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.
Ferdinand:
At August 22, 2010 at 1:20 am you assert:
“Again read the literature: how much liquid water exists at -40 C, the average temperature of the Vostok ice core? Moreover, CO2 measurements are done under vacuum, which removes all CO2 and liquid water as vapour, the latter is trapped in a cold trap as ice at -70 C.”
No!
That is a physical impossibility.
As I have repeatedly explained to you (including above at August 21, 2010 at 4:29 am) all ice – including ice crystals – is covered in a liquid phase at all temperatures down to -40deg.C. This surface film is what makes ice slippery. The amount of this water is of little importance but its existence throughout the ice matters greatly.
If, as you say, “the average temperature of the Vostok ice core” is “-40 C” then much of the Vostock ice is permeated by a 3-dimensional matrix of liquid water.
As in the last thread you hosted, you seem incapable of accepting demonstrable (and incontrovertible) facts that counter your assertions, so you fail to consider their implications.
For examle, you dispute the stomata data because you say they are “proxies”. But the ice cores are proxies, too.
Bubbles in ice cores are not sealed containers that keep any air they contain in a pristine state. They cannot be because
(a) all ice – including ice crystals – is covered in a liquid phase at all temperatures down to -40deg.C
and
(b) different gases dissolve preferentially in water
and
(c) dissolved gases diffuse from regions of high concentration.
All proxies have their uses but their limitations need to be acknowledged.
You refuse to recognise the limitations of the ice core data because you refuse to acknowledge that it is proxy data so you accept it at face value. And this refusal induces a fundamental flaw in your argument because you take the ice core data at face value and ignore that it cannot record past high values of atmospheric CO2 concentrations.
Richard
Fred H. Haynie says:
August 21, 2010 at 9:49 am
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.
Also recommended by Tony B., Stephen Wilde and Lucy Skywalker.
For Tony and Lucy: hi, some time ago we have met!
About the work of Fred Haynie: sorry but that is completely unrealistic (I could use stronger words, but you know me…):
It starts on page 6:
This seasonal variation has been attributed to the cyclical respiration of the terrestrial biosphere. It is more likely related to the oceans as sources and sinks for both organic and inorganic carbon dioxide. Oceans cover most of the earth and are the greatest reservoir of carbon. Fluxes in and out of the sea surface are temperature change dependent, which is seasonal.
I t seems that Haynie has no knowledge of any of the current data, or hasn’t read anything in the scientific literature recently:
To begin with: if the sea surface temperature was the origin of the seasonal cycle, why is there practically no seasonal cycle in the SH and a large one in the NH, where there are less oceans and more land? Further:
Warmer ocean temperatures means less CO2 solubility in the seawater and increased CO2 in the atmosphere. So far so good, for the long term trend. Not so for the seasonal variation, where warmer summer temperatures show the lowest CO2 levels in the atmosphere and winters the highest. And the d13C changes are opposite to the CO2 level changes. The latter is a sign of vegetation uptake in summer: CO2 is consumed in summer, but preferentially 12CO2, leaving more 13CO2 in the atmosphere. A third point is that oxygen levels increase in summer, decrease in winter. Again a sign of vegetation at work.
The combination of all three points is consistent with vegetation growth, but conflicting with ocean temperatures for open water and conflicting for two of the three items (d13C changes and oxygen changes) for sea ice extent. But the assumption of the third item, that more ice blocks the uptake of CO2 is refuted by the increase of the THC flow (including sink rate) in winter.
Thus just by looking at the observations would have prevented Haynie to make such a remark.
Page 7:
The 308 year cycle is highly significant and fits the “hockey stick” shape of the long term curve better than an exponential form which has been attributed to anthropogenic emissions.
Come on, curve fitting to prove that humans are not the cause??? Where is the scientific feeling gone? Haynie based the 308 year cycle on 50 years of flask data, thus on less than 20% of the full period. No physical explanation, no reference to what might explain the cycle, no (proxy) data which show such a cycle. A peak of 100 ppmv each 308 years would be noticed in all ice cores, including even these with the worst resolution (Vostok about 600 years). And in stomata data and in sediments and in coralline sponges and…
Moreover, the emissions even do better than Haynie’s curve fitting:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/acc_co2_1900_2004.jpg
99.66% of the increase in the atmosphere explained by the anthropogenic emissions for over 100 years…
Correlation is not causation! Well, curve fitting is even worse in that way…
No further comment on Haynies work from my side. If Anthony wants a guest post by Haynie, we can have a more thorough discussion.
