Guest Post by Willis Eschenbach
There’s a new study entitled “Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation”, Shakun et al. (paywalled, hereinafter Shakun2012). The paper claims to show that in the warming since the last ice age, CO2 leads temperature. Anthony wrote about it in his post “A new paper in Nature suggests CO2 leads temperature, but has some serious problems“. The press release says (emphasis mine):
A new study, funded by the National Science Foundation and published in the journal Nature, identifies this relationship and provides compelling evidence that rising CO2 caused much of the global warming.
Lead author Jeremy Shakun, who conducted much of the research as a doctoral student at Oregon State University, said the key to understanding the role of CO2 is to reconstruct globally averaged temperature changes during the end of the last Ice Age, which contrasts with previous efforts that only compared local temperatures in Antarctica to carbon dioxide levels.
“Carbon dioxide has been suspected as an important factor in ending the last Ice Age, but its exact role has always been unclear because rising temperatures reflected in Antarctic ice cores came before rising levels of CO2,” said Shakun, who is a National Oceanic and Atmospheric Administration (NOAA) Post-doctoral Fellow at Harvard University and Columbia University.
“But 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,” Shakun added.
The good news about the paper is that they have provided the temperature records (Excel spreadsheet) for the 80 proxies used in the study. My compliments to them.
Me being a suspicious fellow, however, I figured “trust but verify”, so I plotted up the temperature records that they used. I always begin with the original data, without any additions or distractions. Figure 1 shows the data that they used.
Figure 1. Records and types of proxies used in the Shakun2012 study
As you can see, some of the ice core records are down where we’d expect them to be, well below zero. Those are the GRIP and NGRIP records from Greenland. But there are some oddities about these proxies.
One problem that is immediately obvious is the timing. The peaks for the previous interglacial period (the Eemian, about 130,000 BC) don’t line up. That may not be much of a problem, though, because the paper is about the warming from the most recent ice age.
One oddity is that there are ice core records that are right around freezing (0°C). In addition, there are pollen records around freezing as well. This shows that we actually have a mix of anomaly records and actual temperature records. This is not a problem, just an oddity.
Next, let’s take a look at the location of the proxies. Figure 2 is from their paper:
Figure 2. Location of the proxies used in the Shakun2012 study.
This looks good, it looks like there may be passable coverage. So let’s look at the last glacial transition, we’ll look at the time since 26,000 BC.
Figure 3. Same data as in Figure 1, but showing the warming from the last ice age.
Here, you can see the Antarctic ice core records (yellow and green lines near 0°C) mentioned above that are shown as variations, with the modern value taken to be 0°C.
Some other observations. Greenland (yellow temperatures at bottom) seems to be an outlier in terms of change in temperature. The Antarctic ice cores and all of the rest of the records show much less warming since the ice age.
In order to compare these eighty proxies to each other, what we need to do is to “standardize” them. This means to first subtract the mean (average) of each proxy from the individual values. Then each of the individual values is divided by the standard deviation of the entire record for that proxy. The result will vary between about -3 and 3. Standardizing preserves the shape and timing of the data, it just makes all the proxies have a mean of 0 and a standard deviation of 1.
Next comes the part that the authors of these multi-proxy studies seem to have generally ignored. This is to look at each and every one of these proxy records and think about what they seem to mean. I’ll look at them sixteen at a time. Figure 3 shows the first sixteen of the Shakun2012 proxies.
Figure 4. Proxies from the Shakur2012 study. All of these cover the period from 26,000 BC to 1980 AD. Vertical dashed lines show the minimum (light blue) and maximum (dark red) values for the each proxy. Minimum and maximum times rounded to nearest 100 years. Colors as shown in Figure 1. Click for larger version.
NOTES BY NUMBER
1, 2: These are the Greenland ice cores. They show a warming of 32 and 27 degrees respectively, which is much more than any other proxy. Warming begins earlier than 20,000 BC.
