By Don J. Easterbrook, PhD.
In a paper “Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation”, Shakun et al.(Nature 2012) contend that rising temperature at the end of the last Pleistocene glaciation were preceded by increasing atmospheric CO2. In his usual masterful fashion, Willis Eschenbach has dug deeply into the data used in the paper and shredded the conclusions in it (see http://wattsupwiththat.com/2012/04/06/a-reply-shakun-et-al-dr-munchausen-explains-science-by-proxy/
and http://wattsupwiththat.com/2012/04/07/shakun-redux-master-tricksed-us-i-told-you-he-was-tricksy/#more-60932/. So rather than dwell on the things that Willis has already shown so well, I thought I’d take a look at some of the assumptions and misconceptions that paper is built upon.
When reading a paper like this, I always like to ask myself, what are the basic assumptions that underlie the methodology involved? What contentions are simply stated as fact or generated in a computer model, rather than demonstrated with real, physical evidence? I will confess here that I don’t believe computer models really prove anything. Sure, they can suggest many things and point out areas of interest, but I live the real world and prefer real physical evidence upon which to base important conclusions. That doesn’t mean I discount models out of hand—it simply means that I look for physical evidence to confirm or deny what the models are saying. So I asked myself a series of questions about the basic issues in this paper. Here are some of the questions that I came up with (the answers follow).
1. Can the Antarctic ice cores be dated with sufficient accuracy to establish a firm temperature chronology?
2. Are the 80 temperature proxies used in the paper sufficiently accurate to establish a solid global temperature chronology?
3. Can CO2 in the ice cores be measured with validity and accuracy?
4. Can the difference in the age of the trapped air and the age of the enclosing ice be determined and is it constant with age?
5. Are CO2 measurements from air bubbles valid or do diffusion and the uncertainty in the timing of isolation of air in bubbles render them invalid?
6. Is the data from Antarctic ice cores consistent with data from the Greenland ice cores?
7. Is the temperature chronology of the ice cores and global proxies consistent with the well-dated, global glacial record?
8. Is the so-called ‘see-saw’ of climate changes between hemispheres valid, i.e, are climate changes in the Northern Hemisphere out of phase with those in the Southern Hemisphere?
9. Would correlation between CO2 and temperature necessarily prove that CO2 causes climatic warming?
10. Since CO2 is incapable of causing climatic warming by itself (CO2 makes up only 0.038% of the atmosphere and accounts for only a few percent of the greenhouse gas effect), is there evidence of concomitant increase in water vapor (which causes more than 90% of the greenhouse gas effect)?
11. Is the AMOC the only viable causal mechanism? What about the influence of the Pacific Ocean, which covers about half the Earth’s surface
So, what is the main contention of this paper and what does it imply? The authors claim to have “compelling evidence that rising CO2 caused much of the global warming” at the end of the last ice age, roughly 11,000 to 25,000 years ago. According to the authors, “if you reconstruct temperatures on a global scale – and not just examine Antarctic temperatures – it becomes apparent that the CO2 change slightly preceded much of the global warming, and this means the global greenhouse effect had an important role in driving up global temperatures and bringing the planet out of the last Ice Age.” The crux of their contention is illustrated in their Figure 2.
Shakun et al. Figure 2. The Red line is Antarctic temperature curve based on ice cores; the yellow dots are CO2 measurements from ice cores; the blue line is composite global temperature from 80 proxies.
Willis has sliced and diced the data behind these curves so be sure to read his analyses. I’ll refer to some of his graphs and conclusions but look at the Shakun et al. contentions from a somewhat different angle. Because this is such a marked divergence from the widely held view that CO2 lagged rising temperatures at the end of the last ice age, careful scrutiny must be given to evidence and assumptions upon which this contention is based. Right off the bat, a most surprising conclusion in this paper is that the authors claim that correlation proves cause. Simply showing that CO2 correlates with anything surely doesn’t prove that CO2 was the cause. It’s the same kind of mindset involved with the oft-heard claim that if we have had global warming while CO2 was rising that proves the cause was the rise in CO2. Heck, I had hair before CO2 began to rise, but I don’t blame that on CO2.
So let’s look at each of questions posed above.
