Guest Post by Willis Eschenbach
The quote above is from Lord of the Rings, an exchange between Gollum and Smeagol, and it encapsulates my latest results from looking into the Shakun 2012 paper, “Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation” (paywalled, at Nature hereinafter Shakun2012). I discussed the paper in my post “Dr. Munchausen Explains Science By Proxy“. Please see that post for the underlying concepts and citations.
When I left off in that post of mine, I had investigated each of the 80 proxies used in Shakun2012. I plotted them all, and I compared them to the CO2 record used in their paper. I showed there was no way that the proxies could support the title of the paper. Figure 1 recaps that result, showing the difficulty of establishing whether CO2 leads or lags the warming.
Figure 1. All proxies (green dots) from Shakun2012 (Excel spreadsheet). CO2 values digitized from Shakun 2012 Figure 1a. There is pretty good agreement between the warming and the changes in CO2.
Note that the proxies say the earth generally warmed from the last ice age, starting somewhere about 15,000 BC, and the warming lasted until about 9,000 BC. Since then, the proxies have the greatest agreement (darkest green). They say that the globe generally cooled over the length of the Holocene, the current interglacial period since the last ice age.
Today I was thinking about that single record that they used for the CO2 changes. I got to wondering what other ice core CO2 records might show about the change in CO2. So I went and downloaded every ice core CO2 record that I could find that covered the time period 26,000 BC to modern times. I found a number of ice core records that cover the period.
Then I collated all of them in Excel, saved them as a CSV file, opened the file in R, and plotted every ice core CO2 record that covered the record from 26,000 BC up to the present. I standardized them over the same period covered by the Shakun2012 CO2 data. There was excellent agreement between the Shakun2012 data and the ice core records I had downloaded … but there was also a surprise.
Figure 2 shows the surprise …
Figure 2. As in Figure 1. Black circles show Shakun2012 CO2. Additional colored dots show the ice core CO2 records which have data from 26,000 BC to the present.
Dang, I didn’t expect that rise in CO2 that started about 6,000 BC. I do love climate science, it always surprises me … but the big surprise was not what the ice core records showed. It was what the Shakun2012 authors didn’t show.
I’m sure you can see just what those bad-boy scientists have done. Look how they have cut the modern end of the ice core CO2 record short, right at the time when CO2 started to rise again …
I leave the readers to consider the fact that for most of the Holocene, eight centuries millennia or so, half a dozen different ice core records say that CO2 levels were rising pretty fast by geological standards … and despite that, the temperatures have been dropping over the last eight millennia …
And I leave everyone to ponder how far climate “science” has fallen, that a tricksy study of this nature can be published in Nature, and can get touted around the world as being strong support for the AGW hypothesis. The only thing this study supports is the need for better peer review, and at a more basic level, better science education.
My best to all, stay skeptical,
w.
Source data:
ICE CORE CO2 DATA: All ice core CO2 data are from the NOAA Paleoclimatology site, the “Ice Core Gateway” page, in the section “Gases”.
[UPDATE] A hat tip to Jostein, in the comments he points out that the original Shakun Nature paper is here (pdf).
On all the graphs showing also CO2 change the effect on global temperature seems to be linear in stead of logarithmic?
So this study is also based on the assumption that the effect of co2 on global temperature is linear?
The Inconvenient Skeptic has a very succint take on the Shakun paper
Sorry forgot link:
http://theinconvenientskeptic.com/2012/04/flagrant-attempt-to-mislead-the-public-about-the-holocene-onset/
Eric Adler says:
April 9, 2012 at 5:32 pm
phlogiston says:
April 9, 2012 at 9:47 am
If you look at figure 2a in the Shakun paper, during the Younger Dryas, the temperature drops were not simulataneuos in the 2 Hemispheres. As a result The global temperature did not drop; during the Younger Dryas, it stayed constant during this period. This is simple to see from the graph by taking the average of the two hemispherical temperatures.
The 80 proxies representing different regions of the earth do not behave simultaneously. They should not be expected to. The ocean currents are constantly shifting. Your adjective convenient has absolutely no meaning here. Proxies do not understand the concept of convenience. Proxies are not humans.engaging in a conspiracy to deceive global warming skeptics.
You wrote further,
It is clear from your reply that you didn’t follow, or care to follow, my answer to this question, and are asking it again. Your objection seems to be that the proxies are engaged in a conspiracy to deceive global warming skeptics. Are you for real?