4: The warmest date is at 1200 AD.
6: Warmest date is 1000 AD. Warming doesn’t start until 12,600 BC.
9: Maximum warmth is at 14,600 BC.
15: Very unusual shape, 11° warming.
Figure 5. Same as Figure 4, proxies from the Shakur2012 study. All of these cover the period from 26,000 BC to 1980 AD. Vertical dashed lines show the minimum (light blue) and maximum (dark red) values for the each proxy. Minimum and maximum times rounded to nearest 100 years. Click for larger version.
19: Warming doesn’t start until 10,800 BC
21: Maximum warmth precedes maximum cold.
28. Maximum doesn’t occur until 400 BC.
30. Maximum doesn’t occur until 1400 AD.
31. Maximum doesn’t occur until 2400 BC.
32. Maximum doesn’t occur until 1500 AD.
Figure 6. Same as Figure 4. Click for larger version.
34: Maximum at 1600 AD
35: Maximum at 14,000 BC
36: Strange shape, constant warming until the present.
42. Maximum not until 400 AD.
44: Warming until the end of the record in 8200 BC.
Figure 7. Same as Figure 4. Click for larger version.
50: Maximum not until 1100 AD.
51: Constant rise beginning to end.
52: Large drop and rise after maximum warmth.
53: Rises beginning to end.
54: Rises beginning to end.
58: Maximum not until 1300 AD.
59: Maximum not until 1600 AD.
60: Large rise in 1100-1200
Figure 8. Same as Figure 4. Click for larger version.
67: Warming starts at 25,900 BC.
68: Warming only one tenth of a degree
76: Warming occurs almost instantaneously
Discussion
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. In some proxies it starts in 25,000 BC, in others it starts in 15,000 BC. Sometimes the warming peaks as early as 14,000 BC, and sometimes around 5,000 BC or later. Sometimes the warming continues right up to the present.
The problem becomes evident when we plot all of these 80 standardized proxies together. Figure 9 shows all of the standardized temperature traces.
Figure 9. All 80 temperature proxies from Shakun2012. Colors as shown in Figure 1.
Now, there’s plenty of things of interest in there. It’s clear that there is warming since the last ice age. The median value for the warming is 4.3°C, although the range is quite wide.
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.
Final Conclusion
The reviewers should have taken the time to plot the proxies … but then, the authors should have taken the time to plot the proxies.
w.
[UPDATE] A hat tip to Jostein, who pointed in the comments to the Shakun Nature paper being available here.
[UPDATE] Some folks wanted to see the CO2 data they used on the same timescale. Other folks said the colors in Figure 9 were misleading, since ice cores were printed on top, obscuring others below. We’re a full-service website, so here’s both in one:
Figure 10. All proxies, along with CO2 record used in Shakun2012.
My best to all,
w.
I decided to take a look at the various proxies by proxy type. There are ten different kinds of proxies.
Figure 11. Proxies averaged by type.
A few notes, in no particular order. The ice core records are similar, but the timing is different.
Foram assemblages seem to be useless. The same is true of the Tex86 proxies.
Pollen has a consistent signal, but the warming doesn’t start until about 10,000 BC.
MBT/CBT perfectly exemplifies the problems with this approach. Which one are we supposed to believe? Which one is it that is lagging the CO2?
Finally, the Mg/Ca and the UK’37 proxies kinda sorta have the same shape, but no uniformity at all regarding the timing of the rise.
Let me close with a black-and-white version of the above chart. This allows you to see where the denser areas are located.
Figure 12. Proxies by type. Blue line shows CO2 data as used in the study.
Note the difference in the underlying shapes of the different types of proxies, and the differences in their timing with respect to the rise of CO2.
Next, note that the CO2 record they are using is from Antarctica. That is the reason for the good fit with the single “ice core ∂18O and dD” proxy (left graph, second row) and the “ice core dD” (center graph, second row). Both of those are Antarctic records as well.
