Guest post by William F. McClenney
This post is essentially an update to The Antithesis and On “Trap Speed”, the ACC and the SNR.
The entire non-debate on anthropogenic climate effects has always struck me “as two fleas arguing over who owns the dog they are riding on” (Crocodile Dundee). One of the required paradigms of AGW is patently ignoring “when we live” (ignorance of signal to noise ratio, or SNR).
We live today possibly near the end of the most recent interglacial, the Holocene, or the 11,715 years since we melted our way out of the last glacial, the Wisconsin Ice Age, the interglacial in which all of human civilization has occurred. Five of the last six interglacials have each lasted about half a precession cycle. The precession cycle itself varies between 19,000 and 23,000 years and we are close to the 23kyr point now, making 11,715 years about half……..which is why this discussion has relevance.
So when will the Holocene end?
Even if you are not presently afraid of
But first a look at the often painful, difficult advance of Science.
Who was Alfred Lohar Wegener?
“He was the object of a kind of loathing that is only rarely seen in science.
“It wasn’t long before the established authorities closed ranks against Wegener’s concept as if they were stamping out a plague. He never understood the depth of resistance to his thinking. Continental drift was received not merely as a mistaken idea but as an evil that jeopardized the credibility of geology as a science and the professional reputation of anyone who espoused it. Wegener was denied professorships at German universities, but eventually he found himself at the University of Graz in Austria. Ironically, though, in 1928, he was asked to lead a German expedition to Greenland.”
–John D. Cox, “Climate Crash: Abrupt Climate Change and What it Means for Our Future”, ISBN: 0-309-54565-X, Joseph Henry Press (an imprint of the National Academies Press), 2005
The expedition got underway in 1930. In November,1930, Ernst Sorge, of Wegener’s Greenland meteorological expedition, discovered for the first time the records of paleoclimate preserved in the ice.
“It would be some years before researchers would fully appreciate the value of Ernst Sorge’s cold and lonely work in the winter of 1930 when he sawed and chipped and shoveled a shaft 54 feet down into the Greenland ice. Glaciologists at the time thought of the ice sheets almost exclusively as geological features whose movement across the landscape chronicled the slow waltz of a changing climate.”
Wegener died that winter of 1930. His Continental Drift theory of 1912 would not be proven until the 1960’s, revolutionizing geology as the Theory of Plate Tectonics. It would be 30 years beyond that (the 1990s) before the scientific contributions of Ernst Sorge were fully recognized as another revolutionary concept: Abrupt Climate Change.
When Do We Live?
Concern about abrupt climate change is especially inversely healthy today, as the Holocene is but the latest of the post Mid Pleistocene Transition (MPT) Extreme Interglacials, a thing almost nobody knows. An Extreme Interglacial can be variously described as a technical aspect of Ice Rafted Debris (IRD) in the ocean stratigraphic record, or more frequently as an interglacial that has achieved at least our sea level or our isotopic temps (<3.6 o/oo dO18). There is also a bit of controversy as to just which of the post MPT interglacials qualify. For the purposes of this essay we will define them as Marine Isotope Stages (MIS) 11, 5e (the Eemian) and 1 (the Holocene), with provisional inclusion of MIS-19, for reasons we will delve into.
Figure 1 Post-MPT interglacials with an expansion of part of the last glacial period and the Holocene. (Note: MIS-19 is unlabeled at the far left – click to enlarge)
As one may glean from Figure 1, something seems to have happened to the 100kyr amplitude about 400kyrs ago, the climate ride got a tad wilder from then to present. The speculation is long and worth researching yourself, however it is not exactly the subject of this piece.
As discussed in The Antithesis, we could very well be at the end of the most recent extreme interglacial. Although it is quite likely this thought will strike many as trivial, for some inexplicable reason it seems reasonable to wonder what the ends of the other extreme interglacials might have been like.
If AGW/CAGW causes you qualms, queasiness or abject terror/irrational rage, then you would be wise to take the exit ramp here.
Because there is, and has been, a long-running debate in the paleoclimatology literature that I suspect few of you have ever heard of, and it kicked off at the same time as the AGW hypothesis (or theory for post-normal scientists).
Wallace Broecker, arguably one of the fathers of modern paleoclimatology provides the best of the earliest quotes as regards this debate:
The next year (1999), in a paper posted on the Cambridge Conference Network (CCNet) by famous astronomer Fred Hoyle (originator of the now disfavored Steady State Theory Hypothesis), it was stated:
“This is why the past million years has been essentially a continuing ice-age, broken occasionally by short-lived interglacials. It is also why those who have engaged in lurid talk over an enhanced greenhouse effect raising the Earth’s temperature by a degree or two should be seen as both demented and dangerous. The problem for the present swollen human species is of a drift back into an ice-age, not away from an ice-age.”
Bringing it up to the present, we have this:
Public release date: 8-Jan-2012
Contact: Jim Channell
352-392-3658
University of Florida
Global warming caused by greenhouse gases delays natural patterns of glaciation, researchers say
GAINESVILLE, Fla. — published online Jan. 8 in Nature Geoscience.
“The Earth’s current warm period that began about 11,000 years ago should give way to another ice age within about 1,500 years, according to accepted astronomical models. However, current levels of carbon dioxide are trapping too much heat in the atmosphere to allow the Earth to cool as it has in its prehistoric past in response to changes in Earth’s orbital pattern.”
Which is more or less where Broecker was coming from in 1998 and where we ended up in “The Antithesis”. A hypothesis that we might extend the present interglacial by the timely venting of a “climate security blanket”, if you will. Also known as the Industrial Age.
Just to recap a bit of that, Loutre and Berger (Loutre M. F. and Berger A.: Marine Isotope Stage 11 as an analogue for the present interglacial, Global Planet Change, 36, 209–217, 2003) predicted, from a computer model, that the current interglacial, the Holocene, might very well last another 50,000 years, particularly if CO2 were factored in. This would make the Holocene the longest lived interglacial since the onset of the Northern Hemisphere Glaciations some 2.8 million years ago (some say over the last 5MY).
Of course, this was a model, for those enamored with models. It was soon put to rest by Lisiecki and Raymo (A Pliocene-Pleistocene stack of 57 globally distributed benthic D18O records, Paleoceanography, Vol. 20, PA1003, doi:10.1029/2004PA001071, 2005) which was quoted in “The Antithesis”, and will be again later in this discussion.
So this does indeed bear some serious scrutiny. We will begin with the Cenozoic and work our way to better and better resolutions. I again apologize for the presentation of some of these graphics. I whipped some of them together from professional papers for a slide show some years back, but, unfortunately, failed to take the time to properly reference them.
Figure 2. The Cenozoic
There are a great many things to be pondered in Figure 2. Why have we been roughly cooling off since the PETM? Is the increase in climate variability about the mean since the dinosaurs to present indicative of (a) poorer proxies or less data with time? or (b) truly indicative of a gradually more variable climate? Would comparisons of climate at the PETM be valid for a post Panama Seaway closed world? And those are just a few.
Figure 3. Expanding out the last 5 million years of climate (the LR04 Age Model)
In Figure 3 we expand out the past 5 million years of climate change developed from those 57 deep ocean drilling program cores of Lisiecki and Raymo (2005). We see the beginning of the 41kyr obliquity paced million years of glacial/interglacial oscillation about 2.8mya and we see the initiation of the eccentricity paced 100kyr pairings at about 0.8-1mya. We see again the onset of the extreme interglaciations at about 400kyrs.
Figure 4. Expanding out post MPT time. (Note the different time scales on the lower merged image at about 140kyrs)
In Figure 4, we zoom-in yet more on the post-MPT time beginning with MIS-19. In this depiction we see that MIS-19 did not appear to achieve temperatures of the true extreme interglacials, but it does have a lot more to offer. Orbitaly, it could be our closest interglacial analog in the climate record, although this is a matter of some debate in the literature.
The End Extreme Interglacials
MIS-19
Which brings us to the point of this essay, what were the end extreme interglacials like? Although MIS-19 may not satisfy everyone as being an extreme interglacial, it did occur at an eccentricity minimum just like MIS-11 was and MIS-1 presently is. So in terms of trying to comprehend what might be the end extreme interglacial natural climate noise it has “standing”.
Figure 5. Multi-proxy view of post-MPT time.
So what was the end of MIS-19 like?
Figure 6. Three Consecutive Warm Events at Glacial Inception During MIS-19
Well, MIS-19 appears to have had at least 3 abrupt warming events during glacial inception. Had the genus Homo gone all-civilized on us during MIS-19, we would all have had one heck of a time settling our AGW damage claims with our climate-change insurers, especially with the final one being of the highest dD amplitude. If any insurance types are here, I just gave you the proverbial “silver bullet” for rejecting AGW related climate damage claims. So collect your premiums with the appropriate conceit of a proper Wall Streeter, unless, of course, you also issue coverage for natural climate changes or “Acts of God”.
K. Pol et al. (2010) also attempt various astronomic and MIS-1 fittings to see how ours “stacks up” (Figure 6). Could we also be in range of such events?
MIS-11
Which brings us to MIS-11, the Holsteinian interglacial. Remember I said that 5 of the last 6 interglacials all lasted about half of a precessional cycle? Well that 6th one was MIS-11.
Figure 7. New MIS-11 as Corrected for Isotopic Fractionation (K.Pol et al, 2011)
MIS-11 has long been shown to consist of at least two insolation peaks, a fairly sharp one soon after glacial termination, and a long, fairly broad one after an interval of cooling. But if you take the time to closely inspect all of the figures presented here, you will likely note that they are not all the same everywhere and in every study. It’s called science. The estimated length of MIS-11 seems to vary from 20-33kyrs, depending upon which study you are reading.
At the risk of repetition from “The Antithesis”, Lisiecki and Raymo (2005) state:
“Recent research has focused on MIS 11 as a possible analog for the present interglacial [e.g., Loutre and Berger, 2003; EPICA community members, 2004] because both occur during times of low eccentricity. The LR04 age model establishes that MIS 11 spans two precession cycles, with 18O values below 3.6o/oo for 20 kyr, from 398-418 ka. In comparison, stages 9 and 5 remained below 3.6o/oo for 13 and 12 kyr, respectively, and the Holocene interglacial has lasted 11 kyr so far. In the LR04 age model, the average LSR of 29 sites is the same from 398-418 ka as from 250-650 ka; consequently, stage 11 is unlikely to be artificially stretched. However, the June 21 insolation minimum at 65N during MIS 11 is only 489 W/m2, much less pronounced than the present minimum of 474 W/m2. In addition, current insolation values are not predicted to return to the high values of late MIS 11 for another 65 kyr. We propose that this effectivelyprecludes a ‘double precession-cycle’ interglacial [e.g., Raymo, 1997] in the Holocene without human influence.”
Chronis Tzedakis, in an exhaustive look at the MIS-1/MIS-11/MIS-19 conundrum (Tzedakis, 2010, The MIS 11 – MIS 1 analogy, southern European vegetation, atmospheric methane and the “early anthropogenic hypothesis”, Climate of the Past, vol. 6, pp 131-144, European Geosciences Union) considers the matter thusly:
“While the astronomical analogy between MIS 1 and MIS11 has been incorporated in mainstream literature, there is a distinct difference between the two intervals: the Holocene contains one insolation peak so far, while the MIS 11 interval of full interglacial conditions (Substage 11c of the marine isotopic stratigraphy) extends over two insolation peaks. Thus an interesting situation has arisen with regard to the precise alignment of the two intervals.”
“The two schemes lead to very different conclusions about the length of the current interglacial, in the absence of anthropogenic forcing, …
“… the precessional alignment would suggest that the Holocene is nearing its end, “while the obliquity alignment would suggest it has another 12,000 years to run its course.
“In this view, the two Terminations are incommensurate and MIS-1 is analogous only to the second part of MIS-11c.”
Figure 8. Tzedakis’ 2010 Alignments of the EDC3 core for the Holocene and MIS-11
Figure 9. Another recent view of the Twin-Peak Nature of MIS-11
Figure 10. MIS-11 from Lake Baikal sediments.
Multiple views of MIS-11 clearly indicate a Twin-Peak configuration, though, as one might well expect, varies from one place to the next. K, Pol et al (2011) and Tzedakis (2010) both tend to show an elongated and higher amplitude late peak for MIS-11a whereas Voelker et al (2009) and Prokopenko et al (Clim. Past, 6, 31–48, 2010, www.clim-past.net/6/31/2010/) show a broader, more symmetrical pair of peaks.
Apparently, the second one was a real doosie:
As we leave the double insolation-peak MIS-11, with it’s possible +21.3m amsl highstand and 20-33kyr length, I am again struck by the magnitude of both the natural noise and the difficulty one will have winning an argument with a clued-in climate change insurer over a whopping IPCC AR4 worst case +0.59m amsl fizzle, with or without it’s consensus accolades.
MIS-5e
Which brings us to the most recent interglacial, the Eemian, or MIS-5e. As it occurred midway between the last eccentricity maximum and our present minimum it is not considered to be a good orbital analog. However it seems to have also been quite the extreme little interglacial.
I will again be using some citations quoted in “The Antithesis” to “insure” against the risk that some of the “insured” won’t get it.