Ferdinand
Ferdinand:
I wrote my last post before I reached your post at August 22, 2010 at 2:38 am which did attempt to answer my post at August 21, 2010 at 4:29 am.
Please accept my sincere apology.
I am now responding to your reply.
You assert:
“There is liquid water at the ice crystals – air surface, but there is no liquid water in between crystals, except for dust/acid/salt inclusions. These are minor in the inland ice cores. And these ice cores are at or below -40 deg.C.”
Sorry, but as others have stated in their posts (e.g. Brego at August 21, 2010 at 10:47 am) it is an incontrovertible fact that a liquid phase exists between the ice crystals.
And you assert:
“Ice cores of extremely different circumstances from coastal to far inland, show very little difference in CO2 levels for the same gas age. And as already said, if there was even the slightest migration, the 100 ppmv differences between warm and cold periods would fade away more and more over longer periods of time.”
Again, this was answered by another poster. Ian W said at August 21, 2010 at 5:09 am:
As Richard S Courtney says there is diffusion of gases within the ice and the tendency would be for that diffusion to remove variance and end with a balanced concentration of CO2 in the ice layers. This has been measured and modeled.
Thus finding that other ice cores of similar age have similar concentrations is unsurprising and does not prove that the concentration of CO2 in the atmosphere when the firn formed was the concentration now found in the bubbles in the ice or that those values matched.”
And in response to my having written:
“This is supported by the degree of adjustment the IPCC applied to ice core indications of atmospheric CO2 to provide them with agreement with the Mauna Loa data. The IPCC set the ‘ice age/gas age’ difference at 83 years to obtain that agreement.”
You have replied:
“This is pure nonsense from Jaworowski. The gas age was calculated for the Siple Dome ice core as 10 years older than atmosphere, which gives the 80-85 difference between gas age and ice age for that core. For Law Dome ice cores, the CO2 levels in the firn were measured top down: 7 years old at sealing depth, 30 years gas-ice age difference. One must compare gas composition of the same gas age with the atmospheric measurements, that has nothing to do with the age of the ice layer or the gas-ice age difference. Thus there was no “correction” at all by the IPCC.”
Well, Jaworowski and I have been in contact for decades. This is why he trusted me to present his paper at the first Heartland Climate Conference when illness prevented his attendance. So, I cannot swear if it derives from him or from me, but I am willing to agree that it is his because Jaworowski was one of the first to conduct ice core studies and he devised most of the methods for them (Neftel et al. were still in school when he was travelling the world to obtain and analyse ice cores).
So, if I were to assume “nonsense” concerning ice core data the I would think it was from you and not him.
And there WAS an adjustment of 83 years to get the ice core data to fit the Mauna Loa data. This is a simple fact and your denal of it is “nonsense”. But, since you say Jaworowski presents “nonsense” I commend readers of this thread to assess it for themselves by reading
http://www.warwickhughes.com/icecore/zjmar07.pdf
I commend readers to view his Figures 2(a) and 2(b) at that link then to check the references he provides to that data. Simply, the IPCC set the ‘ice age/gas age’ difference at 83 years to obtain agreement between the ice core data and the Mauna Loa data”. Anybody who does this check can see that this is NOT – as you assert – “pure nonsense from Jaworowski” but is an undeniable fact.
The remainder of your response at August 22, 2010 at 2:38 am is entirely based on your unsupportable denial of the facts I state above and, therefore, is nonsense.
Richard
Ed Murphy says:
August 21, 2010 at 10:39 am
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!
Volcanoes (estimated) emit about 1% of what humans emit. Even very large eruptions like the 1992 Pinatubo caused a drop (!) in CO2 levels as the drop in temperature removed more CO2 than the volcano emitted…
All,
Sorry, but I can’t speed up to respond on all comments, it is going quite fast now, after all I still have a life besides commenting… Thus sorry, if there is some delay and if I miss a few ones…
Ed Caryl says:
August 21, 2010 at 7:20 am
I have two problems with ice core data:
1. Ice crystals grow over time. Eventually, the ice crystals will grow larger than the ice core diameter. As ice crystals grow the grain boundaries sweep impurities, including bubbles, away. What does this do to the measurements? This is never mentioned.
2. I have doubts about measurements below 200 ppm. Photosynthesis begins to shut down at those levels. Wouldn’t rotting vegetation hold the CO2 level above 200 ppm?
1. Ice crystal growth is mainly when growing in water. In this case, snow crystals are directly formed from water vapor. The ice in glaciers is formed by compacting the snowflakes, first into firn, later into ice under pressure.