- How accurate is the dating of Antarctic ice cores? How can you date ice that has nothing in it that can be directly dated? The Shakun et al. paper states that they use the methodology of Lemieux-Dudon et al. (2010), which involves construction of a model using estimates of snow accumulation rates, temperature, firn densification rates, and ice flow rates, all of which vary from glacier to glacier and from glaciation to interglaciation (thus introducing large potential errors). The modeling data is then modified by matching with tephra horizons, sulfate spikes, δ18O, firn densification model results, and orbital tuning. All of the assumptions built into the modeling are cumulative, resulting in large possible age errors. As Lemieux-Dudon point out “One special feature of glaciological models is a large model error due to unresolved physics and errors on the forcing fields, clearly affecting the quality of the inferred dating scenarios.” What this means of course is that the age determinations of the Antarctic cores are, at best, educated guesses with large uncertainties. Because chronology is so critical to the Shakun et al. contention, the ages of the Antarctic cores shown in their Figure 2 cannot be considered accurate.
- Are the 80 temperature proxies used in the paper sufficiently accurate to establish a solid global temperature chronology? Willis Eschenbach has made a detailed analysis of the data used to construct the global temperature curve in Figure 2 of Shakun et al.(see this in his web posting) He plotted individual curves for each of the 80 temperature proxies used to create Figure 2 in the Shakun et al. paper. What he found was large variability in the data, which led him to conclude that “The variety in the shapes of these graphs is quite surprising Yes, they’re all vaguely alike, but that’s about all. The main curiosity about these, other than the wide variety of amounts of warming, is the different timing of the warming.” When he ploted all the individual proxies all together (see below), the scatter is readily apparent, leading him to conclude: “It’s clear that there is warming since the last ice age.” “But if you want to make the claim that CO2 precedes the warming? I fear that this set of proxies is perfectly useless for that. How on earth could you claim anything about the timing of the warming from this group of proxies? It’s all over the map.”
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Dr. Easterbrook requested this correction below saying:
As one of your readers pointed out, Willis used ‘Year’ for his time scale (meaning years BC, rather than years BP). I didn’t notice this (geologists always use years BP for events older than a few thousand years), so there really isn’t a discrepancy between the Shakun global curve and Willis’s data points. That graph and the text with it should be replaced with the attached file “dje response to Nature paper x.doc”) or it can just be removed from the posted version. That also means that the YD shown vertical time lines in the previous graph needs to be moved over 2000 yrs so we might as well just Willis’s graph (see attached file).
Sorry for the glitch–my fault–I should have caught it, but the thought never occurred to me that Willis would use 25,000 years BC. It doesn’t change any other of the other material.
Large scatter of individual data points on Willis’s plot from the 80 proxies used in the construction of the Shakun et al. temperature curve. I’ve added lines to show the age of Younger Dryas interval, which doesn’t correspond to the dip in the Shakun et al. temperature data.
Just for fun, I superimposed the curves on Shakun et al. figure 2 over Willis’s data point plot (see below). Because the global temperature curve (the blue curve) was presumably derived from the data in Willis’s plot, it should fit well with it. Interestingly, it doesn’t. I’ve shown with a blue arrow the dip in temperature that corresponds to the Younger Dryas and a black arrow pointing to what should be the same dip in temperature on the plot of individual data points. Other arrows point to similar differences for the end of the Younger Dryas. Now you would think that since the Shakun et al. blue curve was constructed from the individual data points shown on the graph, the two should surely be compatible! I’ve also shown on the graph the well-established age of the Younger Dryas—note that the Shakun et al. global temperature data points show a dip in temperature (presumably the Younger Dryas) that is considerably younger. Makes you wonder!
==============================================================
3. Can CO2 in the ice cores be measured with validity and accuracy?
4. Can the difference in the age of the trapped air and the age of the enclosing ice be determined and is it constant with age?
5. Are CO2 measurements from air bubbles valid or do diffusion and the uncertainty in the timing of isolation of air in bubbles render them invalid?
Because these questions are all inter-related let’s consider them together. The validity of measurement of CO2 from bubbles in ice cores has been challenged in a number of studies. There are several basic problems: (1) air becomes trapped in ice during the conversion of snow to firn to ice. Air in the snow/firn phase remains in contact with surface air until it turns to ice and seals off air bubbles from further mixing with surface air. The depth at which sealing occurs varies considerably, depending on the rate of firn densification, and may extend to more than 100 meters and take a thousand years or more. This means that the age of air in a bubble is not the same as the age of the inclosing ice. Snow densification rates vary considerably between temperate and polar glaciers and between glacial and interglacial climates, making it difficult to measure and date adequately. In any case, rates are not likely to be constant. (2) a second problem results from possible diffusion along the walls of an air bubble, which can upset the CO2 concentration in the bubble. These and other problems mean that measurement of CO2 in ice cores is not straight forward—measurement of CO2 concentrations in ice bubbles and determination of the age of the air are likely to be quite variable. General trends are apparent in CO2 ice core measurements, but variability in CO2 concentrations and age remains problematic.