Hearty and Neumann (Quaternary Science Reviews 20 [2001] 1881–1895) abstracting their work in the Bahamas state:
“The geology of the Last Interglaciation (sensu stricto, marine isotope substage MIS 5e) in the Bahamas records the nature of sea level and climate change. After a period of quasi-stability for most of the interglaciation, during which reefs grew to +2.5 m, sea level rose rapidly at the end of the period, incising notches in older limestone. After brief stillstands at +6 and perhaps +8.5 m, sea level fell with apparent speed to the MIS 5d lowstand and much cooler climatic conditions. It was during this regression from the MIS 5e highstand that the North Atlantic suffered an oceanographic ‘‘reorganization’’ about 11873 ka ago. During this same interval, massive dune-building greatly enlarged the Bahama Islands. Giant waves reshaped exposed lowlands into chevron-shaped beach ridges, ran up on older coastal ridges, and also broke off and threw megaboulders onto and over 20 m-high cliffs. The oolitic rocks recording these features yield concordant whole-rock amino acid ratios across the archipelago. Whether or not the Last Interglaciation serves as an appropriate analog for our ‘‘greenhouse’’ world, it nonetheless reveals the intricate details of climatic transitions between warm interglaciations and near glacial conditions.”
Savvy insurers take note to make appropriate use of the “Acts of God” clauses.
Boettger, et al (Quaternary International 207 [2009] 137–144) abstract it:
“In terrestrial records from Central and Eastern Europe the end of the Last Interglacial seems to be characterized by evident climatic and environmental instabilities recorded by geochemical and vegetation indicators. The transition (MIS 5e/5d) from the Last Interglacial (Eemian, Mikulino) to the Early Last Glacial (Early Weichselian, Early Valdai) is marked by at least two warming events as observed in geochemical data on the lake sediment profiles of Central (Gro¨bern, Neumark–Nord, Klinge) and of Eastern Europe (Ples). Results of palynological studies of all these sequences indicate simultaneously a strong increase of environmental oscillations during the very end of the Last Interglacial and the beginning of the Last Glaciation. This paper discusses possible correlations of these events between regions in Central and Eastern Europe. The pronounced climate and environment instability during the interglacial/glacial transition could be consistent with the assumption that it is about a natural phenomenon, characteristic for transitional stages. Taking into consideration that currently observed ‘‘human-induced’’ global warming coincides with the natural trend to cooling, the study of such transitional stages is important for understanding the underlying processes of the climate changes.”
Figure 11. Hearty et al (2007) End Eemian highstand(s)
Figure 12. Hearty et al (2007) modern MIS-1 notch and MIS-5e notches in the Bahamas and Barbados
Figure 13. MIS-5e Sea Levels Compiled from Around the World (modified after Hearty et al, 2007, red estimates added)
In Figures 10-13, we see the End Eemian in quite remarkable detail. This is predominantly due to its relatively young age compared to any other interglacial. One needs but to consider the effects of the average 400 foot sea level swings in and out of each of them, some going higher than others, to grasp how each of them tend to erase the evidence from the others. For instance, paleoclimatologists that are adept at deep sea diving might be able to uncover evidences of say MIS-7 and MIS-9 sea level highstands because they are presently below sea level. I wouldn’t take out to much insurance on that though.
And look at the range of estimates, +6m to +45m amsl, and often detecting the highstands at the very end of the Eemian.
In discussing the Late Eemian Aridity Pulse (LEAP) at the end-Eemian, Sirocko et al (A late Eemian aridity pulse in central Europe during the last glacial inception, nature, vol. 436, 11 August 2005, doi:10.1038/nature03905, pp 833-836) opine:
“Investigating the processes that led to the end of the last interglacial period is relevant for understanding how our ongoing interglacial will end, which has been a matter of much debate…..”
“The onset of the LEAP occurred within less than two decades, demonstrating the existence of a sharp threshold, which must be near 416 Wm2, which is the 65oN July insolation for 118 kyr BP (ref. 9). This value is only slightly below today’s value of 428 Wm2. Insolation will remain at this level slightly above the inception for the next 4,000 years before it then increases again.”
Now that is some bombshell! We may only have about the next 4,000 years, a little less than half the time since we “Homos” learned how to write, where climate sensitivity will be alarmingly close to glacial inception.
“The Antithesis” provides documentation of CO2 effects during the latter half of the last glacial, so I will refer you to that essay for the succulent details. Suffice it to say that what this may boil down to is strip the appropriate amount of “climate security blanket” out of the late Holocene atmosphere as fast as is humanly possible (perhaps tipping us into the next ice age), or keep a decently healthy dose of it up there for at least the next 4,000 years.
So there you have it, all tipping points now in play.
THE END HOLOCENE
So we now have quite the conundrum. Will we do a typical eccentricity minima sea-level “Cha-Cha” at our very end? It would appear to be the norm, and may not be restricted just to eccentricity minima end extreme interglacials given the “competition” from MIS-5e, which occurred neither at an eccentricity minima or maxima.
And they do appear to be rather extreme, don’t they? So do not be too shy about investing in savvy climate change policy writing insurers. If they read this, they will probably never have to pay out a claim. Pay attention Big Oil etc., you could have a field day on Kivalina and other Public Trust Doctrine style litigation just by “stocking-up” on what has “gone down” climate-wise, without even having to be exposed to the heathen devil gas itself.
From I what I have been able to glean, this seems to boil down to three competing hypotheses:
- Anthropogenic Global Warming/Catastrophic AGW. World will continue to warm, perhaps catastrophically, as a result of GHG emissions.
IPCC AR4 worst case estimate for sea level by 2100 is +0.59 meters amsl. End Eemian achieved, at least, 10 times this (if we use +6 meters amsl), almost an order of magnitude more if we use the +45m estimate. End Holsteinian achieved 36 times this predicted excursion (using 21.3 meters amsl), covering the low and high ends of natural, end extreme interglacial, climate noise.
The Signal to Noise Ratio (SNR) range for AGW predictions to 2100 come in at a range of 0.1 to 0.03 compared to “normal” end extreme interglacial climate noise. Worst case projections are therefore woefully not anomalous (at best 10% of natural noise), with the projected AGW/CAGW signal scoring a measly 3-10% of normal end extreme interglacial climate noise levels.
Such a signal will be difficult to distinguish.
- Holocene Interglacial (Loutre and Berger, 2003) will “go-long” (perhaps another 50,000 years), outlasting every previous interglacial in the past 5 million years.
“With the end of MIS 11 full interglacial conditions and the start of ice accumulation estimated to have occurred at 395 kyr BP (de Abreu et al., 2005; Ruddiman 2005a, 2007), the precessional alignment would suggest that the Holocene is nearing its end, while the obliquity alignment would suggest it has another 12 000 years to run its course.” (Tzedakis, 2010)
“In essence, this alignment represents a synchronization of the obliquity signal instead of precession, which according to Masson-Delmotte et al. (2006) may be more appropriate, because of the role of obliquity changes in triggering deglaciation especially during intervals of weak precessional variations, as is the case for MIS 11 and 1.” (Tzedakis, 2010)
- Holocene is a tad over half-a precession cycle old now. If a precession match, it might be “winding-up” to “wind-down”, like all previous end extreme interglacials.
The possibility consequently exists that at perhaps precisely the right moment near the end-Holocene, the latest iteration of the genus Homo unwittingly stumbled on the correct atmospheric GHG recipe to perhaps ease or delay the transition into the next glacial.
We may have actually already “engineered” a “climate security blanket” capable of dealing with:
“The onset of the LEAP occurred within less than two decades, demonstrating the existence of a sharp threshold, which must be near 416 Wm2, which is the 65oN July insolation for 118 kyr BP (ref. 9). This value is only slightly below today’s value of 428 Wm2. Insolation will remain at this level slightly above the glacial inception for the next 4,000 years before it then increases again.”
Apologies for quoting Sirocko et al (2005) twice in rapid succession.
Which rather handily devolves to,
Have a wonderful end extreme interglacial!
William F. McClenney
Finally!
Isn’t geology only about rocks? So we can never know about the end of a geoage until its dead and buried.
Good post. Thanks
I always invoke the precautionary principle when its invoked on global warming.
Global warming, for any potential harm, pales beside the scraping of much of the Northern Hemisphere down to bed rock.
The precautionary principle dictates that we must release CO2 to prevent such a calamity.
Thanks for the extensive and clear presentation. If you analyze the ice-core CO2 data as well, you can’t quantify any significant influence on temperature, rather, CO2 seems to be essentially a consequence of temperature. If we are going to stave off the next glacial, we might try to do it with gases with better IR absorption, but I think changing albedo will be more effective. During previous glacials, no-one was out there blackening the surfaces of the advancing ice-sheets. We had better hope it works.
Can someone please explain why we measure the holocene from the END of the Younger Dryas, and not from the beginning of the brief warm period before it?
Problem here is that you have to combine all the geologic records and not the selection that we think we understand. For instance if we only look at the last glacial maximum around 20k years ago, how can we explain the recent found mammoth mummies dated around that time?
Concrete evidence for that megafauna is present in detailed research of three mammoth mummies dated well into the Last Glacial Maximum (ca 18.5-20.5 Ka 14C BP), the Jarkov Mammoth, the Fishhook Mammoth and the Yukagir Mammoth (Mol et al 2004, Mol et al 2006, Aptroot and Van Geel 2006), It was inferred that their biotope resembled a dry and cold steppe with tundra elements. The abundance of ascospores of certain fungi is considered a clear indication of a high population density of the herbivores. This is supported by a large fossil collection event on the Taimyr Peninsula, and it’s carbon dating (MacPhee et al 2002). We assume the LGM bounderies to be between 19 Ka and 26.5 Ka (Clark et al 2009), which would have been carbon dated between ~22 and 16 Ky 14C years BP (INTCAL09). In the collection 5 out 35 mammoth remains between 10Ka and 50Ka date in that period, 7 out of 16 are from Muskox during the Last Glacial maximum, 2 out of the 4 horses and 2 out of two 2 wolves. Hence the fossils dated to the Last Glacial Maximum are at least in ratio to the whole period, giving no grounds to the assumption of declining megafauna during the last glacial maximum.
Furthermore, a larch needle was found in the intestines of the Fishhook mammoth mummy, which was found 200km north of the present timber line. Abundant were also several remains of aquatic plants in relation to all three. This would suggest ample high summer temperatures as done earlier by Kienast et al 2005 and Sher et al 2005 not only to have open water for a sufficient growth period for the aquatic plants, but also to grow enough fodder to sustain the megafauna.
So if a new ice age will result again in this climate for Siberia, maybe things are quite different than we think they are.
Aptroot A,B and van Geel 2006 Fungi of the colon of the Yukagir Mammoth and from stratigraphically related permafrost samples, Review of Palaeobotany and Palynology 141 (2006) 225–230
Clark, P.U. et al 2009 “The Last Glacial Maximum” American Association for the Advancement of Science. 7 August 2009: Vol. 325. no. 5941, pp. 710 – 714. doi:10.1126/science.1172873.
Kienast, F., et al, 2005. Palaeobotanical evidence for warm summers in the East Siberian Arctic during the last cold stage. Quaternary Research 63, 283e300.
Mol, D., L et al, 2004 Brief history , 14C dates, individual age, gender and size of the Yukagir mammoth. Symposium: The Yukagir mammoth: outcome of the first stageof research work. Academy of Sciences of the Republicof Sahka .(Yakutsk) p. 51-55
Mol, D., et al, 2006. Results of theCERPOLEX/Mammuthus Expeditions on the Taimyr Peninsula, Arctic Siberia. Russian Federation Quaternary International,January volumes 142-143 pp. 186-202.
Sher, A.V., et al, 2005. New insights into the Weichselian environment and climate of the Eastern-Siberian Arctic, derived from fossil insects, plants, and mammals. Quaternary Science Reviews 24, 533e569.
Outstanding geologic context to real climate change…
caused a dramatic upgrade in my respect for Paleoclimatology [which is Geology in disguise]
Human civilisation arose in this interglacial period and the human species since the beginning of the ice epoch, some dozens of ice ages past. Can the species survive the combination of civilisation and the end of the interglacial?
I’ll put the ‘climate security blanket’ as another instance of AGW-related miracles, thank you very much…
A very British understated presentation!
Re: “should give way to another ice age within about 1,500 years,”
In context, the consequences of a “moderate” cooling:
Great Famine of Finland (1695–1697)
Neumann, J.; Lindgrén, S. (1979). “Great Historical Events That Were Significantly Affected by the Weather: 4, The Great Famines in Finland and Estonia”. Bulletin of the American Meteorological Society 60 (7): pp775–787. doi:10.1175/1520-0477(1979)0602.0.CO;2. ISSN 1520-0477.
For a much milder cooling:
Weather Conditions in Northern Europe in the Exceptionally Cold Spring Season of the Famine Year 1867 Juha Jantunen and Kimmo Ruosteenoja, Geophysica (2000), 36(1–2), 69–84
Even mild changes have strong impacts on human health. e.g.
Ch 9 Human Health Effects NIPCC Climate Change Reconsidered 2009.
Such evidence indicates that we need all the “global warming” we can get!
Wallace Broecker does not have a clue about the mechanism – I think he just assumes(d) that the science that more CO2 does cause more warming than cooling is “settled”.
