Guest Post by Willis Eschenbach
Well, either it’s a genetic defect or I’m just a glutton for punishment, but I’m going to delve some more into the ice ages. This is a followup to my previous post, Into and Out Of The Icebox. Let me start by looking at the cycles in the insolation and the cycles in the geological temperature. I’ll use the same temperature proxy dataset used in the discussion by Science of Doom here and here, which is the Huybers ∂18O dataset . For the insolation, I’m using the same Berger dataset that I used in my last post. Figure 1 shows the cycles in the two datasets:
Figure 1. Periodogram of the Huybers temperature proxy dataset (blue) and the June insolation at 65°N from the Berger geological insolation dataset.
This graph demonstrates extremely clearly what is called the “100,000 year problem”. As you can see, the length of the ice ages has a very strong 100,000 year cycle, with a cycle amplitude greater than 40% of the swing of the data.
But in total contradiction to that, the June insolation at 65°N, which is the insolation that is supposed to cause the interruptions of the ice ages, has virtually no cycle strength in the 100,000 year (100 Kyr) range. The insolation has its greatest cycle strength between 19 and 24 Kya, and a smaller peak at 41 Kyr, but there is almost no power at all in the 100 Kya range.
It is worth noting that both the temperature and the insolation do show power in the ~ 23 Kyr and the ~ 41 Kyr range … but only the temperature has power in the 100 Kyr range.
Now, back in 2006 Gerald Roe wrote a paper called “In Defense of Milankovich”. In that paper, he said that the reason there was little relationship between the Northern Hemisphere insolation and the ice ages was that people were looking at the wrong thing. His point was that when the sun increases, the ice doesn’t immediately disappear. Instead, what changes is the rate of melting of the ice. This is also called the “first difference” of the ice volume. Roe used an earlier version of the same Huybers temperature proxy dataset I’m using to demonstrate his hypothesis, reasoning that the ice volume is a function of the global temperature.
So let’s start by looking at the effect of taking the first differences on the underlying cycles. Figure 2 is the same as Figure 1, except that I’m using first differences instead of using the raw Huybers temperature proxy data.
Figure 2. Periodogram of the first difference of the Huybers temperature proxy dataset (blue) and the June insolation at 65°N from the Berger geological insolation dataset.
Now, that is an interesting result. As you might imagine, it hasn’t introduced any new frequencies into the mix. However, it has greatly decreased the size of the 100 Kyr cycle, slightly increased the size of the 23 Kyr cycle, and slightly decreased the size of the 41 Kyr cycle.
And what would be the result of those changes? Well, the correlation will indeed be better, as Roe observed … but for the wrong reasons. The correlation will be greater because in the temperature data (blue) the ~ 20 Kyr cycle and 41 Kyr cycles are now about the same size as the 100 Kyr cycle. So those cycles will fit better … but we still have no explanation for the 100 Kyr cycle.
In any case, here’s the match between the June insolation at 65°N and the first difference of the temperature proxy:
Figure 3. A comparison of the June insolation at 65°N (red) and the first difference of the ∂18O temperature proxy. I am using the negative of the ∂18O data, so that increasing values show increasing temperatures.
Looks good, doesn’t it … but it’s not. Unfortunately, this is merely a wonderful example of the human propensity for seeing patterns. If you look at parts of this, it looks like a perfect match. The problem is, humans are shaped and bred by millions of years of evolution to find visual patterns … and as a result we find patterns even where no such patterns exist. The best example I can give you is that virtually every culture has found constellations in the stars. We identify Orion and Gemini and a host of others … and despite that, the stars contain no such patterns, just a random scatter.
And when we look closely at Figure 3, we can see that in many of the cases, the blue lines are in between the red lines … in all, they seem to be aligned at around 600 Kyr BP and also around the present, but badly out of alignment in between.
In order to keep ourselves from making such mistakes in pattern identification (among other reasons), we’ve invented an entire branch of mathematics called statistics. It allows us to do things like measure just how much of one variable is explained by another variable. The measure of this is called “R^2”. It varies from 0.0 (no relationship) to 1.0 (one variable totally explains the other).
And the R^2 value for the two variables above? How much of the first difference of the temperature variation is explained by the variation in northern insolation?
Well, the R^2 of the two is a mere 0.05 … that is to say, the June insolation at 65°N only explains about 5% of the variations in the first difference in temperature. Color me unimpressed.
Now, it’s possible that there is some lag in the data. To check that, we can run a “cross correlation”. This looks at the correlation, not just at the same time, but at a variety of time lags. Here is the cross correlation of the two variables:
Figure 4. Cross correlation of insolation and first difference of temperature. Positive lags show temperature changes lagging insolation changes. Blue lines show the level where the p-vaule is 0.05, which must be exceeded to achieve statistical significance.
So … there you have it. The relationship just barely achieves statistical significance. Is it true that looking at the first difference of the temperature improves the correlation? Yes, it is … but for the wrong reason. Taking the first difference of the temperature proxy reduces the amplitude of the 100 Kyr signal and increases the amplitude of the ~20 Kyr signal. Since the ~ 20 Kyr signal is the largest signal in the insolation, as a result the overall correlation increases … but this still doesn’t help us at all with the “100,000 year problem”. Not only that, but at the end of the day, the relationship is so weak as to scarcely achieve statistical significance.
