through it.
56. DSL at 06:09 AM on 11 April, 2012
    wsugaimd, how do you explain the Keeling Curve? The steady rise of atmospheric CO2 cannot be explained by a nearby volcano. Also, the Hawaiian measurements are corroborated by independent measurements. Read the article above.
57. Tom Curtis at 09:13 AM on 11 April, 2012
    danielc's comment of 6:14 AM, April 11th, 2012:

    "@wsugaimd: Go here: Movie showing CO2 levels measured over the last 50 years it includes information from ice cores, and there are MANY data points, not just at hawaii. Go here: impact of eruptions on global CO2 levels - essentially unmeasurable. and go here: satellite measurements of CO2 compared to Mauna Loa Being skeptical of measurements taken at one point, using one method is reasonable, but CO2 measurements have been made at many, many points using many, many methods...

    Jim Eager's comment of 6:21 AM, April 11th 2012:

    Wsugaimd @38, your skepticism seems highly selective, since Mauna Loa is not the only location where atmospheric CO2 is monitored. Similarly, ocean pH is monitored at many locations around the globe. If you are truly skeptical then you should be noting what those locations also show, not just those in Hawaii. As for comparing human CO2 emissions to total CO2 content of the atmosphere, your 1% figure suggests that you are no skeptic, but rather that you are using the trace gas argument distraction (see the "Argument" button in the top bar). Consider that every single natural source of CO2 is offset by a natural absorption of CO2. The ocean continuously exchanges CO2 with the atmosphere, making it both a source and a sink for CO2. However, it is currently a net sink, meaning it absorbs more CO2 than it emits, which is why ocean pH is decreasing. Similarly, the terrestrial biosphere both emits and absorbs CO2, and it, too is currently a net absorber, although that may well change. Even volcanic emissions of CO2 are offset by geologic sequestration of CO2 via silicate rock weathering and calcium carbonate shell deposition on the sea floor. However, there is no human absorption of CO2. Zero. There is only human emission of CO2. Every gram of CO2 we emit must either be absorbed by a natural sink or remain in the atmosphere. Fortunately the ocean, biosphere and lithosphere absorb 100% of natural emissions, *plus* roughly half of the carbon that humans emit, leaving only half of it to accumulate in the atmosphere. In other words, we humans have been responsible for 200% of the measured 38% increase in atmospheric CO2. A true skeptic should be able to tell the difference between a 1% annual emission rate and a 38% cumulative increase, don't you think?"

    danielc's comment of 6:33 AM, April 11th 2012:

    "@Jim Eager #42: The argument I like to use is this: Say you have 10,000 dollars in the bank (that's 1 million pennies). 300 of those pennies are red pennies, and they earn triple interest. Every day, I am going to add three red pennies to your bank account. For every time you earn triple interest, another free red penny is added to your bank account (positive feedback). Are you going to refuse? NO! Are the red pennies in your account, and the extra red pennies I add year on year (and the triple compound interest they receive going to add significant amounts of money to your account? YES! Esp. over significant amounts of time."

    Response: TC: The three quoted comments above are in response to wsugaimd's of topic comment here, and have been quoted here in lieu of simple deletion.
58. Tom Curtis at 09:47 AM on 11 April, 2012
    wusgaimd, would you care to inform us which volcano is contaminating the CO2 measurements at the South Pole (shown @53 above)? For comparison, here is the full Keeling Curve from Mauna Loa:
59. ajc at 05:38 AM on 5 December, 2013

    How can we be confident that the CO2 concentration measurements from the ice core samples, which may have been contaminated in some way, either historically through leakage or in the recent withdrawal process, gives a reading comprable to those from Mauna Loa? Has there been a good rebuttal to the work of Zbigniew Jaworowski in this area. I have not done exhaustive research in the area (really just debating amongst non-science friends), but one brought up this line of argument to discredit the top graph here on historical CO2 concentrations. In researching the issue of comparability and the reliability of the CO2 measurements, I found Jaworowski and few folks countering his arguments. I'm genuinely not trolling here, just interested in the topic.

60. DSL at 06:15 AM on 5 December, 2013

    ajc, which of ZJ's claims would you like a response to?  Tamino responded to the "too smooth" concern here.