Sorry, but personally I could not find anyone to show me a balance sheet on how much warming and how much cooling is caused by more of the CO2, including the cooling by CO2 due to increased greenery. Plants need warmth and CO2 to grow, you know.
http://www.letterdash.com/HenryP/the-greenhouse-effect-and-the-principle-of-re-radiation-11-Aug-2011
Remember that the only way that dinosaurs and other gigantic animals could have existed on earth (many millions of years ago) was because there were enormous amounts of plants and greenery available for them to eat from. That is where our reserves of coal and oil actually came from. We know from the records that in those days CO2 was many times higher then what it is now. So to now put a limit on CO2 in the air is as stupid as to ask for a limit on H2O. Both are needed to stimulate growth. Unless you want to live in desert?
So, the problem is now that (C)AGW really stands in the way of progress. That is why we have to tackle their “religion”. It is based on lies. That makes it a FALSE religion.
For example: the next step in human progress would be to terraform Mars. You want to try that with 400 ppm’s of CO2 in the atmosphere when you know that 10 x that much is going to make things grow so much faster?
(they already use up to 8000 ppm’s in real greenhouses to stimulate growth ).
Ice cores and climate change.
Ice core researcher Jørgen Peder Steffensen from the Niels Bohr Institute, tells how, in 4 videos about the NGRIP ice core from Greenland, wich mapped the last 60,000 years of snowfall each year. This has made it possible to track and pinpoint sudden and violent events such as volcanic eruptions and climate change. Ice cores can add new knowledge to a number of historic and prehistoric events that have affected humans.
The first video start at 4:15
http://youtu.be/c0midUwYMS4
http://youtu.be/2iq7fEVwnsk
http://youtu.be/nGA4Clu4-V8
http://youtu.be/Lza3iCtGAZQ
Hide the decline!
Typo: In the paragraph after Figure 7, you have “Nut if you take the time to closely inspect all of the figures presented here,”
[Reply:Thanks! Fixed to “But if you take…” -ModE]
Notches. Clearly showing Mastodonogenic global warming.
Hard to argue with history. The real question is how sharp is the edge.
OT but interesting report on CO2 experiment at:
http://www.london24.com/news/health/royal_free_doctor_experiment_living_in_box_plants_secret_life_1_1210337
We are at the mercy of the Milky Way, but no doubt they will find a tax to fix it.
I really liked the author’s breezy and cheerful treatment of such a vast subject, but it seems to me that the addition of one part in 14,000 (by volume) of man-made CO2 to the mix won’t make much difference in any event. But I suppose, like the butterfly sneeze causing a tornado, its possible.
I have looked in some detail at the Arctic-North Atlantic barrier (Greenland Scotland ridge) and concluded that, despite the Milankovic effect on the insolation, conditions do not exist any longer for another Ice Age.
http://www.vukcevic.talktalk.net/NA3R.htm
The possibility consequently exists that at perhaps precisely the right moment near the end-Holocene, the latest iteration of the genus Homo unwittingly stumbled on the correct atmospheric GHG recipe to perhaps ease or delay the transition into the next glacial.
And the possibility exists that it will have no effect what so ever.
William: Well done, nice one, I enjoyed that, thank you for educating me.
It is not nice to post this just before I have to leave the house!
I thought the Holocene ended a few decades ago when the Anthropocene started.
Rats,
I just put a down payment on some Saskatchewan farmland.
Thanks William, these are the posts w/alot of “meat”. You’ve obviously put quite a bit of work into this. I especially like real historical evidence to munch on and absorb.
The sea-level highstands at the end of the interglacials are interesting. The temp proxies don’t show unusually high temps, but the sea-levels suggest that there should have been — how else do they rise so high so quickly? Maybe ice-sheet instabilities in Greenland/Antarctica caused some ice disintegration, flooding the polar oceans? That might explain the sudden highstand & the subsequent rapid cooling.
I will aggregate some first responses here. Sorry folks, WordPress impresses me as the elite of post-normal word processor/publishing systems, so since there are no easily accessible tools all responses will be as basic as WordPress enabled possible.
Mark Smith: It’s the study of the earth which also includes rocks.
Caz: It is sort of a convention. I remember reading a paper some while back on re-establishing some aspects of this, and I do not remember the name of the body which issues these conventions.
Maurizio: From the same Broecker 1998 paper cited above we also have this (which I forgot to include in the essay):
“It is frequently suggested that the warming expected from the buildup of man-made greenhouse gases might be a blessing in that it will counter the natural cooling expected if Earth climate continues to track Milankovitch’s insolation cycles. But, if the Earth’s climate is destined to undergo an abrupt rather than a gradual cooling, then the likelihood of a compensation by the ongoing greenhouse warming is indeed small.”
I tend to agree with you.
Alan: If you like that typo, see if you can find the one in Figure 13’s caption! Given that I sent this to Anthony after hours of frustration with WordPress and the recently installed, instantly AWOL Greasemonkey Comment Ninja, I am not sure if I personally can change either of them.
[Reply: Fixed 3007 to 2007. -ModE (who uses Linux / Unix so likes command line interfaces 😉]
trbixler: You got it! You too Kelvin.
P.S. If anyone has a non-pretzel logic solution to using WordPress efficiently, I am all ears. At the moment I think of it just like the old command-line UNIX of old where “When a mathematician sits down to solve a math problem with a pencil, which should he be more concerned with? The math problem? Or the pencil?”
Nowhere in that intricate record is there any indication that CO2 was “forcing”, yet now it will be? That’s paw-waving, I think.
Edit (one of many):
“
NutBut if you take the time”OTOH, maybe …
😉
Continental Drift is NOT the same as Plate Tectonics. They are based on many of the same observations but invoke entirely different mechanisms for movement of the Earth’s crust.
vukcevic says:
March 16, 2012 at 6:13 am
I have looked in some detail at the Arctic-North Atlantic barrier (Greenland Scotland ridge) and concluded that, despite the Milankovic effect on the insolation, conditions do not exist any longer for another Ice Age.
http://www.vukcevic.talktalk.net/NA3R.htm
===================================================
Are Greenland and Scotland, and the ridge between them new in the last 12,000 years? How have things changed?
I believe it was Glen Beck who published information on the people who shill the chicken-little climate change hype but also own ocean-front property which would be underwater if the AGW claims about sea-level rise were true.
Would Al Gore really by that condo in San Francisco if he thought it would be worthless in a few years?
More Soylent Green! says:
And I hadn’t realized that man suddenly appeared on the scene just a few decades ago.
vukcevic says:
March 16, 2012 at 6:13 am
I have looked in some detail at the Arctic-North Atlantic barrier (Greenland Scotland ridge) and concluded that, despite the Milankovic effect on the insolation, conditions do not exist any longer for another Ice Age.
My understading is the Earth is in an ice age…we are just in the warm part (inter-glacial)
is, I love your brief synopsis of the earth’s recent (geologically speaking) climate history. I also like the way you used Wegener. This was a man who took a lot of grief because he disputed the “settled” science. The current crop of “climate” scientists (I use the word “scientist” loosely when describing them) should take note when they throw the phrase “the science is settled” around. It’s been my impression when reading their output though, that they really have very little knowledge of past research and theories pertaining to their fields. It appears they only look at past work that agrees with their viewpoint.
On a lighter note, I’ll do my best to save civilization as we know it by using the grill every chance I get to produce CO2 and particulate carbon. At least that’s the excuse I’ll use to my wife and friends.
HenryP says: ” there were enormous amounts of plants and greenery available for them to eat from. That is where our reserves of coal and oil actually came from”.
I had heard that the coal deposits came about when plants invented lignin and there was a delay before the fungi invented a way to eat it.
Is this urban legend? I am quite prepared to believe it is. Help unclutter my brain.
A few more un-enhanced responses:
Brian H: You are correct. This question was settled by 2003, 2 years before Gore’s propaganda video. I would point you to Sole, Turiel and Llebot (Physics Letters A (366 [2007] 184–189) for a fascinating discussion on the D-O events and CO2’s efficacy as a GHG. Sorry, the advanced absent commenting tools of WordPress disallow me from posting a proper link.
Steve M: The issue of what is an ice age and what is a glacial gets blurred throughout the literature. Many workers define an ice age as the 100myr climate cyclicity, which may be proper. However this is not always adhered to in the vast majority of the literature.
EDS Anthony – maybe im misunderstanding something but –
“We live today possibly near the end of the most recent interglacial, the Holocene, or the 11,715 years since we melted our way out of the last glacial…”
“or the” ? Im thinking the the is superfluous.
David A says:
……………..
No it is not new. The island of Surtsey is less than 50 year old.
Thanks for this wonderful post!
And:
HenryP says:
March 16, 2012 at 5:20 am
“Remember that the only way that dinosaurs and other gigantic animals could have existed on earth (many millions of years ago) was because there were enormous amounts of plants and greenery available for them to eat from. That is where our reserves of coal and oil actually came from. We know from the records that in those days CO2 was many times higher then what it is now. So to now put a limit on CO2 in the air is as stupid as to ask for a limit on H2O.”
Agreed. Maybe it’s time to call for really significant CO2 emissions. The precautionary principle. Stop the coolers! (new name for “warmists”)
I guess you’ll be spending this summer in re-education camp, then. See if you can get into one of the ones where you get food.
Very,very interesting and well done !!
William F. McClenney,
Your article is well done. It provides a necessary context to counter the hysteria induced by the IPCC centric CAGWism that is publicly failing to masquerade as unbiased and balanced open science.
QUESTION: In your researches did you run across interesting competing theories to the Milankovic theory for cause of the ice age cycles of glacial/interglacial periods?
John
So we need icecap formation to cause climate to go into another mode.
The reminds me of something I read about early snowfall in siberia and early onset of winter.
DirkH;
There’s a lovely brain-busting version of that analysis of dino environments here:
http://dinosaurtheory.com/index.html
Long story short: the pterosaurs flew lightly thru and the dinos were buoyed by an atmosphere 2/3 the density of water, about 370 bar! Long necks didn’t need multiple hearts to get blood to the head, bone strength was adequate to support brachiosaurs etc. on dry land, not just eternally wading, and the wedge-body shape of the predators was for powering thru the heavy air.
Delightful icono-smashing stuff.
John Whitman: Yes indeed, there are quite a few papers that question the attribution of the Milankovitch cycles. It would probably take me a few days to dig some of them up from my “cybrary” (which at this moment contains 7,530 papers and other files divided into 259 folders and subfolders). So suffice it to say that eccentricity is thought to be the weakest of the 3 (or 4) orbital forcings, yet is seems to pace the most dramatic recent climate of the extreme interglacials. Go figure. A lot of workers indeed have……
Personally I wouldn’t put to much faith in those late-MIS 5e and Late-MIS 11 extreme highstands. There is no evidence of them anywhere in the World except on Bermuda and in the Caribbean.
For example there is no trace of them in southern Australia (Coorong coastal plain) which has probably the best preserved interglacial sealevel record in the World.
Note that Bermuda and the Caribbean are both very much affected by hurricanes and that there is good evidence that arctic-tropic temperature gradients become extremely steep at the end of interglacials.
tty: Uh, did you actually take a look at Figure 13 as regards MIS-5e? MIS-11 is another matter as it is MIS-1, NIS-5e, MIS-9 and MIS-7 interglacials back. Been a little bit of geologic action over the past 400kyrs, tectonics, erosion etc. so MIS-11 is a little more of a crap shoot given that a lot of evidence for it has been erased or displaced. What seems clear is that MIS-11 is the longest and possibly the warmest of the post-MPT interglaciations. One wonders if more heat for something like 2-3 times the age of the Holocene might have melted just a little bit more icecaps. Or would you be more inclined to agree that more warming causes cooling?
I had noticed this about a year ago. I remember thinking at the time that insolation would possibly not drop to the point where we tip into glaciation and some global warming hucksters would attempt to spin that extended interglacial as somehow caused by man and use that to justify their supercalifragilistic global warming hyperbole. It will, in my opinion, all depend on summer ice extent in the Arctic Ocean as I rather firmly believe that is what flips the state of the system. Too much summer ice cover in the Arctic Ocean and the system “flips” cold. Once it flips to that state, it takes much greater insolation to flip it back. We will be very close. A major volcanic eruption might be enough to tip the balance to the cold state. Once we get to a point where we have substantial summer ice in the Arctic, I believe we’re done for 80K years or so.
William McClenney says:
March 16, 2012 at 8:27 am
———–
William McClenney,
Hey, thanks for the comment about the existence of many papers critical of Milankovitch cycle theory. One or two references would be helpful. But please no extra effort on your part is expected . . . . you have already done much with your wonderful article here.
On another thought. To dampen any potential of sense of urgency and hysteria about the potential ‘End of the Holocene’ we should consider the approximate rate of change of the temperature drop from the peak at the end of the previous interglacial about 140k years ago. The end of that interglacial had (from its peak temperature) a drop in temperature (based on figs 1 & 4 shown in McClenney’s post) on the rough order of ~1C/~+1000yrs. I confirmed that estimate from figs 1 & 4 by seeing what Prof Murry L. Salby shows in his very recent new textbook ‘Physics of the Atmosphere and Climate’ (January 2012, Cambridge University Press). Salby has a graph in Chapter 1 a graph from Petit et al. (1999) that shows ‘Reconstructions of atmospheric temperatures, carbon dioxide and methane as function of time before present, inferred from ice core drilled at Vostok Antarctica’; the timescale being a period of 450Kyr before present. That Petit et al. (1999) figure is very similar to figs 1 & 4 of this post by McClenney.