Due I think to delays in appearance of some of my postings, all your replies to my posts appeared after all my posts – so this is my first change to answer your comments – I did not see them before.
It would appear you are trying to deny the existence of the Younger Dryas – rather like other well-known AGW denials of for instance the MWP and LIA. The YD is defined as a transient fall in temperatures as shown in ice core and other records. You are not contradicting my argument – that two temperature rises before and after YD but the reactive CO2 increase flat-lining during the YD allows the later, post-YD part of the temperature rise to be claimed as responsive to CO2. Instead you appear to be casting doubt over whether the YD was real or not – a YD temperature pause only, not fall, is not really a YD.
This addresses the main point of Willis’ initial “Munchausen” post – that there is so much variation between all 80 proxies that the merged result scarcely confirms the Holocene’s existence, let alone the YD. Many of these proxies are biological and relate to ecological factors of ecosystem development at the start of the interglacial. They thus are poor direct indicators of temperature. The approach of combining all 80 is not an approach aimed at clarifying what went on, but the opposite – it is aimed at obscuring it.
The same can be said for the argument you repeatedly make about the non-synchrony of the two hemispheres. If they are non-synchronous, then WHY MERGE THEM? – why not study them separately? In scientific analysis of difficult and variable data we seek to minimise confounding variables, not maximise them.
In a court of law evidence is rigourously filtered for its quality. Allowing equal footing for a crowd of “shaky” witnesses would allow every criminal off the hook. We in scientific research need equal rigour – the 80 proxies should be ranked in reliability and only the best few of them selected for actual temperature reproduction. And if the hemispheres behave differently, then better resolution is achieved by studying them separately. The results from north and south can be looked at in parallel, for instance in interpreting global CO2, but merging them together does not advance truth.
MODS
It seems the italics got inverted in my last post – maybe a syntax error by me. Eric’s first quote should be in italics, my response in normal text.
[Corrected … I think … -w.]
Reblogged this on gottadobetterthanthis and commented:
Willis does it again. It is amazing how simply these things can be shown in skillful hands.
A nonlinear oscillating system does not need an external forcer to exactly drive its transitions – such dynamics can come from within the system with no external driver and no apparent cause. Consider the Belousov-Zhabotinsky oscillatory A nonlinear oscillating system does not need an external forcer to exactly drive its transitions – such dynamics can come from within the system with no external driver and no apparent cause. Consider the Belousov-Zhabotinsky oscillatory reaction for example. That said however, although some nonlinear oscillators are non forced, others are externally forced, and they fall into two categories – strongly and weakly forced. reaction for example. That said however, although some nonlinear oscillators are non forced, others are externally forced, and they fall into two categories – strongly and weakly forced.
Perhaps I should have been more explicit. The Earth is describeable in the coarsest of terms by a differential system that is almost identical in structure to the one I studied years ago in the context of nonlinear laser optics (perhaps without the resonant structure). It is an open system with a known primary driver — Mr. Sun. Energy in, energy out, energy trapped, and some sort of internal feedback that switches the system from a state with large amounts of stored energy to one with smaller amounts of stored energy.
In the case of optical bistability — where the Earth as noted is a large, complex, optically bistable oscillator — bistability is caused by the absorbing atoms in a resonant cavity becoming transparent as their mean excitation increases and they start to be driven through complete Rabi cycles — it is a resonance phenomenon. In the low excitation (opaque) state, atoms remain in a state such that spontaneous emission can keep up with excitation. Such a system exhibits classic first order transition behavior and hysteresis with two stable branches over certain ranges of the external driver.
In the case of the Earth, the simplest model is a greybody — sunlight in, some reflected by the albedo, some absorbed, all that which is absorbed reradiated via blackbody radiation to equilibrium. No possibility of bistability barring a stable modulation of albedo. Add an atmosphere (with GHGs) and you warm the planet relative to greybody but still everything is in balance, and unless you have nonlinear feedback of either albedo or the GHGs themselves you still don’t have bistability. Add oceans, add circulation, add mountains, deserts, currents — add the moon (which alters vertical mixing of the oceans), add sources and sinks of GHGs and aerosols, add the fact that the Sun is a somewhat variable start — and we have an embarrassment of riches. Somewhere in there we did enable sufficient nonlinearity to facilitate bistability, but we still cannot even describe the system well enough to capture the locally linear behavior in the stable mode. Worse, there are periodicities such as 110,000 years in the bistable oscillation frequency, and the warm mode behavior is in some ways “like” the temperature 3 million years ago when everything was different — especially oceanic circulation patterns through the still open panama seaway.