Also, as you can see, even within each proxy type there is no unanimity regarding the timing of either the onset or the end of the warming from the last ice age.
CO2 is the blue line … so was the warming before or after the blue line?
w.
[UPDATE]—The discussion continues at Shakun Redux: Master tricksed us! I told you he was tricksy!
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The ice core data represent the ice that didn’t melt during a “deglaciation”. Think about it.
Arno Arrak says:
April 6, 2012 at 6:32 pm
Sorry, I agree with Anthony. I doubt many people are reading your comments, it’s hard to figure out the sentence structure.
Do you want people to read your comments? Then you need to write text that pulls them in and reinforces that attraction with every new thought. I didn’t read your one paragraph tome – a big, solid text post that cries out to be split into multiple paragraphs.
His blog, his standard. If you don’t like it, feel free to make one of your own.
-Ric
Al Fin says:
April 6, 2012 at 9:43 am
Nice punchline, Willis. Too bad members of the orthodoxy are not allowed to think for themselves. They might save themselves some embarrassment.
You have to have a conscience before you can be embarrassed…
michael hart says:
April 6, 2012 at 10:29 pm
OK, I thought about it … now what?
w.
And only six ice-core proxies. I wonder how many unique combinations of proxies Shakun et. al. tried, which ones were discarded etc. before settling on the 80.
Does any one know approximately how many proxies are actually available for use covering this (deglaciation) event?
Is it not obvious Willis has taken all the temperature records and not shown them as a global temperature? Even if at different times in different areas of the planet temperatures did not match up, you simply take an average over all..
A good example of what proxies can indicate, and what they can’t;, they are proxies after all, and they don’t all respond the same way, otherwise they wouldn’t be ‘proxies’ would they, they would be what are called measurements.
Too much of this sort of averaging between apples and oranges going on in the literature, to make proxies say whatever you want them to say.
“Take the blue pill, and you can believe whatever you want to believe”. Too many academics have taken the blue pill, I suspect.
Willis, here is a Greenland core
“Precise timing and characterization of abrupt climate change 8200 years ago from air trapped in polar ice”
Kobashi et al.,
http://icebubbles.ucsd.edu/Publications/Kobashi_8k_QSR.pdf
They have measured the entrapped Argon. As it is an inert gas, the levels of Ar should only respond to the oceanic temperature altering the aq/air partition coefficient.
The 8,200 event is also found contemporaneously in the South Atlantic; lovely pollen and carbon/sulfur records
South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event
Ljung e al.,
http://www.clim-past.net/4/35/2008/cp-4-35-2008.pdf
This event would be the best bet to establish the true data of each level in a core.
Hey “UK”, remember, over here In the US, we speak softly but carry a BIG stick. 🙂
“You’re averaging a lemon and a watermelon, it’s meaningless.”
Did you know that an orange is a cross between a mandarin, and a pumello? It isn’t actually an original, naturally occuring fruit in the wild, which I’ve always found curious.
On another note, I learnt an interesting principle in chemistry 1 years ago, about combining, or averaging different things, to make a product. In chemistry, a compound of two different elements doesn’t necassarily have properties in any way similar to, or an ‘average’ of, its constituent elements. So water’s (H20) properties are totally unlike 2 single hydrogen atoms and one oxygen atom. Same goes for e.g. salt-NaCl-which as a compound has properties nothing like its constituent atoms, Na, and Cl, one of which is highly toxic-Cl.
Simply making the point that combining different things together doesnt necassarily mean you get something which is anywhere near an ‘average’, of the two. You can get a different beast altogether.
Poor proxy siteing, watermelons, cantaloup, squash, and radishes averaged, lack of thought and/or understanding of the individual data sets, what could go wrong with a recipe like that?
More bogus science pops out during another run-up to “Critical World Climate Meeting.”
