Guest Post by Willis Eschenbach
There’s been a recent paper claiming a long-term correlation between CO2 and sea level, discussed here at WUWT. The paper implies that CO2 controls temperature and thus indirectly sea level. I thought I might follow up the comments on that thread by looking at what the ice core records actually tell us about variations in CO2. There is plenty of dispute about the ice core records, but I don’t want to touch on that here, that’s a separate discussion. Instead, let me take the ice core records as given and see where that leads us. Figure 1 shows the Vostok ice core CO2 and temperature variations.
Figure 1. Temperature and CO2 variations as per the cited data sources. Temperature variations have been divided by 2, as discussed in the text. Graph ends at 1950, most recent CO2 data is from about 2,300 years ago. Maximum temperature during the previous interglacial was about a degree and a half warmer than 1950. Photograph shows that Photo Source http://dxing.at-communication.com/en/ri1anc_vostok-base_antarctica/
These two data traces, unfortunately, are from two different records. The temperature record contains almost ten times the number of data points as the CO2 record (~ 3,100 vs ~360). Accordingly, I have smoothed the temperature data (17-point Gaussian) and then interpolated it to match the dates of the CO2 data points.
In addition, the temperature record is (presumably) a proxy for the temperature of Southern Ocean and environs. This, like all areas near the Poles, tends to experience larger temperature swings than the world as a whole. As a result, I’ve followed the common practice of making a rough estimate of global average temperature changes by dividing the Vostok changes in half.
So what can we learn from these graphs? Well, first off, we can see that this is the coldest interglacial we’ve enjoyed in the last hundreds of thousands of years. I note that humans, and indeed the majority of all species, survived the previous warmer interglacials without thermal meltdown. Next, we can tell from this data whether CO2 is causing the temperature variations, or vice versa.
Let me introduce and discuss five pieces of evidence that all show that the likely direction of the causation is that the temperature is causing the CO2 change, and not the other way around. These are 1) the linearity of the relationship, 2) the agreement with known physics, 3) the lag in the CO2 with respect to temperature, 4) the Granger causality of the relationship, and 5) the disagreement with the IPCC values for climate sensitivity.
The weakest piece of evidence is the linearity of the relationship. The outgassing of the ocean is a linear function of temperature. Looked at the other way, the temperature of the world is said to relate, not linearly to CO2, but to the logarithm of CO2 to the base 2. In the data above, the R^2 (a measure of correlation) between the temperature and the CO2 is 0.68 … but the R^2 between the temperature and the logarithm of CO2, rather than being better as we’d expect if CO2 were actually driving temperature, is marginally worse for the logarithmic relationship (0.67) than the linear. Weak evidence, as noted, but you’d expect the correlation with log CO2 to be better than linear, if not a lot better, if the relationship were actually logarithmic.
Second, the agreement with known physics. Given the data above, I calculate that for every 1°C of temperature increase, CO2 goes up by about 15 ppmv. According to this source, for every 1°C of temperature increase, CO2 goes up by about 12.5 ppmv … so the number I calculate from the data is in rough agreement with known physics.
Third, the lag. Direct correlation of the two datasets is 0.83 (with 1.0 indicating total agreement). The correlation between the two datasets is better (0.86) with a one-point lag, with the change in CO2 lagging the change in temperature. That is to say, first the temperature changes, and then the CO2 changes at some later date. Additionally, correlation is worse (0.79) with the opposite lag (CO2 leading temperature). Again, this is in general agreement with other findings that the changes in CO2 lag the changes in temperature.
Fourth, the Granger causality. You can’t establish a cause statistically, but you can say whether something “Granger-causes” something else. A Granger test establishes whether you have a better chance of predicting variable A if you know variable B. If you do, if knowing B gives you a better handle on A (beyond random chance), we say that B “Granger-causes” A.