2. Also my opinion: average levels over land where plants grow are some 30-50 ppmv higher than “background”.
Was a little to fast in hitting the “post comment” button for my previous response:
2. Also my opinion: average levels over land where plants grow are some 30-50 ppmv higher than “background”. But background levels can sink to 180 ppmv, without starving plants, but as said by somebody: even the 180 ppmv need not be the bottom line…
Richard S Courtney says:
August 22, 2010 at 11:28 am
(c) dissolved gases diffuse from regions of high concentration.
—————–
What matters is not that gases diffuse, but how fast they diffuse.
Can you suggest any diffusion speeds sufficient to erase the high frequency variation you believe to be there, but slow enough to maintain the glacial interglacial differences, as well as step changes in CH4 and 15N?
“2. Also my opinion: average levels over land where plants grow are some 30-50 ppmv higher than “background”.”
—
Dubious. Perhaps under a forest canopy. If CO2 levels were this much higher over land, it would suggest that the land was a huge source of CO2.
In August 1986 in Africa, Lake Nyos released 1.6 million tons of carbon dioxide that suffocated 1,700 villagers as well as animals in valleys up to 25 kilometers (15.5 miles) away. Two years earlier in Lake Monoun, Cameroon, a smaller release of CO2 killed 37 people. Wikipedia states: Although Nyos is situated within an extinct volcano, magma still exists beneath it. Approximately 50 miles (80 km) directly below the lake resides a pool of magma, which lets off carbon dioxide and other gases; the gasses then travel upward through the earth.
What are all of the non-biological sources of CO2 on this earth? If magma possesses large amounts of CO2 under the earth’s mantle, its out-gassing might be more widespread and diffuse than in these occasional burps in volcanic lakes. …and how much CO2 escapes from earth into outer space?
Ferdinand,
Your comments are very telling as to who has a better understanding of the complexity of the math, chemistry, and physics associated with global climate change. Those that read my presentations http://www.kidswincom.net/climate.pdf and http://www.kidswincom.net/CO2OLR.pdf can be the judge.
Ernst Beck : “Vostoc ice cores show about 800 years time lag CO2 behind temperature […] the 800 years must be an artifact (as the 200 ppm in glacials) and shows distorting activities of bacteria.”
Thank you. I have long thought that the 800-year time lag was wrong, but had no option but to accept it since (a) it was what the data showed, and (b) no-one, as far as I could tell, disputed it. It was also the case, though, that (c) I couldn’t find anyone who could explain it.
Now I don’t blindly accept that what you say is corrrect, but at least you have knocked off (b) above.
Anna v : “Twelve month running averages hide the different breathing of the two hemispheres”
I am not using 12-month averages. I am using rolling 12-month differences (Jan to Jan, Feb to Feb, etc). The purpose is specifically to eliminate the seasonal variations from the figures.
on mixing across the hemispheres: It has been contended that AIRS shows no mixing between the hemispheres. Not having scanned AIRS for this I am in no position to comment on what AIRS shows.
But I do think that the graphs I linked to
http://members.westnet.com.au/jonas1/CO2NorthAndSouth.pdf
indicate that mixing does occur, and how:
We know that the prevailing wind in the centre of Antarctica is downwards – the katabatic wind. So the CO2 at the S Pole must be reaching it from higher in the atnosphere. My graphs suggest that CO2 at the S Pole is influenced by tropical temperatures. So the picture painted by the data, I would suggest, is that CO2 in rising air from the tropics is transported around the globe, north and south, and ends up at the S Pole and Barrow (and everywhere else).
The rising air at the tropics would take in emitted CO2 from the N Hemisphere, thus distributing it worldwide – without a facility such as AIRS being able to show any CO2 crossing from north to south.
Barry Moore I believe was arguing that CO2 must mix across the hemispheres, otherwise it would accumulate in the north. To my mind, he obviously has to be correct, and my graphs suggest how it happens.
*******************
richard telford says:
August 22, 2010 at 12:52 pm
—————–
What matters is not that gases diffuse, but how fast they diffuse.
Can you suggest any diffusion speeds sufficient to erase the high frequency variation you believe to be there, but slow enough to maintain the glacial interglacial differences, as well as step changes in CH4 and 15N?
**************************
1. CO2 can react with water to form carbonic acid. This would be expected to affect the alleged migration of CO2 in ice. It seems experiment with thin but intact slices of ice might shed some light on this. Nitrogen and methane are non-polar molecules and cannot form hydrogen bonds as CO2/carbonate can, so they might not move via the same mechanism.