At this point, answering the remaining questions is quite obviously going to take some time, so they will be considered in Part 2, coming soon.
We need a data set for ice volume/mass.
Let’s start at the beginning. The sun melted large quantities of ice …. Hmmmmm, that would significantly reduce the albedo of the planet. That should lead to warming of the planet. Oh, the planet warmed. What a surprise.
Occam’s razor … the simplest solution …
All the rest is just a shade above pure nonsense and I’m not at all surprised Mosher, along with all the alarmists, wants to believe it. Confirmation bias in action.
BTW Mosher, can you show us the experiment conducted in a 20 mile column of air that “proves” CO2 warms the planet. You assert it exists, please provide a reference.
The 12 easy steps to understanding physics of the minor, but important, GHG effect.
1. The ‘motion’ of Electrons and Protons can be affected by externally applied electric and magnetic fields. Computer CRTs are an example with the electron beam forced towards the phosphor-coated screen by more or less ‘static’ electric field all the while under the back and forth influence of a dynamic magnetic field from the deflection coils (called ‘the yoke’ in the trade).
2. Conversely, when Electrons or Protons move, they create ‘fields’ and then perhaps (propagated) ‘waves’ as well. Electromagnets and antennas are examples.
3. Molecules, such as CO2 and H20 are comprised of atoms the components of which are Protons and Electrons (we ignore the Neutron). This is elementary; consult any HS text for a refresh.
4. Many molecules such as O2 (and even CO2 and H2O) have specific mechanical resonances, at specific frequencies (or wavelengths if one prefers).
5. These mechanical resonances are like miniature tuning forks. The vibrational modes get a little intricate and differ from molecule to molecule on account of the ‘atomic relationship’ of the member atoms.
6. During these vibrational modes, certain ‘member’ atoms can move more than others, and some ‘parts’ are electrically charged … referring to 2. above this will create a ‘field’.
7. Should a particular frequency EM field pass by a resonant molecule, the molecule, like a resonant dipole antenna will ‘pick up’ (the field will induce into the molecule) energy from the passing field .. refer to 1. above.
8. The actual resonant frequencies of resonant molecules is affected by pressure; this means more collisions between atoms, and sometimes vibrational energy can be absorbed in a collision while sometimes energy is given off. ‘Broadening of spectral lines’ is the basic effect.
9. Any vibrational modes amount to ‘stored energy’,
10. Said ‘stored’ energy is also continually being re-radiated (refer to 2. above) in basically all directions (any given molecule will have a given radiation pattern, but in the aggregate among all randomly oriented molecules this yields an ‘omni’ directional pattern).
11. An increased amplitude ‘Vibrational mode’ (no matter how arrived at) amounts to a ‘higher temperature’ locally.
12. From insolation (incoming sunlight), to heating of the earth’s surface, some convective heating of the air near the surface (consult a meteorology text; the MAJORITY of the heating of the air is in the boundary layer), to radiation of LWIR from the earth’s surface, some LWIR is captured’ (excites or is EM induced into) various GHG molecules e.g. CO2 and H2O … and that ‘captured’ EM energy is re-radiated in all directions, *including, and this is very important: BACK to earth … some term this ‘back radiation’, perhaps after the close radio term, ‘back-scatter’ (as used in RADAR to identify energy ‘reflected’ or scattered back from a target).
And so there you have it.
The 12 easy steps to understanding the minor but important (as to moderating the surface temperature) GHG effect.
Refutations with cite(s) of applicable physics law(s)/principle(s) appreciated.
.
Lester Via says:
April 9, 2012 at 9:30 am
It has been my experience as a metrologist many years ago, that researchers often mistake good repeatability for good accuracy. Has anyone taken recently deposited firn, mechanically compressed it to form ice, aged it for a while, then analyzed the ice using the present ice core analysis techniques to see if the results agree with the present atmosphere?
