About the reliability of ice cores…
Guest Post by Ferdinand Engelbeen
There have been hundreds of reactions to part 1 about the mass balance (http://wattsupwiththat.com/2010/08/05/why-the-co2-increase-is-man-made-part-1 ). Many respondents still are not convinced that the mass balance is a firm proof that the observed increase of CO2 in the atmosphere is human made. But there are more indications. Ultimately, any alternative explanation must fit all the observations. If the alternative hypothesis fails even only one of the observations, then the alternative is rejected. But before we start to look at more observations which support an anthropogenic cause, we need to address several misconceptions which fly around on the Internet, mainly on skeptic blogs… This part has a detailed look at the reliability of ice cores, which are quite important for our knowledge of the pre-industrial CO2 levels, but have been subject to a lot of critique.
Note that the ice cores only show CO2 levels back to about 800,000 years, but measurements may in the future be extended to over one million years. What is found in the ice cores is only relevant for the most recent period of our history and not for more distant geological time periods.
About the reliability of ice cores:
Some have objections to the ice core measurements, as these are regarded as the main reason for the “equilibrium” assumption of ancient CO2 levels. The only real problem in this case is the smoothing of CO2 levels. That depends on the snow accumulation rate, as it takes a lot of time to close all air bubbles in between the snow flakes. That happens at a certain depth where the pressure is high enough to transform the snow, then firn (densified snow still with open pores) into ice. The averaging happens partly because at first the firn pores are large enough to let the air in the pores and in the atmosphere exchange with each other, partly because some bubbles close early, others at a lower depth (thus contain air which is different in composition, “age”, than other already closed bubbles). The depth where this happens depends on the pressure from the layers above and the temperature of the ice. The time needed for full closure of all bubbles largely depends on the accumulation rate of snow at the place where the ice core is taken (or upstream if coring at a slope).
That makes that the average smoothing of CO2 levels is about 8 years (Law Dome 2 out of 3 ice cores, 1.2 m ice equivalent/year accumulation), some 21 years (the third Law Dome ice core, 0.6 m ice equivalent, see http://www.agu.org/pubs/crossref/1996/95JD03410.shtml unfortunately behind a pay wall…), some 570 years (Dome C, a few mm/year, see http://www.nature.com/nature/journal/v453/n7193/full/nature06949.html ) and everything in between. The Law Dome closing period of the bubbles was measured, while for Dome C one needed models to estimate the time resolution in the far past.
Thus the smaller the snowfall at a certain place, the longer it takes for the bubbles to fully close and the longer averaging one has. At the other side, the smaller the accumulation rate, the further we can look back in the past, as for the same depth of ice, there are many more years of snowfall.
The fact that the pores still are open over a long period, also means that there are differences in the age of the ice and the age of the enclosed gas. The age of the ice can be counted, as it simply is the result of ice formation from yearly snow accumulation where winter/summer snow density differences gives clearly distinguishable layers if there is sufficient accumulation. If, as depth increases, the pressure and/or flow result in layers that are near invisible, one may use several other methods like electro conduction or X-rays (see http://iopscience.iop.org/1742-6596/41/1/034/pdf/jpconf6_41_034.pdf ) to distinguish the layers/age.
Determining the gas age is not as easy. Over the years of accumulation of the snow/firn, the pressure builds up and the firn becomes more dense with decreasing pore diameter. That reduces the exchange of air in the pores with the air in the atmosphere, until the pores are too small to make any further exchange possible. If there has been considerable accumulation, as in the two fast Law Dome cores, at the depth of the first closing (about 72 meters) the ice is already 40 years old (40 layers), but the air has the average CO2 levels of less than 10 years ago, which makes the average gas age (including the average time for fully closing of all bubbles) about 30 years younger than the ice at the same depth. For the top layers, we have the advantage of direct measurements in the atmosphere for overlapping periods, which makes a comparison possible.
For cores with far less accumulation, the analysis is more problematic, as the difference increases with the reciprocal of the accumulation rate. During ice ages, there was less precipitation, thus increasing the ice age – gas age difference. The ice-gas age difference for the Vostok ice core is over 3,000 years. Be aware that the ice-gas age difference has nothing to do with the resolution of the CO2 levels, as these are in the bubbles themselves, but it makes a chronology of what happens between temperature (measured as dD and d18O proxy in the ice, see further) and CO2 levels (measured in the bubbles) more difficult to establish. But here also different techniques are used: diffusion speed is a matter of pore diameter, directly related to firn/ice density and densification speed is directly related to accumulation speed. This can be used to model the exchanges between air in the pores and the atmosphere.