Me, I’d say that Roe certainly didn’t solve the 100,000 year problem … although as always, YMMV …
Best wishes to everyone,
w.
My usual request—if you disagree with someone, please QUOTE THEIR EXACT WORDS THAT YOU DISAGREE WITH. This is the only way for everyone to be clear as to the exact ideas that you are objecting to.
Further to my comment immediately above. The oceans have a volume of just over 1Billion cubic Kilometres. Assuming the peak ice was about 10 million cubic kilometres and a latent heat of ice of 340 joules per gram the melting of the this volume of ice would reduce the global sea temperature by 3 degrees centigrade. Or putting it another way the pattern would be consistent with the sea taking about 80,000 years to increase by 3 degrees and then 20000 years for it to cool down again as the ice melts. In my mind this sort of time constant is not unreasonable.but it would be pretty inconsistent which explains why the average periodicity is constant but the actual value is not.
How about over 50million km^3 Cal? I commented above that a couple of simple things being missed by all commenters including Willis I believe, is at peak glacial thickness, the low humidity means little or no more accumulation, but sublimation of the ice into the low humidity is a likely significant happening. Remember, even if insolation increases, much of the glacier is a couple of km thick and thus is a topographic high, like the ice on top of a mountain even in mid july. Now sublimation could probably take 50,000 years to reduce the ice to a point were insolation matters a lot more. Of course, gravity flow of the ice is also removing mass from the highs, probably faster as warming begins to have an effect.. .
Willis. Run the numbers. I challenge you. Do the insolation at perihelion and aphelion during minimum eccentricity periods vs during maximum eccentricity periods. Your response will be that it averages out, but that is not the point, it is the seasonal values that are important and when you have the northern hemisphere at aphelion during maximum eccentricity, and with the albedo of the land, and the altitude of the Northern Hemisphere thrown in, that is a major difference in energy input into the system.
There are papers out there that explain this but if you are not willing to listen then just continue to scratch your head.
My friend, that’s your theory, not mine. So I invite you to run the numbers, graph up the results, and come back and present your graph. Note your methods and data sources, please, so we can all understand what you’ve done.
I look forward to your results,
w.
Apropos ‘Milankovitch can’t explain 100K year cycles’, check out the first chart on page 2 of my paper.
http://www.robles-thome.talktalk.net/Milank1.pdf
The total earth insolation has a strong periodicity around 100K years driven by changes in eccentricity.
R.
Willis
I don’t really care that much about it, after doing a lot of research and looking at the data, I am convinced of the 100k orbital forcing, though we don’t have the exact explanation for it. Here are a couple of papers for your interest. I see the difference of about 80 watts/m2 in my satellite data for a year and that is at our low eccentricity of the modern era. At 120-140 watts/m2 at high eccentricity that is all I need to figure it out.
https://www.dropbox.com/s/yimaqatvjh0l9ny/Vostok_420k_CO2.pdf?dl=0
This is the best paper below on long term eccentricity. It may change your calculations because most use an older paper for it (Lasker 1990). Here is a question for you. Do you know who’s work your insolation calculation is based on for eccentricity? Hint: it matters.
No one knows what the driver is but everyone agrees that except for 400k years ago, the orbital eccentricity data best fits our recent ice age periods.
https://www.dropbox.com/s/yfhjreodgrwqhf9/Earth_eccentricty.pdf?dl=0
RERT January 26, 2015 at 2:12 pm
RERT, as your chart shows, the change in insolation due to insolation is a whacking great 0.4 W/m2. On my planet, that’s called an “extremely weak periodicity”, not a “strong periodicity”, and that’s exactly the problem. It’s far too weak to kick the earth either into or out of an ice age.
w.
dennis said:
denniswingo January 26, 2015 at 9:32 am
I replied:
Willis Eschenbach January 26, 2015 at 12:31 pm
dennis says:
denniswingo January 26, 2015 at 3:01 pm
Cute, dennis. You challenge me to do your work for you, and when I decline, you say you don’t really care, and you don’t have any facts … but by gosh, you’re convinced anyhow.
You see why I don’t let folks direct my research? If you don’t care enough to do the work, why should I?
Sorry, but after that little trick, dennis, I’m not interested in the slightest.
w.
—Willis
I don’t really care that much about it, after doing a lot of research and looking at the data, I am convinced of the 100k orbital forcing, though we don’t have the exact explanation for it.—
Well I would say it related to ocean warming and cooling- though that not an exact explanation.
Or temperate glacial advance and retreat is just a symptom rather than causal factor.
Anyways I not sure what causes Earth’s change in eccentricity- I assume some kind a resonance with Jupiter and/or other planets- but that’s about it.
I wonder if the sun is dragged and so Earth follows- [and so all the inner planets] whether planets
changing independently.
So:
“The shape of the Earth’s orbit changes from being elliptical (high eccentricity) to being nearly circular (low eccentricity) in a cycle that takes between 90,000 and 100,000 years. When the orbit is highly elliptical, the amount of insolation received at perihelion would be on the order of 20 to 30 percent greater than at aphelion, resulting in a substantially different climate from what we experience today. ”
http://earthobservatory.nasa.gov/Features/Milankovitch/milankovitch_2.php
Seems to indicate the the earth just moves closer to the Sun.