Even better, there is an overlap of about 20 years between the high accumulation ice cores at Law Dome and the direct atmospheric measurements at the South Pole:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_sp_co2.jpg
Etheridge e.a. measured CO2 in firn top down to closing depth and in ice. There was no difference in CO2 levels between still open pores, measured in sampled air and already closed pores, measured in the normal way of ice crushing.
James Sexton, thank you for pointing to the answer to my question, “I mistakenly thought that Figure 2 ended in the modern age, but it actually ends in 4000BC….why leave out the most recent 6000 years?”
The answer seems to be that CO2 has been stable for the last 6000 years. That is what the first graphic at the link you provided at: http://wattsupwiththat.com/2012/04/07/shakun-redux-master-tricksed-us-i-told-you-he-was-tricksy/ tells me.
Thank you all for your help. I appreciate being responded to with respect while I try to wrap my mind around all this science.
Thanks to all of you who take the time to respond to the non-scientists who are trying to educate themselves. Even when I’m not the one asking the questions, I read through the comment section of every post I read and learn from you.
@Steven Mosher
>The paper argues this.
1. The INITIAL cause of the warming was a change in orbital parameters. THEN
2. Excess warmth in NH. Then
3. ICE melting and a fresh water pulse THEN
4. A warming in the SH, leading to
5. MORE c02 outgassed from the ocean.
C02 both leads ( enhances) and lags ( as a feedback) the temperature rise.
+++++++++++++
Let’s reasonably assume the oceans during the ice age were CO2 balanced with the atmosphere. Melting ice has a tiny amount of CO2 in it. Nearly none. Melting ice makes water that will immediately absorb CO2. Lots. If it did not (which is against basic physics but suppose it did not) it would drop the CO2 level in the oceans by dilution – the oceans and it would not outgas, or not outgas nearly so much, even when warmed. Either way the CO2 is reduced in the atmosphere unless significantly compensated.
Question 1: How much CO2 goes into the atmosphere when there is a small temperature rise in the ocean – enough heat to melt the ice?
Question 2: How much CO2 does the meltwater absorb?
Question 3: Which is greater?
I ask because the paper has a freshwater pulse (taking CO2 out of the air) and later CO2 outgassing from the (diluted) ocean. But that outgassing would only replace, or partially replace, the draw down. Remember we are talking about several hundred feet of ocean rise. The CO2 needed to balance that new water to 300 ppm is many thousands of GTons – more than is in the atmosphere at present.
The claim is that ‘once the melting started…’ the CO2 was immediately released. This is simply not going to happen. Once the melting started it immediately took CO2 from the atmosphere, 300 g/m^3. The ocean volume increase comes from the thousands of cubic miles of new (initially) CO2-free water.
Perhaps it draws it down but the CO2 outgassing from warming oceans eventually starts to catch up – after 800 years.
FerdiEgb says:
April 9, 2012 at 11:02 am
“There was no difference in CO2 levels between still open pores, measured in sampled air and already closed pores, measured in the normal way of ice crushing.”
I guess I failed to make my point. I was wondering if the combination of increased pressure and aging has been proven not to affect the CO2 content of the trapped air bubbles by somehow hiding CO2. The reference you provided didn’t answer that question as the samples were not deep enough in the ice/firn to have been exposed to the presssures of typical ice core samples.. Athough your reference in a previous post showing the sublimation process that can be used was helpful. Is the CO2 analysis data from various ice cores such as Vostok using the sublimation technique available?
_Jim says:
April 9, 2012 at 10:54 am
Jim, I understand the GHE. Too bad you stopped at 12. You needed to go further because there’s more to the physics of GHGs in the atmosphere.
Energy in the atmosphere doesn’t just sit there. It gets radiated to space. What molecules accomplish that? Well, it’s those very same GHGs. So, when these GHGs are energized through normal kinetic collisions they will radiate in all directions. Some of that radiation heads out to space. So, just like the GHE keeps some energy that was heading to space within the planet’s surface-atmosphere, the cooling effect takes energy within that system that was going nowhere and radiates some of it to space.
Do you know how this balances? I don’t, but I suspect it varies by concentration of the GHGs and the global temperature. I suspect the GHE is dominant at low concentrations of GHGs. However, as the concentration increases the effect starts to saturate. At some point the cooling effect may even become stronger the warming effect.
