Perspective by William McClenney on the paper of the same title by:
P. C. Tzedakis, E.W. Wolff, L. C. Skinner, V. Brovkin, D. A. Hodell, J. F. McManus, and D. Raynaud
http://www.clim-past.net/8/1473/2012/cp-8-1473-2012.pdf
I can often be heard, when assailed by the well-informed, climate, to ask the eminently reasonable question “In your opinion, how long will the Holocene last?” Rodney Dangerfield Syndrome then ensues, without exception so far, because astonishingly, few of the climate cognoscenti have even heard of the Holocene, much less pondered how, why, and by what mechanism it might, theoretically, be extended……
This IS the debate we should be having. So far, the Holocene has been quite the historically stable little interglacial, so far not exhibiting the normal climate instabilities of the typical end extreme interglacial.
But “Can we predict the duration of an interglacial?”
This, now week-old paper, explores a fascinating linkage concept, the inception and disintegration of the bipolar seesaw.
“We propose that the interval between the “terminal” oscillation of the bipolar seesaw, preceding an interglacial, and its first major reactivation represents a period of minimum extension of ice sheets away from coastlines.”
I will leave it to the experts to comment and debate as to whether or not we are perhaps seeing the onset of said bipolar seesaw in Arctic/Antarctic sea ice, and whether or not such is applicable in an anthropogenic greenhouse-gas world.
However, we might need to consider:
“…thus, the first major reactivation of the bipolar seesaw would probably constitute an indication that the transition to a glacial state had already taken place.”
As we work our way through this paper, we find:
“With respect to the end of interglacials, the MIS 5e– 5d transition represents the only relevant period with direct sea-level determinations and precise chronologies that allow us to infer a sequence of events around the time of glacial inception (Fig. 2).”
and this….
“Thus, glacial inception occurred ~3 kyr before the onset of significant bipolar-seesaw variability.”
and this…..
“Given the large decrease in summer insolation over the Last Interglacial as a result of the strong eccentricity-precession forcing, we suggest that the value of 3 kyr may be treated as a minimum. We thus estimate interglacial duration as the interval between the terminal occurrence of bipolar-seesaw variability and 3 kyr before its first major reactivation.”
This paper then proceeds to get very deep indeed into the evolution of the post-MPT interglacials, with an eye towards how each might be relevant to our interglacial times.
The take-home context, in terms of CO2 forcing might be encapsulated by this:
“A corollary of all this is that we should also be able to predict the duration of the current interglacial in the absence of anthropogenic interference. The phasing of precession and obliquity (precession minimum/insolation maximum at 11 kyr BP; obliquity maximum at 10 kyr BP) would point to a short duration, although it has been unclear whether the subdued current summer insolation minimum (479Wm−2), the lowest of the last 800 kyr, would be sufficient to lead to glaciation (e.g. Crucifix, 2011). Comparison with MIS 19c, a close astronomical analogue characterized by an equally weak summer insolation minimum (474Wm−2) and a smaller overall decrease from maximum summer solstice insolation values, suggests that glacial inception is possible despite the subdued insolation forcing, if CO2 concentrations were 240±5 ppmv (Tzedakis et al., 2012).”
Would you like fries with your Baked Alaska?
I have sent Anthony the raw and highlighted versions. A bloody good read.
cp-8-1473-2012 (PDF raw)
cp-8-1473-2012 HLT (PDF highlighted)
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Joachim Seifert says:
October 2, 2012 at 11:43 am
The analysis is rather bad science….because
-> not one word about the 50,000 year duration of the Anthropocene…
Your post is rather bad …. because
-> not one word about the 10 year AlGorocene.
captainfish says:
October 2, 2012 at 8:38 pm
I haven’t the foggiest idea what this article is about. I understand the Holocene and the article’s quest to try and see if someone can determine a length till next glaciation. However, everything after that is in non-English.
The bit I found particularly hard to understand was “Would you like fries with your Baked Alaska?”
Certainly we can predict the duration of an interglacial: “It will be long”. But not long enough….
Oh, more precise? It will end in a few thousand years.