2. In order to answer the question concerning the glacial-interglacial differences, one would have to have an independent means of measuring the actual CO2 concentration difference. It could have been much larger than we know. Then the effect of the mechanism to smooth the glacial-interglacial changes might have been more than adequate to remove high frequency information.
Richard S Courtney says:
August 22, 2010 at 12:15 pm
As Richard S Courtney says there is diffusion of gases within the ice and the tendency would be for that diffusion to remove variance and end with a balanced concentration of CO2 in the ice layers. This has been measured and modeled.
and
Thus finding that other ice cores of similar age have similar concentrations is unsurprising and does not prove that the concentration of CO2 in the atmosphere when the firn formed was the concentration now found in the bubbles in the ice or that those values matched.
First, if I remember well, there was a test of a Japanese research group, which found that there was some migration out of ice under the temperature and pressure circumstances of Vostok ice at depth, compared to ambient pressure. That showed an extremely low migration. In fact irrelevant, as there is hardly any pressure difference between ice at 2000 meter and 2001 meter depth. The recent migration calculation deduced from remelted layers at Siple Dome remains to be proven as reliable.
But nevertheless, if we may assume that there was even the slightest migration, that would level off the CO2 level differences between 280 and 180 ppmv from a warm interglacial and a cold glacial period. As the cold periods are about 10 times longer than the warm periods, the level differences would fade away over time until some 190 ppmv would be found over the full period.
If the migration was very slow, that would take a lot of time. But the ice cores present a lot of time too: Vostok shows 420,000 years and 4 warm periods, each some 100,000 years apart. With even the slightest migration, the oldest periods would show less and less difference in CO2 levels between warm and cold periods, but that is not the case. As an extra, one can compare the highs and lows of CO2 levels with the highs and lows of the temperature proxy in the ice layers, where the posibility of migration is far less than for CO2. If there was any migration, the ratio between temperature and CO2 would fade away for each interglacial, 100,000 years apart. Again that is not the case. Thus at least in the Vostok ice core, there is no measurable migration of CO2, and the 800,000 years Dome C core is going the same way…
Further, there are enormous differences in accumulation rate between different ice cores, from 1.2 and 0.6 meter ice equivalent in the Law Dome ice core to a few mm in Vostok. Even if the gas age is the same, the difference in thickness of the ice layers may be a hundredfold. Which makes the possibility that these would show the same degree of depletion/averaging quite remote. That is a fortiori the case for the “hockeystick” part over the past two centuries.
Further, again, there is no liquid water at the intercrystalline boundary. The reference to a Nature article from Brego at August 21, 2010 at 10:47 am reads about the inclusion of minuscule sulphuric acid drops at the triple point of ice crystals, that is at the edge where three crystals come together, not over the full length of the border between two crystals, which is necessary for any migration. Moreover, that was ice from the Peninsula, where salt and sulphur inclusions and higher temperatures are more common than far inland like Vostok.
A nice microscopic picture from the article in Nature can be found on a page of the warmist side, which attacks Jaworowski for misleading people with “water” in ice, while it is sulphuric acid and suggesting that that is a real problem, while it is not:
http://www.someareboojums.org/blog/?p=17
My apologies that I only can concur with their conclusions.
And there WAS an adjustment of 83 years to get the ice core data to fit the Mauna Loa data. This is a simple fact and your denal of it is “nonsense”. But, since you say Jaworowski presents “nonsense” I commend readers of this thread to assess it for themselves by reading
http://www.warwickhughes.com/icecore/zjmar07.pdf
While Jaworowski may have been thé specialist of ice cores in the early days, I have the impression that he hasn’t read anything about ice cores in the scientific literature since 1992.
About the “adjustment” I wrote already a comment in the introduction which you seems not have read, here I repeat:
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.
Either Jaworowski doesn’t know that there is a difference between the age of the ice and the age of the gas inclusions, or he doesn’t believe it for whatever reason:
An ad hoc assumption, not supported by any factual evidence[3, 9], solved the problem: the average age of air was arbitrary decreed to be exactly 83 years younger than the ice in which it was trapped.
Where the references [3, 9] are to articles by… Jaworowski.
Anyway the gas age was calculated in the case of the Siple Dome (but see the explanations by the original author, Neftel, about that topic, here in the introduction), and measured in situ top down in firn of the Law Dome cores. Thus Jaworowski’s claim is complete bogus.
Some year ago I have sent my objections to him, but never received an answer. This part 2 was sent to him too, and to J.J. Drake as a matter of courtesy.