The bottom line is I have never seen these two opposite effects handled anywhere. When Mosher and you claim that the GHE is proven by physics that is all fine. But, that doesn’t mean GHGs net effect is that of warming. You need to look at the big picture which is why I made the comment about an experiment on a 20 mile column of air.
C02 both leads ( enhances) and lags ( as a feedback) the temperature rise.
==============================
rotfl……….that covers it all
warmcold, wetdry, snowrain, droughtflood………………
@FerdiEgb says:
In ancient times, CO2 was following temperature: indeed if seawater warms, it releases CO2 and becomes more alkaline. But that is limited: 1°C increase for the global ocean surface gives ~16 ppmv extra in the atmosphere when everything is again in dynamic equilibrium.
++++++++++
Hang on a minute! If the oceans rise 50 feet, how many million cubic miles of water is that? We have ice melting to water with no CO2, absorbing 300 ppm by the time it is seawater, and you are saying that the release of CO2 is only a miserable 16 ppm per degree?? How many tens of degrees did the ocean temperature supposedly rise?
How on earth does this outgassing lead to a net increase in the atmosphere when the ice is still melting? The argument in the paper is that ‘once the heating gets started, the CO2 outgassing drives the melting’. That just don’t add up!
If the CO2 magically rose 100 ppm, and then melted a few million cubic miles of ice, that would become sea water and absorb 300 ppm (-ish). There is a heck> of a lot more new ocean water than there is new CO2 in the atmosphere. It is plan bad arithmetic to say that outgassing 16 ppm per degree, even for the whole ocean, can feed an uptake of 300 ppm for the new seawater when the rise was what, 400 ft?? Come on!
The paper treats the ice as if it already contains the same amount of CO2 as the ocean which is patently not the case, then attempts to tinker with the timing of the ‘releases’ to have that precede melting. Thanks for the 16 ppm number. A simple BOE calculation shows several orders of magnitude of impossibility. The paper’s proposed mechanism is bunk.
Please, elaborate (I see that you may have tried), but, you also skimmed right over an important part I wrote, and which I’ve bolded below:
12. From insolation (incoming sunlight), to heating of the earth’s surface, some convective heating of the air near the surface (consult a meteorology text; the MAJORITY of the heating of the air is in the boundary layer), to radiation of LWIR from the earth’s surface, some LWIR is captured’ (excites or is EM induced into) various GHG molecules e.g. CO2 and H2O … and that ‘captured’ EM energy is re-radiated in all directions, *including, and this is very important: BACK to earth … some term this ‘back radiation’, perhaps after the close radio term, ‘back-scatter’ (as used in RADAR to identify energy ‘reflected’ or scattered back from a target).
So, in a word: “covered”. (How elaborate do you think one gets in a “12 easy step” elavator speech anyway?)
It might help you if you had a few concepds in mind too when considering this subject, like ‘space’ is the big energy ‘sink’ with old sol (and the internal heat generating processes (including nuclear) of the earth) as sources … any mechanism that results in a delay of energy leaving earth, such as a ‘bounce-back’ or a re-rad of energy (like back radiation) certainly is going to increase the ‘energy flux’ in the system, and this in any way you want to frame the argument translates to a ‘higher’ energy state, and a higher so-called temperature” (movement in matter, velocity of air molecules or oscillations in certain ‘resonant molecules) as well.
This really is a pretty ‘basic’ system to set up, but, owing to size, owing to energy affecting phase ‘state’ phase changes (e.g. liquid to vapor etc), owing to physical transport to area other than where it was initially ‘radiated’ (insolation) onto the earth get to be problematic in actually modeling.
Now, with your initial complaint being to Mosher in the form of:
I’d like to see how you would support the proposal on how ‘physics’ would work with a GHG to make the surface of the earth cooler.
.
Ferdinand
Do the oceans outgas and absorb at the same rate when temperatures rise and fall in equal measure?
As an example, in a real world situation if 5000 sq miles of ocean at our sort of latitude, warmed by 10 degree centigrade during one summer, fell back the same amount in the winter, then rose again by 12 degress centigrade the next summer and fell back the same amount in the winter and so on, over a ten year period, would the co2 outgassing and absorption be exactly the same?
Tonyb
_Jim says:
April 9, 2012 at 1:29 pm
Please, elaborate (I see that you may have tried), but, you also skimmed right over an important part I wrote, and which I’ve bolded below: “and that ‘captured’ EM energy is re-radiated in all directions”.