61. scaddenp at 06:35 AM on 5 December, 2013

    It's hard to take ZJ seriously, but for detailed look at the ice core CO2 process and validation, see Etheridge 1996.

    and follow cites for more recent work. For a direct rebuttal, see here. The consilience of CO2 levels between ice cores from different location (eg Greenland, Antarctica) would be big hint that the method is fundamentally sound. Furthermore, the idea that AGW is based on icecore data is hopelessly wrong. ZJ would appear to be a classic case of a scientist "gone emeritus"

62. Rob Honeycutt at 09:22 AM on 5 December, 2013

    ajc...  Watch this small section of the Richard Alley lecture and he tells it like it is on this point.  Start at min 12:10.

63. Dikran Marsupial at 19:03 PM on 5 December, 2013

    A good way to check on claims that have been made in journal papers is to use Google Scholar to identify papers that have cited the paper and see if any of them are critical or provide evidence that answers the claims made.  I this case, I found

    T. GüllükF. SlemrB. Stauffer, "Simultaneous measurements of CO2, CH4, and N2O in air extracted by sublimation from Antarctica ice cores: Confirmation of the data obtained using other extraction techniques", Journal of Geophysical Research: Atmospheres (1984–2012)l Volume 103, Issue D13, pages 15971–15978, 20 July 1998

    A sublimation technique has been developed to extract air samples from polar ice cores for subsequent simultaneous measurement of several trace gases by frequency-modulated tunable diode laser absorption spectroscopy. This extraction and analysis technique is shown to be suitable as an extraction method for the determination of concentrations of the greenhouse gases CO2, CH4, and N2O in air samples of ∼1–5 cm3 recovered from ice samples of 10–50 g. Air samples from the Siple ice core have been analyzed covering the period between 1772 and 1973. In addition, a few samples from two different ice cores from Vostok station have been analyzed. Our results are in a good agreement with results obtained by other researchers using melting and crushing extraction techniques. This agreement indicates that processes connected with the formation of clathrates in ice under high pressure at greater depths and their destruction after drilling are not affecting the CO2, CH4, and N2O measurements significantly.

    [emphasis mine]
    

    Which appears to provide experimental evidence directly refuting one of Jaworowski's arguments (in addition to that provided by Etheridge).  Essentially the scientists that work on ice core data do know what they are doing and do their best to examine possible sources of bias or error and eliminate them, as these two papers demonstrate.

64. nick at 07:25 AM on 29 May, 2015

    humanity can take spot CO2 measurements but this assumes homogeneous concentrations, which are not always true. The Committee has often spoken and said, on gases, most of Earth's heat is internal, the reason similar temperatures are found a certain distance below the surface no matter where they are taken. Under Antarctica or along the equator will have similar temperatures at a certain depth (I think it’s fairly shallow, also) Sunlight and surface heat causes daily weather and seasons, of course, but this cycle is on top of the underlying base, natural heat. This is what controls climate, says The Committee.
    Greater CO2 and heat cause greater evaporation, more rainfall and both carbon dioxide and rainfall encourage plant growth which consumes the CO2 to produces oxygen. The equilibrium of oxygen and CO2 has been reached long ago and fluctuates along a very narrow band too small to have climate effect. This they say, is because of the principal atmospheric gas, nitrogen, which as we know, dominates.
    They say CO2 emissions caused by human activity are insufficient to alter the equilibrium; the plant response to increased rain and carbon dioxide is very efficient. The proportion remains well inside the narrow band that does not affect weather.
    Earth climate is affected by the magnetosphere and the planet's molten iron core, from which heat dissipates. Most of Earth's surface is ocean; heat reaches the seafloor, where we do not and cannot measure temperatures. This affects sea water temperatures and currents, much more sensitive to small changes. (liquids much denser than gases) These are the causes of the erratic weather patterns we have felt on Earth, attributed erroneously to manmade global warming.

    Response:

    Welcome to Sks. Please take the time to study the comments policy on this site. When you make a claim that is contrary to well known facts, then you should provide link to the sources of your information. Whatever your "committee" is, it's source of information is laughably and grossly wrong. Please dont waste people's time by commenting on an article you obviously havent bothered to read.

    For the point of this article, note the linked video showing the variation of CO2 both vertically and horizontally. Note also this image which demonstrably show no such assumption of uniformity is made. You might like to also note the OCO-2 satellite which continuously measures CO2 concentration.

    I suggest you take time to read some of the climate myth articles to become better informed before commenting further. And note that the extra heating from CO2 is around 100x greater than the total geothermal heat flux.