Now, there’s an oddity about Granger causation. There are four possibilities for Granger causation with two variables, viz:
1) Variable A doesn’t Granger-cause variable B, and B doesn’t Granger-cause A
2) Variable A Granger-causes variable B, and B doesn’t Granger-cause A
3) Variable A doesn’t Granger-cause variable B, and B Granger-causes A
4) Variable A Granger-causes variable B, and B also Granger-causes A
It is this last one that is an oddity … for example, this last one is true about the CO2 variation versus temperature on a monthly basis. This makes sense, because of the seasonally varying drawdown of CO2 by plant life and the seasonal temperature variations. CO2 levels affect plant life, and plant life also affects CO2 levels, and all of that is in a complex dance with the seasonal temperature changes. So the dual causality is not surprising.
In the current example, however, the results of the Granger test in the case of the Vostok data is that temperature variations Granger-cause changes in CO2, but not the other way around—CO2 doesn’t Granger-cause the temperature.
Finally, the disagreement with the IPCC values for “climate sensitivity”. If we use the data above, and we assume that the temperature actually is a function of the CO2 level, we can calculate the climate sensitivity. This is a notional value for the change in temperature due to a doubling of CO2. When we calculate this from the Vostok data given above, we find that to work, the climate sensitivity would have to be 23°C 7°C per doubling of CO2 (corrected, thanks to commenters) … and not even the most rabid alarmist would believe that.
So those are my five reasons. The correspondence with log(CO2) is slightly worse than that with CO2. The CO2 change is about what we’d expect from oceanic degassing. CO2 lags temperature in the record. Temperature Granger-causes CO2, not the other way round. And (proof by contradiction) IF the CO2 were controlling temperature the climate sensitivity would be seven degrees per doubling, for which there is no evidence.
Now, the standard response from AGW supporters is that the CO2, when it comes along, is some kind of positive feedback that makes the temperature rise more than it would be otherwise. Is this possible? I would say sure, it’s possible … but that we have no evidence that that is the case. In fact, the changes in CO2 at the end of the last ice age argue that there is no such feedback. You can see in Figure 1 that the temperatures rise and then stabilize, while the CO2 keeps on rising. The same is shown in more detail in the Greenland ice core data, where it is clear that the temperature fell slightly while the CO2 continued to rise.
As I said, this does not negate the possibility that CO2 played a small part. Further inquiry into that angle is not encouraging, however. If we assume that the CO2 is giving 3° per doubling of warming per the IPCC hypothesis, then the problem is that raises the rate of thermal outgassing up to 17 ppmv per degree of warming instead of 15 ppmv. This is in the wrong direction, given that the cited value in the literature is lower at 12.5 ppmv
Finally, this is all somewhat sensitive to the assumption that I made early on, which is that the global temperature variation is about half of the variation shown in the Vostok data. However, this is only a question of degree. It does not negate any of the five points listed above.
w.
PS—One final thought. IF we assume that the change in CO2 is due to the temperature change, as my five arguments support, this would indicate that the degassing from temperature changes is far from sufficient to cause the recent rise in CO2. I hold that the recent rise in CO2 is anthropogenic, but others have claimed that it is not from the burning of fossil fuels, that it is (at least in significant part) due to the temperature change.
But my calculations, as well as those in the reference I cited, show that CO2 only goes up by ten or fifteen ppmv for a one-degree temperature rise. As such, this is way too small to explain the rise in atmospheric CO2, which has been on the order of 75 ppmv since 1959.
SOURCES
Willis:
Thankyou for your very fine article. Even by the high standards of your articles, it is of exceptional quality.
I concur with everything in your article but I write to dispute a conclusion in your Post Script that says
Please note that I don’t know what has caused the recent increase to atmospheric CO2 concentration, but I want to know. And anybody who thinks they know is mistaken because available data permits either an anthropogenic or a natural cause to be attributed (ref. Rorsch A, Courtney RS & Thoenes D, ‘The Interaction of Climate Change and the Carbon Dioxide Cycle’ E&E v16no2 (2005) ).
The Vostock ice core data cannot resolve the issue of what has caused the recent increase to atmospheric CO2 concentration because its temporal resolution is too low. Hence, your calculations (which assess that data) are not a relevant consideration to the issue. I explain this as follows.
Ice cores “capture” CO2 because falling snow solidifies to form the solid ice. The solidification takes decades. During those decades the ice exists as ‘fern’ with open porosity. Importantly, this does not affect the analysis in your article but it is relevant to your post script.