And does not say earth move further away from Sun at aphelion. If true that indicates earth orbit lost energy [and then is suppose gain energy??}.
If just the earth perihelion moved nearer, then it would be more “obvious” to all that changes climate. And would guess that is what writer of above article is assuming.
If the sun moved instead earth orbit does need to gain or loss orbital energy, and 365 day orbit would seem to be maintained.And also it’s “less obvious to all” that causes climate change. I think it would, but I am not greenhouse effect theory believer.
So what are the orbital perimeter- the perihelion and aphelion that earth is said to change every 90 to 100 thousand years?
So sort of answering my questions.
“Right now, the elongation of the orbit (the eccentricity) is rather small — about 1.7%. This results in the sun being about 7% brighter at the earth when it is closest, on January 4, than when it is most distant.
Twelve thousand years ago, when the glaciers of the last great ice age were melting, the eccentricity was a bit higher, about 2%. At the same time, the earth was closest to the sun in June, and most distant in January, so the sun was about 7 % brighter in June than it is today.”
http://www2.gi.alaska.edu/ScienceForum/ASF8/825.html
Average earth orbit is 149.6 million km. Times by 1.017 [1.7%] gives our Aphelion of 152.14 million km. And divide by 1.017 gives our Perihelion of 149.09 million km.
So instead 1.7% it’s 2%:
Perihelion: 146.66 and Aphelion of 152.59 million km
Next:
“During the interglacial before the last ice age, about 125,000 years ago, the eccentricity was about 4%. The times of largest eccentricity tend to be about 100,000 years apart.”
So instead 1.7% it’s 4%:
Perihelion: 143.85 and Aphelion of 155.58 million km
So as we know the last interglacial was warmer than our current interglacial.
Oceans About 2 C warmer and sea level 6 meters higher [or somewhere around there]
So another quote from article:
“At various times in the last million years, however, the eccentricity has been much higher — as much as 6%, which would make the sun almost 25% brighter at perihelion (when the earth is closest to the sun) than at aphelion (when the earth is farthest from the sun).”
So instead of 1.7% it’s 6%:
Perihelion: 141.13 and Aphelion of 158.58 million km
So that is maintaining the 365 day year [I believe] and if true, my guess [currently] is the sun
moves [rather than earth [mostly moving]- because it seems simpler.
But I mean mostly the sun moves [or certain both move- but my question was which moves more].
So it seem if Earth has shorter Perihelion Earth gets a warmer ocean. Or at least it does when Earth is in a Ice box climate.
Oh, here calculator for Eccentricity of the orbit of the Earth for 1 million BC to 1 million AD:
http://www.jgiesen.de/kepler/eccentricity1.html
Your loss. The second paper is the best one I have seen for putting together the insolation numbers derived from an analysis of the orbits of the major planets in the solar system. They have an interesting difference from previous numbers. I bet you don’t even know who’s numbers you are using for the eccentricity term. Guess what, they have changed significantly as a result of the paper I provided.
So, I provide you with the best paper on the subject, which you requested research that I don’t have to do, and you reject it. Neat….
Science is a lot more than just grabbing the first thing that is out there, crunching some numbers, and declaring victory.
denniswingo January 27, 2015 at 8:19 am Edit
Well, against my better judgement I went to look at your whiz-bang paper. It says right up there in the abstract:
In other words, guess what? For the period under discussion (within the last million years), the paper you think is so all-fired important doesn’t make one damn bit of difference … why am I not surprised?
It was neat, and I should have stuck to my guns, because the paper was useless.
How would you know? I asked you to do a bit of science regarding your own claim and you refused. So I did your work, I took a look at your recommended paper and found out that your claim that the numbers have “changed significantly” only applies to a period of time that is not under discussion.
In other words, you just grabbed the first thing that is out there, you didn’t even bother crunching some numbers, and you declared victory …
Neat …
w.
–Willis Eschenbach
January 26, 2015 at 12:31 pm
My friend, that’s your theory, not mine. So I invite you to run the numbers, graph up the results, and come back and present your graph. —
–Willis
I don’t really care that much about it, after doing a lot of research and looking at the data, I am convinced of the 100k orbital forcing, though we don’t have the exact explanation for it. —
To sum it up.
There is no theory which allows us to exactly explain the past climate, and thereby enable anyone to predict the future.
For example we have climate record going back hundreds of thousands of years, which is not random but instead has a somewhat clear pattern to them. The orbital changes of Earth appear they could provide explanation of this pattern, but there is not a known way to do this.
So the fairly well known changes of orbital characteristics of the past and fairly well know orbital changes which will occur in the future, are not currently helpful to predict the future of earth climate.
The climate record itself is more predictive of the future climate than milankovitch cycles which attempts to explain them. Which is to say our climate record give a clue that within thousands of years we could return to glacial conditions and the milankovitch cycles/earth orbital characteristics do not help clarify this.