The calculations to establish the gas age did fit quite well for the Law Dome ice cores, where besides ice age, the average gas age was established by measuring CO2 levels top down in the firn. That showed that the gas age at closing depth was less than 10 years old on average, but more importantly, the CO2 levels in the already fully closed bubbles and the still open pores were the same. For the low accumulation ice cores like Vostok, there is more discussion about the ice-gas age difference and different time scales were established…
The accuracy of the measurements in the three Law Dome ice cores for the same gas age is about 1.2 ppmv (1 sigma). Later works compared different ice cores for CO2 levels at the same average gas age. These show differences of only 5 ppmv, despite huge differences in average temperature (coastal -20°C, inland -40°C), salt inclusions (coastal), accumulation rate and resolution. There are a lot of overlapping periods between the ice cores, the resolution decreases with increasing length of period (from 150 years – for 2 of 3 Law Dome ice cores – to 800,000 years – Dome C), but even so, the measurements (done by different labs of different organizations) show a remarkable correspondence for the same average gas age. This is a nice indication that the CO2 levels of the ice cores indeed represent the ancient levels.
Data over the past 10,000 years of average gas age in ice cores from:
http://www.ncdc.noaa.gov/paleo/icecore/current.html
As result, for the past 150 years (Law Dome) we have accurate data with a reasonable resolution. The cores average the CO2 levels over 8 years, so any peak of 20 ppmv during one year or 2 ppmv difference sustained over 10 years would be observable. For older periods, the resolution is less and the averaging applies to the full period of resolution (about 570 years for Dome C).
The visual correlation between temperature and CO2 levels in ice cores is well known to everybody, as that was used by Al Gore and many others, although he forgot to tell his audience that the CO2 levels lagged by some 800 years during a deglaciation and many thousands of years at the onset of new glaciations:
Data from the Vostok ice core via:
The temperature is derived from dD and d18O proxies in the ice. dD means the change in the deuterium/hydrogen ratio measured in the water molecules of the ice and d18O is the change in 18O/16O ratio of the water molecules in the ice. Both heavier isotopes of hydrogen resp. oxygen increase in ratio to the lighter ones, when the ocean temperature, from where the precipitation originates, increases. Thus the change in ratio is an indication of the ocean temperature changes. For coastal ice cores, that indicates the temperature changes in the nearby Southern Ocean, while the deep inland cores receive their precipitation from the more widespread SH oceans, thus representing the temperature changes of about the whole SH. The NH ocean temperature changes are more or less represented in the Greenland ice cores, which show similar changes (over the last about 120,000 years), but with some differences in timing and more detailed extreme events (like the Younger Dryas).
There is a remarkable near-linear ratio between ice core CO2 and the temperature proxy record in the same core over 420,000 years of Vostok. Work is under way to confirm this ratio in the 800,000 years of Dome C (for the overlapping period, the CO2 levels are already confirmed similar): about 8 ppmv/°C:
Data of the Vostok ice core from NOAA, temperature proxy indication shows zero at current temperature. From:
http://www.ncdc.noaa.gov/paleo/icecore/current.html
The spread in temperature/ CO2 data, mainly at the high side, is from the long lag of CO2 levels which remain high for thousands of years at the end of a warm period, while the temperature is dropping back to a minimum. The 8 ppmv/°C is not absolutely right, because temperature at best represents a hemispheric ocean temperature, but not far off, as the pCO2 in seawater dependency of temperature shows about 16 ppmv/°C. But besides pCO2 of seawater, other land and (deep) ocean items also play a role.
This all is an indication that temperature is not the cause of the sharp increase of CO2 in the last 150 years, as that wouldn’t give more than 8 ppmv (or 16 ppmv based on ocean solubility) increase with a maximum 1°C temperature increase since the depth of the LIA, while the current increase is over 100 ppmv.
Be aware that, besides some fractionation of the smallest atoms/molecules (not of CO2), and a small fractionation of isotopes, the bubbles still reflect the ancient atmosphere as it was. Ice core CO2 thus is not a proxy but a direct measurement, be it smoothed, of what actually happened in the (far) past.
The objections of Jaworowski:
What about the objections of Jaworowski against the reliability of ice cores (http://www.warwickhughes.com/icecore/ )?
Jaworowski assumes that CO2 “leaks” via cracks in the ice, caused by the drilling and pressure release of the deep core ice. But how can they measure 180-300 ppmv levels of CO2, when the outside world is at 380 ppmv? If cracks (and drilling fluid) are found in the ice, that would show levels which were too high, compared to other neighbouring layers, never too low.
The formation of clathrates (solid forms of O2, N2 and CO2 with water at very cold temperatures and high pressure) depletes CO2 levels, according to Jaworowski. This is well known in the ice core world. Therefore they allow the ice cores to relax up to a year after drilling. Moreover: O2 and N2 clathrates would decompose first, thus escaping as first via microcracks (as Jaworowski alleges). This would lead to too high CO2 levels, not too low.