    Offtopic comment has been deleted but a commentator has helpfully provided you with more information. See here

65. bozzza at 09:01 AM on 29 May, 2015

    @25, heat is the last form of energy... it is not a physical object like CO2 therefore they obey completely different rules!

66. APT at 22:18 PM on 23 June, 2015

    Hello,

    Can somebody please explain why only ice core data is used for the pre-instrumental measurement period? I understand that stomatal index data has certain problems, but then so does ice core data. Fossilized stomata data is used for the more distant past, and some Holocene studies seem pretty robust and use multiple locations, e.g. Steinthorsdottir et al. (2013).
    Surely any issues with the stomatal data could be taken into account and it could be combined with ice core data to make a more accurate reconstruction of past CO2 levels. Is there simply not enough of it?
    Stomata studies showing high levels of CO2 in the relatively recent past are being used to suggest that current levels are not unusual in human history, even though this contradicts ice core data. I understand the obvious problems with the Beck (2007) work for example, but what about studies suggesting higher CO2 at the end of the Younger Dryas?

67. Daniel Bailey at 01:30 AM on 24 June, 2015

    "Can somebody please explain why only ice core data is used for the pre-instrumental measurement period"

    It's not.  Temperature measurements began in 1659. Stations were added throughout the centuries since then, becoming a truly global network beginning in 1880. Multiple proxy records extend that record literally millions of years into the past.

    http://www.ncdc.noaa.gov/paleo/globalwarming/instrumental.html
    http://www.ncdc.noaa.gov/oa/climate/research/1998/anomalies/anomalies.html
    http://www.ncdc.noaa.gov/ghcnm/v3.php
    http://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets
    http://www.realclimate.org/index.php/data-sources/
    http://en.wikipedia.org/wiki/Instrumental_temperature_record

    Multiproxy reconstructions are now commonplace.  For example, per the PAGES 2000 reconstruction, current global surface temperatures are hotter than at ANY time in the past 1,400 years, and that while the Medieval Warm Period and Little Ice Age are clearly visible events in their reconstruction, they were not globally synchronized events.

    http://www.skepticalscience.com/pages2k-confirms-hockey-stick.html

    From the peak temps and CO2 at the height of the Holocene Climatic Optimum some 7,000 years ago, temps and CO2 went into a long, slow decline, until about 100 years ago. Global temperatures dropped about 0.8 degrees C.

    Over the past 100 years we have entirely erased that 5,000+ years of natural cooling (Marcott et al 2013), with global temperatures rising a full degree C:
    http://www.realclimate.org/images//Marcott.png
    http://climatedesk.org/wp-content/uploads/2013/03/marcott-B-1000.jpg
    http://www.realclimate.org/index.php/archives/2013/09/paleoclimate-the-end-of-the-holocene/
    http://www.sciencemag.org/content/339/6124/1198

    Given that orbital forcing is still negative, and will continue to be negative for the next several thousand years, natural forcings are not responsible for this current warming period.

    Please place relevant comments and questions on the pertinent thread.

68. APT at 05:49 AM on 24 June, 2015

    @Daniel Bailey
    Sorry, perhaps I didn't phrase my question clearly enough. My question was specifically about reconstructions of CO2 levels, not temperature data.
    I'm aware of the multiple proxies used for temperature reconstruction, but I can't find reconstructions of CO2 levels over the last several thousand years that use anything other than ice core data, although reconstructions over millions of years use stomata and ocean sediment for the earliest periods.
    Given that stomata-based data indicate higher levels of CO2, how do we know ice core data for CO2 levels is more reliable? Once local variability and other factors are taken into account, aren't stomata indices useful proxies? Are there other proxies which could be used to back up ice core CO2 results?

69. scaddenp at 09:49 AM on 24 June, 2015

    APT - It is easier to have a discussion when you properly cite the papers you are referring to. I assume it is this.

    My understanding is that problems with stomata are much larger than with ice core and only used when ice core is unavailable. You might like to read the published comment on your reference before being so sure of the superiority of the stomata record.

    There are two further points of note:

    1/ the record of high CO2 at time of Younger Dryas is being presented to support that rapidly rising CO2 levels cause climate change.

    2/ The isotope signatures of CO2 at YD indicate different CO2 source to what is present today.