Nope, you didn’t get it. Is this concept really that hard to understand. There’s no question that the energy gets radiated randomly in all directions. That is not the issue. There is no question that the surface radiates LWIR. That is not the issue. You have to quit assuming I’m talking about these issues.
I’m talking about energy in the atmosphere. It may have got there in any number of ways. From the sun, from conduction, from latent heat, from thermalization of LWIR. It doesn’t matter. It’s now in the atmosphere.
Now what happens to that energy? That is what I was trying to get across. It gets radiated, but consider that the energy is already in the surface-atmosphere system. If it gets radiated to the surface it still exists within that system. It hasn’t changed the overall energy content of the system. But, if it gets radiated to space it is no longer within surface-atmosphere system. Hence, it constitutes a cooling effect on the overall system.
Or, to use your own words slightly modified:
“any mechanism that results in a quicker path for energy leaving earth, such as a outward radiation, certainly is going to decrease the ‘energy flux’ in the system, and this in any way you want to frame the argument translates to a ‘lower’ energy state, and a lower so-called temperature.”
.deadwood05 says:
All this is akin to measuring mass differences of micrograms with a spring scale and using the average of several thousand measurements out to four decimal places.
Indeed, but when you do a further several thousand measurements, will they give the same four digits? For independent random errors with the same mean (i.e., no drift), the accuracy increases with the square root of the number of measurements. Thus ten thousand measurements will get you two decimal places. Four places requires a million measurements, but how do you know they’re drift free? By doing another million and getting the same answer!
@Interstellar Bill
“For independent random errors with the same mean (i.e., no drift), the accuracy increases with the square root of the number of measurements. ”
I think it does not increase the accuracy, it establishes a mean value with greater and greater confidence. The accuracy (and the standard deviation about the mean) remain an unvarying feature of the measurement system.
Std error in the mean = Stdev/Sqrt(N) where N is the number of readings
Will you refute that incoming solar IR to the top of the atmosphere is as similarly affected by GHG but in the opposite direction? Where’s that in the IR balance of climate models?
Steven Mosher says:
“This study by Shakun implies a LOWER number actually. It implies 2.5C”
How are you arriving at 2.5C? Just taking the data off Shakun et al. Figure 2, it is suggesting ~3.5 degree C rise in temperature from a CO2 induced heat flux increase of ~ 1.7 W/m2?
5.35 x ln(260/190) = ~1.7 W/m2.
That would take climate sensitivity to 2xCO2 (3.7 W/m2) to ~ 7.6 degrees C.
I think it’s been pretty well established that it isn’t anywhere near that high.
major9985 says:
April 9, 2012 at 3:52 am Thank you for your response to my post.
However ot seems to me that the scenario you are describing does not need any input from CO2. You describe changes in the Earth’s albedo at various places which no doubt will increase the warming from the initial solar or orbital event. Where is the need to add CO2 to this well recognised process of a change in albedo.
My second thought is why do we chase the mouse around the house when there is an elephant in the room. The change in water vapour content will reinforce the warming from orbital change until cloud increases and sets in the negative feedback. If it was CO2 doing it there would be an endless positive feedback and we would all be toast.
Why do we chase the CO2 mouse when water vapour is well known to be the main greenhouse gas, the Earth is 70% ocean..plenty of it. It strikes me, as this is the simplest explanation as science requires, that we can ignore the minor influence of a small increase in CO2 caused by outgassing.
Disko Troop says:
April 10, 2012 at 4:13 am
“Where is the need to add CO2 to this well recognised process of a change in albedo.”
CO2 is causing the global warming and in turn the glaciers to melt. This increase in albedo would affect the temperature proxy records in the regions which lost ice. New tree growth would also have an effect on the regional proxy records. The orbit/tilt warming is only seen in the far northern hemisphere. Shakun et al paper shows that when you added up all the warming that took place, 93% of it was due to CO2.
“If it was CO2 doing it there would be an endless positive feedback and we would all be toast.”
Runaway warming isn’t real something that can happen on Earth. The warming associated with increased CO2 is best explained here http://tinyurl.com/72b4p36 and here http://tinyurl.com/6psx47k both are short reads.
Steven Mosher says:
April 8, 2012 at 10:35 pm
A couple of points. The proof that C02 causes warming is not from corelation. Its from experiemental evidence and basic engineering.