Jaworowski accuses Neftel of “arbitrary” shifting the Siple data with 83 years to match the ice core CO2 with the Mauna Loa data. But the page from Neftel’s report ( http://www.biokurs.de/treibhaus/180CO2/neftel82-85.pdf ) contains two columns in the table: the counted ice age and the calculated gas age, the latter based on porosity measurements of the firn. Jaworoski used the age of the ice, not of the air bubbles, to base his accusation on, which is quite remarkable for a specialist in these matters. CO2 is in the air, not in the ice and the average age of the gas is (much) younger than the ice where it is enclosed. Neftel even made specific remarks about the gas age, which was compared to the South Pole atmospheric data, to confirm the average age of the gas bubbles at depth:
If the 328 p.p.m. measured at a depth of 68.5 m.b.s. [note: meters below surface] is matched with the atmospheric South Pole record, the mean gas age is 10 yr, corresponding to a difference between mean gas age and ice age of 82 yr, which lies in the above estimated range. The difference is used in calculating the mean gas age for all depths.
That the CO2 concentration measured on the subsequent samples from 72.5 and 76.5 m.b.s. corresponds with the atmospheric South Pole record justifies this age determination…
This clearly indicates that Neftel based his gas age estimate on firm grounds and there is nothing arbitrary in “shifting” the data, as there was no shifting at all. Thus for the Siple ice core, the ice age – gas age difference is about 82 years (Neftel estimated 80-85 years) for an average gas age resolution of about 22 years in this case.
Many of the objections of Jaworowski were answered by Etheridge (already in 1996) by drilling three cores at Law Dome, with three drilling methods (wet and dry), using different materials for sampling, avoiding cracks and clathrates, allowing a lot of relaxation time and measuring the CO2 levels top down in firn and ice. No difference was found in CO2 levels between firn and ice at closing depth and there is an overlap of some 20 years of the ice core CO2 data with the South Pole data:
Figure from Etheridge e.a.: http://www.agu.org/pubs/crossref/1996/95JD03410.shtml
See more comment and further links about Jaworowski at:
http://www.ferdinand-engelbeen.be/klimaat/jaworowski.html
The “corrections” of J.J. Drake:
JJ Drake (http://homepage.ntlworld.com/jdrake/Questioning_Climate/userfiles/Ice-core_corrections_report_1.pdf ) claimed to have established that the CO2 levels needed a correction for the ice-gas age difference. The result of the “correction” is that the CO2 levels are much higher with little variation and the very good correlation with temperature vanished. This conflicts already with our knowledge of the influence of temperature on CO2 levels in current times…
Even so, the “correction” might be all right, but the reason he provided has no bearing in any physical relationship. He makes the basic mistake of conflating a good correlation with a causation: The error is of the kind:
A causes B and shows a good correlation.
A causes C and shows a good corelation.
Thus B causes C, because there is a good correlation between the two. But that correlation is completely spurious, as there is not the slightest physical connection between B and C.
The explanation for his observation is quite simple:
Temperature (“A”) causes the ice-gas age lag (“B”), as temperature is directly connected with humidity of the atmosphere, thus influences the amount of snowfall, thus the accumulation rate and as reciprocal the speed of closing the bubbles: higher temperature, higher snowfall, smaller ice-gas difference.
Temperature (“A”) influences CO2 levels (“C”) directly: higher temperature means higher CO2 levels.
Because the previous two results have a high correlation with temperature, that gives that the ice-gas age difference and the CO2 levels also show a high correlation, but there is no physical mechanism that shows any direct or indirect action of ice-gas age difference on CO2 levels or vice versa. It is a completely spurious correlation, without any causation involved, but both share the same cause. Any “correction” of CO2 levels found in ice cores based on the correlation with ice-gas age difference is meaningless.
Migration of CO2 in ice cores
Ice shows a thin layer of unstructured (liquid waterlike) water molecules near the surface of the air bubbles. Some CO2 may dissolve in this layer, but that is not a problem at measurement time, as measurements are made at low temperature under vacuum, effectively removing all CO2 from the opened bubbles in the crushed ice, while removing any water vapor as ice over an extra cold trap. Water in-between the ice crystals is very unlikely, as there is still the direct influence of ordered structural ice from both sides.
Migration in even the oldest cores is no real problem. The recent fuss about “migration” speed was deduced from the Siple core, based on layers where remelting occurred, something not seen in any high elevation ice core like Vostok or Dome C. It remains to be seen to what extent the Siple Dome results are applicable to other ice cores.
But if there was even the slightest migration of CO2, that would affect the ppmv/°C ratio of the above Vostok CO2/temperature graph over time: the proxy temperature indication is fixed in the ice, while CO2 is measured in the gas bubbles. If there was any substantial migration of CO2, the ratio between CO2 and temperature over warm and cold periods would fade away over the recurrent 100,000 years of time difference between the warm periods, but that is not observed.