So yeah, I agree that there is enough interesting and complex physics for bistability to arise without an external major nonlinearity but — I doubt it. Not with the quasi-periodic behavior observed. The dimensionality of the solution isn’t that high, at least not in the last half-million to million years. Understanding the critical control dimension is key to resolving the probable near-term behavior of the climate, which is a necessary prior to being able to predict the behavior of the climate system as it responds to e.g. increased CO_2.
rgb
A lot been said here, a lot beyond my scope, but intriguing nevertheless. For me this simple statement is a gem:
BernieH says:
April 8, 2012 at 9:35 pm
Averaging always destroys some information, often useful information.
– – – – –
This points to a very fundamental phenomenon in all science, not just statistics. Aggregating data and deriving patterns or formula’s or even laws at the same time always is a sifting process necessarily discarding a lot of “non-relevant” data or information. And the more you focus, the more you will leave out. This is not a mere peculiarity to ponder for amusement, it has deep consequences. If not realized it gives grave misconceptions. Like the well known statement: “ the whole is more than the sum of its parts”. This idea is everywhere, but that doesn’t mean it is right. It is wrong. Actually, it is the opposite: the whole is less than the sum of its parts.
This is so for two reasons. The first being “the whole” as an abstraction leaves out may of the peculiarities of the parts by definition, so basic mathematics makes this principle clear. The second reason being the parts always at the same time belong to may other sets outside the scope of the current investigation or discipline. From the perspective of the conceived “whole” a part is a mere object to aggregate or manipulate. But the part itself as a unique phenomenon has an almost infinite multi-dimensional richness, belonging to many many different sets. So you not only lose sight of many aspects of the part itself and their unique combination giving it “individuality”, you also loose sight of the many other sets it belongs to.
A humbling insight for any science. I know this line of thought is a bit OT in this thread, but as doing science the proper way is so central in many discussions on WUWT I might as well put it forward here. These intrinsic limitations give fragility to the theoretical scientific edifice. The more reason to be very dedicated and true regarding scientific procedures. And be very careful if not humble in your conclusions and generalizations. Nature’s editorial shows a lot of hubris. It’s about time Nature goes back to its origin: nature itself.
No, it doesn’t, and it is wrong of Willis to claim that it does.
It has long been posited from meager data that the Northern Hemisphere deglaciation lagged CO2 rise, and the CO2 rise lagged Antarctic temp increase (cf, Petit et al, 1999, Caillion et 2003).
Quote from Petit et al 1999
Quote from Caillion et al 2003
This latest paper just adds more detail to the understanding of the process. CO2 lags temps in the Southern Hemisphere, and leads temps in the Northern Hemisphere during the glacial temination. The general picture is not new at all, it’s just that people spinning the story for skeptical audiences have always omitted the parts of earlier studies (CO2 leads in the North) that are confirmed by the recent one.
To the best of our knowledge, deglaciation events are triggered by changes in insolation from lower to higher latitudes. The warming is not limited to the regions receiving more insolation, but is global. Both poles AND the sub-tropics and tropics all warm up at around the same time. If not well-mixed CO2, what mechanisms, in the minds of critics, are supposed to convert a local change in insolation to a world-wide change in temperature? Unless someone has a good theory about how the whole world heats up from insolation changes in specific regions, then it’s obvious that CO2 rise will lead temps in some parts of the world during transitions. It just makes sense.
Barry, I can understand your argument, that CO2 and temperature changes may differ in order in different regions, and how that doesn’t necessarily enable any side of the debate to claim anything. What it does say though, that even if one of the regions has CO2 lagging temoerature, this falsilfies any direct causation by CO2 on temperature, there must be other forces/factors in play that are/can be dominant. This is the central issue of all the CAGW debate, whether CO2 drives temperature or not.
Jurgen April 10, 2012 at 7:52 am:
I really like your comment and agree with it.
Maybe climate science needs a volatility index (maybe it already has one?), like the stock market.
If it gets both hotter and colder around the world, it could average out to NO CHANGE.
However, it would seem to me that it would be relevant that it was both 5C hotter and 5C colder (just an example) in one period versus another – even though the average was identical.