So at this point, have to say the milankovitch cycles do *not* help explain why our last interglacial
was warmer [despite my earlier assertion] , nor I am able to explain how it effects our current interglacial.
I can’t say what the effect of orbital changes have, though they seem they *should* or *could* have a large effect.
Or I would say the changes in earth orbital characteristics are clue, but then again we seem to have many clues.
And it appear most relevant issur to me at the moment about the near term future is that we had more than century of ocean warming and departure from the Little Ice age, and this probably will continue to be the case for next 50 years or more. And that solar activity in next couple decades will probably be lower than has been for a 100 years, and I expect the 18 year pause to continue for next 5 to 10 year. And none of this has anything to do with milankovitch cycles.
[And in next 5 years I expect CO2 levels to rise to about 410 ppm and this rise will continue to have unmeasurable effect upon global temperatures. And polar sea ice will not completely melt, the polar bears are doing ok, and of course, Obama has actually done nothing to stop the sea from rising.]
The albedo causing or triggering Glacial periods is only another such figment..
Whiten says to me.
My reply
Which is not what I am trying to convey. What I am trying to convey is not a change in albedo triggering glaciation. What I am trying to say is why does the POSITIVE FEEDBACK between an increase in snow cover/ice cover which will result in a higher albedo hence colder global temperatures does not feed upon itself once it gets established? One would think it would with all other things being equal but this is not the case.
The question is what is it that causes this not only not to happen but reverse ?
I can not get away from the notion it must be tied up with solar variability and the associated primary /secondary effects associated with this variability.
Anyone have any other possible explanations?
The problem with Milankovitch cycles is two fold ,first glaciation occurs in both hemispheres at the same time and secondly the abrupt climatic changes are far to rapid and occur far to often in order to be explained by the very slow Milankovitch Cycles.
Ice core data shows evidence of the earth transitioning from inter-glacial to glacial conditions in decades . I have come up with some thoughts on this in my earlier post.
The YOUNGER DRYAS – that event alone is a nail in Milankovitch Cycles as the prime mover of the climate.
That said I do think Milankovitch Cycles have a back-ground role in the climate variability but only that.
I could even see how the S.H. could cool even when Milankovitch Cycles favor warming there, due to the N.H. cooling /increase albedo, over powering the globe as a whole.
Salvatore The weight of evidence suggests that the rapid cooling of the YD and 8200 year events are caused by comet impacts – they have no relation to Milankovic cycles.
4) The warming oceans melt the ice from below as the ice thickens above creating huge instability in the ice shelves from CAL
My Reply
What factor or explanation do you have to explain why all of a sudden, in an increasingly colder higher albedo world, the oceans all of a sudden start to warm? What happened to bring that on?
The oceans do not suddenly start to warm. They gradually warm as a result of the very low cloud cover because of the low humidity bordering the ice caps. Thus the equatorial waters receive huge amounts of energy. Instead of flowing north and radiating energy at most latitudes south of the arctic circle they flow north under the ice. This prevents radiation to space. There is strong evidence that the Baltic sea was indeed warm under the ice.It is this lack of radiation to space that causes the positive radiation balance and the gradual warming.
However, what is clear is that the short irregular interruptions of the glacial epoch are correctly identified by the Milankovic cycles of increase in the N. Hemisphere’s solar irradiation. Vuk says
My reply
Wrong , and all one has to do is look at the historical climatic record 22,000 to 10,000 years ago to see the many abrupt climatic changes are in no way related to the very slow Milankovitch Cycles.
If the first difference makes a better correlation, then does using the second difference, which will de-emphasize the 100kyr cycle with respect to those at lower period even more, help the correlation further? In other words, is it the case that rate of change of the rate of change of temperature, or ice volume, is what the orbital elements drive? I’m not a fan of continuing down such a path, I’d rather have an understanding of actual physics drive the analysis, rather than transform the input in various ways to improve correlation.
There is a explanation of the 100kyr problem in the data, however. The figure doesn’t place a peak at 100kyr in the insolation periodogram, but there is power at 100kyr. So, let’s think of the climate as a linear black-box system. If Delta-T/Delta-I is admittance, at 100kyr the admittance is very large. The transfer function has a pole, with high Q, near 100kyr. Why? I don’t know–some combination of climate force and inertia, or feedback, or lag in the system. But my point is, as long as some some power exists at 100kyr in the insolation periodogram, there is a basis for explaining the 100kyr temperature swing using it.
http://wattsupwiththat.com/2013/06/02/multiple-intense-abrupt-late-pleisitocene-warming-and-cooling-implications-for-understanding-the-cause-of-global-climate-change/
Milankovich cycles can NOT explain these abrupt climatic changes which means it is not the main reason for why the climate changes. It is that clear cut..
Feedback, and momentum! R.
Dr. Norman Page I doubt that is the reason and even if it was how do you explain all of the other abrupt climatic changes which I just posted? It is by no means limited to the YD or 8200 year cold period. There are countless other abrupt climatic changes besides those two. It is very unlikely that impacts were the cause.
To make it even more unlikely it was some sort of impact it is not just the beginning or ending of the YD but all of the abrupt climatic changes within the YD.
I would say the impact theory has a 0% chance of being correct.