The fern takes several years to solidify to form solid ice which ‘traps’ the air containing CO2. The IPCC suggests the solidification takes 83 years and David Middleton suggests 30-40 years in an article on WUWT
http://wattsupwiththat.com/2012/12/07/a-brief-history-of-atmospheric-carbon-dioxide-record-breaking/
The air and its CO2 will be ‘smeared’ throughout the fern prior to the fern becoming solid ice. This ‘smearing’ is induced by diffusion and physical mixing of the air entrained in the fern. Atmospheric pressure varies with the weather, and the pressure variations will act to expand and contract the entrained air to physically mix air entrained in the fern.
The effect of the ‘smearing’ smooths the observed time series of atmospheric CO2 obtained from the ice core. The smearing is similar to conduct of a running mean on CO2 measurement data from ice which solidified in each single year.
The smoothing is severe.
If the IPCC is right that solidification takes 83 years then the Mauna Loa data cannot be compared to the Vostock ice core data: the measurements of atmospheric CO2 at Mauna Loa have only been conducted for the 55 years since 1958. And if Middleton’s minimum closure time estimate of 30 years is correct then fluctuations similar to the rise in the Mauna Loa data would be more than halved in the ice core data.
Of course, the smoothing would not overcome the order-of-magnitude difference which you mention in your PS. However, that difference assumes that temperature is the only reason for a change to the equilibrium of CO2 concentration between ocean and air. Beck’s data suggests that short-term (i.e. less than 40 years) ‘spikes’ in atmospheric CO2 concentration may have happened in the recent past (e.g. 410 ppmv around 1940) and the fluctuations are not always directly related to temperature: see
http://www.bing.com/search?q=Beck+CO2&form=TSHMHP&mkt=en-gb&qs=n&sk=&pc=MATB&x=115&y=19
Such short-term variations would not be discernible in the smoothed ice core data. And there are possible explanations for them. As example, I provide one such explanation.
CO2 is in various compartments of the carbon cycle system, and it is exchanged between them. Almost all of the CO2 is in the deep oceans. Much is in the upper ocean surface layer. Much is in the biosphere. Some is in the atmosphere. etc..
The equilibrium state of the carbon cycle system defines the stable distribution of CO2 among the compartments of the system. And at any moment the system is adjusting towards that stable distribution. But the equilibrium state is not a constant: it varies at all time scales.
Any change to the equilibrium state of the carbon cycle system induces a change to the amount of CO2 in the atmosphere. Indeed, this is seen as the ‘seasonal variation’ in the Mauna Loa data. However, some of the mechanisms for exchange between the compartments have rate constants of years and decades. Hence, it takes decades for the system to adjust to an altered equilibrium state.
The observed increase of atmospheric CO2 over recent decades could be an effect of such a change to the equilibrium state. If so, then the cause of the change is not known.
One such unknown variable is volcanic emission of sulphur ions below the sea decades or centuries ago.
The thermohaline circulation carries ocean water through the deeps for centuries before those waters return to ocean surface. The water acquires sulphur ions as it passes undersea volcanoes and it carries that sulphur with it to the ocean surface layer decades or centuries later. The resulting change to sulphur in the ocean surface layer alters the pH of the layer.
An alteration of ocean surface layer pH alters the equilibrium concentration of atmospheric CO2.
A reduction to surface layer pH of only 0.1 (which is much too small to be detectable) would induce more than all the change to atmospheric CO2 concentration of 290 ppmv to ~400 ppmv which has happened since before the industrial revolution.
I don’t know if this volcanic effect has happened, and I doubt that it has. But it demonstrates how changed equilibrium conditions could have had the observed recent effect on atmospheric CO2 concentration whether or not there was a change in temperature and whether or not the anthropogenic CO2 emission existed.
Of course, none of this detracts from the analysis in your fine article: it is only relevant to your post script and its stated assumption.
Richard
We should be thinking of Vegetation as playing a role in the CO2-feedback on temperature.