Conclusion
The ice cores are a reliable source of knowledge of ancient atmospheres, if handled with care. The resolution heavily depends of the accumulation rate, with as result that the data measured in enclosed air bubbles are smoothed, ranging from 8 years for the past 150 years to near 600 years for the past 800,000 years.
Ben says:
August 21, 2010 at 12:06 am
clathrates aside, what about the existence of water within ice at a large range of p/t?
not only that but ice itself is a FLUID and behaves very dynamically. Huge lakes exist under the ice and the water didnt just melt down the bottom. It flows through the ice. I totaly disagree that ice bubbles are a closed system. Ice cores are interesting and there is a lot too learn about climate science from them. But ice bubbles are not a record of the past atmosphere, they are only a relict from it. The geological record shows much higher CO2 in the past when climates were relatively cool. Fossil evidence such as stomatal indicies show much greater variation in CO2, which is more probable due to variability in volcanism.
A lot of allegations, some true, most not. Waterlike structures exist at the top layers of the border between ice and air, because air doesn’t show a forcing on the water molecules like the orderly structure of the ice crystal itself, which increases in disorder towards the air (if I remember well, some 5 molecules thick at low temperature). Not in between the ice crystals, where the ice layer has deformities, but both crystals still exert enough attraction on the intermediate molecules from both sides. This is seen under an electronmicroscope. Unfortunately I have lost the original reference to that article, but that there is no liquid water in between to hide the CO2, as Jaworowski says is seriously rebutted here:
http://www.someareboojums.org/blog/?p=17
Below -2 C there is probably no liquid water between the ice crystals, as measured by dielectric permittivity:
http://jeeg.geoscienceworld.org/cgi/content/abstract/12/1/37
The rest of your discours may be true for near-meltpoint mountain ice cores, but certainly not for most Antarctic ice cores, where temperatures are much lower.
Btw, glass is also a “liquid”, but I don’t think that there is much migration of gases through glass…
wayne says:
August 21, 2010 at 12:37 am
“Ferdinand Engelbeen, why the emphatic “either/or” when asking of the source of the excess CO2? Basic science says it is not an “either/or” question or source, colder water holds more dissolved CO2, warmth speeds up all chemical reactions including fixation AND liberation reactions concerning CO2 or any substance for that matter, the list goes on and on. So why the either/or? Does man burn all kinds of compounds which all release CO2, yes, but the question is still moot.
I read recently that there are approximately 30 major underground coal fires burning around the world that are known to be set by lightning where the coal intersects the surface, they will burn for decades with no real way to put them out, millions of tons of CO2 per year being ejected into the atmosphere..”
There is also ample geologic evidence, as seen in the scoria rock formations, of such naturally caused underground coal fires having been a regular happening, geologically speaking. Just one of the many potential variables that are unknown in the equation. Many, many leaps of faith in this paper with all the standard implied causality one should not use in scientific analyses.
Ferdinand as always puts a compelling case. And yet…And yet…
For those interested in the history of Co2 readings-which date back to 1820- I wrote this article which appeared on TAV
http://noconsensus.wordpress.com/2010/03/06/historic-variations-in-co2-measurements/#comment-34865
It attracted hundeds of comments and since then there have been a number of other threads which I have linked to. The comments and the links make fascinating reading and if you want to know the history and the detailed science arguements from both sides of the fence it provides a considerable resource.
I have two main concerns.
The first is that historic readings are so comprehensively dismissed as inaccurate. Yet taking Co2 measurements is a science that has developed from 1820 and was practised by literally hundreds of highly competent-indeed internationally known- scientists. Can their hundreds of thousands of reading taken over 130 years ALL have been wrong?
There remain a number of doubts in my mind which neither Ferdinand- nor any of the other highly competent commenters- have ever answered to my complete satisfaction;
* How come we were able to split the atom yet were still not able to accurately determine the composition of our atmosphere?
* How was Charles Keeling-a novice in these matters- able to instantly come up with the highly accurate readings that we are asked to believe completely eluded his more illustrious (at the time) predecessors for over a century?
* Why were Keelings readings in acordance with the research by Callendar which can be clearly seen to have been cherry picked to tie in with his own AGW theory-which was comprehensively dismissed at the time?
* Is the highly complex business of analysing ice cores foolproof and do they therefore definitively prove that our Co2 concentration had not changed until the industrial age?
I don’t pretend to have the answers. I remain uneasy that such a huge body of (apparently) reputable science is so routinely dismissed, as history shows us that taking Co2 readings was a matter of routine throughout much of the 19th century.
Ferdinand may be right-I can’t say with certainty either way-but I do know I would feel more at ease if the numerous records of historic CO2 readings were independently analysed so this can be laid to rest once and for all.