Since the onset of ice is sawtoothed with the growth mass transfer limited, but the melt rain accelerated, the growth of the ice sheet to full size takes about 80,000 years. As it’s about 1800 miles form the residual of the ice sheet on Greenland to where it ended in New York (wild ass guess from looking at map) I make that about 9/400 mile / year (or about 120 feet per year). That means you can walk away from the advancing glacial onset with a short stroll once per decade. The average person will need to move one and 1/2 mile further south each lifetime, so tell your kids to pack up and move 3 miles south of you and they will be all set until the grand kids are grown and done…
(Even if off by a factor of 2, it’s an irrelevancy)
I’d even go so far as to assert that the Interglacial has already ended. There are some long cycle processes ( one 5000 years, another about 180 years) and the Little Ice Age was the start of the drop. But it arrived during a ‘dip’ of one of those longer cycles, so we rode a rising wave out of it. Just not as warm as the PRIOR rise… We’re having “lower lows” and “lower highs” already. When this cycle tops and falls, we go further into cold than during the L.I.A.; then in 200 to 400 years warm out of it again… just not as warm as THIS time. Repeat…
So more important to most of us is ‘when this oscillation ends’ and we head back to a L.I.A. drop (as it’s faster than the glacial). IMHO, that’s in the current sleepy sun period from now to 2040.
Looked at another way, a long human lifetime is 1/1000 of the glaciation process. We just don’t live long enough to even notice it…. The warming out of a glacial is a different matter….
Look at the (inverted) ice volume in this graph:
It slowly builds over the entire glacial, then suddenly melts in one spectacular rush. (It does get cold fast, but folks in Canada and Russia are already used to cold 😉
For folks thinking we’re doing a nice flat with ringing wobble from the chart in a comment above; that’s the orbit. Look at the historic very long term temperature trend, and we’re colder:
https://en.wikipedia.org/w/index.php?title=File:Five_Myr_Climate_Change.svg&page=1
That’s 5 million years. Steadily colder. So it takes less “orbital change” to get to making ice cold over time. Where we used to warm enough to exit an ice episode every 41 kyrs, it is now only warm enough every 100 kyrs. Eventually even that won’t be enough. (The last 1/2 million years we’ve dipped deeper and spend more time colder…) Basically, our “natural state” is frozen. Only rarely do we enter an odd configuration that can melt the ice; but that’s going to run out too…
Hopefully not too long after that the continents will move enough to warm things up.
I really think folks need to fully absorb the point that the natural state is FROZEN. Only rarely is it warm enough to melt north polar ice. As soon as we have persistent multi year ice at the North Pole that accumulates decade over decade, we’re headed back into the freezer…
At the start of this interglacial obliquity was approaching highest (24.5) and NH summer solstice was nearing perihelion. This combination will not come together again for another 80,000 years or so. If Leif is correct and the climate stays warm until then due to low eccentricity it may be that the Earth will not return to glaciation for another 90 – 100,000 years.
Tom;
Oh, yeah? I betcha 2 bn. quatloos yer wrong. Lief, too.
REPLY: You probably ought to learn how to spell Leif’s name correctly before saying he’s wrong. – Anthony
E.M.Smith said “We’re having “lower lows” and “lower highs” already. When this cycle tops and falls, we go further into cold than during the L.I.A”
If we see temperatures dip below those of the LIA, in the coming 20+ years then I reckon that may be a reasonable indicator that we are stepping down from our current interglacial towards the next full glacial.
This last graph on the linked page below from Tallbloke’s Blog suggests that that might be the case, if only they had extended it another two hundred years. Note that the two largest curves didn’t fully coincide during the Maunder Minimum, but it looks as if they will come much closer to doing so during the forthcoming minimum, thus producing temperatures lower than those reached in the Maunder.
http://tallbloke.wordpress.com/2012/09/20/how-the-temperature-datasets-tell-us-extra-co2-has-little-effect/
Tom in Florida says:
October 3, 2012 at 7:52 am
At the start of this interglacial obliquity was approaching highest (24.5) and NH summer solstice was nearing perihelion. This combination will not come together again for another 80,000 years or so. If Leif is correct and the climate stays warm until then due to low eccentricity it may be that the Earth will not return to glaciation for another 90 – 100,000 years.