Salvatore Just eyeballing roughly the number of peaks between 11500 and 13000 it looks very much like the good old 60 year cycle ( see following comment) also there is no scale on the graph to show the amplitude of the cycles.
It is obvious that the glacial cycles are Milankovic related .
The evidence for impact at the beginning of the YD is substantial. The evidence for impact at the beginning of the 8200 year event is certainly much less than for the YD.
There is clear evidence for solar activity quasi periodicitiesin the Holocene For the 1000 and 60 year periodicities seen in the temperature data. see Figs 5-9 and 15-16 at
http://climatesense-norpag.blogspot.com/2014/07/climate-forecasting-methods-and-cooling.html
The solar driver connection to temperature is shown in the relations between Fig 9,10 C,D 11 and 12.
The reasons why we are just past the millennial cycle peak are seen in Figs 13 – 14.
and the millennial cycle trend peak at about 2003 is seen in the graph
http://www.woodfortrees.org/plot/rss/from:1980.1/plot/rss/from:1980.1/to:2003.6/trend/plot/rss/from:2003.6/trend
As a limited test of this approach I am suggesting a significant cooling in 2017- 18 based on the sharp Ap index break at 2005-6 in Fig 13.
It is also clear that particularly during glacial and cooler periods the climate is in a state of unstable equilibrium so that small changes in some variable eg volcanic activity can cross some threshold and trigger rapid temperature changes,
Dr. Page my reply to you.
I do not agree entirely with your explanation as to why/how the climate changes. Some of your thoughts I do agree with.
I am more in the camp of Don Easterbrook as far as why Milankovtich Cycles influences on the climate but not exactly 100%.
Like yourself I expect cooling going forward but primarily from solar variability and the primary and secondary effects associated with this solar variability. Again I know you feel this way to some extent also. I think however I emphasize solar variability as having a bigger role in the scheme of things then you do.
From Don Easterbrook – Aside from the statistical analyses, there are very serious problems with the Milankovitch theory. For example, (1) as John Mercer pointed out decades ago, the synchroniety of glaciations in both hemispheres is ‘’a fly in the Milakovitch soup,’ (2) glaciations typically end very abruptly, not slowly, (3) the Dansgaard-Oeschger events are so abrupt that they could not possibility be caused by Milankovitch changes (this is why the YD is so significant), and (4) since the magnitude of the Younger Dryas changes were from full non-glacial to full glacial temperatures for 1000+ years and back to full non-glacial temperatures (20+ degrees in a century), it is clear that something other than Milankovitch cycles can cause full Pleistocene glaciations. Until we more clearly understand abrupt climate changes that are simultaneous in both hemispheres we will not understand the cause of glaciations and climate changes.
My reply
All the above which is what the data shows lends support to my thoughts that solar variability and the primary and secondary effects associated with this solar variability are a big player in glacial/inter-glacial cycles when taken into consideration with these factors which are , land/ocean arrangements , mean land elevation ,mean magnetic field strength of the earth(magnetic excursions), the mean state of the climate (average global temp), the initial state of the earth’s climate(how close to interglacial-glacial threshold it is) the state of random terrestrial(violent volcanic eruption) /extra terrestrial events (super-nova in vicinity of earth or a random impact) along with Milankovitch Cycles. These factors setting the back ground for a general climatic trend for the earth to move in if solar variability did not exist at all.
What I think happens is those factors keep the climate of the earth moving in a general trend toward either cooling or warming on a very loose cyclic or semi cyclic beat but get consistently interrupted by solar variability and the associated primary and secondary effects with this solar variability which brings about at times counter trends in the climate of the earth within the overall trend , or at other times when all the factors I have mentioned setting the back ground for the climate trend for cooling or warming along with what solar variability has been doing or a random terrestrial /extra terrestrial event (which can explain some of the dramatic climate changes maybe 10%of them) in conjunction with these factors( which are land/ocean arrangements, mean land elevation ,mean state of the climate and initial state of the climate, Milankovitch Cycles) , then drive the climate of the earth gradually into a cooler/warmer trend(unless it is a random terrestrial or extra terrestrial event in which case it would be rapid even if the climate initially is far from the glacial /inter-glacial threshold ) UNTIL it is near that inter- glacial/glacial threshold or climate intersection that makes any further solar variability no matter how slight at that point to be enough to cascade the climate into an abrupt climatic change. The back ground for the abrupt climatic change being in the making all along but when the threshold glacial/inter-glacial intersection for the climate is reached that is NOT ONLY when the abrupt climatic changes occur but the constant swings in the climate from glacial to inter-glacial over short periods of time can take place .
The climatic back ground factors along with the general trend in solar activity driving the climate gradually toward the climate intersection or threshold of glacial versus interglacial, then once there at the intersection the climate gets wild and abrupt. Although random terrestrial events and extra terrestrial events could be involved some times to account for some of the swings in the climatic history of the earth but not all of them ,maybe 10 % of them.
The climate is chaotic, random and non linear but in addition is never in the same mean state or initial state which makes given forcing to the climatic system not resulting in a given outcome which is why I think there is a semi cyclic nature to the climate but it is consistently being disrupted with counter- trends at times or abrupt changes at times.