70. Daniel Bailey at 09:52 AM on 24 June, 2015

    "I understand that stomatal index data has certain problems, but then so does ice core data"

    Feel free to delineate what you feel those limitations might be and cite your sources.  The ice core data are among the best we have for the past 800,000 or so years for atmospheric gases.  You're going to have to do better than just an argument from incredulity.

    "some Holocene studies seem pretty robust"

    "seem" is hardly an objective assessment.

    "Surely any issues with the stomatal data could be taken into account"

    Surely.  But still an argument from incredulity.  This venue deals in evidence.  Since you seem bent on making an assertion about ice core CO2 data, the burden of proof is on you, the claimant, to mount an evidence-based claim and to support it with links to the primary literature.

    "Stomata studies showing high levels of CO2 in the relatively recent past are being used to suggest that current levels are not unusual in human history"

    Citation, please.

    "what about studies suggesting higher CO2 at the end of the Younger Dryas"

    Nebulous assertion; citation please.

    "I can't find reconstructions of CO2 levels over the last several thousand years that use anything other than ice core data, although reconstructions over millions of years use stomata and ocean sediment for the earliest periods"

    Off the top of my head, Ziegler et al 2013 does just that.  Further, it covers the period of the past 360,000 years.

    "how do we know ice core data for CO2 levels is more reliable"

    How do you know that ice core data is less reliable than stomata data?

    "aren't stomata indices useful proxies"

    Yep.  When used with proper contexts.  Which is how they are used.

    "Are there other proxies which could be used to back up ice core CO2 results"

    There are.  I gave you a link to them in my previous comment.  Here it is, again.

71. APT at 07:42 AM on 25 June, 2015

    @Scaddenp
    My apologies for not giving a full reference or link to the relevant paper. I will do so in future posts. The one you've linked to is indeed the one I was referring to, and I thank you for including the published comment on it, I had read the reply to that comment but not the comment itself, which looks like it contains the kind of information I was looking for.

    At no point did I say I was sure of the superiority of stomatal records. Far from it in fact. I simply requested information about them in order to be able to explain why ice core data was considered more reliable. I am also well aware that far from being an argument against AGW, that paper supports the consensus. I'm sorry to say that I find your response to my simple and polite request for information to be rather hostile in tone and not very encouraging for those seeking information.

72. APT at 07:58 AM on 25 June, 2015

    @Daniel Bailey
    Thank you for the link to the Zeigler et al. paper. That's interesting and useful.
    Since you had misunderstood my previous request, I had assumed that the link to the NOAA paleoclimate data related to temperatures rather than CO2 levels, but I see know that there are data relating to other factors affecting climate. It would be useful to know which ones relate specifically to CO2 levels but I'll search through and find them.
    The rest of your post is, unfortunately, unhelpful, since I wasn't putting forward an argument of any kind but simply seeking information to counter an argument put forward by someone else. As a response to a polite request for information it is, like saddenp's, rather hostile in tone.
    Even if I had been trying to cast doubt on climate science, which I wasn't, this type of response is uncalled for and hardly conducive to promoting understanding.

73. Rob Honeycutt at 08:23 AM on 25 June, 2015

    APT... "...how do we know ice core data for CO2 levels [are] more reliable?"

    Perhaps because ice core data are actually measuring CO2 concentrations. It's a direct measurement of CO2 (or as direct as you can get before Keeling). Whereas, somata are clearly only a proxy for CO2.

74. scaddenp at 08:53 AM on 25 June, 2015

    APT - sorry if tone appeared hostile. We get a lot of pseudo-skeptics here with faux arguments, so knee-jerk reactions are hard to avoid. You said "used to suggest that current levels are not unusual in human history,"  from which I thought you were implying the "skeptic" corrollary "so no need to worry" despite YD being in our pre-civilization past. Genuine inquiry is actually very welcome so apologies.

    What have read that casts doubt on ice-core measurements for CO2? A reference would be helpful.

75. APT at 11:41 AM on 25 June, 2015

    @Rob Honeycutt - Thanks. That's a good answer, my favourite so far.
    