Incidentally, Ferdinands views on whether increased Co2 concentration materially affects our climate appears to be surprisingly nuanced and an additional article on his thoughts on this aspect would be illuminating.
Tonyb
wayne says:
August 21, 2010 at 12:37 am
Long story, but here a short answer on:
Your bubbles in the ice cores is interesting but I don’t find it very convincing. We have had good scientists over many decades in the past measuring CO2 and you and many like you find it hard to trust their work but you trust 100% bubbles in ice cores in Antarctica?
The scientists from the past were good with the means they had at that time. Accuracy of atmospheric measurements typically +/- 10 ppmv. Differences between two measurements (same place, diurnal or sometimes with only 15 minutes in between): several hundreds of ppmv’s. Main problem: wrong place where measured (near huge sources and sinks).
Accuracy of ice cores with today’s technique +/-1.2 ppmv (one sigma, same ice core). +/- 5 ppmv between largely different ice cores for same gas age.
Thank you Mr. Courtenay, exactly a point I wanted to make.
It is also not believable that current atmospheric CO2 concentrations can diffuse 10s of meters into increasingly compressed snow. Also ice cores, stored to allow relaxation, are not stored at extreme temperatures (<-40)C, so can also allow out diffusion. Depressurization and out diffusion probably takes place down to some fairly constant level at one standard atmosphere, regardless of initial concentration. Also there is some fractonation prior to fern closure, small but some. Combining these factors, with the smoothing from long closure times means that we simply don't know what short term variations (the last 100 years of fairly fast CO2 concentration change is a fairly short time) in CO2 concentration may have taken place in the past. There could have been substantial spikes as suggested by some stomata studies, that are simply smoothed out.
While Beck is forbidden it is clear even from the selected data accepted from his whole cited data bank, that atmospheric CO2 ca 1780 was at least 20 ppm higher than suggested by ice core data, and probably near 10 ppm of the increase since then has been due to warming, so the actual anthropogenic increase is almost certainly near 30% less than usually stated.
I agree with Mr, Englebeen that the bulk of the increase in the last 2 centuries is man made, but disagree that the ice cores are a good reflection of past concentrations.
John Silver says:
August 21, 2010 at 12:35 am
“The ice cores are a reliable source of knowledge of ancient atmospheres”
The plants seems to disagree:
http://www.geocraft.com/WVFossils/stomata.html
Stomata data are calibrated over the past century… against ice cores and direct measurements. And they have their own problems: they react on CO2 levels of the previous year, which are by definition on land near other huge sources/sinks. Which may change over time (and with climate) for types of plants, land use changes, ocean currents (LIA!), wind direction…
Englebert,
reading ice cores is the modern equivalent of reading chicken gizzards and other less savory practices. Get over it.
The old saw that extraordinary claims require extraordinary proof should have a couple of corollaries:
1. claims that run counter to common sense require extraordinary proof
2. claims that support secondary gain for the presenter require extraordinary proof.
In the case of atmospheric CO2 and human emissions #1 above is partly invoked (I am not invoking #2 in this posting; I do not think it is an issue here). If it is true that human CO2 production is only 4% of total production, then common sense indicates that a relatively small change in the other 96% (which must be biological, for the most part) could overwhelm any human change. For example a few percent change in CO2 production from the huge reservoirs of biologically available carbon (rotting vegetation, peat, coal, oil seeps, etc) could produce big changes in the overall flows in the Earth’s CO2 cycle.
The huge increases in CO2 during some interglacials in the past came from somewhere, as yet not known with certainty.
So long as these sorts of issues remain, the truth about effects of human production of CO2 should be considered as in some doubt.
tty says:
August 21, 2010 at 1:25 am
(The stomata data is for part 3, but I did give already a short reaction)
Also that 8 year figure for Law dome has always seemed quite implausible to me. Closure occurs when firn turns to ice, which happens at a depth of 90-100 meter. Surely there is not a 10+ meter-per-year accumulation rate at Law Dome? However there is another closure mechanism that may complicate matters in marginal areas of Antarctica. If there is a widespread melting event (which do happen in some parts of Antarctica), then the firn below the ice layer that forms on re-freezing will be effectively sealed from the atmosphere.
There is about 1.2 meters ice equivalent precipitation at Law Dome summit.
Until the layers are dense enough (eventually by summer melt), there are exchanges with the atmosphere. As we have nowadays a change in atmospheric CO2 levels (monotone increase), one can compare the CO2 levels at sealing depth) with those of the atmosphere, which shows only 7 years difference for the Law Dome ice cores, 10 years for Siple Dome, etc… That makes that the ice age – gas age difference is 30 years for Law Dome and some 80-85 years for Siple Dome.
According to Etheridge e.a. most of the air at sealing depth is from diffusion and very little from advection to the ice. Thus one may use the air age as is at that point.