If what I say is not on the correct path then why is it whenever the climate strays from its mean in either a negative or positive direction it is ALWAYS brought back to its mean. Why does the climate never go in the same direction once it heads in that direction?
Why is it that when the ice sheets expand the higher albedo /lower temperature more ice expansion positive feedback does not keep going once it is set into motion? What causes it not only to stop but reverse?
Vice Versa why is it when the Paleocene – Eocene Thermal Maximum came about that the increase CO2/higher temperature positive feedback not only did not keep proceeding but reversed?
.
Like I said before, this graph is sufficient proof for M cycles as the driver: http://en.wikipedia.org/wiki/Milankovitch_cycles#mediaviewer/File:Vostok_420ky_4curves_insolation.jpg
R is next to meaningless: does it vary according to the number of cycles of correlation? Each additional cycle of correlation multiplies the unlikelihood of spurious correlation. And of what use is lag analysis if the lag varies between each cycle, according to variably sized ice caps? How can albedo be taken into account? It’s all reminiscent of the denial of the statistical force of Wegener’s observations.
To melt 1km of ice in 10ky requires 3w/m^2 (average). M cycles are quite capable of delivering it, or not. Not all the ice is a mile thick; thinner ice at lower latitudes can melt in a hurry: http://www.nature.com/nature/journal/v502/n7473/full/nature12609.html
…causing a step change in albedo to add to growing insolation. All the ice has to do is melt faster than it snows. Not even that, really. All that is needed is for snow to change to rain. –AGF
Salvatore I agree that for forecasting climate on time scales of interest to civilization ie the next 1000 years the solar driven quasi-millennial cycle seen in the temperature data is key. As to the processes involved I say
in the link above
“NOTE!! The connection between solar “activity” and climate is poorly understood and highly controversial. Solar “activity” encompasses changes in solar magnetic field strength, IMF, CRF, TSI, EUV, solar wind density and velocity, CMEs, proton events etc. The idea of using the neutron count and the 10Be record as the most useful proxy for changing solar activity and temperature forecasting is agnostic as to the physical mechanisms involved.
having said that, however, it is reasonable to suggest that the three main solar activity related climate drivers are:
a) the changing GCR flux – via the changes in cloud cover and natural aerosols (optical depth)
b) the changing EUV radiation – top down effects via the Ozone layer
c) the changing TSI – especially on millennial and centennial scales.
The effect on climate of the combination of these solar drivers will vary non-linearly depending on the particular phases of the eccentricity, obliquity and precession orbital cycles at any particular time.
Of particular interest is whether the perihelion of the precession falls in the northern or southern summer at times of higher or lower obliquity.”
It is simply not necessary to understand all the problems of the beginning end of the ice ages and the temperature variations during glacial episodes or the PETM in order to make perfectly reasonable forecasts for the next 1000 and especially for the next 100 years. These matters are of important academic interest but the state of the system as a whole during those events was very different from the present and are of limited relevance to forecasting the next thousand years.
If we can understand Fig 5 at
http://climatesense-norpag.blogspot.com/2014/07/climate-forecasting-methods-and-cooling.html
that is really all we need- at least if our main interest is forecasting the next 1000 years.
Salvatore Check my 2:21 comment.
I suspect that the continental ice network has a clock frequency of 1 / 100K years.
I think we agree in principal.
I think one difference is you see the climate as more cyclic ,I see it as being semi cyclic with a random pattern superimposed upon the semi cyclic pattern . I also think I put much more evidence on the initial state of the climate to attain a given climate result then you do.
I am of the opinion that much more information is going to be coming forth about solar/ climate connections and variability of the sun as this prolonged solar minimum period extends.
Look at my post jan 25th at 11:23am
The key will be the neutron count at the next solar minimum (count maximum) in about 2021. If it peaks significantly above the 2009 count, temperatures will really be heading down for the following 15 years at least and I will have more confidence in my 2035,2100 and 2600 forecasts.
that we agree on 100%
Willis,
here is a paper that should interest you: The Albedo of Earth,
http://onlinelibrary.wiley.com/doi/10.1002/2014RG000449/abstract?campaign=wolacceptedarticle
Send me an email if you need a copy.
They show that Earth’s albedo is amazingly constant in time and between hemispheres. The GCMs do not capture this at all.
Interesting, but not relevant to the question of M cycles. –AGF
I take that back: if clouds disperse with growing sea ice, I suppose the same could mysteriously happen with land ice.
Thanks, Matt. I’d noted and commented on that in my investigations into the CERES data. Do you have a citation for the inability of the GCMs to capture this oddity?
w.
Salvatore
I can not get away from the notion it must be tied up with solar variability ..
No you cant, and this is looking more and more problematic. To say “everything imaginable in climate can only be caused by one thing – direct response to solar changes – and nothing else” is very similar to saying “everything imaginable in climate can only be caused by one thing – direct response to CO2 changes – and nothing else”.
Disputing Milankovich pacing of the glacial cycle is the same as disputing Galileo and Copernicus and trying to thread-bomb us all back to epi-cycles. From 1-3 million yrs ago interglacials were paced by 41 kyr intervals, the length of the obliquity cycle. After than (the MPR) the pacing changed to 100 kyrs – the eccentricity cycle. An orbital pacing signature is hard to deny (although that’s clearly not stopping you from trying).