    @scaddenp - As someone who's defended the science on public forums, I understand the frustration of dealing with pseudo-scientists and conspiracy theorists. In fact, that was the reason for my request. However, as friendly advice, I suggest you tone it down a bit, since such defensiveness is more likely to provoke suspicion than promote understanding.
    I was able to deal with the other references I was given, since some weren't even peer-reviewed science and I was able to find strong rebuttals of those that were. The only one that seemed to cast any real doubt on the reliability of ice core data was the Steinthorsdottir (2013) paper. Incidentally, there was a response to Kohler's comment on the paper, which you can read here: LINK

    Having briefly read through it all, I'd still conclude that the ice-core data is more reliable, but the issue of disagreement between ice-core data and these results doesn't seem to be fully resolved.

    Steinthosdottir references two papers regarding intra-ice diffusion, Ikeda et al (2000) and Ahm et al (2008). It seems to me that these might reflect problems of identifying short term variability rather than concentration in general, but I'm no expert on such things. Is this a real issue with ice core data? Is it accounted for?

    Response:

    [RH] Shortened link.

76. APT at 21:27 PM on 25 June, 2015

    Thanks again for your help. These are the relevant links to the papers referenced above.
    http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/32477/1/P393-421.pdf
    http://mail.geocraft.com/WVFossils/Reference_Docs/CO2_diffusion_in_polar_ice_2008.pdf
    It seems to me that these papers conclude that diffusion probably doesn't have a very significant effect on ice core CO2 measurements, at least over longer timescales, but I'd appreciate it if someone with deeper knowledge and understanding of the topic could confirm that.

    
    I also found a couple more relevant papers which I hope will be useful if anyone comes across arguments about ice core reliability or stomata records disgreeing with ice core data:
    The first is a discussion of uncertainties in ice core measurements and how to deal with them:
    ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/ice-cores.pdf
    The second is a reconstruction using stomata data which in fact agrees with the ice core data and suggests that climate sensitivity to CO2 concentration is greater than previously thought:
    http://droyer.web.wesleyan.edu/Franks_et_al_2014_GRL_new_stomatal-CO2_proxy.pdf

77. MA Rodger at 22:28 PM on 25 June, 2015

    APT @75/76.

    The two papers you link to are actually referenced by Steinthorsdottir et al., (2014) - 'Response to: Comment on “Synchronous records of pCO2 and D14C suggest rapid, ocean-derived pCO2 fluctuations at the onset of Younger Dryas”' 

78. APT at 23:20 PM on 25 June, 2015

    @MA Rodger

    Do you mean the first 2 papers or the last 2 papers in post 76?
    I mentioned in post 75 that the the first 2 were referenced by Steinthorsdottir, although I appreciate that without the full reference I didn't make it clear that it was from the "Response to: Comment..." paper and not from the original article.

    I can't see references to the second 2 papers in either of the Steinthorsdottir papers.

79. Tom Curtis at 01:11 AM on 26 June, 2015

    APT @78, Kohler et al reference Marcott et al 2014 as being a high resolution ice core CO2 concentration record.  Marcott et al in turn say:

    "The West Antarctic Ice Sheet Divide ice core (WDC) (79.467u S, 112.085u W, 1,766 m above sea level) was drilled to a depth of 3,405 m in 2011 and spans the past,68 kyr.At present, the site has amean annual snow accumulation of 22 cm ice equivalent per year and a surface temperature of 230 uC. Annual layer counting to 2,800 m depth (,30 kyr ago) provides a very accurate timescale for comparison with data from other archives11. The difference in age (Dage) between the ice and the gas trapped within it, which is critical for developing a gas-age chronology, is 205 6 10 yr at present and was 525 6 100 yr at the last glacial maximum (LGM) (Extended Data Fig. 1).Given the high accumulation at the site, minimal smoothing due to gas transport and gradual occlusion, and precise chronological constraints, WDC is the best Antarctic
    analogue to central Greenlandic deep ice cores, with a substantially better-dated gas chronology during the glacial period, and is able to resolve atmospheric CO2 at sub-centennial resolution."

    (My emphasis)

    What that means in practise is seen by considering Figure 3, where temporal resolution is indicated to be +/- 20 to 40 years at various time intervals:

    

     Even at +/- 40 years, that is too good a time resolution to not have captured Steinthorsdottir's peak in CO2 at the Younger Dryas if it in fact existed.  More importantly, the the +/- 1 ppm resolution of CO2 concentration at all ages shows the fluctuations in CO2 content to not be measurement error.  They are fluctuations in the CO2 concentration in the ice.  That is significant because the sharp variations in CO2 concentration shown are inconsistent with the record being more heavilly smoothed than shown.  Smoothing through diffusion will reduces peaks, fill troughs, and turn "cliffs" into slopes.  If the peaks, troughs and cliffs persist in the ice, the CO2 has not significantly diffused after the firn has closed.