Jim says:
August 22, 2010 at 2:50 pm
1) And someone has already done it:
http://cat.inist.fr/?aModele=afficheN&cpsidt=20841572
And the effect of diffusion is equivalent to the smoothing by the firn (before bubble closure) by 70ka – much less at shallow, Holocene, depths
John Whitman says:
August 22, 2010 at 10:38 am
My Single Bullet Descriptor => An example of mass conservation law is claimed as evidence that CO2 directly warms atmosphere
Not at all, only written (some time ago already) because there was too much nonsense told about the origin of the increase of CO2 in the atmosphere. I am only interested what science tells me, not interested where science brings me…
My Single Bullet Descriptor =>Paleo-reconstruction of atmospheric CO2 by ice core proxies is reviewed as a potential support/basis for another future Engelbeen post on why current CO2 increase is anthropogenic.
In part yes.
Note regarding context: In my view we are only discussing this topic here today because of an a priori concept/idea that a net significant AGW (compared to natural GW) is caused by anthropogenic (compared to natural source) CO2. I always need to keep that context in mind.
I have not the slightest intention to write an article about the influence of CO2 on temperature, as I haven’t studied that in detail and the discussions I have read on that topic are partly over my head. But your conspiracy theory of WUWT slowly changing into a (C)AWG propaganda machine sounds interesting. Maybe some research grants for Anthony underway? /sarc off.
If you look at this Vostok chart, the dust and temperature measurements look more noisy than the CO2 ones. This would seem to indicate a smoothing mechanism for CO2. Also, it really looks like dust caused cooling which then caused an absorption of CO2 by oceans.
http://www.globalwarmingart.com/wiki/File:Vostok_Plot_png
Barry Moore says:
August 21, 2010 at 8:30 pm
with about 8.5 GT of carbon released in the north and .5 in the south with no significant mixing why is the average northern concentration not considerably higher than the south if human emissions have such a large effect. In fact there is barely 1 ppm difference in the averages.
There is a substantial lag between CO2 levels in the NH and the SH of about 6-24 months, depending of which stations are compared with lags over altitude and latitude, see:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/co2_trends_1995_2004.jpg
There is of course some exchange between the NH and the SH, but it is slowed down by the ITCZ, with upwelling near the equator. That may mix only a part of air from each hemisphere. Higher air layers in the SH near the equator show slightly higher CO2 levels (1 ppmv) than lower air layers, due to that mixing.
Further, AIRS has an accuracy of about (+/-?) 10 ppmv, thus probably can’t see the differences in average, although the animation shows a little more weigth of the NH CO2 levels.
Question for Anna V.: what is the accuracy of the Japanese satellite?
Ferdinand:
Thank you for your detailed response at August 22, 2010 at 2:54 pm to my comments at August 22, 2010 at 12:15 pm.
Firstly, your comments concerning probable diffusion of CO2 through frozen ice are mistaken.
You refer to migration affected by physical pressure induced by the depth of the ice. But this is probably not relevant.
The bubbles in the ice enclose air. And the surfaces of the bubbles are coated with liquid water at all temperatures down to -40deg.C (which you admit is the average temperature of Vostock ice). But the liquid coating is only a few molecules thick.
Gases in air dissolve at a rate dependent on the partial pressures of the gas in the air and in the solvent (i.e. the solvent in this case is the layer of liquid on the bubbles’ surfaces). The physical pressure has little relevance to this.
But there is very little liquid on the surface of each bubble so little of the gas in a bubble can dissolve initially.
But there is a 3-dimensional matrix of the liquid phase on the surfaces of the ice crystals. The dissolved ions must migrate by diffusion through this matrix and, thus, reduce the concentration of the solution in the liquid on each bubble’s surface.
The migration by diffusion will provide a concentration gradient along the diffusion path(s) between the ice crystals. It is this gradient that powers the migration.
Initially the gradient is infinite, but it progressively reduces as diffusion occurs. Therefore, the rate of diffusion will reduce with time as the gradient diminishes.
But the migration depletes the gas in the liquid layer on the surface of each bubble. And this depletion will induce more of the gas enclosed in the bubble to dissolve in the liquid layer. But the amount of this gas that becomes additionally dissolved is determined by the partial pressure of the enclosed gas. And this partial pressure progressively reduces as the enclosed gas depletes (by being dissolved).
Eventually, a quasi-equilibrium of the gas in each bubble will be achieved. This quasi-equilibrium will result from
(a) the rate of the migration through the 3-dimensional matrix of the liquid phase on the surfaces of the ice crystals
and
(b) the initial concentration (so, partial pressure) of the gas in the bubbles.