More and more I think of Willis as THE FIREMAN, ’cause he sure puts out the CAGW fires. No, he’s not perfect, but when he makes a mistake, he admits it and goes on. But the vast majority of the time, he’s dead on, and thinking those marvelously clear, unconventional thougts about our world’s climate data, and I’m learning – admittedly five rows back from the front – from a Master of Science Fu.
Keep it up Willis, I’ve got so much more to learn. Thank you again.
————–
Kadaka (KD Knoebel) asks: What about the Stott2007 paper “Southern Hemisphere and deep sea temperature rise led deglacial CO2 rise and temperature warming”?
————–
Kada, that Shakun2012 article *DOES* discuss the Stott2007 article, and it discusses also a similar article by Hubers et al “Antarctic temperature at orbital timescales controlled by local summer duration” (2008).
In essence Shakun2012 argue — very reasonably IMHO — that because northern hemisphere temperature proxies substantially lead *ALL* southern hemisphere temperature proxies (including in particular the Stott 2007 and Hubers2008 proxies), the dominant climate-change drives are to be found in the northern hemisphere.
Willis, this point would be strikingly evident in your own analysis … if only you would color-code your data by latitude (per Shakun2012 Figure 5, for example).
Just to mention, it looks peculiar when WUWT criticizes an article for poor plotting practices … and yet WUWT the chooses to plot the data by methods that obscure the data’s most striking feature … namely, the north-to-south time-ordering of temperature rise.
For the above reasons, it has become plain that the WUWT/Eisenbach analysis *DOES* broadly verify with the Shakun2012 analysis. So just plot the data the best and clearest way, Willis … you’ll feel better for it, and WUWT will be better for it.
It would at least seem to be relatively easy to determine if temps precede CO2 changes. Take your paper-thin slice of ice from the ice-core just before the end of the glacial period, say 15 – 20 kyrs ago & analyze. Keep taking thin slices forward in time. When does the dO18 (temp proxy) begin rising? When does CO2 begin rising? I understand there’s a resolution issue — the thinnest slice may represent several hundred yrs, more or less. I’d assume that’s already been done & it was determined that dO18 started changing before the CO2 & that’s where the original conclusion that temps preceded CO2 came from. Is Shakun saying they got it backwards?
PS. Yes, I understand that temp drops at the end of interglacials occurred quite clearly before CO2 drops (by 1000-2000 yrs). I’m talking about the interglacial beginnings, which seem less clear.
Willis,
I can’t find any CO2 time series data in their S2 supplemental file “nature10915-s2.xls”. Can you point me to the source URI for the CO2 data?
RobRoy says: April 6, 2012 at 8:49 am
“It is my layman’s understanding that seawater, as it warms, releases CO2 dissolved therein. As seawater warms its ability to keep CO2 in solution decreases. This leaching of CO2 as the oceans warm is a great explanation for the correlation between temperature and atmospheric CO2 concentration. It explains why CO2 lags warming. Warming first then atmospheric CO2 increase. This is provable in a laboratory..”.
____________
First of all Rob, you are possibly on the right track – see Henry’s Law (1803) and the bit about temperature.
http://en.wikipedia.org/wiki/Henry's_law
Next, Shakun et al is nonsense. The paper is a veritable cornucopia of apples and oranges, grapes and bananas – and let’s not forget the watermelons.
It is interesting how often the global warming alarmists choose to ignore the Uniformitarian Principle AND Occam’s Razor.
CO2 lags temperature at all measured time scales from ~~600-800 years in the ice core records on a long temperature-time cycle, to 9 months on a much shorter time scale.
http://icecap.us/images/uploads/CO2vsTMacRae.pdf
We really don’t know how much of the recent increase in atmospheric CO2 is natural and how much is manmade – possibilities range from entirely natural (~~600-800 years ago was the Medieval Warm Period) to entirely manmade (the “material balance argument). I lean towards mostly natural, but I’m not certain.