    In fact, it is definitely below par for Steinthorsdottir to simply wave her hand at possible high diffusion rates as an "explanation" of discrepancy between ice core and stomatal records.  If diffusion is a problem, she ought to be able to (and ought to have) created a smoothed model of the stomatal record that reproduces the ice core record.  Marcott et al did exactly that when comparing the higher reolution West Antarctic Divide data (WDC) with the lower resolution East Antarctic Divide data (EDC) in extended data figure 5:

    

    "a, The red line is the Green’s function (smoothing function) produced by a firn model using an assumed EDC accumulation rate of 0.015 m yr−1 and a temperature of 209 K. b, CO2 data from WDC (dots) and EDC (dots) plotted against artificially smoothed CO2 data from WDC using the EDC firn smoothing function (red line in both plots). WDC data have been systematically lowered by 4 p.p.m. for direct comparison with EDC."

    Given this, it appears to me that the stomata data Steinthorsdottir uses is an inaccurate proxy of CO2 concentrationin the Younger Dryas.

80. APT at 21:27 PM on 4 July, 2015

    Tom Curtis @79
    Thanks for the reference and explanation. Interesting and useful.

81. h4x354x0r at 14:19 PM on 20 March, 2016

    The Keeling Curve seems almost uniquely consistent to me, compared to almost every other type of measurement in the natural world, which tends to be highly variable, regardless of long-term trends. The Keeling Curve, by comparison, is almost eerily rigid in trajectory, especially compared to variability of total carbon releases over time. It's like it's got some kind of governor that simply keeps the increase and accelleration from going any faster, no matter how much more carbon we pump into the atmosphere. 
    
    Can anyone help me understand how the Keeling Curve is so "tight", while so many other measurements have so much higher variability? Is it just because the other sinks - ocean, land, and plants - have so much more capacity that they can absorb whatever else the atmosphere can't? Even if that's a reasonable simple explanation, I still feel like I'm missing something from the 'limiter' aspect of the phenomenon.
    
    I mean don't get me wrong, I'm figuratively poop-my-pants scared about climate change, particularly that "unprecidented rate" part. I've just recently been struck by the relatively tight natural regulation of the Keeling Curve, compared to a much greater variability I observe in almost every other aspect of nature. 
    
    Appreciate anything that might help a mostly layman level understanding of things dude wrap his head around that. Thanks! 

82. h4x354x0r at 14:34 PM on 20 March, 2016

    Regarding the issue of accuracy or agreement of various sampling methods or ice cores: Dendrochronology (tree rings) provide another surprisingly rich, near continuous data source that includes decipherable clues about CO2 levels. Data from dendrochronology agrees, very strongly, with data from the ice cores. 

83. Tom Curtis at 14:50 PM on 20 March, 2016

    h4x354xOr @82, the 'eerily rigid' trajectory is effectively explained by this graph:

    

    The ratio between cumulative emissions and cumulative atmospheric increase in CO2 is explained by the equilibrium of partial pressure of CO2 in the oceans relative to the atmosphere, ie, Henry's Law (with a couple or nuances relating to the biosphere and the deep ocean).

    The variation in actual atmospheric concentration from that predicted by that curve from year to year is almost entirely explained by variation in GMST and to a lesser extent precipitation, ie, by the temperature dependance in Henry's Law and by increase or decrease of global vegetation driven by changes in precipitation.

    That is the bare bones explanation.  Scientists specializing in the CO2 cycle have modelled the various exchanges in detail and are able to reproduce the increase in CO2 given anthropogenic emissions and GMST changes with surprising accuracy.

84. h4x354x0r at 00:25 AM on 31 March, 2016

    Thank you for the explanation, Tom Curtis. I had to get into my wayback machine and go visit my high school physics class, but the pointer towards Henry's Law helped break my metal logam, there. The annual variability is between 6-7 PPM; the annual increase is now a solid 3 PPM, and of course growing. It would be nice not to find out what will happen when the annual increase overtakes annual variability. 
    
    Again, thank you! 