The averaging is mostly from the time needed for full sealing of the bubbles, which is about 8 years for Law Dome, as these contains bubbles which were closed in different sealing periods.
I don’t think there’s any doubt we’ve contributed CO2 to the atmosphere and that any ‘extra’ should be attributed to our activities.
I also don’t think that a scatter plot is a useful mechanism to portray chronological data. Without knowing how each point on the plot was trending, we can’t decide if the variability in the CO2 causes the variability in the temperature record based on this plot. Scatter plots are useful for trending such variables as mortality rate versus toxicity levels, but not for showing a relationship between chronological data points.
What we can see from the scatter plot is that there appears to be no reliable relationship between temperature and CO2. Look at the variability along the T = -6 and T = -4 lines. Clearly a wide range of CO2 concentrations existed for those two temperature points, and without seeing the trend, I have to find that a doubling of CO2 does not raise temperature by 2 degrees. Along T = -6, the amount of CO2 seems to vary between 200 ppmv and 265 ppmv. (take the ratio whichever direction you want, I read enough bickering about it a couple posts ago) Along T = (about) -4, the CO2 concentration seems to vary between 190 ppmv to about 272 ppmv.
What do we get from the chronological data? We do see an apparent relationship between CO2 and temperatures, we see that there is a lag between the two. How is the lag explained by the climate modelers? Well, we have the explanation that the gasses escape from between the ice crystals until sufficient pressure makes that escape impossible.
I accept that, it’s really a good explanation. However, narrowing down when the pressure seals the gasses within the ice is very difficult to say with any certainty.
The statement is made that Al Gore “forgot to tell his audience that the CO2 levels lagged by some 800 years during a deglaciation and many thousands of years at the onset of new glaciations”. This statement seems apologetic to me. I would wonder if the theory of sealing gasses in the ice cores was well established prior to the drilling of the first ice core, or if the theory was developed afterward to explain away the apparent non-fit of the observed data to the climate theories? I expect the latter is true.
When the pressure would have sealed the gasses depends on (as stated in the post) how much snow falls during what period of time. It is the compressive weight of snow that seals the gasses, all very good and reasonable. However, the statement that during colder times there would be less humidity and therefore less precipitation and therefore less snow in a given area is unsupportable. I agree that colder temperature would produce less humidity and therefore less precipitation for water sealed in a lab flask. In the real world though, weather systems drive precipitation around the world, regardless of the temperature at Vostok or the Law Dome, regional or global weather patterns could certainly deliver more precipitation to the area. Freak snow storms occur.
Here is another paper behind many of the ideas in this post: http://www.scienceonline.org/cgi/content/abstract/317/5839/793 (requires registration)
Here is a statement given by the authors regarding their conclusions: “Experiments performed with an atmospheric general circulation model including water isotopes support [the paper’s] temperature interpretation.”
Modeling past weather is of course impossible. We cannot say with any certainly exactly how much snow fell over a given period of time in a specific location thousands of years ago. We therefore have no reliable method for judging how much gas escape to attribute to each slice of the ice core, and therefore how to ‘correct’ the data. I recognize that we can date modern ice by the signature of recent volcanoes, but we’re talking about ice cores dating back hundreds of thousands of years where the time for volcanic eruption includes error bars that exceed the lag time between CO2 and temperature.
Occam’s razor leaves me with one conclusion: the main driver of temperatures on the Earth is the Sun and the reason that temperature and CO2 seem related but off by varying amounts of time is that the amounts of plants and animals increase under good conditions and decrease under poor conditions, in addition to the heat and gas exchanges occurring between the atmosphere and the oceans. CO2 and temperatures are generally related to one another through solar activity and biomass, with periodic disruptions in the relationship caused by volcanoes, meteor strikes, earthquakes, forest fires, and other natural occurrences. The relationship is impossible to predict or model with any degree of certainty.
John Marshall says:
August 21, 2010 at 1:36 am
It seems funny to me that the Vostok ice core atmospheric CO2 level graph for the past 400,000 years shows CO2 levels below that which will sustain plant life. As far as I know plants have never had problems growing and reproducing, if they had we would not be here now.
Plants probably didn’t starve, because CO2 levels over land tend to be average 30-50 ppmv higher than “background” CO2 levels.
Another problem with this paper is that the annual global CO2 budget contains both natural and anthropomorphic productions. According to the US Dept. of Energy our bit of this is 3%. This is way below the errors accrued of the estimations of natural producers.
Wrong topic, see the previous discussion in part 1.
This paper also assumes that the theory of Greenhouse warming due to GHG’s is correct. The laws of thermodynamics show this theory to be false so CO2 is absolutely no problem.
This paper doesn’t assume anything of that kind, as that is a complete separate item.