Hence, it could be expected that
(i) bubbles which originally contained, for example, concentrations of CO2 in the range 400 to 500 ppmv would all eventually achieve a similar quasi-equilibrium
and
(ii) bubbles which originally contained, for example, concentrations of CO2 in the range 200 to 300 ppmv would all eventually achieve a similar quasi-equilibrium
but
(iii) bubbles that originally contained 400 to 500 ppmv of CO2 would eventually contain more CO2 than bubbles that originally contained 200 to 300 ppmv.
This model is consistent with known physics (while your is not) and is consistent with observations. And it explains why stomata data provide higher atmospheric CO2 indications than ice core data.
Secondly, your dismissal of the fact that Neftel made the ’83-year adjustment’ consists solely of unfounded ad homs. concerning Jaworowski and an untrue assertion that the references I said people should check are to references of Jaworowski.
THAT IS NOT TRUE.
Those references in Jaworowski’s paper at
http://www.warwickhughes.com/icecore/zjmar07.pdf
are
Friedli, H., Lotscher, H., Oeschger, H., Siegenthaler, U. and Stauffer, B., 1986. “Ice core record of the 13C/12C ratio of atmospheric CO2in the past two centuries.” Nature, Vol. 324, pp. 237-238.
And
Neftel, A., Moor, E., Oeschger, H. and Stauffer, B., 1985. “Evidence from polar ice cores for the increase in atmospheric CO2 in the past two centuries.” Nature, Vol. 315, pp. 45-47.
Richard
design aims in accuracy for IBUKI:
http://directory.eoportal.org/presentations/330/7450.html
• Observation of the CO2 and CH4 column density (CH4 column density during orbital nighttime):
Question for Anna V.: what is the accuracy of the Japanese satellite?
– at a spatial scale of 100-1000 km
– with relative accuracy of 1% for CO2 (4ppmv, 3 month average) and 2% for CH4
They aim at a factor of two improvement in estimates.
They were supposed to give validated data end of January this year, but I guess they are having a hard time to fit them into the expectations of AGW .
Nevertheless, the data that has been shown shows a spread larger than 10%.
First of all Ferdinand since I have had a professional engineers license for 50 years I would have been around 45 years ago to be your examiner. In the past 50 years I have occasion to perform many mass balance calculations considerably more complex than the carbon cycle.
Now ¼ of 860 Gigatonnes is still 215 Gigatonnes (mass) so your argument that fractions cannot form part of a mass balance calculation has no validity. To assume that the increase in atmospheric carbon over the last 60 years say 70 ppm at 2.2 GT per ppm = 154 GT (approximately) is nonsense since it totally ignores all the other sources and sinks which have caused all the variations in the last 800 000 years as per the ice core data. In addition we emit approximately 9 GT a year which should cause an increase of 4.1 ppm by your logic, in fact the increase in CO2 is only 1.7 ppm per year. So you not only get an F in Physics but also in basic math. Your numbers just do not compute.
If you wish to argue that only 40% of anthropogenic emissions are causing the increase as per the 1.7 v’s 4.1 then 40% of all the anthropogenic emissions in the last 60 years is nowhere near 154 GT. Please refer to Fig 7.3 Page 515 of IPCC AR4. Total all time anthropogenic emissions is 244 GT of which 100 GT is already sequestered in the deep ocean which leaves 144 GT 40% of which is 58 GT..
The half life of a CO2 molecule in the atmosphere is 4 years or less and if you put this factor into your mass balance calculation you will see how far wrong you are.
Barry Moore says:
August 22, 2010 at 10:15 pm
In addition we emit approximately 9 GT a year which should cause an increase of 4.1 ppm by your logic, in fact the increase in CO2 is only 1.7 ppm per year. So you not only get an F in Physics but also in basic math.
Sorry, but my math only calculated that the difference between the observed increase and the calculated increase is what nature has absorbed (thus 2.4 ppmv) or released, whatever the natural changes were. In this case, nature was a net sink for CO2, not a source, and the human emissions thus were the only source of the increase, regardless if part or all anthropogenic CO2 molecules were exchanged by natural ones within a minute. How much of the original anthro CO2 still resides in the atmosphere has not the slightest connection with the cause of the increase in total mass of the atmosphere.