Although this questions is scientifically crucial, it is not that critical to the current “social debate” about alleged catastrophic manmade global warming (CAGW), since it is obvious to sensible people that IF CO2 truly drives temperature, it is an insignificant driver (climate sensitivity to CO2 is very low; “feedbacks” are negative) and minor increased warmth and increased atmospheric CO2 are both beneficial to humanity AND the environment.
In summary, the “climate skeptics” are trouncing the warming alarmists in the “mainstream CAGW debate”.
Back to the crucial scientific question – is the current increase in atmospheric CO2 largely natural or manmade?
Please see this 15fps AIRS data animation of global CO2 at
http://svs.gsfc.nasa.gov/vis/a000000/a003500/a003562/carbonDioxideSequence2002_2008_at15fps.mp4
It is difficult to see the impact of humanity in this impressive display of nature’s power.
All I can see is the bountiful impact of Spring, dominated by the Northern Hemisphere with its larger land mass, and some possible ocean sources and sinks.
I’m pretty sure all the data is there to figure this out, and I suspect some already have – perhaps Jan Veizer and colleagues.
Best wishes to all for the Easter Weekend.
So Willis, are you going to write this up as a comment and submit to Nature? You should.
rgb
P.S. — thanks for the kind words about reading my posts, and I assure you that it is mutual and then some. I just wish I had more time to do some of what you are doing…
P.P.S. — what we really need is to get a clue as to why the current ice age — the one that started 2.5 million years ago — started. Without understanding this, trying to understand the physics underlying the current 110 ky bistability is pointless, as we do not understand the baseline of EITHER branch. I’m very tempted to try to write a simple cubic nonlinear differential model to try to model the base behavior, and then add various kinds of periodic noise to see if it can provide a clue concerning the quasiperiodic oscillations.
One very interesting thing revealed by this data is that (at least as far as this mostly coastal data is concerned) the Holocene peak occurred almost immediately after the warming that ended the Younger Dryas (that is now more visible in the B&W data, thanks, although I suspect that the downturn is dominated by the antarctic data from the colored plot — still something very interesting to look at here, separating out the datasets into ones that have a YD downturn and ones that apparently do not!). It would be extremely interesting to compare this temperature curve to Ushokin:
http://solarphysics.livingreviews.org/Articles/lrsp-2008-3/fulltext.html
(section 4.1, esp. figure 17). This figure more or less directly contradicts Lief’s litany that there was nothing unusual about the 20th century solar maximum. However, the really interesting thing about the temperature itself is that it has been gradually reducing since the peak — what’s up with that? The timescale of the decrease is millennial, a very slow, very gradual degradation. What kind of process in the Earth’s energy balance could be responsible for this? Are there critical points in the decrease?
What is missing, of course, is any evidence whatsoever that there is a third, still warmer, stable phase accessible in the Earth’s climate system. Its stable warm phase 5 million years ago was perhaps a degree warmer than the present. If we could stabilize the climate out of the ice age about this warm phase attractor, it would be totally amazing. Otherwise our ass is hanging out over a deep freeze that something could trigger, where we have no good idea of what that something is.
rgb
Thanks Willis, I learned a lot. Very interesting commentary too, thanks, almost everyone.
Ed Scott says:
April 6, 2012 at 8:26 am
April5, 2012
Climategate Heads to Court
By S. Fred Singer
http://www.americanthinker.com/2012/04/climategate_heads_to_court.html
Thank for posting this link; it is a good article.
From Skepticus on April 7, 2012 at 7:02 am:
Do you have a copy of Shakun2012 or was that mentioned elsewhere?
Stott 2007 and Hubers 2008 were too inconvenient to include, eh?
The Northern Hemisphere is weighted more to land area (low heat capacity) vs ocean area (greater heat capacity) than the Southern Hemisphere, it has greater fluctuations. The Southern has more ocean area and Antarctica, which “anchors” the climate.