Note I use the word “pacing” and not “forcing”. The climate is a chaotic-nonlinear system. Again, no amount of thresdbombing will change this fact. The AGW crowd imagine climate to be passive and driven by CO2 radiative forcing. You believe the climate to be passive and driven by solar forcing. You are both wrong. Climate is dynamic and drives itself (its more than 18 years old!) BUT – nonlinear oscillators CAN be periodically forced from the outside. This can be strong forcing, where the forcing frequency is reflected in the driven system. But it can also be weak forcing – where the responsive oscillation timing is related only in a very complex way to the forcing frequency. I strongly believe that the role of solar fluctuations, since the percent changes in energy are so small, is weak periodic forcing. Milankovich cycles are also a combination of strong and/or weak forcing. In fact the “Mid Pleistocene revolution” or change from 41k obliquity pacing to approximately 100 kyr pacing may well represent a transition from strong to weak nonlinear periodic forcing.
Climate study will only emergy into the sunlight and stop wasting time when it acknowledges fully the chaotic-nonlinear character of the system and all its implications.
FYI, processing André Berger’s insolation data is somewhat of a pain because the files are split up into tiny 144k chunks. Most likely an ‘artifact’ of the early 1990’s when he generated these files and floppy diskettes were restricted in capacity to 720kb:
http://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/orbital_variations/berger_insolation/
But now there’s a much easier way to generate this same data in R using the ‘palinsol’ package, which was written by Berger’s protegé, Michel Crucifix at the University of Louvain in Belgium:
http://cran.r-project.org/web/packages/palinsol/palinsol.pdf
Just use the ‘install packages’ tool in R to install it. (But you’ll need the latest version of R, ver3).
I wrote a little script to generate the same 0-800kyr range that Willis used.
The palinsol package actually computes the insolation, from computed solar system orbitals and perturbations, using Berger’s very detailed algorithms. You can select either the 1978 or 1990 versions of the code. The 1990 version used more terms in the regression and corrected some minor errors in planet masses etc. But for the first 1.5 million years the outputs are the same. So I used the 1978 version.
My script also computes the periodogram of the data using the ‘spectrum()’ function in R (right panel)
http://i62.tinypic.com/5agm6p.png
Note that the spectrum is logarithmic, not linear like Willis’. So the data looks more compressed. Also there are more peaks. Probably because I didn’t smooth the data. (But there is a default 0.1 cosine taper applied by the spectrum() to suppress some of the sync() side lobes)
So I think it captured all of the signals that Willis saw (and more), but it didn’t generate a signal at 2kyr, which I think may be aliasing, as noted by others earlier. I zoomed the plot a bit and used the locator() function to extract the 16 largest peaks (marked with red +’s)
http://i59.tinypic.com/2bbrli.jpg
http://i58.tinypic.com/htu0ps.png
Disregard the decimal precision of these numbers, because they depended on my manual dexterity while positioning the +’s. They’re probably off by 5% or so, but close enough for ‘government work’.
Note the 100kyr signal is there and looks pretty large in the log plot. But its true intensity is less than 5% of the procession peaks at 23.3kyr. So comparable with Willis’ results.
But I’m curious why Willis’ plot doesn’t show the 400kyr wave, which is readily apparent, even in the time domain plot.
Here’s the R script to generate this plot and data: 801 samples, 1 per kyr, from 0 to 800kyr BP
#————- mysol.R ——————-
require(palinsol)
require(graphics)
insolation = function(times, astrosol=ber90,…)
sapply(times, function(tt) Insol(orbit=astrosol(tt)))
tts = seq(from = -800e3, to = 0, by = 1e3)
isl = insolation(tts, ber78)
par(mfrow=c(1,2))
plot(tts, isl, typ=’l’, main=’berger78: -800ky to Present’)
spectrum(isl,main=’Spectrum: freq.res=1/1602kyr period.max=2kyr’)
grid()
n=16
loc=locator(n)
text(loc, ‘+’,col=’red’)
print(1/loc$x[1:n])
print(sqrt(loc$y[1:n]))
I said:
“…didn’t generate a signal at 2kyr, which I think may be aliasing, as noted by others earlier. ”
Upon reflecting further, I don’t think it’s aliasing, because that always starts at the low-frequency end of the spectrum, and 2kyr is the very highest frequency possible in this sampling regime.
So there must be some other reason I don’t see any significant energy at 2kyr comparable to Willis’ plot.
Johanus said: “Upon reflecting further, I don’t think it’s aliasing, because that always starts at the low-frequency end of the spectrum.”
There is obviously “high frequency” content in temperature data. There was a larger temperature range here today from morning to afternoon (one cycle per day) than in all of the subject data. Thus, aliasing error is certainly possible. There is likely some sort of natural low pass filtering of this in the ice core generation and analysis process, but it’s characteristics are unknown, at least to me. A perfect boxcar shaped filter would allow all of the Nyquist frequency content (one cycle per 2000 years) through, and completely eliminate all other higher frequencies. This would be highly unlikely for any number of reasons. So lets assume there is some sort of realistic, likely single pole, low pass filter, present in the original ice core generation process.