The more Carbon that is cycling through plants each year, the more Carbon and CO2 that will be cycling through the atmosphere each year. Therefore, the more vegetation, the more CO2 in the atmosphere. The warmer and wetter it is, the more vegetation there will be and thus, the circle is completed. In addition, the mix of vegetation plays a role as well.
Right now, more than half of the Carbon cycle is from Vegetation. During the ice ages, C3 bushes and trees died back considerably and most of the land surface was composed of grassland, desert, tundra and ice. Less C3 plants, less Carbon cycling through the system each year.
C4 grasses are actually a very efficient sink of Carbon into soils. So more grass, less CO2. [C4 grasses also evolved between 32 and 24 million years ago. By coincidence, there was also two step-changes downward in the CO2 content in the atmosphere at 32 and 24 million years ago. CO2 went from 1,400 ppm down to 800 ppm at 32 Mya and down to 270 ppm at 24 Mya ].
I’m just guessing, but the CO2-feedback on temperature is probably about half and half, oceans and vegetation/soils.
This 800 year lag between temperature and co2 rise only happens as a ‘trigger’ to end the last ice age, due to orbital forcing. And then as co2 becomes a forcing factor to temperature it becomes the largest influence on temperature to end the ice age Do the Vostock cores not prove this?
crosspatch says:
January 3, 2013 at 8:16 pm
it would take about 600-800 years for the ocean to completely give up all the CO2 it absorbed during the LIA.
As the quantity out of the air absorbed by the oceans during the LIA is negligible compared to the total amount of carbon in the deep oceans, that hardly matters. During the LIA, the atmosphere had some 6 ppmv less CO2 than during the MWP. That is about 12 GtC less CO2. The deep oceans contain some 56,000 GtC… Only temperature matters in this case.
Dr Burns says:
January 4, 2013 at 2:00 am
Various areas of the ocean at different times of the year absorb, as other areas desorb, to a total of almost 20 times man’s CO2 output. A slight imbalance might be sufficient to account for recent increases.
There is a good overvieuw of the CO2 absorption/release rates over a year with a lot of background information at:
http://www.pmel.noaa.gov/pubs/outstand/feel2331/exchange.shtml and following pages. Be it that the area/wind information is not completely correct. But the main direction is.
Even if the temperature e.g. at the poles, the sink places, dropped 1°C more than average, that doesn’t make much difference: the current CO2 level at about 400 ppmv gives about the same partial pressure of 400 microatm everywhere over the oceans (minus a few % due to water vapour). The pCO2 of seawater at near freezing is about 150 microatm. That gives a certain absorption rate, depending mainly of mixing speed by wind. With 1°C less temperature, the 150 microatm drops to 134 microatm, increasing the absorption of CO2 with some 6%. That reduces the CO2 content of the atmosphere, but as the CO2 pressure drops, more is released at the equator and less is absorbed near the poles. At last somewhere halfway the extra pressure drop at the sink places (a drop of about 8 ppmv in the atmosphere), a new dynamic equilibrium is reached…
Thus local temperatures matter locally, but the global, area weighted average temperature is what matters.
I also find the claims that ice cores trap an exact representation of the air at the time the core is dated, extremely dubious. Beck and Jaworowski have been dismissed too easily.
Both are dismissed on firm grounds: many of the historic measurements were taken at completely unsuitable places and the late Jaworowsky’s knowledge ended in 1992 and was completely refuted by the work of Etheridge e.a. from 1996 on three Law Dome ice cores… See:
http://www.ferdinand-engelbeen.be/klimaat/beck_data.html
and
http://www.ferdinand-engelbeen.be/klimaat/jaworowski.html
If tou use the dust record, EPICA C, as Log)dust). You get a better correlation with temperatue over the last400 ky. In addition, dust changes before temperature.
There is a nice figure showing changes in Argon, as well as CO2 and Temperature. The Ar/N2 tracks temperature much bettwer than CO2.
Willis – I admired the hell out of you. The CO2 sensitivity argument is beautiful, forehead-slapping stuff. Doh! ;-D
But temperature rise by itself isn’t sufficient to explain the rise in CO2. Besides human input of CO2 (easy to default to this, confirmation bias, can’t think of anything else so this is the answer) – what other factors could explain? Changing CCD depth? What if the ‘ocean’ isn’t a single, well-mixed tank?