Look to the large movements up North, figure that the movement is first there and then later down South so the South can be ignored as it doesn’t lead, seems as sensible as paying attention to the dog’s tail as the indicator of how the dog will move. The tail moves first and most, the body follows, therefore it’s obvious the tail indicates what’s controlling the dog so just pay attention to the tail only. Makes sense to you?
Skepticus says:
April 7, 2012 at 7:02 am
In essence Shakun2012 argue — very reasonably IMHO — that because northern hemisphere temperature proxies substantially lead *ALL* southern hemisphere temperature proxies (including in particular the Stott 2007 and Hubers2008 proxies), the dominant climate-change drives are to be found in the northern hemisphere.
No, the NH proxies do NOT “substantially lead *ALL*” SH proxies. Here’s the reality:
Going from north to south, the northernmost proxies (60N to 90N) are generally warming after the CO2 dataset that they use. Unfortunately, the pattern breaks down there. From 30S to 60N, there is no significant difference in the timing.
Then 60S to 30S is a bit earlier … and then to spoil the picture entirely, 90S-60S is later than 60S-30S …
No, it’s not “strikingly evident”, it’s not even true. There is no smooth transition from north to south as you claim. The majority of the planet (60N to 30S) shows no N/S gradient at all.
There is no significant “north-to-south time-ordering”. The furthest north data is somewhat different from the 60S-30S data … but the order reverses from there southwards.
Is that significant? Given the huge scatter in the data, it is very difficult ascribe statistical significance … but you’ll jump in feet-first nonetheless. They can’t find statistical significance using the proper 2-sigma error bars, so instead they show 1-sigma errors, ignoring autocorrelation … bad scientists, no cookies. If they showed 2-sigma errors including autocorrelation, you’d laugh. Or perhaps not, maybe you don’t understand significance and autocorrelation. They clearly don’t, here’s their Figure 5a
Note that when the error bars overlap, the result is NOT STATISTICALLY SIGNIFICANT, aka meaningless. Note that the error bars overlap on eight of the fourteen latitude bands. Note that they are using 1-sigma error bars. Note that if we take the proper 2-sigma error bars (twice as long), they all overlap, every one of them, and thus they are all meaningless. And that doesn’t even include autocorrelation, which will make things worse …
First, even their own data doesn’t “broadly verify” their own conclusions. They can only show the weakest, 1-sigma significance. If they used the proper 2-sigma error bars, they would have no significant results at all. They can’t even “broadly verify” their own claims.
Second, you say I’ll “feel better for it”? You are a nasty little man, sir, to accuse me of underhanded dealings in such a roundabout way. I am an honest man doing my best to present actual facts. Go wash your mouth out with soap, you’ll feel better for it, and WUWT will be better for it. Then go take a class in statistics, your knowledge is woefully deficient.
w.
Hugo M says:
April 7, 2012 at 7:50 am
I couldn’t find one either, so I digitized it from their graph …
w.
Great work all around, including Shakun who has provided the data and “forced” us to think in terms of synthesizing all this disparate proxy data.
Using the Antarctic CO2 is reasonable as CO2 is a well mixed (why does my inner voice keep singing “well dressed”?) non-condensing greenhouse gas.
I like aaron’s instinct to focus on the meridional trend. We need lots more data points.
In the end we are left where we started, knowing that CO2 and temperature are hitched, yet unsure which is the cart and which the horse.
But we may stumble with the locomotive metaphor. Uphill the horse pulls the cart, downhill the cart pushes the horse. We may even have a situation where carts can grow legs and horses wheels.
I did the mean and standard deviation of all of the studies, this time for the minimumtemperature observed. For all 80 studies those values are:
Mean ± sd = 23579 YrBP ± 15946
The median minimum temp. was 20367
Eliminating 2 sigma outliers (there were 3 of the 80) gives:
21023 ± 5908 YrBP (median: 20300) for the coldest interglacial time recorded by these proxies.