A lot of my posts on this thread have been held up in moderation or have disappeared.
REPLY: I count 17 on this thread, and 713 comments in total on WUWT, and I’m not aware of any in moderation or that have been dropped. Bear in mind sir that you were once banned from this forum for your constant threadbombing, disruptions, and generally boorish behavior. Against my better judgement, I’ve allowed you to post again, but let’s be clear, the tolerance level for you is low, particularly when you start whining. My advice – go find something else to do for a few days. – Anthony
REPLY: I have never “disappeared” a post in all of the time I have been involved with WUWT. As to “held up in moderation”, all moderation is done by volunteers, and it is necessary to cover incoming posts 24/7/365 … so sometimes posts don’t get seen immediately. But generally, the team of moderators does an incredible and under-appreciated job of moving the comments through swiftly. – w.
Eric Adler says:
April 10, 2012 at 11:38 am
A lot of my posts on this thread have been held up in moderation or have disappeared.
A few of mine disappeared temporarily but always appear eventually. Maybe I’m on the bad boy list also? (Cant imagine why – I’m always so polite.)
REPLY: if you reload the page immediately after you post, your post will always disappear, because it has not been moderated. It will reappear after the moderators approve it. So they all “disappear”, but you’ve only noticed it a few times. -w.
rgbatduke says:
April 10, 2012 at 5:57 am
A nonlinear oscillating system does not need an external forcer to exactly drive its transitions – such dynamics can come from within the system with no external driver and no apparent cause. Consider the Belousov-Zhabotinsky oscillatory A nonlinear oscillating system does not need an external forcer to exactly drive its transitions – such dynamics can come from within the system with no external driver and no apparent cause. Consider the Belousov-Zhabotinsky oscillatory reaction for example. That said however, although some nonlinear oscillators are non forced, others are externally forced, and they fall into two categories – strongly and weakly forced. reaction for example. That said however, although some nonlinear oscillators are non forced, others are externally forced, and they fall into two categories – strongly and weakly forced.
Perhaps I should have been more explicit. The Earth is describeable in the coarsest of terms by a differential system that is almost identical in structure to the one I studied years ago in the context of nonlinear laser optics (perhaps without the resonant structure). It is an open system with a known primary driver — Mr. Sun. Energy in, energy out, energy trapped, and some sort of internal feedback that switches the system from a state with large amounts of stored energy to one with smaller amounts of stored energy.
An “open” system can also be described as a dissipative system in energy terms – again a key ingredient for emergent nonequilibrium pattern including oscillations.
Indeed the system is formidably complex and in that category where the only effective model of the system is the system itself. For this reason perhaps the best we can do is find other systems – experimental or natural (e.g. biological) with similar attributes of complexity and emergent nonlinear spatiotemporal pattern. In the light of any such systems that are better understood, look for analogies or similarities.
You say that 3 million years ago “everything was different” but it seems enough was similar for the succession of ice ages and interglacials to follow the same pattern of astrophysical forcing, with the exception of the switch from following obliquity forcing (41 kyrs) to following eccentricity forcing (the weakest of all the forcings, 100 kyrs) about a million years ago. I cant help thinking there must be some clues in this transition.
“La plus ce change, la plus c’est la meme chose”. (The more it changes, the more it stays the same).
barry says:
April 10, 2012 at 8:15 am
Thanks, Barry. I find this claim curious. My understanding has been that the ice ages are triggered by the Milankovich decrease in NH summer temperatures. This is said to lead to more snow and ice in the NH, which in turn increases the albedo. And over time, this feedback drives the average global temperature lower, by greatly increasing the average global albedo.
Note that we don’t need CO2 to explain any of that … and yet, in your words, it is able to “convert a local change in insolation to a world-wide change in temperature”, something you claim is not explainable other than by CO2.
Best to you,
w.
From barry on April 10, 2012 at 8:15 am:
Petit et al 1999 dealt with Vostok. My source:
http://www.uvm.edu/~bbeckage/Teaching/GlobalChangeEcology_2011/AssignedPapers/Petit.Vostok.Nature.1999.pdf
You should read past the first page. Publication pg 434, pdf pg 6:
So Petit et al 1999 basically says you can’t tell whether CO₂ lags, leads, or is in phase with the temperature rise at the start of the terminations. Yet you have determined Petit et al 1999 is showing CO₂ was lagging the temperature in the Antarctic, and by extension the Southern Hemisphere, during glacial terminations. Where did you get this?