John
This is simply more baffle-gab from the true believers and has nothing to do with geological sciences what so ever.
There is no evidence that marginal changes in CO2 has enough of a warming effect to make a difference. Yes, it has SOME warming effect, but little effects don’t cut it. This is the lesson of abrupt change. The most likely candidate (a near certainty) is albedo feedbacks. As snow and ice build up, they reflect away more sun, cooling the planet and inducing more snow and ice.
Starting from a warm period, with relatively little snow and ice, this cooling feedback rapidly increases in strength as snow and ice descend to lower latitudes. That’s because the land area covered by one degree of latitude rapidly increases as latitudes decrease. The angle of insolation is similarly getting steeper, so the amount sunlight reflected away by snow and ice ramps up by both of these factors.
Take away the IPCC misattribution of solar magnetic warming effects to CO2 and the puny warming effect of CO2 that is left is NOTHING compared to these massive albedo feedbacks. The only way CO2 could stop glaciaton is if it were in a position to make just enough difference at some key inflection point. For instance, the little ice age that will result if the sun stays quiet for a couple of solar cycles would have to bring temperatures down to just the tipping point to the next glaciation. Then CO2 could make a difference.
But we are much more likely to go roaring into the next glaciation, in which case the tiny effect of CO2 will be completely overwhelmed by the much larger albedo feedback effects. What are the chances that the sun will rebound just in time to stop albedo feedbacks from running away? The chance that a tiny marginal effect is going to make the difference is tiny.
What we need to be prepared to do is to interrupt the albedo feedback effects. My thought has long been to dot the great white north with coal-electric generating plants that burn clean in the summer in the old fashioned sense of not producing soot, but still producing CO2, then run them dirty in the winter in the old fashioned sense of producing lots and lots of snow-darkening soot.
But generating plants would probably not the best way to darken the snow. It just sounds good because it is a two-fer, but building the transmission lines necessary to make use of the electricity would almost certainly not be economically viable, so the efficient thing would just be to design the most efficient soot-producing plants possible and have them produce just enough electricity to operate and provide for support operations. Maybe the plants would be built near coal deposits where they could support mini-mining operations to pull out the fuel.
We should be building such plants NOW, just in case the present solar minimum does spawn alarming albedo feedbacks that we suddenly realize we need to try to interrupt. If the capacity is not already in place, it will be too late.
Dennis Nikols, P. Geo says:
March 16, 2012 at 9:29 am
This is simply more baffle-gab from the true believers and has nothing to do with geological sciences what so ever.
Dennis: One P.Geo. to another, please be more specific about who or what you are addressing.
Alec Rawls says:
March 16, 2012 at 9:49 am
There is no evidence that marginal changes in CO2 has enough of a warming effect to make a difference.
Well, there is some evidence, but in my opinion, not all that much:
Sole, Turiel and Llebot writing in Physics Letters A (366 [2007] 184–189) identified three classes of D-O oscillations in the Greenland GISP2 ice cores A (brief), B (medium) and C (long), reflecting the speed at which the warming relaxes back to the cold glacial state:
“In this work ice-core CO2 time evolution in the period going from 20 to 60 kyr BP [15] has been qualitatively compared to our temperature cycles, according to the class they belong to. It can be observed in Fig. 6 that class A cycles are completely unrelated to changes in CO2 concentration. We have observed some correlation between B and C cycles and CO2 concentration, but of the opposite sign to the one expected: maxima in atmospheric CO2 concentration tend to correspond to the middle part or the end the cooling period. The role of CO2 in the oscillation phenomena seems to be more related to extend the duration of the cooling phase than to trigger warming. This could explain why cycles not coincident in time with maxima of CO2 (A cycles) rapidly decay back to the cold state. ”
The rest I tend to mostly agree. I find your subarctic power plants a fascinating bit of geo-engineering if either/both CO2 and soot phenomena prove out to be insurance against the next glacial, whenever it finally gets here.
Ken Harvey says:
March 16, 2012 at 5:58 am
We are at the mercy of the Milky Way, but no doubt they will find a tax to fix it.
—————————
Ken, I bet they can.
Anthony
Is there any chance you can offer this as a pdf?
REPLY: Sure, look for an update to the main post soon – A
William McClenny quotes:
Makes sense. CO2’s power to mitigate cooling gets stronger as cooling progresses. This is because cooling dries out the atmosphere, making CO2’s IR absorption less redundant with water vapor. If albedo feedback effects were already exerting enough cooling force to overcome the heat trapping of both CO2 and the water vapor of a warm atmosphere it will certainly continue to overcome the heat trapping of CO2 alone, so the descent into glaciation will continue, but it won’t be as fast as if the ever-more effective heat-trapping of the CO2 were not there.
Eventually the CO2 will re-absorb into the cooler oceans, with their greater CO2 holding capacity.
Alec Rawls says:
http://wattsupwiththat.com/2012/03/16/the-end-holocene-or-how-to-make-out-like-a-madoff-climate-change-insurer/#comment-925282
Henry @Alec
Good post. I agree with most of it, but personally I am not (yet) sure if the net effect of more CO2 is that of (a tiny little bit) more warming or cooling. I have not seen anyone produce an actual balance sheet. Remember that the available graphs that we have on the sun’s and earth’s irradiance are rather crude and inconclusive (if I eyeball them). The actual absorptions (that overlap) of water vapor and oxygen/ozone at 14-16 um could be much higher then that indicated to be caused by the CO2.
If you are interested in looking into that a bit more, see CO2 re-radiation 101:
http://www.letterdash.com/HenryP/the-greenhouse-effect-and-the-principle-of-re-radiation-11-Aug-2011
As far as the next ice age is concerned – and even a little ice age could be devastating – I agree that we do not need some kind of action plan if snow and ice cover becomes so big that it could cause earth to tip back to its “natural” state of ice and snow. I suppose there might be other ways to stop the increasing albedo and melt the snow other than to throw soot on it?
In my last post, last sentence, should be:
I agree that we DO need some kind of action plan if snow and ice cover becomes so big that it could cause earth to tip back to its “natural” state of ice and snow. I suppose there might be other ways to stop the increasing albedo and melt the snow other than to throw soot on it?
William F. McClenney, great post, really great. This will require multiple reads.
I have been trying to put this overall Holocene climate big picture into words but you did it way better. A few weeks ago I wrote:
Where are we? That really is the biggest question of all. There is another important graph at Wikipedia Post Glacial Sea-Level Rise. Question: Is it not likely that the only real indicator that humans will detect of the turnaround from Holocene warming to re-glaciation will be when sea-level becomes flat and decreases? What other possible signals could someone envision?
About Milankovic … I think that his ‘theory’ must be placed in perspective. IMHO, it is more important to appreciate his quality of work rather than the final details of the theory because it would be absolutely stunning if he could have nailed it down 100% in his lifetime. He was practically a POW during WWI when he fleshed out all these orbital variables and insolation – quite an accomplishment and all without a computer and Internet access. He helped shift the focus from pseudo-science to real hard-science and mathematics with respect to the climate of the Earth and the Sun. Truly he was a pure Scientist, something that appears to be in very short supply these days. (Curiously, there is a fortuitous tie-in at the Milankovic Wikpedia entry to Wegener: “The results set forth in his [Milankovic’s] work won him a considerable reputation in the scientific world, notably for his “curve of insolation at the Earth’s surface”. This solar curve was not really accepted until 1924, when the great meteorologist and climatologist Wladimir Köppen, with his son-in-law Alfred Wegener, introduced the curve in their work entitled Climates of the geological past.”)
Finally, speaking of bucking the trend, later in the 20th century two more great Scientists, a father-son team had to swim against strong prevailing currents to advance our understanding of the K/T boundary and dinosaur extinction. I remember Luis and Walter Alvarez ideas’ being scoffed at practically as science fiction in the beginning on early Usenet discussion threads.
Anyway, in my opinion all of them, Milankovic, Wegener and the Alvarez team courageously dragged Science out of the dusty ivory towers and into the modern real world. And now the great pretenders like Jones, Mann, Hansen and Trenberth are trying to drag it right back to alarmism. It is our duty to stop them.
Very interesting article. I think this may also have an effect.
And I’ve noticed comments like this more often lately:
Global warming caused by greenhouse gases delays natural patterns of glaciation, researchers say
GAINESVILLE, Fla. — published online Jan. 8 in Nature Geoscience.
“…current levels of carbon dioxide are trapping too much heat in the atmosphere to allow the Earth to cool as it has in its prehistoric past in response to changes in Earth’s orbital pattern.”
So what they’re claiming is that the ≈40% rise in CO2 is just enough to balance the planet’s temperature to within 0.8K over the past century and a half. In other words, human emissions are calibrated to keep global temperatures on an even keel.
That is preposterous. If true, it means we know exactly how much CO2 to emit to keep temperatures from changing. Conclusion: don’t worry about the end of the Holocene, we can just tweak the climate.
As if.
Smokey says:
March 16, 2012 at 11:18 am
“That is preposterous. If true, it means we know exactly how much CO2 to emit to keep temperatures from changing.”
I am not sure what you are trying to convey here. So a shot in the dark. From what I have been able ferret out this is not about “exactly”, it’s about the general direction things might head and under what conditions we might find ourselves in. All informed speculation, at this point in our relative comprehension of the relevant sciences, tends to suggest that no one hypothesis gets the nomination because the results are not yet in from all precincts. Even if they were, somebody is bound to petition for a recount since vote counting is not exactly an exact science.
Strike, ball, first base or out?
William,
I wasn’t being critical of anything you wrote, I was commenting on one of the common alarmist talking points: that human CO2 emissions are keeping the next glaciation at bay. They specifically claimed that current levels of CO2 are preventing the earth from cooling. Since there has been no global warming for about 15 years now, their explanation is that CO2 emissions are exactly the right amount to cause neither global warming nor global cooling. Really, that’s how ridiculous their arguments have become.
Smokey says:
March 16, 2012 at 11:57 am
No worries, I actually took this route first, then backspaced it out and went the wrong direction, My bad not yours Smokey!
The complex science of global climate change has always been secondary to a few simply stated facts of what will directly impact humanity.
a) Moderate warming very good (MWP)
b) Allot of warming (3 deg. C), (may be bad, may be OK, we really don’t know)
c) A little cooling, very bad (LIA)
e) Allot of cooling, a global disaster (ice age)
Note: man made CO2 has very little or nothing to do with all of the above.
Thanks for this great post ! Ice ages are a fascinating conundrum.
The main effect of changes in eccentricity is to modulate the effect of the precession terms at 23,000 years. Indeed if the orbit was circular then the precession of the equinoxes would have no effect whatsoever. However the direct effect on insolation of the increase in ellipticity of the Earth’s orbit averaged over a year is negligible. This is the paradox as to why regular glaciations and warm interglacials occur every 100,000 years in phase with the eccentricity.
The clearest insolation effect on climate is the obliqueness signal which when averaged out over the combined ellipticity and precession yields a regular variation of around 25 watts/m2 in maximum flux. The delta 18O data show a clear signal throughout the 5 million year period in phase with obliquity. The precession signal is directly dependent on eccentricity and is less evident in the data. However there is no explanation for the primary 100,000 year variation in phase with ellipticity. An excellent review of this problem has been given by Maya Elkibbin & JoseA. Rial [Earth-Science Reviews 56 Ž2001. 161–177
] which highlights the questions that any complete theory of the evolution of Ice Ages must answer namely:
1. The observed gradual decrease in temperatures starting just over 3 million years ago.
2. The 43,000 year continuous signal dominated until about 1 million years ago when the onset of 70-100,00000 glacial cycles begin. Why did this happen ?
3. What is the cause of the recent 100,000y glacial cycles, since Insolation changes caused by ellipticity are too small to be an explanation ?
4. Why did the frequency change from about 70,000 years between 900-700,000 ybp to the current cycle of 100,000 years ?
5. Why is the larger 400,000 year eccentricity signal absent from recent data ?
Muller et al. have proposed an alternative explanation for the 100,000y cycle. They suggested that the driver is the change in inclination of the Earth’s orbit. This follows an 80,000 year cycle relative to the current ecliptic plane, but when projected to the invariate plane defined as the centre of mass plane of the solar system this is extended to 100,000 years. The physical process envisaged is that the interplanetary dust cloud is centerd on the invariate plane and the Earth passes through this during its orbit. Evidence from ocean sediments show a 100,000 year cycle of H3 deposits associated with cosmic dust [3]. In effect, changes to orbital parameters of eccentricity, inclination and longitude of ascending node are all caused by the mutual gravitation of solar system planets as they orbit the Sun. Similarly all bodies in the solar system will follow such cycles including dust clouds.