I am not understanding where you get the 23c sensitivity here. In the previous interglcial, temperature went from -4.5 to 1.4 as CO2 went from 195 to 270. Doesn’t that imply 8 to 10 C for a doubling?
Engelbeen: “An interesting part of the Vostok record is the end of the previous interglacial, the Eemian: while CO2 and temperature go up in parallel, temperatures go down while CO2 levels remain high. At the moment that the temperature is again at a new minimum (and ice sheet growth at a maximum). CO2 starts to go down. The 40 ppmv drop in CO2 level has no observable effect on the temperature record… See:
http://www.ferdinand-engelbeen.be/klimaat/eemian.html“
This is an extremely key point and is ignored by Mosher and others who are still trying to tie CO2 to temperature. While the “cartwheel paper” paper Mosher references (my name for it because it seems like they are turning cartwheels to find some plausible reasoning that CO2 lead temps) shows one possible explanation, it ignores the back end of the cycle where temperatures lead CO2 at a much longer timescale.
S. Meyer says:
January 3, 2013 at 11:35 pm
Professor Hayden at the ICCC7 reported a very striking 99% correlation between sea surface temperature anomalies and atmospheric log(CO2 ratio).
For a short period, yes, but that disappears if you extend the period back in time. Compare the emissions and temperature graphs with the increase in the atmosphere over a longer time span:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/temp_emiss_increase.jpg
The correlations over the full period 1900-2004 are here:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/acc_co2_1900_2004.jpg
and
http://www.ferdinand-engelbeen.be/klimaat/klim_img/temp_co2_1900_2004.jpg
The latter still shows some correlation, but a huge change in temperature of halve the scale has a small influence on CO2 levels, while the total change in temperature over 104 years should have a huge influence. As the ice cores with a medium resolution (21 years for the Law Dome DSS core) still show a small influence of about 8 ppmv/°C between the MWP and LIA, the strong influence of temperature on CO2 levels is entirely spurious…
Certainly. This is called feedback. Postitve feedbacks amplify, negative feedbacks damp the cause.
LearDog:
At January 4, 2013 at 4:57 am you ask
I answer: anything which alters the equilibrium state of the carbon cycle.
One such possible alteration is provided in my above post at January 4, 2013 at 3:21 am.
Please note that I provided that post because I suspected that Willis’ post script to his article could deflect from discussion of the forcing/feedback analysis in his excellent article and – instead – induce discussion of the cause of recent rise in atmospheric CO2 concentration. My purpose in providing that post was to explain that the cause of the recent rise cannot be resolved with now available data so discussion of it would be a pointless distraction from the analysis in Willis’ article.
Richard
richardscourtney says:
January 4, 2013 at 3:21 am
And if Middleton’s minimum closure time estimate of 30 years is correct then fluctuations similar to the rise in the Mauna Loa data would be more than halved in the ice core data.
The smearing within the ice cores mainly is near closing depth, where the density of the firn increased so much that exchanges with the open air are firmly restricted. Above closing depth there still is a lot of exchange with the above air by diffusion over the period to closure (40 years in the case of Law Dome). That makes that the average age of the air mixture at closing depth of the high resolution Law Dome ice cores is only 7 years older than in the above atmosphere. As the closing proces also takes a few years, the resolution of the bulk of the air in the bubbles is about 10 years, with some recent air and some older air, a long tail of up to 40 years. See:
http://courses.washington.edu/proxies/GHG.pdf
Fig. 11 gives the theoretical gas age distribution of the Law Dome ice cores, where the averages are confirmed by in situ measurements.
There is a 20 years overlap between the Law Dome ice core data and atmospheric data at the South Pole:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/law_dome_sp_co2.jpg
That makes that the resolution of the CO2 levels (including the changes in 13C/12C and 14C/12C ratio’s) is by far enough to show any one-sided peak of 20 ppmv during one year or a sustained change of 2 ppmv over 10 years at the accuracy of the measurements in the Law Dome ice cores. Even a one-sided event as the current 100+ ppmv increase over the past 160 years (80 ppmv over the past 50 years) would show up in the Vostok and Dome C data…
Willis,
I call your attention to slides 51 through 56 of http://www.kidswincom.net/climate.pdf which is a similar analysis of the ice core data.