Nature loves hysteresis. Why would anyone expect the processes involved with entombing CO2 in ice cores to conveniently reverse themselves in exactly the opposite fashion when CO2 is released? It cannot be that simple to expect CO2 measurements upon their release from the cores to reflect what they measured when they went in. If only things were that simple.
I collect old bottles and canning jars. One can see bubbles in the glass. Has anyone done CO2 measurements on these? – or would the glass-making environment skew the amount?
REPLY: well think about it, fire, factory, city…
-Anthony
Ferdinand,
The problem with Jonathan Drake’s analysis is that he ignores the rate of accumulation as the cause of the variation in the difference between gas age and ice age. Since the rate of accumulation is a strong function of temperature, there will be a correlation between temperature and the difference in gas age and ice age that is completely independent of the CO2 level. The rate of accumulation can be determined fairly well in the last cycle in the Vostok core by looking at the layer thickness vs. time. For the deeper parts of the core, the layers have been thinned out by pressure and the uncorrected variation is much smaller (see this plot of accumulation rate in m/year and Ice age Gas age Difference (IGD)). In keeping with my contention that irony always increases, Drake has the statement “Correlation is Not Causation” in the banner at the top of his home page.
For a different take on the ice core data read http://www.kidswincom.net/climate.pdf and decide which is more consistent with physics and real world observations. Pay attention to what happens when you use the CO2 measurements with their relationship to estimated temperatures to predict temperatures to the present. The relationship holds up until about 4000 BC. after that you get a nice hockey stick that gives you unrealistically high temperatures in the last century. Something changes the CO2 at pressures and temperatures at these depths.
We are considering very cold dry locations well away from natural CO2 sources.
About one fifth of the world’s volcanoes are between 10°S and the South Pole.
http://www.volcano.si.edu/world/volcanocriteria.cfm
My CO2 Hoax Alarm is buzzing!
Cutting right to the chase: Regardless the CO2 content of the current atmosphere, it has been shown repeatedly —in the geological record— that in almost every instance of CO2 rise or fall, atmospheric heat preceded those changes.
Well, if the CO2 increased after a temperature increase in the geological past, it had to have come from someplace, and if it consonantly fell when the temperature fell, then it had to have gone someplace.
Does it really make any difference from whence the CO2 doth arrive?
That horse is dead, it’s carcass having long since been absconded with by the denizens of the night.
It therefore seems as though some people are flogging the ground under which the dead horse once lay.
In closing, allow me a neat bit of sarcasm: It’s all those scientists whom are drilling all those holes and releasing all that trapped CO2 back into the atmosphere that are the cause of the increased CO2 we currently experience …
:o)
Re: Ferdinand Engelbeen says:
August 21, 2010 at 8:26 am
You said: “Waterlike structures exist at the top layers of the border between ice and air, because air doesn’t show a forcing on the water molecules like the orderly structure of the ice crystal itself, which increases in disorder towards the air (if I remember well, some 5 molecules thick at low temperature). Not in between the ice crystals, where the ice layer has deformities, but both crystals still exert enough attraction on the intermediate molecules from both sides. ”
But there is liquid water between the ice crystals. The reason why is that the water is highly acidic (>1M).
http://www.nature.com/nature/journal/v331/n6153/abs/331247a0.html#more_articles
This has been demonstrated by others as well.
bushy says:
August 21, 2010 at 3:13 am
Of course there is the issue of exteremophiles living in the ice changing the gas composition. “Some quantitative anomalies in the greenhouse gases CO2, CH4, and N2O have been attributed to microbial metabolism (40, 42), but this issue has not been yet experimentally addressed (30). ”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC321287/
The link you provided is from the last meters of a Greenland ice core, where organic material was found of some 120,000 years ago, that was genetically analysed and shows relationships with plants now found in Northern Canada. That has nothing to do with what is found in the rest of the ice core.
But there are algues and microbes found in ice. Algues produce oxygen and use CO2 as long as there is sufficient sunlight, but algues are more prevalent near the coast.
Some bacteria can survive even the extreme long period en temperatures where they are enclosed in the Vostok ice core. Survive is all they can, and they use N2O and CO2 for DNA repair. The maximum is about 0.1 ppmv CO2, if we assume that they use all available N2O as energy source in a ratio of 40:1 to CO2. See section K in:
http://www.pnas.org/content/101/13/4631.full.pdf
I would like to see a phase-space plot.
How much C02 is dissolved in the snow as it falls?
What are the effects of organisms living on the surface of the ice? In aquatic ecosystems, nutrients tend to be transported to the surface of deposits.
Has anyone determined the mobility of CO2 in ice over temp and delta pressure?
This statement, made just above the CO2/Temperature graphs makes me curious.