If there were such a realistic filter, and if there were also no aliasing errors, there would be no content at the Nyquist frequency. The filter would eliminate it in the process of eliminating other aliasing error. The fact that there is, at least in Willis’ chart, means that there are some aliasing errors present in the data. With broadband white noise data, and properly selected multi-pole anti-aliasing filters, the largest aliasing error occurs at the Nyquist frequency, and reduces for lower frequencies. Since the data are not white and the high pass filter is likely not multi-pole and certainly not “properly selected”, the aliasing errors are likely to be at any of the frequencies in the chart.
Tom:“There is obviously “high frequency” content in temperature data. “
But this is about the Berger insolation dataset. There is no ‘temperature’ data in that. It’s all synthetic astronomical data, generated from orbital mechanics.
Willis’ periodogram of the Berger data (red trace) had a 2kyr ‘bump’ which did not show up in my equivalent periodogram generated from palinsol data.
Oops. I was thinking of the wrong data. There may or may not even be an issue with aliasing, depending on the method of generating and of reading the Berger insolation data.
Johanus, thank you so much for your link to the marvelous R package, and also for posting your R code. Very neat.
Also, the reason I don’t show the 400 kyr cycle is that I was working with only only 1,000 kyrs of data, and I cut off any such analysis at a third of the length of the data.
I believe that what you’ve found is an artifact of the short time span. I just tested it by looking at 1,600 kyr of the Berger78 data, and there’s no significant 400 kyr cycle.
w.
Thanks.
“I just tested it by looking at 1,600 kyr of the Berger78 data”
I did the same with my script using this statement to expand the times sequence to 1600kyr:
tts = seq(from = -1600e3, to = 0, by = 1e3)
The resulting plot still shows the 400kyr spectral line and a new one at 1.2 myr. I think these are “real” signals (in the synthetic data, heh).
You can actually “see” a 400kyr wave in your time domain plot (with peak amplitudes at -600 and -200 kyr):
PHLOGISTON – if you read my recent post you would see that what I am saying is very similar to what you have said.
The only difference is I believe solar variability is a bigger player in the overall climate scheme of things then you do.
First, why should the 60th or 65th parallel temperature matter? Why not the 40th or 45th parallels where most glaciations stopped?
Second, 100Kya is an average and you should know better than to pin an argument on a mathematical construct that doesn’t reflect a multi-dominate mode. The modes of ice ages run at 82 and 123 kyrs. The use of average or mean leads to false conclusions when the mode is so strong. You’re making the exact same mistake as taking the average temp of the Northern Hemisphere and Southern Hemisphere to come up with the GAT. The volatile NH overrides the SH stable temperature paradigm giving the false idea that the WHOLE of the planet is heating when only part of it is.
Third, you make the assumption using the Milankovichcycle that obliquity change is constant throughout the cycle. Does it not occur to you that when the ocean level drops 450 feet during the depth of the ice age that weight is mostly redistributed from the water dominated SH to the land dominated NH? Do you honestly believe there is ZERO impact on the rate of obliquity during the ice accumulation phase and the melting phase when so much weight is redistributed from South to North?
A couple of interesting excerpts from posts.
This one from “Ask a scientist UK”
Question “What caused reduction in CO2 leading to the ice ages?”
Answer by Michael de Podesta April 27, 2012:
“It’s a great question, but does not have a simple answer. There are two parts to the answer and to understand these I need to ask you to distinguish between the ‘trigger’ events which started the transitions into and out of ice ages and the ‘drivers’ which kept the change going
Trigger: We believe that triggers for the ice ages and interglacial warming periods are small changes in the attitude of the Earth in its annual journey around the Sun. These ‘orbital wobbles’ are small and barely alter the average amount of energy reaching the Earth. But they do alter day length and summer length at high latitudes. Imagine what happens at the ‘snow line’ – the line of latitude at which snow just lies on the ground over summer. If summer lengthens or intensifies then this can cause snow to melt, which changes the albedo of the surface – making it darker and increases the rate of warming. Orbital changes trigger this kind of change.
Driver: When the Earth warms up microbes wake up and digest biological matter in the Earth and release methane (CH4) which reacts after about 10 years to make CO2 which stays in the atmosphere for hundreds of years – causing more warming and making the release of further CO2 more likely. So the ice core record shows changes in CO2 that correlate with ice ages. But these did not trigger the ice ages or interglacial periods. However, the changes in CO2 concentrations did drive the changes once they began.”
http://askascientist.co.uk/chemistry/what-caused-reduction-in-co2-leading-to-ice-ages/
The next one in the next post.
The temperature fluctuates through Earth’s history sometimes it becomes warmer and sometimes cooler.
Periodically it becomes drastically cooler like the ice ages, which would wipe out Europe and North America.
The idiot alarmists, greenies and tree-huggers would want a cooler world, when a cooler climate brings only death, destruction and misery.
Tambora: The Eruption That Changed the World, by Gillen D’Arcy Wood
http://www.timeshighereducation.co.uk/books/tambora-the-eruption-that-changed-the-world-by-gillen-darcy-wood/2014089.article