That is the same as bringing your money to the bank: the turnover of money is gigantic, so your money disappears within seconds in the mass of transfers, but even then, the gain/loss in the balance at the end of the day can tell you if your money is part of the gain, all the gain (if the bank shows less gain than your contribution) or no gain at all. How many of your own original banknotes are still in the bank (electronically it is even zero) is of no interest for the balance.
If you wish to argue that only 40% of anthropogenic emissions are causing the increase as per the 1.7 v’s 4.1 then 40% of all the anthropogenic emissions in the last 60 years is nowhere near 154 GT. Please refer to Fig 7.3 Page 515 of IPCC AR4. Total all time anthropogenic emissions is 244 GT of which 100 GT is already sequestered in the deep ocean which leaves 144 GT 40% of which is 58 GT..
I always argued that the increase is 100% caused by humans, at least over the past 50 years, for the simple reason that nature was not a source, always a sink, for CO2.
244 GtC emitted, 144 GtC increase in the atmosphere, 100 GtC captured in other reservoirs. That is what one calls a mass balance.
The half life of a CO2 molecule in the atmosphere is 4 years or less and if you put this factor into your mass balance calculation you will see how far wrong you are.
The residence time of a CO2 molecule of about 5 years doesn’t change one gram of the mass balance or the decay time of an excess amount of CO2 in the atmosphere, which is about 40 years half life. If you don’t know the difference between a residence time, which is based on a throughput (150 GtC/year on 800 GtC), and a decay time, which is based on a sink rate (4 GtC per year), then your process knowledge is even rustier than mine…
richard telford:
I provide an explanation of the matter which you query (at August 22, 2010 at 12:52 pm) in my response to Ferdinand at August 22, 2010 at 4:24 pm.
However, the precise quantification that you request is not possible without much more research to determine diffusion rates and their decay with time.
The imortant point is (as I said in my response to Ferdinand at August 22, 2010 at 4:24 pm):
“This model is consistent with known physics (while yours is not) and is consistent with observations. And it explains why stomata data provide higher atmospheric CO2 indications than ice core data.”
Richard
Richard S Courtney says:
August 23, 2010 at 12:52 am
richard telford:
I provide an explanation of the matter which you query (at August 22, 2010 at 12:52 pm) in my response to Ferdinand at August 22, 2010 at 4:24 pm.
However, the precise quantification that you request is not possible without much more research to determine diffusion rates and their decay with time.
——————
Basically you mean you cannot be bothered to spend thirty seconds on google (try ice CO2 diffusion), or better still ISI, to find out what is known about the diffusion rates of CO2. Is ignorance that bliss?
Richard S Courtney says:
August 22, 2010 at 4:24 pm
You refer to migration affected by physical pressure induced by the depth of the ice. But this is probably not relevant.
The main force is the difference in CO2 levels. That is for all ice cores which go far enough back in time, the difference of CO2 levels between warm and cold periods, as I explained in my message. Pressure differences are of interest, as these may help to establish migration speed. But that showed very little migration and is of no interest for the circumstances in the Vostok ice core. Of more interest is that the Vostok ice core CO2 measurements show no measurable flattening over time, neither on itself, nor in ratio with the temperature variations. This points to an extremely low migration speed.
The bubbles in the ice enclose air. And the surfaces of the bubbles are coated with liquid water at all temperatures down to -40deg.C (which you admit is the average temperature of Vostock ice). But the liquid coating is only a few molecules thick.
But there is a 3-dimensional matrix of the liquid phase on the surfaces of the ice crystals. The dissolved ions must migrate by diffusion through this matrix and, thus, reduce the concentration of the solution in the liquid on each bubble’s surface.
Here you make again the same mistake: the liquid-like layer is only at the ice-air surface, not in between the ice crystals, as quite different forces come into play. That is clearly seen under scanning electron microscope and X-ray diffraction.
Further, even an older work shows the water layer thickness as a function of temperature:
http://www.phys.unsw.edu.au/music/people/publications/Fletcher1962.pdf
At -20 C that is about 15 Å, at -30 C about zero. The dynamic diameter of CO2 is about 3.9 Å, that are not really huge quantities of CO2 dissolved in the liquid layer. Below -30 C, as in the Vostok ice core, there is even no migration possible, if there was grain boundery water at all, except via relative large inclusions.
The migration by diffusion will provide a concentration gradient along the diffusion path(s) between the ice crystals. It is this gradient that powers the migration.
Initially the gradient is infinite, but it progressively reduces as diffusion occurs. Therefore, the rate of diffusion will reduce with time as the gradient diminishes.