85. billev at 03:19 AM on 5 January, 2019

    From the comments above, I feel that the current capability for measuring atmospheric CO2 is grossly inadequate.  For example,  I would think that if the Governor of California wished to concentrate on levels of CO2 in his state that might be problematic then he should have access to CO2 measurements at a number of surface CO2 measuring sites scattered across the state.  He could then better determine if actions to reduce human induced CO2 emissions would have any significant impact on the overall CO2 levels in the state.  He might well discover that the CO2 output from the states areas of intense vegetation could not be significantly countered by reducing the level of human induced CO2 emissions.  Then again, he could receive evidence that such measures might well reduce the CO2 level to an acceptable amount. 

86. billev at 03:31 AM on 5 January, 2019

    My previous comment is based upon the idea that the current CO2 level in the atmosphere has an effect on global warming.  In fact it is more likely an effect of global warming rather than a cause of it.   

87. RickG at 07:46 AM on 5 January, 2019

    @Billev (86).  I'm not quite sure what you are suggesting.  Are you saying that gloal warming is causing a rise in CO2 and not the reason for global warming?

88. One Planet Only Forever at 08:01 AM on 5 January, 2019

    Billev @85 and 85,

    In addition to RickG's question I am curious about why you mention that the Governor of California would care about the atmospheric CO2 levels in that State.

    Identifying sources of CO2 emissions or other GHGs by satellite survey could be helpful. But other than identifying concentrated human production sources of GHGs, the level of CO2 in a region is rather 'beside the point'.

    Increased CO2 is happening globally (it is seen at every location that measures CO2 levels).

    The Global Warming and resulting Global Climate Changes are the problem.

    Please provide more detail regarding exactly what you are suggesting or asking about.

89. billev at 12:14 PM on 5 January, 2019

    My point is this.  The Governor of California is attempting to install laws to limit the use of fossil fuels in order to reduce GHG emissions.  This may prove to be costly to the citizens of California in terms of higher operating costs and the departure of manufacturers and jobs.  If a better understanding of the sources of GHG (particularly CO2) can demonstrate that the laws limiting human consumption of fossil fuels will not significantly diminish the growth of CO2 levels then unnecessary costs caused by those laws can be avoided.  In other words if it is found that increasing vegetation due to a warming Earth is the only significant source of increased atmospheric CO2 then the futility of costly policies to limit fossil fuel use might be avoided.  To this end it would be valuable to political leaders to have much more detailed measurement and analysis of the sources of atmospheric CO2 than is now available.  

90. Eclectic at 13:52 PM on 5 January, 2019

    Billev @ 85/89 , if you are talking about science ~ then the sources of atmospheric CO2 are already well-known (and have been, for decades).

    If you are talking about politics (the best policies for abating the global warming problem, and the most speedy but economical & socially-advantageous ways of achieving zero nett carbon emission) ~ then this is not the right thread for such discussion [perhaps try one of the Weekly Digests?].   As always, you would need to give consideration to jobs lost versus jobs gained in advancing renewable-type industries & services . . . and put everything in perspective wrt past & present out-sourcing of jobs to China, Mexico, etcetera, in both the short term and longer term.

    B.  Your comment at #86 is bizarre.  Please read Climate Myths 12 and 91.

91. One Planet Only Forever at 03:08 AM on 6 January, 2019

    billev @89,

    Your clarifying of what you are suggesting or asking about has been helpful.

    As Eclectic has pointed out, politics related to climate science can be discussed on Weekly Digests.

    I can add more science related points to what Eclectic mentioned.

    All global leaders, in business and politics, have been increasingly informed about the constantly improving awareness and understanding of climate science through the collective global expertise evaluating the science and consolidating summaries of scientific understanding (with regular updates - because science by its nature is constantly increasing and improving awareness and understanding).

    The IPCC is the global body that does that. Many IPCC Reports have been produced, starting with the AR1 series of reports that were published in 1990. The IPCC is currently working on the AR6 series of reports planned for publication starting in 2021 with the last document of the series planned to be published in 2022.

    So there is very little 'climate science' awareness and understanding that the Governor of any state (or elected official at a Federal level) would be 'unaware of'.

    Consider that understanding of history of availability of awareness and understanding of climate science the next time you read about some elected official questioning how much is really understood about climate science. You should seriously question, be skeptical of, the motives of such a questioner.

    Climate science has confirmed that future negative climate change consequences are being caused by the continued increase of CO2 in the atmosphere due to human activity, mainly the burning of fossil fuels. And the scientifically understood solution is to stop increasing the CO2 in the atmosphere. So every regional leadership is tasked with the responsibility of figuring out how to get their portion of the global population to stop contributing in any way to the increase of CO2 or other human activity created GHGs.