Not according to the geologic record.
An Ice Age does not come to an end at the top of every obliquity cycle at 24.5 degrees, it only ends at that point on the 2nd or 3rd time of the max. Precession may indeed determine IF an Ice Age ends but only in combination with the peak of the obliquity cycle. However, the geologic record is clear without exception, EVERY interglacial ends at the down swing of the obliquity cycle when it passes 23.5 degrees. NO EXCEPTIONS!!!!! The only relevant question is at what degree below 23.5 does the interglacial actually officially end? 23.44, 23.43, 23.41? This is an event driven process, not a time driven process. Time is merely the derivative of the cause not some magical effect. 100 kya is an average of the Ice Age cycles that last 80 kya and 120 kya, this why it does not look like it matches the 41 kya obliquity cycle. It’s a basic math error employed by those who refuse to accept the Milankovich theory by obfuscating the timing.
Empirical analysis is the only valid scientific method that ends in reproducible results. Magical thinking in terms of the effects of CO2 at such absurdly low atmospheric concentrations does not bear out in reality. Earth is not Venus with it’s 90 bar pressure CO2 dominated composition, thus not an analog as many warmists would like you to accept.
Chaos is not the absence of order, chaos is the inability to understand the order. Weather and Climate seem chaotic because we don’t understand the variables.
Brian H says:
October 3, 2012 at 9:52 am
“Tom; Oh, yeah? I betcha 2 bn. quatloos yer wrong. Leif, too.”
You are on! Let’s meet in 92012 so I can collect.
23.5 degrees obliquity is where we are now.
Combine that with our reducing magnetic field and the Livingston & Penn goodbye to sunspots graph and this minimum we are currently embarked on might go somewhat deeper and longer than many would like. It will almost certainly reduce the church of co2 to the smallest religious congregation anywhere.
A closer look at obliquity and those inter-glacial terminations would indeed be interesting.
I vote that we pour money into Thorium and Fusion research like there’s no tomorrow.
Up to now we have named minimums, Dalton, Maunder, Sporer etc. with a split over the name for the next one (this one) between Eddy and Landscheidt. Yes Eddy was a great solar scientist, but Landscheidt predicted this minimum back in 83. Perhaps this pending glaciation will be named after one of those two gentlemen.
dscott says:
October 3, 2012 at 12:32 pm
“.An Ice Age does not come to an end at the top of every obliquity cycle at 24.5 degrees, it only ends at that point on the 2nd or 3rd time of the max. Precession may indeed determine IF an Ice Age ends but only in combination with the peak of the obliquity cycle.”
That’s what I said.
“Tom in Florida says: October 3, 2012 at 7:52 am:
“At the start of this interglacial obliquity was approaching highest (24.5) and NH summer solstice was nearing perihelion. This combination will not come together again for another 80,000 years or so…..” ”
Perhaps I should have added “when another interglacial will commence”.
I did add IF (that’s a big IF) Leif is correct about the influence of eccentricity, the climate may not enter a frozen period until we get close to the next time conditions are ripe for an interglacial, which would mean one long period of the Earth not being in a glacial state.
I wasn’t as clear as I should have been.
23.5 degrees to 23.4 degrees takes about 500 years, so maybe I don’t need to move to Australia just yet, assuming that’s a good choice.
dscott.
Is your 23.5 degrees based on Antarctic ice cores, presumably Vostok, or Greenland ice cores, or other cores, or what.
Where do you get this info from ?
Tom in Florida says:
October 3, 2012 at 2:07 pm
I did add IF (that’s a big IF) Leif is correct about the influence of eccentricity, the climate may not enter a frozen period until we get close to the next time conditions are ripe for an interglacial, which would mean one long period of the Earth not being in a glacial state.
This idea by Leif Svalgaard and others that the current low amplitude node of eccentricity oscillation means no glaciation, is contradicted both by the fact that an interglacial ended as normal about 400 kYrs ago in exactly the same eccentricity setup, and also by the research of Tzedakis posted by William McClenney, who has repeatedly published the finding that the lack of insolation forcing does not prevent an interglacial from ending.