“The visual correlation between temperature and CO2 levels in ice cores is well known to everybody, as that was used by Al Gore and many others, although he forgot to tell his audience that the CO2 levels lagged by some 800 years during a deglaciation and many thousands of years at the onset of new glaciations:”
In what way is there a lag during deglaciation? Is the CO2 still coming down at that point as temperatures rise, or is it at its low point but stays there for hundreds of years before starting to rise again?
Similarly, if CO2 lags by thousands of years at the onset of new glaciations, what is causing the temperature declines? If it is the CO2, it would be a leading indicator, not a lagging one. If the CO2 remains high well after temps drop, it would be hard to blame it for the high temperature in the first place, would it not? Obviously the CO2 isn’t holding the energy in anymore, so I’d think it would be hard to argue that increases now are making things warmer. If the CO2 were responsible, we’d have an equilibrium, not a new ice age. Personally, I blame the sun, not to mention I think warm is better for the world than cold.
A few people have commented on plants shutting down at low CO2 levels. Are there any natural, but non-biological or non-plant processes that reduce atmospheric CO2?
We know roughly how much CO2 we’re putting into the atmosphere because we know how much is used because we need to know for measuring economic issues. So what is the rough, ballpark amount that we’ve put into the atmosphere in the last 150 years? And then how does that compare with the total volume of the atmosphere and the measured increase in CO2?
I know we put CO2 into the atmosphere, but do we put all of it in? Since CO2 has lagged temps for hundreds of thousands of years through many cycles, humans weren’t involved in previous cycles. The increases had to be due to other things like amounts dissolved in the oceans coming out of solution and other processes. So if anyone wants to take a shot at these questions, I’d appreciate answers.
Oh, and I very much appreciate this post as it was very informative. Thanks Mr. Ferdinand Engelbeen. I also appreciate the comments too. This was a very informative discussion.
“misconceptions which fly around on the Internet, mainly on skeptic blogs…”
Dr FE, I find this offensive and moreover the probability is that a thorough analysis of the blogs would find misconceptions more rife in the “consensus” blogs where they don’t have the advantage of cleaning and polishing that a truly open blog like WUWT , that allows such as yourself a space to make your case. Like the Chinese government, the consensus blogs don’t allow “misconceptions” to get aired and therefore, like the Chinese government, weeding out misconceptions keeps the party-line on the straight and narrow. I think an apology is in order.
Tell me you didn’t find any thought-provoking issues on the subject raised here by a throng of intelligent, international, talented scientists and amateurs. At WUWT, you can come as you are but you will go away different (to steal a jingle from the State of Louisiana’s tourist bureau.). You just have to look at the great pains that such blogs as the “misonceptions-free” Real Climate and Climate Progress take to try to rebut material that appears on WUWT. Why would they do that?
A little point on the ice core stuff: I believe an interesting proposition has been framed by the many excellent ideas by posters here. Experiment. Here is a gift for you. Design a series of experiments with ice, artificial atmospheres, bubbles, pressure, temperature, solubility of the gasses in water, ice, differential diffusion of the gases through ice (heck elements in hydrothermal fluids in solid rock diffuse from cracks into the uncracked wall rock – frozen water is highly likely more welcoming – I’m suspicious of the long term apparent stability of level of CO2 gleaned from ice cores). Also, another poster mentioned the Oxygen isotope ratios in the CO2 itself – this seems to me a natural line of inquiry for anyone that really wants to clear away the mystery.
Charles S. Opalek, PE
August 21, 2010 at 9:36 am
“Nature loves hysteresis. ”
In other words CO2 concentrations really are “catastrophic”!
Fred Haynie said above
For a different take on the ice core data read
http://www.kidswincom.net/climate.pdf
and decide which is more consistent with physics and real world observations
Fred’s link to his own work provides a completely believable version of atmospheric changes with particular reference to CO2 variations and ice cores.
I must say I agree fully with his comments and would very much like to see this presented as a thread and let others try to take it apart. Perhaps that has already happened but I missed it?
tonyb
Ferdinand, you dont want to comment on this list? ;
http://c3headlines.typepad.com/.a/6a010536b58035970c0120a5e507c9970c-pi
I can understand that.
I remember the first time I realized that someone claimed they could measure CO2 levels back hundreds of thousands of years. I was very impressed by this scientific achievement.
Especially when I know how few people that manage to measure anything at all, without fooling themselves. Especially nowadays.
And especially if these people have some degree on some university. In that case you can be almost 100% sure they cannot even measure a voltage using a multimetre. And absolutely NOT use an oscilloscope. Or a spectral analyser.
I was also shocked once when a fresh guy came from a university in Glasgow, and could’nt solder two wires together. He said he had an MSc degree, but he certainly could not Master a multimetre or a soldering iron. I dont think he could make his own food.
Well, well, I guess these CO2 students are much better at the art of measuring. I am sure I could never measure CO2 from that far back, and claim that I knew 100% what I was doing, and be so sure it was okay…….