The question is how much warming.
The paper argues this.
1. The INITIAL cause of the warming was a change in orbital parameters. THEN
2. Excess warmth in NH. Then
3. ICE melting and a fresh water pulse THEN
So the ice melted before the CO2 increased
I picked this up surfing the internt:
“Glaciation
For a number of reasons, the volume of glacial ice near the poles
waxes and wanes over time. As a result, water is alternately taken from or added
to the world oceans. This can result in sea-level oscillations of up to 200
meters. For example, modern continental glaciers are 1.5 to 2.5 km thick and have
a total estimated volume of 33 million km3. If we assume the maximum volume
of Pleistocene glaciers to have been 71.3 million km3, Flint, 1971 then
the difference is 38 million km3. Using the assumption that glacial water
volume is 91.7% of the volume of sea water from which it is derived, a sea-level
drop of 106 m can be accounted for by Pleistocene glaciation. Melting of the
present Greenland and Antarctic glaciers would produce a sea-level rise of
approximately 60 meters.
The specific latent heat of fusion of ice at 0 ºC, for example, is 334
kJ.kg-1 This means that to convert 1 kg of ice at 0 ºC to 1 kg of water at 0
ºC, 334 kJ of heat must be absorbed by the ice. Conversely, when 1 kg of water at
0 ºC freezes to give 1 kg of ice at 0 ºC, 334 kJ of heat will be released
to the surroundings. (Note for educators).
“The total mean mass of the atmosphere is 5.1480×1018 kg with an
annual range due to water vapor of 1.2 or 1.5×1015 kg depending on
whether surface pressure or water vapor data are used; somewhat
smaller than the previous estimate. The mean mass of water vapor is
estimated as 1.27×1016 kg and the dry air mass as 5.1352
A 4C rise or higher this century would see the world warm almost as
much in 100 years as it did during the 15,000 years since the end of
the last ice age.”
Putting it all together, 71.3 million k3 ice *0.917 vol ice/vol
water= 65.3821 million cubic kilometers of water.
1 cubic meter= 1000 kg.
1 cubic km = 10^12 kg
65.3821 million cubic km= 65.3821*10^18 kg
Total heat to melt glaciers =65.3821 *10^18 *1000*334 kj=2.18*10^25
joules
Cp air= 1.012 joules/gram K
1012 Joules/kg K * 5.148^10^18 =5.209776 *10^21 joules
4degree increase=2.0839 *10^22 joules
So about 1000 times as much heat went into melting the glaciers at
the end of the Pleistocene as went into heating the atmosphere,
implying CO2 had only a negligible effect- A. McIntire
Alan D McIntire says:
April 10, 2012 at 5:50 am
So about 1000 times as much heat went into melting the glaciers at
the end of the Pleistocene as went into heating the atmosphere,
implying CO2 had only a negligible effect- A. McIntire
It seems to me that the heat first went into the atmosphere (regardless of its source) and then the glaciers melted. Hard to believe the mere release of CO2 into the atmosphere could propagate such melting. How much CO2 would that take? Shouldn’t we be able to take a known quantity of ice, seal it in a vessel, and then introduce CO2 and watch it melt? Isn’t that what we’re told? That CO2 warms the atmosphere?
Crispin in Johannesburg says:
April 9, 2012 at 12:41 pm
Hang on a minute! If the oceans rise 50 feet, how many million cubic miles of water is that? We have ice melting to water with no CO2, absorbing 300 ppm by the time it is seawater, and you are saying that the release of CO2 is only a miserable 16 ppm per degree?? How many tens of degrees did the ocean temperature supposedly rise?
The equilibrium between CO2 in the oceans and in the atmosphere is a matter of pressure, not a matter of quantity. Even when a ~100 ppmv increase in the atmosphere increases the partial pressure of CO2 (pCO2) of the upper part of the oceans with ~100 microatm, the total amount in the atmosphere increases with 30%, but in the ocean surface layer (the “mixed layer”) with only 3% (that is called the Revelle factor, ~10). That is because in the oceans, an increase of CO2 uptake reduces the pH, and that has a tremendous influence on the equilibrium reactions which then goes back from carbonate to bicarbonate to free CO2. Thus the 210 GtC extra CO2 in the atmosphere is in equilibrium with ~30 GtC extra CO2+bi+carbonate (total Dissolved Inorganic Carbon – DIC) in the upper ocean layers (there is about 800 GtC in the atmosphere and 1000 GtC in the oceans mixed layer). Fresh water can absorb even less CO2, as that has no buffer factor at all and any CO2 in solution will cause a sharp drop in pH and thus push it back into the atmosphere.