If there were to be tens to hundreds of thousands of years of (unprecedented) sustained interglacial, this would effectively mean the end of the current glacial epoch. One would – presumably – require something resembling evidence to support such a dramatic prediction.
From 1 million Yrs ago to 2 million Yrs ago, the 41 kYr obliquity oscillation controlled glacial / interglacial timing. Then for the last million years the system switched to being entrained by the 100 kYr eccentricity oscillation. No one has come close to explaining this transition – few indeed even pay it any attention. The “science” of analysing what causes glacial / interglacial switching and pattern is in utter infancy and has a very long way to go before becoming serious and effective science with anything like real answers. And until it incorporates a understanding of the dynamics of weakly forced nonlinear oscillators, there is zero chance of it doing so, ever.
E.M.Smith says:
October 3, 2012 at 2:36 am
Since the onset of ice is sawtoothed with the growth mass transfer limited, but the melt rain accelerated, the growth of the ice sheet to full size takes about 80,000 years.
Its not quite such a simple, saw-tooth. Looking at the last million years or so temperature record, you cant really say you have a linear decline from end of interglacial to glacial minimum, 80,000 years later. In fact every interglacial ends with a steep fall, usually to something like “half glacial”, a state much, much colder than a mere little ice age. So cooling at the end of an interglacial can at times be more rapid than you suggest.
Another interesting thing is that, while global temperatures are cooling toward glacial, temperatures are more unstable with higher amplitude fluctuations. Supposed glacial periods are punctuated by “micro-interglacials” lasting less than a century.
It is interesting to speculate if fractal property of climatic processes means the same at shorter timescales, that is, on a century or decadal scale, or even month to month scale, more fluctuation in global temperature is observed during periods of falling as opposed to rising temperatures.
Love all the comments folks. I wanted to just lay this one out there with minimal introduction to see the range of reactions. The range is what is fascinating! We have a tantalizing paper to be released by Joachim Seifert, which I hope he makes available to us, to Jack Linard whom I hope may now realize that the future of this rather pleasant little interglacial is also a matter of some debate.
Because even on things which actually have happened, the sciences is not that particularly well-settled. Which makes consideration of the science being settled on things which have not happened yet a bit unsettling………
When I add a half-precessional cycle old post-MPT interglacial with anomalous, but otherwise typical end-interglacial overshoots of CO2 with the triple thermal peaks at end-MIS-19, the single peak at end-MIS-11, the pair of thermals at end-MIS-5e, a polar see-saw with record-breaking (anthropogenic only, not paleo) Arctic melt and record Antarctic sea-ice the math comes face to face with “We thus estimate interglacial duration as the interval between the terminal occurrence of bipolar-seesaw variability and 3 kyr before its first major reactivation.”
The variable “major reactivation” operative given our paucity of concise late Holocene records. Did we just see it happen? Is that what we are seeing at the poles? Was the LIA a LEAP (Late Eemian Aridity Pulse)? Did the Holocene end 3kyrs ago based on this year’s polar ice?
Regardless, there is all this disquieting activity not going on with the quiet sun. The PDO negative, the AMDO will follow when? The 20th century grand solar maximum dwarfed by the hypsithermal, Roman, Minoan, and Medieval decaying thermal spikes.
Fact is, we don’t really know when this one will end. But to use the popular vernacular of the Post-Literate Age we “could” “might” “possibly” “irreversibly” descend into the next glacial or experience who knows how many normal natural end extreme interglacial thermal spikes.
It’s the gaining of the perspective that a chaotic, possibly stochastic yet rhythmic system as we presently observe HAS contained such end extreme interglacial noise that our current prognosticated anthropogenic “signal(s)” will be all but impossible to discern.
The end-game being simply this. CO2 had better be the heathen devil gas it is made out to be. If you can think of another way to avoid the slide into a glacial I am sure the geoengineers will (eventually) be all ears. Not that CO2, already in the throes of IR saturation, provides any sentient comfort. I just can’t see how more plant food can hurt at a possible/probable end extreme interglacial. This from someone that has spent over half his life cleaning up our worst toxic cocktails.