For Caillon et al 2003, you should have included more of the abstract:
So they start by saying the CO₂ to temperature timing relationship is too uncertain to determine, except they think they’ve got it by looking at the argon isotopes, but they can’t provide a valid mechanism to explain it.
Moreover, from publication pg 1730, pdf pg 3, mentioning methane, comes the important part concerning the timing between the hemispheres:
So here’s the big timeline:
1. Antarctica (and the Southern Hemisphere by extension) begins warming at the start of the glaciation termination.
2. CO₂ starts rising about 800 years later.
3. About 6000 years later after Antarctica starts warming, the Northern Hemisphere begins warming as well.
So “CO₂ leads warming in the Northern Hemisphere” since the NH starts warming so much later after the SH warming and the subsequent CO₂ increase.
The temperature increase at Antarctica, and by extension the Southern Hemisphere, leads all. And CO₂ comes off as a bit player in later warming, at most.
By the sources you have offered, both poles and the sub-tropics and the tropics are not warming up at the same time. There is more than enough time for ocean currents to spread around the Southern warmth, for the SH glacial sheets to shrink and go away, with the NH ones following, leading to the albedo changes that allow more insolation. But CO₂ increases would lead temperature increases in some parts of the world, by coincidence.
i;ma630, Willis,
The trigger for glacial changes (in the quaternary period) is orbital variations. CO2 responds. But it also amplifies and leads. 1;ma630, there is no binary logic that requires only one or the other to happen. Both may, and apparently, both have. I am of the understanding that thoughtful skeptics
at WUWT do not deny the radiative properties of CO2 in the atmosphere, so there should be no bar to the notion thar CO2 acts as a feedback and leads temps in some parts of the world.
Remember, too, that the insolation change is a very weak forcing. The solar intensity itself does not change, it is only that the point of focus (insolation) changes. It is the system of feedbacks that increases the power of localised changes, and makes those changes global.
kadaka,
I was responding to the notion that this study refuted previous work. It does not. Petit and Caillion speculate on the processes, and both studies indicate CO2 both lagging and leading temperature change and deglaciation, in line with this study. There are differences between the papers, but the basic point on lag/lead, the one that has got people here incensed, is no turnaround. It is an extension and a refinement of an older idea. No doubt further investigation will come up with slightly different timings and weighting of various feedbacks.
You seem to believe that CO2 has no radiative property that could enhance warming. I doubt I could change your mind about that.
Willis,
I’m not sure that you realised I was talking about deglaciation periods – the change from glacial to interglacial. The transition I focussed on has sharper and more pertinent characteristics (ie, warming) for the general debate.
But the point would be the same in each direction. I’ll apply it now to the onset of an ice age, per your reply.
If insolation tracks from high latitudes to low over the millennial orbital variation, one would expect that the high latitudes would get slightly cooler, and the lower latitudes would get slightly warmer all else being equal. Even while the polar ice sheets extend, increasing albedo in those regions, and high latitude oceans cool, low latitude oceans and landmasses should warm. But what happens is that the entire globe changes temperature in the same direction. Therefore, other processes must amplify and extend the initial weak, localised forcing. Some deeper process/es convey the temperature change occuring in the high latitudes to the entire globe, sufficient to counteract the insolation forcing in the opposite direction (at low latitudes in this glaciation example). As CO2 is well-mixed in the atmosphere, it is an obvious candidate for making a regional effect global. And indeed, the amplifying response of GHGs to insolation changes over Milankovitch cycles is consistent across all studies of late quaternary ice age transitions that consider these factors, not just this latest study. Of course, there are other processes at play (aerosols, dust, vegetation changes, ocean and atmospheric circulation, cloudiness etc), there is uncertainty in the data, and the details and timings will continue to be investigated. But there seems to be little uncertainty that CO2 both lags and leads (amplifies) temperature changes in the geologic record. This has been a consistent understanding for more than a decade, a standard rebuttal from mainstreamer blogs for nearly as long, and easily discovered in older studies of ice age transitions. (How have the skeptics missed it?)
The focus on ice age transitions has corrollary value. Late quaternary ice age shifts (as well as LIA, volcanic eruptions and other data-based estimates of climate sensitivity), is one source of observationally based climate sensitivity estimates. No GCMs are required here, just simple equations. And no need to factor in tectonic redistribution or solar variance. The arrangement of the continents and associated heat flows are consistent for the late quaternary period, as is solar output (no ‘faint sun’ paradox to deal wth). We can compare apples with apples.