If CO2 lags ocean temps by 800 years, then we have a giant low pass filter and one will find little correlation between short term temperature changes and CO2 levels. The current rise in CO2 has more to do with the increase in temperature since the LIA.
Perhaps the thing about the Vostok graph which most non-specialists would be interested in hearing about is why the exit from ice ages is very rapid, but the descent into them is rather slow.
This does rather suggest that a unique input factor provides the stimulus to trigger exit, whereas the ice age stable state is merely reverted to through passive evolution of the earth back to base camp.
The key question is what that trigger/those triggers are??
Willis writes “They would not melt instantaneously, so deglaciation would necessarily lag temperature rise by some years. Since the deglaciation and CO2 rise are contemporaneous, we can conclude that the NH temperature rise must have preceded the CO2 rise, and not the other way around as they claim.”
I always find its the other end of the cycle to be most convincing (and least discussed by AGWers) When it begins to cool, CO2 continues to go up and maintains that lag. This can only mean that something else is driving the cooling and its so powerful that the current and increasing level of CO2 is overcome by it.
So “something else” forces the warming at the beginning and “something else” forces the cooling at the end and right the way through to at least when the CO2 levels have dropped again but more likely through to the beginning of the next interglacial and we’re supposed to believe that the “something else” takes a back seat in the middle of the warming bit to leave CO2 to drive the continued warming? Its a joke and a bad case of wishful thinking to support a theory.
History clearly shows us that CO2 comes along for the ride and that the other non-CO2 “natural” forcings are stronger than CO2.
I’m surprised more discussion of land use changes hasn’t occurred. We’ve seriously reduced the ability of the biosphere to absorb the CO2 added to the atmosphere. IIRC, the satellite survey of CO2 levels showed highest levels in 3rd world countries that have experienced a lot of deforestation.
“climate sensitivity would have to be 23°C per doubling of CO2”
When you get an answer that absurd, it might be prudent to ask first if the calculation was done correctly. Over the last termination, from your graph temperature increased by ~4C while CO2 increased by about 50% from 180 to 270ppm. This implies that a doubling of CO2 from 180 to 360 ppm would cause an 8C temperature increase, not a 23C increase.
This is still large relative to the 3C IPCC estimate, but that estimate excludes some slow feedback mechanisms like vegetation change and icesheet decay. Including these gives a higher earth system sensitivity of perhaps 3-6C. Still smaller than the 8C calculated above, but the 8C is not due to CO2 forcing and feedbacks, but to insolation forcing and feedbacks, so it is unreasonable to attribute it all to CO2.
Your Granger causality analysis is erroneous as it assumes that Vostock temperatures are in phase with global temperatures. At the first approximation they are – interglacials are approximately simultaneous in both hemispheres. But you just need to compare the details of Greenland and Antarctic records over the last termination to show that global temperatures cannot be adequately represented by a single location. Warming in Greenland started later than in Antarctica, so even if temperature leads CO2 in Antarctica (and that is in doubt with newer age models) it does not demonstrate that temperature leads CO2 on a global basis.
On the final episode of Star Trek the Next Generation, Picard and the Enterprise battle an anomaly that grows backwards in time, eventually effecting the future of humanity by preventing life on earth from ever starting. So if Hollywood teaches us anything, the future can change the past.
Otherwise, rising CO2 levels can’t cause the temperatures to increase first.
In the ace ages, CO2 changes from 185 ppm (glacial maximum) to 270 ppm (average interglacial at +1.0C) – while temperatures change by about 6.0C in an average glacial-interglacial transition.
5.35 Ln(185/270) = 2.2 W/m2 (add another 0.5 or so for CH4 and N20 GHGs for 2.7 W/m2 total).
But what was the Ice Albedo forcing? This is the pea under the thimble used by the pro-AGW climate scientists. If you deliberately under-state this forcing, then you can increase the CO2 climate sensitivity.