The hypothesis that the Earth passes through a static interplanetary dust cloud aligned with the invariate plane attenuating sunlight is attractive. Furthermore there is direct evidence in ocean sediments of a regular 100,000 cycle of He3 deposits [4]. Unfortunately the data do not seem to support inclination as being responsible, despite the similarity in timespans. One would expect colder temperatures at low alignment where presumably the Earth crosses the dust plane. The correlation with eccentricity is better with high eccentricity seemingly algning with warmer interglacial periods. So what is really happening and can we explain how the climate changed to regular glaciations ?
I investigated the possibility that the local IPD cloud was resonant with the Earth’s orbit and increased the density between Earth and Sun sychronised with changes in eccentricity. This would then accentuate slightly incident solar radiation with a 100 y cycle. However one would expect a signal for gthis in the TSR(solar constant) measurements, and none is apparent. So the full details of Ice ages are still a mystery (at least to me !)
AGW
A doubling of CO2 levels in the atmosphere by the end of this century will cause a direct radiative forcing of 5.3Ln(2) watts/m2 or 3.67 watts/m2. IPCC models usually assume a further feedback mainly from water vapor of 2 watts/m2/degC. A reasonable assumption would be that AGW would induce a warming term of about 5-6 watts/m2 after which CO2 levels are expected to stabilize. The net effect of all human induced global warming could be to increase radiative forcing by something like between 4 and 8 watts/m2.
The eccentricity of the Earth’s orbit is currently decreasing with cooling likely beginning in 2000 years time leading eventually to another intense Ice age after 20,000 years and lasting a further 60,000 years. A new Ice Age would be disastrous for human and animal life at large latitudes. To fully offset another Ice Age, I estimate it would be necessary to keep CO2 levels above about 700 ppm for another 70,000 years !
Gotta run folks. Dr.s’ appointment. Later……..
William McClenney, thank you so much for this article.
Now incorporate this article with the recent run on Farmland in Africa…. (Google African landgrab)
Hi William.
One thing that always bothers me when we see historical sea-levels relative to land – indeed you cite “Hearty et al (2007) End Eemian highstand(s)” with anything from +6 to +45 amsl.
However, to what extent do we know that the relative land-mass is stable vertically?
i.e. has sea-level truly gone down 45m, or has the land risen – or a combination of the two?
Excellent article. Thanks both, and another one here who will keep a look out for the pdf. (Which hasn’t stopped me running the page through CutePDF to read meanwhile!)
By my calculation it’s about a 2.8% drop in insolation between the non-glacial and glacial states.
So we’re betting it all on the notion that solar output can’t drop over that in this Sleepy Sun period.
Well, that sure makes me feel better /sarcoff;>
AndiC:
Again, it is a lot more complicated than you might think. The Bahamas (hope my fever-adled brain picked the right set of islands, but it might be the Caymans…) look to be on a stable platform of oceanic plate sliding sideways some distance from the mid-Atlantic Ridge. But stable platform conditions where evidence of highstands has been found are rather rare. From there it becomes necessary for the workers to attempt to work out what they think rates of change for each locale where evidence has been found. Under the hairy eyeball, this can seem a lot like adjusting data to fit ones preconceptions, regardless of how well justified. Meaning a varying depth of assumptions blurring the line with modeling.
So, as with anything scientific, the level of due diligence you practice will determine your degree of vision and understanding. Assuming you are not wearing polarizing shades. Where tectonism is active, one is more or less compelled to understand the minutiae of how the authors arrived at whatever their conclusions are, and how you weigh all of that objectively. For instance, a lot of very riveting work has been done in the Mediterranean, several Italian studies come to mind, some speleothem (stalagmite/stalagtite), some sedimentary and geomorphic etc. Your success at perceiving all of this is more or less a factor of how much such reading, studying and comparative thought you can apply. This tends to grow in concert with exposure to the literature, your comprehension of it, and just how many stones you decide to leave unturned……
If you are unfamiliar with this, find the Hearty et al 2007 paper:
http://www.uow.edu.au/sbs/content/groups/public/@web/@sci/@eesc/documents/doc/uow045009.pdf
Proceed to their Figure 2 (page 2092), then check each reference cited therein in the References section, run each of them down, be prepared to shell out some bucks for the paywalled ones, knowing full well that thorough due diligence often incurs expenditures to turn over more and more stones (to leave no stone unturned, etc.). In order to vet some of the incorporated science, such as jumping headfirst into the state-of-the-art firn understanding, for example, you might have to wander along myriad tangents. And it gets harder and harder to stooge you.
Get good at it and the intensity of litigation support can be addictive…….
E.M.Smith says:
March 16, 2012 at 4:33 pm
“By my calculation it’s about a 2.8% drop in insolation between the non-glacial and glacial states….)
Yeah, the state of the furnace at this juncture should escape no one’s attention. If the furnace goes all funky its got to mean something. It qualifies as a difficult to dismiss potential “tipping point” in my estimation.
Interesting post, but the only thing I could gleam out of the post was the world would not go into an ice age in the near future and there were vastly different time frames as to when it would happen. I hope they are right. If not the effects would be devastating.
The primary driver of atmospheric CO2 increase does not appear to be human. I say this because human CO2 emissions are highly variable. Global human CO2 emissions declined in 2009 in absolute terms (fewer tons of human produced CO2) but the rate of increase of CO2 was unchanged. I believe the primary sources of atmospheric CO2 increase are a combination of a continued warming of the abyssal deep where CO2 is released upon ventilation of deep sea water and continued anaerobic biological activity in swampy tundra-muskeg-bog areas that have been activated since glacial ice and permafrost receded since the end of the LIA.
What that means to me in the context of this thread is that if we should see a cooling of arctic areas and a refreezing of many of these swampy areas and if temperatures decline to the point where the ocean goes to net cooling, we are likely to see atmospheric CO2 decline. I have not yet seen any evidence that shows human CO2 emissions are a significant contributor to global atmospheric CO2 load. If we were, the absolute decline in human CO2 emissions should have shown a clear decline in the rate of atmospheric CO2 increase in 2009. We didn’t see any such change in rate of increase.
It takes about 700 years (I think I remember reading recently) to ventilate the abyssal deep but that is uneven, some parts are ventilated faster than that, other parts are more stagnant. But overall, temperatures are warmer these days than they have been for most of the past 700 years so I would expect net ocean CO2 degassing. Should temperatures take a significant drop *and* if ocean degassing is the primary source of atmospheric CO2 increase, we should see a rather significant drop in the rate of atmospheric CO2 rise at that time. The deactivation of bio activity in bogs due to re-freezing would have a significant impact, too, I would expect. Such a drop in CO2 can act as a feedback on temperatures in that once atmospheric CO2 begins to decline due to colder temperatures, it results in more temperature decline.
The Little Ice Age lasted about 300 years. We have been in about 150 years of recovery from it. Because of convection, it is easier to cool the ocean from above than it is to warm it. That is to say that reducing atmospheric temperature will have a faster impact on cooling overall ocean temperature than warm atmospheric temperatures will warm it. So it would probably take longer than 300 years to warm the oceans to where they were before the LIA if atmospheric temperatures were to return to where they were before the LIA, which they have not yet fully returned to yet. All of that is a round about way of saying that atmospheric CO2 rise could be nothing more than continued recovery from the LIA and that increase in atmospheric CO2 could begin to decline should temperatures decline significantly.
If the oceans do not gain back as much heat during this warm period as they lost during the LIA, the next cold period could be deeper than the LIA was as the oceans will be starting from a cooler point. In other words, we would be seeing net ocean cooling on a millennial scale (while seeing recent warming on a century scale). The next few decades will be interesting times.
Many thanks for this excellent post William.
For anyone that’s interested, the Git finally found a copy of Seidov et al’s excellent collection of papers: The Oceans and Rapid Climate Change for a reasonable price. Sadly, they will not ship to Australia.
http://www.amazon.com/gp/offer-listing/087590985X/ref=dp_olp_used?ie=UTF8&condition=used
For another perspective on how fast and how dramatically a climate can change, consider the frozen mammoths.
We know from the freshness of the meat that they have remained frozen from their time of freezing to the present day. We know from analyzing stomach contents that they were feeding on flowers and that the climate was tropical. We know that the these very large animals froze solid before they could finish digesting their last meal.
As far as how those observations fit the historical climate models, I don’t know.
“The entire non-debate on anthropogenic climate effects has always struck me “as two fleas arguing over who owns the dog they are riding on” (Crocodile Dundee). One of the required paradigms of AGW is patently ignoring “when we live” (ignorance of signal to noise ratio, or SNR). — William F. McClenney
Is it too early for quote of the year?
Susann M says:
March 16, 2012 at 5:35 pm
“Interesting post, but the only thing I could gleam out of the post was the world would not go into an ice age in the near future and there were vastly different time frames as to when it would happen. I hope they are right. If not the effects would be devastating.”
I wouldn’t be too sure Suzanne M. Both the PDO and AMDO went negative not too long ago, and the sun has gone all quiet on us. Both verging on about half a precession cycle old. With the insolation level in close proximity to MIS-5e glacial inception. In the absence of anthropogenic forcing, would this not score as something uncomfortably close to a tipping point into the next glacial?
Yet many questions persist. The most cogent of which might be what is the state of our science on this? How well have we nailed-down the devils we know? And what about those we may still be unaware of? Such as the greatest mystery in all of paleoclimatology: what causes the glacial terminations? The D-O events?
If we cannot answer, succinctly, those fundamental but striking questions, then this may be nothing more than a silly-buggers game. Integrate the Surfacestations.org, JoNova’s and the NIWA instrumental, data/data management messes into that non-linear, chaotic mix, then do the smell test.
“Cloudy with a Chance of Meatballs” comes to mind, for some reason………
For evidence regarding the trigger behind the begin/end glacial events, and why they are so extreme, one only needs to research the varying interactions between the solar wind and the Earth’s magnetic field…so called archeomagnetic jerks, and geomagnetic perturbation events…you will find that they coincide to the beginning and end of almost all interglaciation and glaciation periods. This lends support to the fact that these cycles are driven by changes in atmospheric circulation/atmospheric angular momentum.
We are currently experiencing an archeomagnetic jerk, evidenced in the weakening of the geomagnetic field, and the jerking of the N pole in recent times, especially over the past decade…and will accelerate to an even quicker rate in due time.
The Sun’s activity, and relative inertial motion of various celestial bodies acting on the COM, also follow the same exact cycle…
E.M.Smith says: @ March 16, 2012 at 4:33 pm
“By my calculation it’s about a 2.8% drop in insolation between the non-glacial and glacial states….)
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William McClenney says: @ March 16, 2012 at 5:01 pm
Yeah, the state of the furnace at this juncture should escape no one’s attention. If the furnace goes all funky its got to mean something. It qualifies as a difficult to dismiss potential “tipping point” in my estimation.
___________________________
Here are a few other papers just to make you feel warm and Fuzzy…
Total solar irradiance since 1996: is there a long-term variation unrelated to solar surface magnetic phenomena?
Total solar irradiance (TSI) has been measured with space-based instruments since 1978. The TSI during the recent solar minimum in 2009 has been lower than the two former minima around the years 1986 and 1996, which points to a long-term decrease…
Results. The TSI is reconstructed from June 1996 to May 2010. From the solar minimum of 1996 to the solar maximum of 2004 the model reproduces the observations well, but it fails to explain the observed decrease in TSI in the solar minimum of 2009 and the very recent data of 2010…..
Conclusions. The difference between modeled and observed TSI might be the result of underrepresented weak magnetic fields in the Carrington rotation synoptic charts, an uncertainty in the TSI measurement, or a decline of the global temperature of the photosphere. If latter were true, this would have important implications for reconstructions of TSI in the past. In order to study if an underrepresentation of weak magnetic fields in the Carrington rotation synoptic charts is the explanation for the difference between our model and the observation, full-disk images with higher spatial and temporal resolution should be analyzed in future.
Also see: http://www.nccr-climate.unibe.ch/research_articles/publications/article_en.html?ID=941
Is this true? If so the next paper has great significance. Seems Sunspots DO correlate with climate. Unless volcanic action interferes according to this study of dust in Greenland ice cores, sunspots, and volcanoes
Finally ! I am no scientist but looking at the Vostok graph I always thought that any 8 years old could predict the next move.
Is there a state of denial in the scientific community and even at wuwt ?
Congratulations for your very interesting post mr McClenney.
Here’s some more interesting stuff on a same/similar topic:
http://www.skepticalscience.com/LIG1-0706.html
Perhaps a little bit off topic. My wife and I were discussing this some time ago. Might there be some people here who can shed some light as to why the Sahara turned into a desert? As far as I know, it is alleged that the great exodus of the Israelites was accompanied by some big volcanic eruption in Greece which might help also explain the disappearance of Atlantis (somewhere in the Aegean) and the ten plagues that befell on Egypt around the same time.
Such volcanic eruption – if true- could help explain the trigger for climate change – but why did it persist to this very day? I cannot for the life of me think why the Pharaos would put their Pyramids *which btw are gigantic* 5kyr bp in the middle of desert country…….
HenryP says: @ March 17, 2012 at 8:20 am
Perhaps a little bit off topic. My wife and I were discussing this some time ago. Might there be some people here who can shed some light as to why the Sahara turned into a desert?
_______________________________
Henry, I have not followed the research closely but I think it had to do with a Bio-feedback. If you kill the grass and trees you change the microclimate and create a desert in a “marginal rain fall areas” Therefore a volcanic eruption that gave poor harvests would mean less food especially for grazing animals. I know around my area (SE USA) during a recent drought farmers were cutting tree branches to feed to their cattle.