If the paper was indeed mainly wish fulfillment, then is it simply a case of Shakun a son gout?
Jurgen says: (April 10, 2012 at 7:52 am) “Actually, it is the opposite: the whole is less than the sum of its parts.”
An enlightening observation, Jurgen.
Thank you.
barry says:
April 10, 2012 at 7:29 pm
The transition I focussed on has sharper and more pertinent characteristics (ie, warming) for the general debate.
If insolation tracks from high latitudes to low over the millennial orbital variation, one would expect that the high latitudes would get slightly cooler, and the lower latitudes would get slightly warmer all else being equal. Even while the polar ice sheets extend, increasing albedo in those regions, and high latitude oceans cool, low latitude oceans and landmasses should warm. But what happens is that the entire globe changes temperature in the same direction.
Some deeper process/es convey the temperature change occuring in the high latitudes to the entire globe, sufficient to counteract the insolation forcing in the opposite direction (at low latitudes in this glaciation example).
… the amplifying response of GHGs to insolation changes over Milankovitch cycles is consistent across all studies of late quaternary ice age transitions that consider these factors, not just this latest study.
It may be that the frequencies of Milankovitch have relations to the terrestrial temperature proxy frequencies, but because the functions of the the Milankovitch oscillations have sinusoid character there is a general problem, to explain a varying physical heat process of a saw tooth oscillation from Vostok. Moreover, there is a problem to explain the geometry of an oscillator with a main frequency of 1/94300 y^-1. A frequency of 1.406 hours^-1 is related to the geometry of the radius/accelaration of the Earth, and for such low frequencies it needs greater geometries like the Sun. If you take a resonance mode of n=2 and a solar photon diffusion time of ½ * 377134 years you get a cycle time of 94284 years [t (y) = pow(2,-2) * 377134]. This is an idea of Robert Ehrlich using the FFT data from Bolshakow.
http://www.volker-doormann.org/images/bolshakov_plot_modes.jpg
I have synthesised some Vostok saw tooth frequencies using the their mode power and it fits good with the (slightly time scaled) Vostok spectra over 1 Million years.
http://www.volker-doormann.org/images/bentic_f_graph.gif
The focus on ice age transitions has corrollary value. Late quaternary ice age shifts (as well as LIA, volcanic eruptions and other data-based estimates of climate sensitivity), is one source of observationally based climate sensitivity estimates. No GCMs are required here, just simple equations. And no need to factor in tectonic redistribution or solar variance. The arrangement of the continents and associated heat flows are consistent for the late quaternary period, as is solar output (no ‘faint sun’ paradox to deal wth). We can compare apples with apples.
If it is rue, that there are low frequency modes in the Sun it remains unclear to what the main phase is coupled. But regarding the more faster heat frequencies observed on the globe, it is evident, that the frequencies are related to solar tide functions from (outer sun) planet couples.
http://www.volker-doormann.org/images/vo_m4k.gif
Also the nature of the function has changed; the variations have lost their saw tooth character, and have changed to a complex triangle characteristic.
While the frequencies of the Vostok data seems to be related to the inner Sun only, the fact that the solar tide functions can be directed to planetary couples there remains neither any molecule idea nor a terrestrial local heat source to explain the temperature spectra in high time resolution. This is shown especially in this graph:
http://www.volker-doormann.org/images/uah_temp_4_rghi11.gif
There is no relevant time constant between the solar tide function of 11 planets and the UAH global temperature function.
V.
Piers Corbyn,
you have been critized for not showing your methods, but your forecast of “major quakes are likelely to come in the present period (~8-10th) ” has been met by the 8.5+ Sumatra quake of today morning. When reading this news, I remembered to have read your forecast here in this thread a few days ago, hence this otherwise off-topic remark.
Hugo M says:
April 11, 2012 at 3:09 am
Ditto Hugo M – Piers Corbyn has correctly predicted a major earthquake (somewhere in the world, not at a specific location). This lends credence for his hypotheses about influence of solar wind and magnetic fields etc on climate and tectonic events.