No Albedo change and the CO2 sensitivity is 6.0C for 2.7 W/m2 or 2.2C/W/m2.
But all those glaciers, sea ice and desert/grasslands and a -6 W/m2 increase in low cloud cover (IPCC feedback estimates) do not result in Zero Albedo change. It has to be a very large number.
I’ve only found TWO numerical estimates of the Ice Albedo forcing in the ice ages. -12 W/m2(surface only and this paper did not pass peer review) and Hansen’s deliberately low -3.5 W/m2.
You cannot estimate CO2 sensitivity in the ice ages or in the paleoclimate without having good Albedo estimates. In fact, you need this for every 500 year tranche of time going back 4.4 billion years in order to answer the question. Maybe there is also a CO2 to Albedo feedback and maybe there is a Albedo to CO2 feedback. We have the CO2 estimates but climate science refuses to put the Albedo numbers on paper in a transparent way. My estimate for the ice ages Albedo is -17 W/m2 based on my Albedo model.
Ice Age forcing = -17 W/m2 Albedo + -2.7 W/m2 GHGs = -19.7W/m2/6.0C = 0.3C/W/m2
Implying 0.3C/W/m2 * 4.2 W/m2 (CO2/GHG doubling) = 1.3C CO2 sensitivity
Richard Telford, wise up. There is no empirical evidence supporting the IPCC’s wild-eyed estimate. They simply picked a scary number and ran with it.
You assert:
“Your Granger causality analysis is erroneous as it assumes that Vostock temperatures are in phase with global temperatures.”
That is wrong. Both Greenland ice cores and Antarctic ice cores show high correlation. In other words, they are in phase.
Face the fact, Telford, that ∆CO2 is caused by ∆T, not vice versa. The alarmists’ premise is backward, therefore their conclusion is wrong. It is that simple.
@S. Meyer:
If there are other sources of CO₂ which increase its partial pressure at the ocean’s surface the ocean would not be able to outgas more. So the correlation woud be the same as if the ocean outgassed this CO₂. That means also that the ocean is a strong regulator in that regard.
FerdiEgb:
I am responding to your post at January 4, 2013 at 5:43 am so you can see I have not ignored it.
However, I am not replying except to say that your logic is very flawed so your conclusion is fallacious. The reality is as I said in my post at January 4, 2013 at 3:21 am.
That is my final comment on the matter because, as I said (at January 4, 2013 at 5:15 am) of my post at January 4, 2013 at 3:21 am
Whether you or I am right about the ice core data does not affect Willis’ analysis in any way: it is only relevant to the cause of recent rise in atmospheric CO2 concentration.
Richard
The title of the article “Does The Effect From The Cause Affect The Cause?” nicely illustrates the nonsensical contortions that are needed to squeeze an AGW story out of a record of CO2 lagging temperatures. (It is also a good example of the two different spellings of “effect/affect” used in the correct way unlike many WUWT posters.)
A lot of trolls have swooped in as usual for a CO2 related thread. The issue of feedbacks is raised but trying to understand feedbacks in climate without a framework of a nonlinear/nonequilibrium dynamic system is like trying to understand chemistry without the periodic table. If we are to believe that temperature first increases for some unknown reason, then causes CO2 to increase, and that CO2, having been caused by the temperature increase, then changes from being the forced to the forcer on account of a strong positive feedback and usurps the leading role… then, a very strong positive feedback would be needed to even come close to causing this strange forcing reversal. Such a strong positive feedback would impose a simple monotonic oscillation on the system.
The heart-beat is an example is a nonlinear oscillation driven be strong positive feedbacks, the result is a regular simple oscillation. (Things which interfere with this simple oscillation making it irregular are the subject of cardiac pathology, there is a lot of published nonlinear maths on the subject.) Conversely negative feedback constitutes damping and introduces complexity to the nonlinear oscillation. Thus the signature of an oscillation dominated by strong positive feedback is clear, a monotonic oscillation, and this is not seen in the climate record. (What is actually seen suggests competition between a number of positive and negative feedbacks).
This proposed CO2-temperature two-step is rather like a biologist proposing that the head and the tail of a dog could exchange places on the animal during the dog’s lifetime.