The outliers are interesting. They give very high values (one is 100,000+ YrBP, far away from the others). When you look into the data for the three, these are operating at the ends of their analytical standard curves, where error is large, or else where they do not have a standard, and are off the curve and have extrapolated into the beyond.
This assumes that these scientists are even using a linear standard curve. However, many of these researchers have to use what we used to call “fancy curves”. Like Log/Logit or some non-linear fit. These only operate within small regions of the curve, and only if a standard is nearby the point. Hence the error over large distances on the curve.
Anyway, 20,000 BC…When the land bridge would have been extensive, and animals could migrate. I would have waited a few thousand years until it warmed up a tad before I made the crossing.
Very cool work (no pun), Willis! Thanks for all of your mind-expanding efforts!
1) The timing of CO2 rising/falling is taken from the antarctic ice core records so they agree that it is a true record of global CO2 levels.
2) The first event in Shakun’s sequence is the tilting of the Earth, moving the North Pole into greater sunlight. Note that this also means that Antarctica gets less sunlight and also that northern oceans get more and southern oceans get less. The Arctic warms and fresh melt water runs off into northern oceans. Whatever happens next, warming started the process not CO2.
3) The northern oceans cool because the desalination stops the ocean circulations that bring heat from the equator to the northern oceans. However when the earth tilts, the line around the earth which gets the most heat from the sun is no longer the equator, the line moves north INTO the northern oceans. So why should the Northern oceans cool?
4) The heat at the equator backs up causing the southern oceans to warm. But the southern oceans are now getting less sunlight plus the heat is in the northern oceans so why should the southern oceans warm?
5) The southern oceans warm and cause an outgassing of CO2 which is accurately recorded in the antarctic ice core samples.
6) Shakun accepts that the ice core samples are a correct record of the antarctic and these records show that the Antarctic had been warming for 800 years before levels of CO2 but the first event was the earth tilting? What warmed antarctica then?
The whole thing just does not stack up.
Skepticus says:
“In essence Shakun2012 argue — very reasonably IMHO — that because northern hemisphere temperature proxies substantially lead *ALL* southern hemisphere temperature proxies (including in particular the Stott 2007 and Hubers2008 proxies), the dominant climate-change drives are to be found in the northern hemisphere.
Willis, this point would be strikingly evident in your own analysis … if only you would color-code your data by latitude (per Shakun2012 Figure 5, for example). ”
Skepticus, I was thinking the same thing. The fact that the different proxies have different time dependencies is nothing surprising. CO2 is a well mixed gas, but temperature change in the modern era is known not to be uniform, so why should we expect it to be so in the distant past? In addition, it is known that the tropical temperatures have about 1/2 of the variation of polar temperatures. The fact that a wide variation of temperature dependence is found among proxies scattered all over the earth is not proof that the proxies are wrong.
Of course, if one has a very strong belief that the Shakun paper is wrong, in order to avoid cognitive dissonance, one will accept any argument that is given, even if it doesn’t make sense.
I haven’t read the full paper, and am not familiar with the validation procedure used to calibrate the proxies, nor am I familiar with dating accuracy of the proxies. It seems to me that an argument about the validity of the proxies would begin with these items.
Eric Adler admits:
“I haven’t read the full paper, and am not familiar with the validation procedure used to calibrate the proxies, nor am I familiar with dating accuracy of the proxies. It seems to me…”
Obviously, Adler is ready to believe the conclusions of a paper that he hasn’t read, and admittedly doesn’t understand. However, preceding his frank admission, Adler says of anyone questioning Shakun’s flawed paper:
“Of course, if one has a very strong belief that the Shakun paper is wrong, in order to avoid cognitive dissonance, one will accept any argument that is given, even if it doesn’t make sense.”
Adler is hopelessly afflicted with psychological projection: imputing his faults, such as his own cognitive dissonance onto others. Appealing to the questionable authority of Shakun’s obviously grant-trolling paper would get a free pass by anti-science blogs like RealClimate or Skeptical Pseudo-Science. But not here.