Piers Corbyn (@Piers_Corbyn) said at April 9, 2012 at 5:16 am
[…]
See pic of Large Coronal Hole heading for center of Suns disc today as we warned: http://spaceweather.com/archive.php?day=09&month=04&year=2012&view=view
and our forecast which apart from weather events also says Major Quakes are likely to come in the present period (~8-10th) as a consequence of this coronal hole and related solar events
http://climaterealists.com/index.php?id=9413
[snip . . OT . . kbmod]
From barry on April 10, 2012 at 3:38 pm:
Nah. You said on April 10, 2012 at 8:15 am:
What did Willis actually say on April 8, 2012 at 2:46 am?:
What was the title? Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation
The “earlier understanding” is the ~800 year lag between temperature rise and CO₂ rise, as famously graphed on Jo Nova’s site “…from 420,000 years to 5,000 years before the present.”:
http://joannenova.com.au/global-warming/ice-core-graph/
Note she also used for “references & more info” your two mentioned sources:
“Petit et all 1999 — analysed 420,000 years of Vostok, and found that as the world cools into an ice age, the delay before carbon falls is several thousand years.”
“Caillon et al 2003 analysed the Vostok data and found a lag (where CO2 rises after temperature) of 800 ± 200 years.”
First off, Shakun et al 2012, per the title, analyzes the last deglaciation. Caillon et al 2003 analyzes Termination III, which is not the last deglaciation but the one preceding it, thus was not relevant.
That leaves Petit et al 1999, which as I’ve previously mentioned decided it can’t be determined which comes first at the start of deglaciation.
So neither of your sources indicate what you said they did in regards to this study (Shakun et al 2012).
Later you said, and I’ll include the same bit of my comment as you included it:
What I do believe is you likely have a profound ignorance of my previous writings on this site. Granted that when painting with such a broad brush, it is common to paint all skeptics with what “the opposition” promotes as the standard “denialist” color set, which includes denying CO₂ has a “…radiative property that could enhance warming.”
In reality, very few skeptics would claim CO₂ is not a greenhouse gas, and we tend to “police our own” and rebuke those who would do so. I, along with almost all skeptics, recognize this property while acknowledging, as the real-world data shows, that water vapor is the dominant GHG, that the posited positive feedbacks that are to amplify CO₂’s effect to catastrophic levels are non-existent in reality, and negative feedbacks that dampen global warming exist and their actions are the rule that controls global temperatures as in the current interglacial.
And that I doubt you could change my mind about.
kadaka,
It’s good that you point out the Jo Nova article (and that you are willing to include several glacial transitions instead of just the one examined by Shakun). Skepticalscience dealt with her take in 2010 – 18 months ago. At that time, more than a year before the Shakun paper came out, they said;
How did they manage to guess what Shakun would write a year and a half later?
They didn’t. They are simply familiar with the science (they cite Caillion, amongst others). I would criticise theit blog post, however, because it does not reflect uncertainty and nuance in the science.
You are trying to wish away what Caillion and Petit said. They highlight uncertainty, they speak of alternative timings. But included in their analyses is the suggestion that CO2 led in the North (as I quoted – it’s pretty plain in their text). Suggestions of CO2 lagging and leading glacial transitions are dotted throughout the literature.
1984 – “Atmospheric carbon dioxide, orbital forcing, and climate” – Shackleton and Pisias
1998 – “The Sequence of Events Surrounding Termination II and their Implications for the Cause of Glacial/Interglacial CO2 Changes” – Broecker and Henderson
2001 – “Atmospheric CO2 Concentrations over the Last Glacial Termination” – Monnin et al
<blockquote.The CO2 increase in interval I, which occurred before any substantial warming in the Northern Hemisphere, is consistent with the present view of the role of the Southern Hemisphere for causing the CO2 increase.
For different Milankovitch events (41K period), the same principle may apply from North to South.
2006 – “Orbital changes and climate” – Ruddiman
Shakun et al have not departed from previous understanding. The notion that CO2 lags at all times and in all places during glacial transitions is peculiar to some in the skeptic camp, who appeared to have favoured a soundbyte over learning about ice age transition processes.
Far more papers than I’ve noted above agree that the CO2 feedback is required to explain a singificant amount of global temperature and ice sheet change during glacial transitions. This
is so for Petit, Cailiion and the other papers cited by Jo Nova. If I close one eye and squint through the other, tilt my head a bit and skim, I just might be able to come away with the impression that the literature only ever mentions CO2 lagging temperature rises, and that CO2 changes have no impact during glacial transitions.