Destruction in action: http://www.lonelyplanet.com/blog/wordpress_uploads/2009/10/2610542294_a7fbf8d580_o2.jpg
desertification: http://pubs.usgs.gov/gip/deserts/desertification/
Planting trees:
Henry, I should also add the Dust Bowl era in the USA is a well documented example. http://www.english.illinois.edu/maps/depression/dustbowl.htm
The pictures are worth the time to look at in both articles. In one article it mentions the Dust blew all the way across the USA to arrive in Washington DC at about the same time the problem was being discussed in Congress.
BTW,
the Holocene ended the moment Reagan removed Carter’s solar panels from the White House. I am not making this up. HuffPo did:
http://www.huffingtonpost.com/gregory-unruh/business-in-a-post-holoce_b_806764.html
HenryP says:
March 17, 2012 at 8:20 am
“Perhaps a little bit off topic. My wife and I were discussing this some time ago. Might there be some people here who can shed some light as to why the Sahara turned into a desert? As far as I know, it is alleged that the great exodus of the Israelites was accompanied by some big volcanic eruption in Greece which might help also explain the disappearance of Atlantis (somewhere in the Aegean) and the ten plagues that befell on Egypt around the same time.”
Santorin. One of the homes of Brangelina.
“Such volcanic eruption – if true- could help explain the trigger for climate change – but why did it persist to this very day? I cannot for the life of me think why the Pharaos would put their Pyramids *which btw are gigantic* 5kyr bp in the middle of desert country…….”
Ancient Egypt was already completely dependent on the Nile. Cairo and the Pyramids and all the other ancient temples are not far from the river Nile. They already had irrigation systems perfected and use of the seasonal Nile floods to provide fertile river sediment for the fields.
Blade says:
March 16, 2012 at 11:15 am
“About Milankovic … I think that his ‘theory’ must be placed in perspective. IMHO, it is more important to appreciate his quality of work rather than the final details of the theory because it would be absolutely stunning if he could have nailed it down 100% in his lifetime.”
Lubos Motl claims somebody’s fixed Milankovic’s formula and it fits like a glove now:
http://motls.blogspot.com/2010/07/in-defense-of-milankovitch-by-gerard.html
Added a derivative term.
William McClenney says:
March 16, 2012 at 9:21 pm
“Cloudy with a Chance of Meatballs” comes to mind, for some reason………”
At least there will be plently to eat while we freeze.
Sometimes I wonder if any researchers ever look to other fields then their own to connect some dots. Maybe then some of your questions might be answered.
HenryP said @ March 17, 2012 at 8:20 am
Africa: Greening of the Sahara
Why can’t someone refute the BS that (C)AWG is caused/amplified by CO2?
Lightrain says:
March 17, 2012 at 9:12 pm
Why can’t someone refute the BS that (C)AWG is caused/amplified by CO2?
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Because of the absorption spectrum: http://wattsupwiththat.files.wordpress.com/2011/02/gw-spectrum-summary1.jpg?w=640&h=388
There is no way to deny that various molecules absorb energy at specific wavelengths. Chemists use these “signatures” to identify different molecules.
This is a graph of Sunlight as it hits the earth including absorption by the ocean: http://lasp.colorado.edu/sorce/images/instruments/sim/fig01.gif
However the elephant in the room is not CO2 but H2O (water) As the last graph shows the Oceans (70% of the earth surface) absorbs the high energy area of the spectrum (UV) As the first graph showed H20 has much wider absorption bands and accounts for most of the infrared radiated by the earth that is absorbed. There are about 20000 ppm of water vapor in the air, versus about 400 ppm of CO2. Also the amount of water vapor varies wildly. When you throw in the albedo (sun reflection) effect of clouds, snow and ice, the heat absorption capacity of the oceans and lakes vs air, as well as the ability of rapid transport of heat to the upper atmosphere by thunderstorms, CO2 is an insignificant ant compared to water.
To me it is incredible that anyone with the least bit of knowledge of science could ignore the fact that water is the big player in our climate and instead pick a minor gas that is a plant food. If there is a “Tipping point” (And I think there is) it is caused by water not CO2. Specifically the accumulation of sun reflecting snow when the TSI reaches the critical number that tips the earth into an Ice Age or into an Interglacial.
Quick explanation of spectrums: http://www.udel.edu/Geography/DeLiberty/Geog474/geog474_energy_interact.html
WUWT discussion: http://wattsupwiththat.com/2011/02/28/visualizing-the-greenhouse-effect-atmospheric-windows/
Gail Combs says:
March 18, 2012 at 1:39 am
Lightrain says:
March 17, 2012 at 9:12 pm
It looks to me like recent research suggests the CO2 feedback response may, in fact, increase atmospheric water content, which in turn increases clouds and albedo suggesting negative feedbacks.
Although the link http://www.scirp.org/Journal/PaperInformation.aspx?paperID=3447&utm_source=newsletter&utm_medium=ijg13&utm_campaign=01%22%20\t%20%22_blank
(open access, look for the link) may satisfy Lightrain as regards the AGW/CAGW pre-debate (since one seems to have never happened, yet), it does not address TSI/UV directly.
It might be sensitivity to solar UV, not TSI, that could be the more interesting solar triggering of climate affects.
“Satellite observations by the Spectral Imager Monitor (SIM) indicate
that variations in solar ultraviolet radiation may be larger than previously
thought, and in particular, much lower during the recent long solar minimum.
Based on these observations Ineson et al. (2011) have driven an ocean-climate
model with UV irradiance. They demonstrate the existence of a solar climate
signal that affects the NAO (North Atlantic Oscillation) and produced the
three last cold winters in Northern Europe and in the United States.”
http://arxiv.org/abs/1202.1954
Although the focus of this paper is not UV specifically, it is part of an observational trending from many workers that we might have given short shrift to yet another of the plethora of variables that pace/force climate.
The GHE does not warm the climate, these are terrible unacceptable physics. It indirectly cools the climate.
1) N2/O2 do not absorb or emit IR, they attain their ‘temperature’ via conduction from the solar heated surface, and compose the large majority of the atmosphere. That is how most of the atmosphere gets it’s ‘temperature’, the contribution of radiation is very small, and the initial impact may be a very minute warming. CO2 and other GHGes, while absorbing/emitting IR from the surface, also collide with O2/N2 molecules in the atmosphere, hence allowing them to shed a portion of their ‘heat’ to space, they cannot do it on their own…some of that is also emitted down to the surface via CO2, but these N2/O2 molecules do NOT absorb IR re-emitted via the surface, only via conduction. So any photon re-mitted Via CO2 must either be intercepted by another GHG molecule, or hit the Earth’s surface… CO2 absorbs various photons and emits them, they do emit IR they attain, N2/O2 do not attain IR, and do not emit, they need help to shed that energy.
2) The S-B constant would be violated by 33C with or without GHGes in the atmosphere, because the Oceans/Surface/Atmosphere do NOT lose all their energy overnight, regardless of whether or not there are GHGes in the atmosphere.
3) The GHE is the reason why we have clouds/albedo…take H2O out of the atmosphere, you have no Clouds/Ice/Snow/Precipitation. The GHE is the reason why a good 30% of all incoming SW is reflected out to space.
No one is disputing the properties of CO2, but it is sillyness to claim the GHE warms the planet’s surface to any measurable extent…it likely cools it indirectly. The Ocean surface is on avg warmer than the surface temp above it, temps lag SSTs, processes like ENSO lag the kinetic energy budget. This whole AGW thing is a load of BS.
Henry@Gail, Lightrain, William, Phil
Interesting discussion
My thinking was that if either more heat were produced by earth (e.g. volcanic action) or by man (heating,cooling and burning stuff) or by increasing GHG’s (causing a delay in cooling, e.g. http://www.letterdash.com/HenryP/the-greenhouse-effect-and-the-principle-of-re-radiation-11-Aug-2011),
one would expect to find minimum temperatures increasing, pushing up the average temperatures.
It was with this in mind that I have done a statistical analysis of 22 weather stations all over earth in the SH and NH.The latest tables show that, over the past 4 decades, the rates of increase of temperatures on earth i.e. maxima, means (=average temperatures) and minima have risen at a ratio of about 7:3:1.So it was the maxima pushing up the average temperature of earth.
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
This implies clearly that the observed warming over past 4 decades was largely due to natural causes. Either the sun shone a bit brighter or there were less clouds or, as William hinted at, – and I have also considered it – (which I think we need to urgently study further), a thinner ozone layer and/.or a greater ozone hole. Note that especially the SH got the brunt of the extra heat although it did not warm there, much. The extra heat in the SH oceans appears to be passed on to the NH by currents and/ or weather systems.
Apart from that, it seems some of the extra warmth is also trapped by the increasing greening of earth. It seems if you want earth to be greener, a natural consequence is that it will also get a bit warmer.
This helpful article points to the fact that the state of knowledge of the dynamics of glacial-interglacial switching is grossly over-stated. We know almost nothing of why these switchings occur. We know phenomenologically that for 1.5 Myrs the switching was synchronised with the obliquity cycle (41 ky) then 1m years ago it transitioned to synchrony with the 100 kyr eccentricity cycle. Why? [stony silence] We know ALMOST NOTHING about any of this. People bandy around supposed threshold values of watts per m2 of insolation as if the mechanism was well understood. It is not.
In fact the picture of periodic regular interglacials and long intervening ice ages is an oversimplification – during these supposedly unbroken ice ages there are often abortive interglacials, some even “micro-interglacials” with temperatures rising more than 10 degrees to remain at interglacial levels for only a few decades before an equally precipitous fall. Some interglacials are double or multi-headed and they all have different shapes. Glacial periods gradually deepen over their (recent) 100 kyr timecourse. Again, why? [again, stony silence]
It seems most reasonable – as recently outlined by Robert Brown – that glacial and interglacial are strange attractors in a non-equilibrium pattern system of nonlinear oscillator. The phase space of such a system has multiple dimensions – in this case these would include insolation, solar cycles, internal global ocean-driven cycles, cosmic ray influences, volcanism, etc.. Al combining to create a convoluted probabilistic landscape in which “glacial” and “interglacial” are valleys of stability linked by saddles of transition.
Insolation by itself wont cut it. And CO2 as we all know is as effective as fart in a thunderstorm.
phlogiston says:
March 18, 2012 at 7:58 am
“This helpful article points to the fact that the state of knowledge of the dynamics of glacial-interglacial switching is grossly over-stated. We know almost nothing of why these switchings occur.”
It is perhaps best observed that the awareness of the abruptness of climate state switches is somewhat still in its infancy, having been ignored by the scientific community (consensus) for 60 or so years after Ernst Sorge’s discovery of it, until it was rediscovered in exactly the same medium (polar ice) in the early 1990’s. Since that time, workers with a vertical knowledge base in one aspect or another have opined on what their research has yielded, but all too often with a built-in bias, which those that practice science quickly note is not science at all.
Although science has yet to yield up the climate agent provocateur is proof to some of a great many individual things, it appears to me merely a function of human fixation that there simply has to be one overriding answer, such as CO2. Those evolved beyond single-variable processing oblige themselves to look for combinations of variables for the climate-state switching phenomena, the complexities of multi-variate processing without all the variables defined their achilles heel.
I find one of the more telling statements integrating our present state of knowledge that issued by Tzedakis (2010):
“On balance, what emerges is that projections on the natural duration of the current
interglacial depend on the choice of analogue, while corroboration or refutation of the
“early anthropogenic hypothesis” on the basis of comparisons with earlier interglacials
remains irritatingly inconclusive.”
I think it rather searingly states the other side of humanity, that as irritating as it all is, we just don’t know at present, a call for more objective science to be done to some, an admission of inadequacy to those more inclined to their single-variable fixates.
This essay was intended primarily to inform that absolutism is itself inadequate given our present state of knowledge. And as a warning, on many levels. It might be nice to know all the answers but perhaps only to the end that we might not be able to do all that much about it, except adapt. Given the vast number of variables we have tentatively identified can any one of us point to which knob to turn? We think we know what happens in the models when we overly turn one of them, even given our obviously irritating true lack of complete understanding. And Climategate/Glaciergate and now Fakegate inform us that the most devilish variable of all can be our very selves.
Psychology.
One area or research, that as a geologist I am not well prepared to pursue properly, is psychology. Burned like a brand in my psyche is a bit of research I was exposed to in a graduate course in psychology (Theories of Personality) where it was stated that the human being is nine times more susceptible to rumor than it is to fact. The Nine Times Rule. My proof of this is an emminently simple question: Which of all mankind’s religions is the correct one?
In your internal deliberations on this question you are allowed to consider how the Greeks
must have felt when someone told them that Zeus, and the pantheon of gods resident on Mount Olympus, were just a myth. The Egyptians had the same problem with the sun god Rah. And if I am not mistaken, the Babylonians once worshipped Shamash and Ishtar before abandoning them in favor of a newer religion, Islam (Babylon lay 90 kilometers south of present-day Baghdad) now all the rage of many hominids. Somewhere back there, not all that long ago by comparison, others of us stopped burning witches at the stake (though this whole thing has given me pause to consider if curtailing that practice was such a wise decision).