    That is as far as the science goes. And that understanding is not going to be changed by new research. All evidence indicates that the urgency to stop the creation of new CO2 is only going to increase as business and political leadership fail to effectively correct the problem that has been developed.

    I hope that helps you understand this issue.

92. scaddenp at 11:35 AM on 7 January, 2019

    billev - perhaps you are unaware of this satellite and its mission? There are several ways to determine what the increase in CO2 can be attributed to from carbon mass balance (we know pretty accurately how much FF is burned), O2 depletion, changing carbon isotope composition (FF has no C14), ocean pH. In fact nature is so far mopping up about half our emissions. More here.

93. MA Rodger at 19:50 PM on 31 January, 2020

    alonerock from elsewhere,

    Articles describing the measurement of the vertical profile of CO2 through the atmosphere include Abshire et al (2010) 'Pulsed airborne lidar measurements of CO 2 column absorption' who measured CO2 levels to 6km (their fig 10 below),

    

    and Foucher et al (2011) 'Carbon dioxide atmospheric vertical profiles retrieved from spaceobservation using ACE-FTS solar occultation instrument' who measured from 5km to 25km (their fig 7 below).

    

94. Ken The Bear at 06:11 AM on 4 December, 2020

    When should we expect to see the global downturn in carbon emissions register on the Keeling Curve?

95. MA Rodger at 06:52 AM on 4 December, 2020

    Ken the Bear @94,

    I don't think the drop in emissions from Covid will be anyway near enough to register a change that will be noticed in the Keeling Curve.

    Recent annual CO2 increases measured at MLO as measured by ESRL run 2010-19 +2.32ppm, +1.91ppm, +2.61ppm, +2.01ppm, +2.20ppm, +2.95ppm, +3.01ppm, +1.90ppm, +2.86ppm,  +2.46ppm. Those numbers have a 90% range of +/-0.8ppm. It seems most folk are still awaiting better understanding of the effect of Covid on emissions before making an assessment on the matter but one estimate of the drop in rising CO2 levels due to Covid has been given as  between 0.08ppm & 0.23ppm. So not enough to make a noticeable dent.

96. orrok at 20:54 PM on 17 March, 2021

    I'm interested in CO2 levels during the 1866-present period. Mainly because
    1) we have direct observational CO2 measurements from 1866 onwards
    2) The period 1866 -present is particulary interesting in terms of human development,the industrial revolution and co2.

    Would it be possible to include a graph for this period with direct measurements, rather than proxy ice core data?

    Of particular note is W. Kreutz, with 25,000 measurements in the period 1930-39 with a mean concentration of 438ppm.
    W. Kreutz,“ Kohlensaure Gehalt der unteren Luftschichten in Abhangigkeit von Witterungsfaktoren,” Angewandte Botanik, vol. 2, 1941, pp. 89-117

97. MA Rodger at 22:17 PM on 17 March, 2021

    orrok @96,

    The work of W Kreutz you cite does not appear to have been published in English but the work features prominently within Beck (2007) '180 Years of Atmospheric CO2 Gass Analysis By Chemical Methods' which did attrach comment from Meijer (2007) & Keeling (2007) [PDF of both] who conclude saying  "His work, however, contains major flaws, such that the conclusions are wrong, as they are based on poor understanding of the atmosphere," and "Unfortunately for Beck—as well as for humanity—the claims don’t stand up."

98. Bob Loblaw at 00:34 AM on 18 March, 2021

    Beck's work seems to come up a lot. There are several other (reliable) places you can read about it on the web:

    http://www.realclimate.org/index.php/archives/2007/05/beck-to-the-future/

    http://rabett.blogspot.com/2006/10/amateur-night.html

    http://rabett.blogspot.com/2008/03/beckies-as-tonstant-weader-knows-eli.html

    ...and an old comment here at SkS by Tom Curtis:

    https://skepticalscience.com/argument.php?a=55&p=2#75463

    Also note that Beck's paper was published in Energy and Environment. Not the highest quality journal.

    https://www.desmogblog.com/energy-and-environment

99. Bob Loblaw at 00:38 AM on 18 March, 2021

    Note that Toms comment I link to in #98 is further up this page (#53)...

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