Agreed, but no measurable changes observed over 4 periods of each 100,000 years longer…
Eventually, a quasi-equilibrium of the gas in each bubble will be achieved. This quasi-equilibrium will result from
(a) the rate of the migration through the 3-dimensional matrix of the liquid phase on the surfaces of the ice crystals
and
(b) the initial concentration (so, partial pressure) of the gas in the bubbles.
Here you are mixing two different mechanisms: an equilibrium between air CO2 and dissolved CO2 and the migration of dissolved CO2 from higher levels to lower levels via intercrystalline water or veins (if that/these exist). There is of course some equilibrium between air CO2 and water CO2 levels, but I don’t see any reason that the migration via water should stop, before all levels are equal everywhere (including the remaining CO2 levels in the air part). Only the speed will reduce with the concentration differences.
To show the same high/low ratio over the four Vostok cycles, high levels for the oldest period would need to be much higher at inclusion time (an 8-fold) than in the current warm period (pre-industrial), for a 100,000 years half life time of leveling. Followed by 4-fold and 2-fold CO2 levels in the next warm periods. Not very likely.
This model is consistent with known physics (while your is not) and is consistent with observations. And it explains why stomata data provide higher atmospheric CO2 indications than ice core data.
Your reasoning is theoretically possible, but very unlikely. Moreover, a leveling over time doesn’t change the height of the total average CO2 level over the full period of leveling, only changes the distribution. The higher levels in the stomata data are inconsistent with the ice core data and probably an artefact of the stomata data…
Secondly, your dismissal of the fact that Neftel made the ’83-year adjustment’ consists solely of unfounded ad homs. concerning Jaworowski and an untrue assertion that the references I said people should check are to references of Jaworowski.
THAT IS NOT TRUE.
Those references in Jaworowski’s paper at
http://www.warwickhughes.com/icecore/zjmar07.pdf
are
Friedli, H., Lotscher, H., Oeschger, H., Siegenthaler, U. and Stauffer, B., 1986. “Ice core record of the 13C/12C ratio of atmospheric CO2in the past two centuries.” Nature, Vol. 324, pp. 237-238.
And
Neftel, A., Moor, E., Oeschger, H. and Stauffer, B., 1985. “Evidence from polar ice cores for the increase in atmospheric CO2 in the past two centuries.” Nature, Vol. 315, pp. 45-47.
I have a similar reference to a paper where Jaworowski uses the same allegations about Neftel’s Siple Dome ice core results:
http://www.warwickhughes.com/icecore/
where he references his own work to show that the shift in ice core data was arbitrarely in
An ad hoc assumption, not supported by any factual evidence[3, 9],…
[3] Jaworowski, Z., T.V. Segalstad, and N. Ono, Do glaciers tell a true atmospheric CO2 story? The Science of the Total Environment, 1992. 114: p. 227-284.
[9] Jaworowski, Z., Ancient atmosphere – validity of ice records. Environ. Sci. & Pollut. Res., 1994. 1(3): p. 161-171.
Further, I noted excerpts from the Neftel reference in the introduction here. The original work can be read at Ernst Beck’s website:
http://www.biokurs.de/treibhaus/180CO2/neftel82-85.pdf
I recommend everybody to read that reference and compare that to what Jaworowski alleges.
Neftel calculated the gas age at closing depth and based his calculation on diffusion speed, which is inversely correlated to pore diameter and thus ice density. He checked his calculation by comparing the CO2 levels in ice bubbles at that depth with the curve of CO2 levels at the South Pole and concluded that the age of the gas phase at closing depth was 10 years older than the atmospheric CO2 levels. At closing depth, there are already 93 layers of ice, thus the difference in ice-gas age was about 83 years. Nothing arbitrarely in defining the ice age – gas age difference, only calculation and checking.
He further checked the calculated ice-gas age difference at two other depths by comparing them to the curve of South Pole levels and these agreed.
If Jaworowski alleges even recently that:
An ad hoc assumption, not supported by any factual evidence[3, 9], solved the problem: the average age of air was arbitrary decreed to be exactly 83 years younger than the ice in which it was trapped.
then in my opinion, Jaworowski is either completely incompetent or… (fill in your own opinion).
Ferdinand Engelbeen : “In this case, nature was a net sink for CO2, not a source, and the human emissions thus were the only source of the increase” and “I always argued that the increase is 100% caused by humans, at least over the past 50 years, for the simple reason that nature was not a source, always a sink, for CO2.”
Dead wrong. If we accept that temperatures have risen over the last 50 years, then the level of CO2 would have risen even without human emissions. Therefore less than 100% of the increase is caused by humans.
Simple.