Seemingly locked in mortal combat with faith we find science, where as a math competitor of mine in the eighth grade once offered: the mind is like a parachute, it must be open in order to function.
I think you are on the right track phlogiston, and I boil it down to the grittiest level that this offers up the choice to everyone to either critically think or accept. But even acceptance of a thing brings three very different vectors. Acceptance due to adherence to authority, no matter what (damn the torpedoes, full speed ahead minimal mentality), to acceptance due to an inability to gather myriad facts and manipulate them mentally seeking to identify the fleeting coincidences which might someday turn out to be a law of nature. The latter being just basic ignorance, but which might have also ascended somewhere in our authority structures (fascism comes to mind here). The third being acceptance after having vetted something against your experience and plunking down on your own conclusions.
Critical thinking, on the other hand, tends to involve the ability to not necessarily come to a conclusion, regardless of how frustrating or irritating this proves. It also means that disproving your very own prejudices could prove to be the key to jumps in your understanding. Those who adhere to a religion while also attempting to do objective science would seem to have a built-in conflict to some degree here, which I imagine makes critical thinking subject to certain subroutine calls.
In this piece my intent was to do more or less what you say. Also to bring some light on what may be an even more poignant debate, are we at an end extreme interglacial? If so what are such rides into a glacial typically composed of? And if so, and if the single-variable CO2 is as capable as some suggest, how does such a mind that purports this also fail to see the serendipity of organizing ourselves of industry which emits vast quantities of stored CO2 at just such a point in time? Which brings us right back to psychology.
Oddly enough, an intriguing quote from George Patton always comes to mind at such a juncture:
“”For over a thousand years, Roman conquerors returning from the wars enjoyed the honor of a triumph, a tumultuous parade. In a procession came trumpeters and musicians and strange animals from the conquered territories, together with carts laden with treasure and captured armaments. The conqueror rode in a triumphal chariot with the dazed prisoners walking in chains before him. Sometimes, his children, robed in white, stood with him in the chariot, or rode the trace horses. A slave stood behind the conqueror, holding a golden crown and whispering in his ear, a warning; that all glory is fleeting …. “
William McClenney says: @ March 18, 2012 at 3:15 am
It looks to me like recent research suggests the CO2 feedback response may, in fact, increase atmospheric water content, which in turn increases clouds and albedo suggesting negative feedbacks.
… link http://www.scirp.org/Journal/PaperInformation.aspx?paperID=3447&utm_source=newsletter&utm_medium=ijg13&utm_campaign=01%22%20\t%20%22_blank
….It might be sensitivity to solar UV, not TSI, that could be the more interesting solar triggering of climate affects…..
http://arxiv.org/abs/1202.1954
_________________________________________________
Thank you for the links. (bookmarked)
On the solar UV subject…
NASA had an Article The Sun’s Sneaky Variability
Add that to the graph I showed of UV energy penetrating the oceans to 10m above.
Then add in Bob Tisdale’s information on ENSO of a “El Nino step-wise warming” on a short term basis during high solar activity where Bob’s GRAPH shows El Niño events add more energy (heat) to the ocean than is lost during La Nina events.
Bob’s comment on the subject.
WUWT Article by Bob Tisdale
William McClenney says:
My proof of this is an emminently simple question:
Which of all mankind’s religions is the correct one?
In your internal deliberations on this question you are allowed to consider how the Greeks
must have felt when someone told them that Zeus, and the pantheon of gods resident on Mount Olympus, were just a myth. The Egyptians had the same problem with the sun god Rah. And if I am not mistaken, the Babylonians once worshipped Shamash and Ishtar before abandoning them in favor of a newer religion, Islam (Babylon lay 90 kilometers south of present-day Baghdad) now all the rage of many hominids. Somewhere back there, not all that long ago by comparison, others of us stopped burning witches at the stake (though this whole thing has given me pause to consider if curtailing that practice was such a wise decision).
Henry@William Howard
Pity your well illustrated reasoned arguments were contaminated with this rather sexist remark and ad hominem attack on religion.
I decided to take some time to answer, since it seems to me you were looking for an answer.
Obviously the correct religion is the one whose existence bore from the resurrection of Jesus Christ from the dead (Acts 2:32). The other religions, well, they all don’t have that. Those who have done intense studies on all available scriptures have concluded that Jesus was indeed dead when they buried Him and that the grave was empty when they went looking for Him. In fact we have His burial cloth, if you take some time to look here,
http://www.shroud.com
I have done some intense study on this cloth and there is no doubt in my mind that the picture you see here is indeed that of Jesus Christ. There is no way that a forgerer, much less a medieval one, could have made this photographic negative of a 3 D image, with all the correct available pathological information, of a crucified man.
The only thing that does not add up is the dating of the cloth. Obviously for someone travelling from the beginning to the end of time, and back, what difference does 12 or 13 centuries make?
If the age of the cloth had exactly been right, you would not need to have any faith?
JC is simply saying: there is a bridge, to the other side of time, but the only way to get there is by faith, through grace. There is no other way.
http://www.letterdash.com/HenryP/why-do-i-believe-in-god
As strangely as it may seem or sound, but this faith changes people, as it did Peter.
Gail Combs says:
March 18, 2012 at 12:48 pm
Yeah, it just gets interestinger and interestinger, doesn’t it?
HenryP says:
March 18, 2012 at 1:30 pm
It’s called perspective Henry. Even on faith we have been on many blind alleys before. Who is to say which of the remaining and later ones is the correct one? Just sayin, read into it what you wish.
William McClenney says:
March 18, 2012 at 1:50 pm
Gail Combs says:
March 18, 2012 at 12:48 pm
Yeah, it just gets interestinger and interestinger, doesn’t it?
________________________________________________________
What happens during the next decade if we do go into a “Solar Grand Minimum” should answer a lot of questions. That is if the Blockheads trying to run the world do not get in the way of real research.
If we are looking at an interglacial to glacial tipping point (with a bit of a push from a major volcanic eruption) it would have been nice to have had science pointed in the correct direction and Thorium Nuclear plants already on line.
The politicians were aware of the possible ending of the holecene in the 1970’s because George Kukla and Robert Matthews of Brown University alerted President Richard Nixon: http://calderup.wordpress.com/2010/05/14/next-ice-age/
In 1974 you had the CIA analysis document: http://omniclimate.wordpress.com/2009/12/03/world-exclusive-cia-1974-document-reveals-emptiness-of-agw-scares-closes-debate-on-global-cooling-consensus-and-more/
Thorium: http://www.mining.com/2012/02/14/why-not-thorium/
Anti – Nuclear economics: http://www.komanoff.net/nuclear_power/10_blows.php
(The Boston Globe had want ads for nuclear protesters $10/hr during the Seabrook “protests” )
I found this really interesting:
So because this young idiot wants a “simple Life” he is going to deny everyone else a choice and possibly kill any chance civilization has of weathering major “Climate Changes”
Gail Combs says:
March 18, 2012 at 2:45 pm
Those who know me, and travel to the depths of the western U.S. deserts in search of “who knows what this time..”, often bask, and sometimes participate in, the decades yet to be amortized application of highly transportable, effective and efficient (as today’s technology permits) compact wind, solar, and yes, power storage systems. Campfires occasionaly augmented with 12v ropelights strung in the trees or the rafters of the aging cabins I have managed to find, feeding off an emminently portable wind jennie, managed through a low-loss capacitance array (to capture power spikes, feeding any excesses to the batteries as fast as they can drain the capacitors) I am often heard to opine “that every penny not spent on fusion research may turn out to be a penny wasted.”
So it isn’t that I am not already vested, somewhat. I just thought the investment in flexible renewable technology, on the personal scale, could deliver real world results, independent of the real world costs. The living room, between deep desert excursions, meaning the TV, cpu and lighting, run mostly off this very flexible approach. The laundry, kitchen and climate control sadly would grossly overtax these quite inadequate independent resources.
I am not too certain of just what this means in juxtaposition with ice sheets whose terminal morraines have reached as far south as Kansas……..
Let’s hope Dorothy lives south of the terminal morraine next time.
Gail Combs says:
March 18, 2012 at 2:45 pm
“So because this young idiot wants a “simple Life” he is going to deny everyone else a choice and possibly kill any chance civilization has of weathering major “Climate Changes””
Well, he’s a YOUNG idiot. As soon as he has kids he’ll have slightly different priorities. I think the Chinese don’t give much on his opinion anyway. Related, there begins an anti-green backlash in Germany… the nuke phase out has forced the Southern states to implement renewables presto so they started felling forests on mountain ridges for wind turbines. Video:
http://notrickszone.com/2012/03/16/germanys-green-fuhrers-we-have-to-destroy-it-in-order-to-rescue-it-green-infallibility-shows-its-ugly-side/
Turns out the locals don’t like it; green approval rating down from 28% post Fukushima to 12 % now. Limits To Idiocy. Even in Germany.
The old nukes had rather low temperatures and pressures compared to a modern gas plant anyway…
Tomorrow I’ll re-read all the comments to be sure I’ve captured the possible issues – but my idea is that at low insolation and M cycle combinations we see solar minimum events not yet identified which serve as tipping mechanisms – that would give us the seeds of the cold cycles – cheers.- best all.
How about 7,000 ppm for just another 7,000 yrs? Has a nice symmetry to it …
😉
WC;
Edit note:
You were perfect in your use of “it’s” up till the final para of the MIS-11 commentary, when you misused it twice. No instances of wrong use of “its”, though.
🙂
The commenters, of course, are cluelessly all over the map.
6-word infallible guideline:
His, hers, its;
He’s, she’s, it’s.
“the precessional alignment would suggest that the Holocene is nearing its end, while the obliquity alignment would suggest it has another 12 000 years to run its course.”
This is conclusion is historically incorrect as EVERY Ice begins when the obliquity declines below 23.5%. Get the obliquity time line out and compare to the ice age cycles. 3/4 of the 41kyr cycle is ice age dominated leaving only 10 to 12 kyr of warming. On the other hand 2 out of 3 obliquity cycles only yields one warming period. Those are the facts as we have them.
BTW- tangentially related, Hansen screwed up on the solar constant (1366 w/m^2), the heat balance he produced if corrected for the proper constant of 1361 w/m^2 yields a slightly negative heat balance. Whoops! http://antigreen.blogspot.com/
Some bargepole treatment of skeptical science
This is even more interesting than it at first seems. A few years ago, most academic journals would happily and rapidly reject any outright challenge to Warmism. Now none of a journal’s reviewers want to bear the responsibility for doing that. Neither accept nor reject is their new cowardly policy: A long way to go yet but an important change in the right direction
An email below from Gerhard Kramm regarding an article submitted to the journal “Atmospheric Chemistry and Physics” (ACP). Dr. Gerhard Kramm is Research Associate Professor of Atmospheric Sciences, University of Alaska Fairbanks, Geophysical Institute and Department of Atmospheric Sciences, College of Natural Science and Mathematics
On February 14, 2012 I uploaded a manuscript entitled “Comments on the Paper ‘Earth’s energy imbalance and implications’ By J. Hansen, M. Sato, P. Kharecha, and K. von Schuckmann” to ACP. The manuscript is authored by Kramm and Dlugi.
Now, I received the e-mail message below in which it was stated that the Editor Assignment has been interrupted. For your information: ACP has an not only an Editorial Board, but also an Advisory Board (See here). Members of this Advisory Board are: Paul Crutzen, Meinrat O. Andreae, Daniel McKenna, Stuart A. Penkett, and Veerabdhadran Ramanathan. In addition, there are five Executive Editors and 120 Co-Editors.
As documented in the Manuscript Record, on March 13, 2012 no editor was available to handle our manuscript. It is unbelievable. What may be the reason?
In our manuscript we showed that the calculation of the radiative imbalance for the top of the atmosphere by Hansen et al. (2011) is based on an invalid value for the solar constant of about 1366 W/m^2. If the SORCE/TIM value of 1361 W/m^2 is used, then there is either no imbalance or a negative imbalance. The latter means that more infrared radiation is emitted to the space as solar radiation is absorbed by the earth-atmosphere system.
It is interesting that before 1978 not only X15-Rocket aircraft measurements, but also satellite measurements suggested a solar constant of 1361 W/m^2 (see Raschke et al., 1973). Several years later, Prof. Dr. Raschke became my M.S. advisor, but I was not involved in this satellite research.
Thanks William for a great post.
Just a few thoughts. We know Milankovitch cycles have been operating since the dawn of time and yet the climate of the Pliocene and Miocene were significantly warmer than today. If memory serves, atmospheric [CO2] was also similar to today. This adds yet another twist to the climate conundrum.
As you have shown, the Pleistocene has heralded a deterioration of climate, at least if you think cold is bad, and has shown baffling changes from a 41 kya cycle to the present 100 kya cycle with amplification of interstadials. The Milankovitch theory, as I understand it, does not explain how this occurred and in fact explains the 41 kya world but not the 100 kya world.
As far as solar insolation goes there are some hints via Be-10 that the sun may not be as constant as we think, but as Dr. S. has pointed out that there may be problems with Be-10 data that introduce noise into the signal. In other words weather patterns may amplify the Be-10 signal and not necessarily give us a solar proxy.