Further the volume in the oceans is not of interest for the pressures involved: It does hardly make a difference if you shake a 0.5, 1.0 or 1.5 liter bottle of coke: at the same temperature, the same pressure will be reached in the air above the coke, as long as there is sufficient CO2 moving from the coke to the air above.
The above also is true for the opposite effect: if there were no other fast releases (like lots of volcanoes spewing lots of CO2 in short time), the ocean temperature will give more or less CO2, until a new dynamic equilibrium between ocean releases (mainly near the tropics) and sinks (mainly near the poles) and the biosphere releases and sinks is reached.
Thus the extra CO2 comes from the oceans, not from the ice and may or may not have helped to melt the ice (which I doubt)… But anyway there is little influence of the ice volume on the CO2 levels in the atmosphere, either direction.
climatereason says:
April 9, 2012 at 1:54 pm
Ferdinand
Do the oceans outgas and absorb at the same rate when temperatures rise and fall in equal measure?
Hello Tony,
Theoretically it should be and it looks like that way, as an increase (1998 El Niño) or decrease (1992 Pinatubo) in temperature has about the same effect in opposite direction, and the ~1°C wobble in temperature over the seasons (due to the difference in land area between the NH and SH) also shows a similar effect. Both give 4-5 ppmv/°C change, from seasonal to decadal, but that is all around the trend which is going up. The ice cores show ~8 ppmv/°C in both directions, be it with long lags: ~50 years for the MWP-LIA cooling, ~800 years for the glacial-interglacial transition and several thousands of years for the interglacial-glacial transition.
Lester Via says:
April 9, 2012 at 12:05 pm
I guess I failed to make my point. I was wondering if the combination of increased pressure and aging has been proven not to affect the CO2 content of the trapped air bubbles by somehow hiding CO2. The reference you provided didn’t answer that question as the samples were not deep enough in the ice/firn to have been exposed to the presssures of typical ice core samples.
At some depth, most CO2 and deeper also N2 and O2 will be compressed in such a way that clathrates are formed and no visible bubbles remain. After substracting these deep ice core parts, they are allowed to relax for at least a year, so that most clathrates are decomposed and the bubbles are reformed. Still remaining clathrates decompose – even violently – under vacuum as used at measurement time, but remaining non-destructed clathrates may hide some of the CO2. This may influence the results.
The “normal” crushing method indeed gives some problems if clathrates are present, see:
http://medias.obs-mip.fr/paleo/taylor/indermuehle99nat.pdf where in 1999 still the crushing method was used both for CO2 levels and d13C levels.
The following describes the sublimation technique to be used on the Dome C ice core, but no publication date is given:
http://www.awi.de/de/forschung/fachbereiche/geowissenschaften/glaziologie/techniques/high_precision_d13c_and_co2_analysis/
The period mentioned for the Dome C ice core is 650,000 years of data, but meanwhile it is already 800,000 years.
Thus I have no knowledge in how far the sublimation technique was used for the latest ice cores…
Lester Via says:
April 9, 2012 at 12:05 pm
I guess I failed to make my point. I was wondering if the combination of increased pressure and aging has been proven not to affect the CO2 content of the trapped air bubbles by somehow hiding CO2.
The main problem in deep ice cores is the formation of clathrates, where CO2 (and N2 or O2) can hide, even if crushed under vacuum. That seems to give the largest error. The sublimation technique has no problem with that, but it is quite recent and I don’t know in how far that was used in the most recent ice cores.
Here a message that it will be used for the Dome C ice core, but nu publication date is given and meanwhile the Dome C CO2 data are extended to 800,000 years…
http://www.awi.de/de/forschung/fachbereiche/geowissenschaften/glaziologie/techniques/high_precision_d13c_and_co2_analysis/
For the past 160,000 years the sublimation method was used (see page 22-23) and the author gives a lot of information about clathrate formation in ice cores:
http://tel.archives-ouvertes.fr/tel-00370658/fr/
Anyway, if the problem was huge, then the oldest ice cores should show a lower CO2/temperature ratio, which is not the case for either Vostok (420 kyr) or Dome C (800 kyr).