The way I see it, at a possible/probable end extreme interglacial, every penny not spent on fusion research will likely turn out to be a penny wasted. And we might just have to pass a planetary law prescribing the precise siting and revisable classification system for weather stations (urban sprawl et al), no mucking about with the data, and if you do you WILL give up every detail. The penalties worse than we thought…….
It “could” be just this simple: how many tipping points constitute glacial inception?
Meanwhile, enjoy the end-extreme-interglacial! While it lasts………………..
To William: Our paper, available already this month:
http://www/knowledgeminer.eu/eoo_paper.html
includes the entire Holocene plus a 500 year’s extention into the
future. The end of the Holocene can clearly be seen, we all have
to only agree on which is the global GMT-temperature level, we all
consider as sufficiently cold/or the END turning point is reached, to
name this point of time the “end point of the Holocene” …..
We will offer our paper soon to Anthony for your inspection…
.Cheers JS
dscott says:
October 3, 2012 at 12:32 pm
“EVERY interglacial ends at the down swing of the obliquity cycle when it passes 23.5 degrees. NO EXCEPTIONS!!!!!”
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Very interesting, but I stare at a Wickipedia graphic from time to time that seems to my eyecrometer to show interglacials ending in every concievable up or down swing in obliquity.
****
William McClenney says:
October 3, 2012 at 8:18 pm
****
William, thanks. Question: Not sure of the specifics of the 65N insolation values (W/m2). Is this an instantaneous value (like noon at summer solstice), or an integrated value? If one could integrate the solar input over a 24hr period @65N summer solstice, then that would include the effect of obliquity (tilt angle) and make better comparisons/correlations possible. Or integrate insolation over an entire melt-season period.
They didn’t mention eccentricity. I’m not convinced that it doesn’t need considering.
****
William McClenney says:
October 3, 2012 at 8:18 pm
The variable “major reactivation” operative given our paucity of concise late Holocene records. Did we just see it happen? Is that what we are seeing at the poles? Was the LIA a LEAP (Late Eemian Aridity Pulse)? Did the Holocene end 3kyrs ago based on this year’s polar ice?
****
Yeah, but now is the opposite of the bipolar-seesaw, defined as an Arctic cooling/Antarctic warming. 🙂 What to make of that?
Very interesting, but I stare at a Wickipedia graphic from time to time that seems to my eyecrometer to show interglacials ending in every concievable up or down swing in obliquity.
Yes, it is difficult to eyeball unless you scale the various obliquity, Vostoc and Antarctic Ice core charts over each other. You have to do some stretching and compacting of the graphics to line up the time lines on the x axis. That’s not the accuracy one likes unless you have the actual data files that would allow you to overlay all three data sets to produce a fairly accurate graphic. This is why I pose the question to the scientific types who have access to the data files. Add in the known sea levels and you will have a reasonably good means of prediction.
Joachim Seifert says:
October 4, 2012 at 8:13 am
http://www.www.com/?f
If I click on the link you provided I end up at the address above ???
Please check the link Joachim, I would like to read your paper.
Thanks!
William, excuse…..one dot after www was wrong….therefore:
http://www.knowledgeminer.eu/eoo_paper.html
this time, it should work. We offer a short summary; please look
for the long summary, which gives you a good idea. We took
care to even explain to the layman. The paper itself has good
Holocene graphs. It will be on-line within a few days…
Have a look, it is all original, new knowledge…Cheers, JS.
beng says:
October 4, 2012 at 9:48 am
“……(like noon at summer solstice)”
Exactly.
****
William McClenney says:
October 3, 2012 at 8:18 pm
The variable “major reactivation” operative given our paucity of concise late Holocene records. Did we just see it happen? Is that what we are seeing at the poles? Was the LIA a LEAP (Late Eemian Aridity Pulse)? Did the Holocene end 3kyrs ago based on this year’s polar ice?
****
That might be true if the LIA was a seesaw event — caused Antarctica to warm. The ice-core graphs of Antarctica I have don’t have the scale/resolution to tell, but I think other proxies indicate the SH cooled. Still, the current polar sea-ice seesaw is interesting…