One bit of data that I found of interest was in Hoyt and Schattens book “The Role of the Sun in Climate Change” and that was that the Ca-II index of sun like variable stars shows twice the variability that we have measured from the sun in modern times. This hints at the idea that perhaps the sun may have another lower mode of operation than we have ever measured. If correct, and if the relationship is linear, my quick calculation says TSI may be able to drop by around 6 watts per square meter. Doesn’t sound like much, but with Milankovitch insolation amplification that would be larger than you may expect at higher latitudes and would be very problematic.
Speaking of amplification or modulation during solar minimums, TSI reduction maybe be additionally indirectly affected via cloud formation. The reduction of TSI may be amplified by cloud cover as more cosmic rays hit the atmosphere while the earth’s magnetosphere is ALSO decreased during a solar minimum in addition to the solar wind (see the AA index). Thus there is an additive effect of both the reduced solar wind AND a reduction in strength of the magnetosphere allowing cosmic rays to produce clouds which help block an already reduced TSI solar output. So there are 3 factors working together to dampen insolation reaching the ground. http://www.appinsys.com/GlobalWarming/AAIndex.htm
——–
The 100 kya ice age cycle is an average corresponding to 80 and 120 kya event lengths, so the confusion of time lines is introduced by this over simplification of ice age cycles. Some ice ages last 2 obliquity cycles (82 kya) and some last 3 cycles (123 kya). As I stated before NOT EVERY 41 kya obliquity cycle yields a warming…but EVERY ice age starts when obliquity falls below 23.5, there are no exceptions in the last million years! The observation of the record is very clear, the only question of timing is when and IF ice age conditions end NOT begin.
Great article! Very informative. Much to digest. Thank you.
Perhaps I missed it, but has anyone done an analysis of the variations in the sunspot cycle over the past million years or so (if that is possible from available data)? And if so, when that cycle is combined with the other cycles you reference, how does that correspond to the historical record? The Milankovitch cycle theory doesn’t include this cycle of solar variability, and that would seem to be a significant factor in a theory that is centered on the sun’s effect on climate.
E. J. Mohr says:
March 19, 2012 at 8:22 pm
The CA-II data looks quite interesting. Perhaps another proxy emerges.
dscott says:
March 20, 2012 at 1:02 pm
There are also proponents of a 105kyr cyclicity. Although I haven’t spent the time to search out a good set of orbital harmonics papers, my sense of what I have read concerns how such records are “tuned” to the various other age models. The cycles we have identified, as regards the sun, are rather numerous. This gets into some interesting alignments, of which, from what I can tell, never really quite match the observational data, throughout time. This tends to suggest that we might not, yet, have all of the variables nailed down, doesn’t it? Svensmark comes to mind at such a moment.
John Work says:
March 20, 2012 at 2:30 pm
Good question. I have not yet researched the literature on sunspot proxies extending beyond the observational record, but I have, somewhere, an recent abstract listing a late Precambrian varve sequence preserving the D-O cyclicity. I remember a field trip to a site in Virginia where we looked at volcanic dropstones long preserved in a lacustrine sequence some 650my old. This was at least 40 years ago, long before anyone had any idea about D-O events.
We may have to rely on the WUWT readership to point us in directions regarding pre-historic evidence of sunspot activity.
William McClenney says:
March 18, 2012 at 11:14 am
phlogiston says:
March 18, 2012 at 7:58 am
William I enjoyed your reflections in reply to my comments. In terms of the search for truth and ability to have an open mind, a couple more quotes spring to mind:
“All lies and jests, till a man hears what he wants to hear and disregards the rest” (Simon and Garfunkel, “The Boxer”)
“We´re philosophers – but we might not be!” Douglas Adams, Restaurant at the end of the universe.
On the religions theme, its interesting to speculate how climatic events might have shaped religious development. The norse religion features the idea of “Ragnarok” when the gods are finally overthrown by men. Gods were associated with ice – the icy halls of Jotunheim. So retreating ice at the starting interglacial perhaps sowed in society this idea of the gods retreat.
E. J. Mohr says:
March 19, 2012 at 8:22 pm
…As you have shown, the Pleistocene has heralded a deterioration of climate, at least if you think cold is bad, and has shown baffling changes from a 41 kya cycle to the present 100 kya cycle with amplification of interstadials. The Milankovitch theory, as I understand it, does not explain how this occurred and in fact explains the 41 kya world but not the 100 kya world.
____________________________________
Geologist think Plate tectonics does.
As I under stand it A shift in the Caribbean tectonic plate joined North and South America… changed the flow of the ocean currents and caused the creation of the Gulf Stream.The Gulf Stream introduced warm and saline water masses to the north creating deepening of the thermocline. http://www-odp.tamu.edu/publications/202_SR/synth/synth_5.htm
The configuration of the planet is still pretty much the same BTW
John Work says:
March 20, 2012 at 2:30 pm
Great article! Very informative. Much to digest. Thank you.
Perhaps I missed it, but has anyone done an analysis of the variations in the sunspot cycle over the past million years or so…
_________________________________
Dr Feynman’s sister. (yeah THAT Dr Feynman)
Popular NASA Article: http://www.jpl.nasa.gov/news/features.cfm?feature=1319
Papers:
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/39770/1/06-1256.pdf
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/40231/1/06-1989.pdf
Its label is “Fig. 2”.
Gail Combs says:
March 23, 2012 at 6:05 pm
I think you are correct Gail. I am not sure that the deep ocean drilling project has yielded up the vagaries that populate oceanic circulation beyond closing of the Panama Seaway. If someone has researched this issue feel free to opine! But the closing of it would seem to reasonably restrict speculation to oceanic circulation from then to present.
A current focus of research concerns what happened about ~400kya? What have we been able to prize from the proxy record as to why the amplification of climatic amplitude we have experienced, whether our stone-age or sentient selves, ever since.
All my papers are stored in a top-level folder entitled “Climate Change and Evolution”, because the two are tied……
phlogiston says:
March 23, 2012 at 5:04 pm
“On the religions theme, its interesting to speculate how climatic events might have shaped religious development.”
I have only grazed this subject at present. But it is intriguing, isn’t it? My present understanding is that the written word extends to about 10kya, another 30kyrs (40kya) for cave paintings.
We may need to call on the WUWT readership, those still following this sun-setting thread, to offer up thoughts they might have objectively researched on the evolution of religion.
Curiosity my addiction.
Brian H says:
March 23, 2012 at 8:57 pm
William McClenney says:
March 16, 2012 at 7:00 am
…
“Alan: If you like that typo, see if you can find the one in Figure 13′s caption!
Its label is “Fig. 2″.”
In the cited paper it is Figure 2. In this essay it is Figure 13.
I spent quite a long time doing a parametric fit to the Ocean sediment data using a combination of Milankotitz terms with wavelengths of 400,000(eccentricity), 100,000(eccentricity), 41,000(obliquity) and 23,000(precession) years. What is really interesting is that you can divide the last 5 million years up into 3 phases.
Phase 1: 5 million to 3 million years ago : There is a clear 400,000 year eccentricity cycle superimposed on a slow linear decrease in temperature, and a continuous 41,000 year signal
Phase 2: 3 million to 900K years ago: Mainly the 41,000 year term dominates, but around 1.5 million years a 100 K term starts to be seen. The 23,000 year term is very small.
Phase 3: 900K years ago to pressent: The 100,000 year term dominates interfering with the 41,000 year obliquity term.
The full fit can be seen here
The only continuous phenomenon throughout is the presence 41,000 year obliquity signal which can be explained by changes in seasonal insolation . No-one to my knowledge has convincingly explained why :
1) The Earth started cooling 5 million years ago
2) The absence of 400,000 year term after 3 million years ago
3) The dominance of 100,000 year term.
I tried one explanation for this based on IPD here , but there is no real evidence to support it from TSI measurements
I spent quite a long time doing a parametric fit to the Ocean sediment data using a combination of Milankotitz terms with wavelengths of 400,000(eccentricity), 100,000(eccentricity), 41,000(obliquity) and 23,000(precession) years. What is really interesting is that you can divide the last 5 million years up into 3 phases.
Phase 1: 5 million to 3 million years ago : There is a clear 400,000 year eccentricity cycle superimposed on a slow linear decrease in temperature, and a continuous 41,000 year signal
Phase 2: 3 million to 900K years ago: Mainly the 41,000 year term dominates, but around 1.5 million years a 100 K term starts to be seen. The 23,000 year term is very small.
Phase 3: 900K years ago to pressent: The 100,000 year term dominates interfering with the 41,000 year obliquity term.
The full fit can be seen here
The only continuous phenomenon throughout is the presence 41,000 year obliquity signal which can be explained by changes in seasonal insolation . No-one to my knowledge has convincingly explained why :
1) The Earth started cooling 5 million years ago
2) The absence of 400,000 year term after 3 million years ago
3) The dominance of 100,000 year term.
I tried one possible explanation for this based on resonant dust clouds see here , but there is no real evidence to support it from TSI measurements.
Repeat Clivebest: The 100 kya ice age cycle is an average corresponding to 80 and 120 kya event lengths, so the confusion of time lines is introduced by this over simplification of ice age cycles. Some ice ages last 2 obliquity cycles (82 kya) and some last 3 cycles (123 kya). As I stated before NOT EVERY 41 kya obliquity cycle yields a warming…but EVERY ice age starts when obliquity falls below 23.5, there are no exceptions in the last million years! The observation of the record is very clear, the only question of timing is when and IF ice age conditions end NOT begin.
@dscott: What you write does indeed seem to be correct !! If we go back 1 million years in Ice ages from the last one we get a sequence of obliquity cycles per ice age of : 3 : 2 : 3 : 2 : 3 : 2 : 2: Earlier than 1 million years ago glaciations follow a regular 1:1:1 obliquity cycle going back to ~ 3 million years ago. You can also see this here http://clivebest.com/blog/wp-content/uploads/2011/10/fig1.png
However this is not an explanation as to why this happens. The earth’s elliptical orbit changes eccentricity on a 100 y and a 400y cycle. The interglacials have remained in phase with BOTH maximum obliquity AND maxima of eccentricity for 1 million years. Why ? and why did the cycle change 1 million years ago ?
clivebest, dscott
How about modelling the system as a periodically forced nonlinear oscillator? In this chapter by Tomita:
http://books.google.be/books?hl=en&lr=&id=-SC8AAAAIAAJ&oi=fnd&pg=PA211&dq=periodically+forced+nonlinear+oscillator&ots=7AEeGZtG52&sig=HjaUyfZXfq_N11HIj_axj9G4Oa8#v=onepage&q=periodically%20forced%20nonlinear%20oscillator&f=false
figure 10.4 (page 218) is interesting in a qualitative sort of way. (Some pages are missing, a book sample only).
This chapter is from the book “Chaos” ed. Arun Holden.
clivebest: However this is not an explanation as to why this happens. The earth’s elliptical orbit changes eccentricity on a 100 y and a 400y cycle. The interglacials have remained in phase with BOTH maximum obliquity AND maxima of eccentricity for 1 million years. Why ? and why did the cycle change 1 million years ago ?
We don’t know the reason why, but that doesn’t change the observed facts and as a result doesn’t change the correlative effect. Just because we don’t understand everything doesn’t mean it doesn’t happen or should immediately cease to happen until we do. We are but an infinitesimal speck in the universe and it does not depend upon our understanding to continue to function. We can only speculate with lessor or greater degrees of confidence about that which we do not know.
So what combination of factors causes a glaciation to end is the real question since by observation we already know what causes it to begin (decreasing obliquity). Eccentricity plus what? Increased cyclical solar output that coincides at just the right combination with obliquity, precession, etc? Are there more factors than these four to tip the balance?
And the change you mentioned from 3 millions years ago. What made the change? An asteroid strike on Earth or Moon to subtly change some dynamic? A near miss of an asteroid that possibly pulled off a significant amount of Earth’s atmosphere, thereby lowering it’s air mass to change it’s heat content? When we look at Venus with it’s 92 bar atmospheric pressure, we observe a different thermal dynamic where that planet’s temperature profile from light to dark side is fairly uniform (rotation longer than it’s year) unlike on earth and a fairly uniform temperature from equator to pole all due to a very thick atmosphere. Interestingly, the air column of Venus in the upper atmosphere where it is at 1 bar is very close to Earths GAT.
I can’t keep enough resolution/definition of the expanded PNG of Fig. 13 to be sure, but it looks on my screen like the “l” in “sedimentology” is either doubled or replaced with some other ASCII character.
@dscott
I think we are in agreement. The Earth will probably begin to cool within 1000 years as obliquity decreases reaching a glacial maximum in about 20,000 years time. Thereafter the length of the next ice age will be either ~82K or ~123K years before another interglacial warm spell. The development of human civilization has mostly occurred within the last interglacial, so the real threat to mankind is another ice age !
@clivebest;
So, there’s a few hundred years to perfect ‘Star Trek’-level climate control. “Let it be so!”
😀
George Kukla has been saying about end of holocene since 1970s. Here is a link to a recent article about him.
http://www.columbia.edu/cu/pr/00/02/iceAge.html
M Chaturvedi
Here is another link to views of Goerge Kukla.
http://www.gelfmagazine.com/archives/an_unrepentant_prognosticator.php
M Chaturvedi