Guest post by David Archibald
Baby boomers like me have enjoyed the most benign period in human history. The superpower nuclear standoff gave us fifty years of relative peace, we had cheap energy from inherent over-supply of oil, grain supply increased faster than population growth and the climate warmed due to the highest solar activity for 8,000 years. All those trends are now reversing. But it will get much worse than that. The next glaciation will wipe out many countries and nothing will stop that from happening. For example, the UK will end up looking like Lapland. As an indication of just how vicious it is going to get, consider that there are rocks on the beaches of Scotland that got blown over on ice from Norway across a frozen North Sea. As scientists, our task is to predict the onset of the next glaciation.
Onset of interglacials is driven by insolation at 65°N. That is where the landmass is that is either snow-covered all year round or not. It seems that insolation above 510 watts/sq metre will end a glacial period. For an interglacial period to end, the oceans have to lose heat content so that snows will linger through the summer and increase the Earth’s albedo. Thanks to the disposition of the continents, our current ice age might last tens of millions of years yet. From the Milankovitch data, this graph shows insolation at 65°N from 50,000 BC to 50,000 AD:
The green box has the Holocene ending at 3,000 AD – an arbitary choice. Insolation is already low enough to trigger glacial onset. For the last 8,000 years, the Earth has been cooling at 0.25°C per thousand years, so the oceans are losing heat. We just have to get to that trigger point at which snows linger through the northern summer. Solar Cycle 25 might be enough to set it off. By the end of this decade, we will be paying more attention to the Rutgers Global Snow Lab data.
From the source at: http://most-likely.blogspot.com/2012/03/milankovitch-cycles-and-glaciations.html
Model input is obliquity and precession and model output is the inverted δ¹⁸O record, with zero mean during the Pleistocene, from Lisiecki and Raymo 2004 and Huybers 2007. Lisiecki and Raymo use orbital tuning to constrain the age of the benthic records, while Huybers explicitly avoids this, consequently the two datasets are occasionally completely out of phase, but generally in good agreement, especially in the late Pleistocene.
As fitness function we take the product of the sum of squared errors (SSE) between the model and the two reference records from 2580 thousand years before present, with 1000 year timesteps.
For the longer term perspective, this is a combined crop (to make a continuous timeline) of the two fulls panel from the model prediction of the Milankovitch data.
The time period represented is from approximately 450,000 BC to 330,000 AD. The scale on the vertical axis is change in O18 content. There is a very good hind-cast match between the model and past temperature change as shown by the work of Lisiecki et al 2005 and Huybers 2007. The next glaciation is fully developed between 55,000 and 60,000 AD, with the next interglacial 20,000 years after that.
References
Huybers, P., 2007, Glacial variability over the last 2Ma: an extended depth-derived age model, continuous obliquity pacing, and the Pleistocene progression, Quaternary Science Reviews 26, 37-55.
Lisiecki, L. E., and M. E. Raymo, 2005, A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O records Paleoceanography, 20, PA1003, doi:10.1029/2004PA001071.
Source Data: Download the consolidated data, including orbital parameters, insolation calculations, reference data and model output: Milankovitch.xlsx
Leif Svalgaard seems to work under the assumption that the default case (low eccentricity/minimal oscillation) is no ice and that extremes are required to bring in on, whereas the record indicates that the default case is an ice age and extremes are required to melt it. –AGF
Well excuse me, when I posted this the previous post was nine something, and I had not seen Svalgaard’s last post, which renders mine off the mark. –AGF (1422 PDT)
agfosterjr says:
September 24, 2012 at 2:09 pm
i.Leif Svalgaard seems to work under the assumption that the default case (low eccentricity/minimal oscillation) is no ice
The default through the ages is no ice. Glaciations are exceptions.
Thank you for your clarification Leif.
In truth, I need more time than I currently have to adequately follow this subject.
I really hope you are correct, because I am beginning to hate the cold but I love living here.
I would much prefer that the warmth come to me that having to travel south to find it.
Best regards, Allan
Leif
Ok, so the green curve here, e, is not eccentricity like the text says?
http://en.wikipedia.org/wiki/Milankovitch_cycles
What is it then? Show us your ‘version’ of the eccentricity.
lgl says:
September 25, 2012 at 7:07 am
Ok, so the green curve here, e, is not eccentricity like the text says?
The important curve is the red one [fourth] from the top.
Leif Svalgaard says:
September 24, 2012 at 4:49 pm
If our definition is by ice volume, I would agree. If by ice area, we might have to specify a latitude for North America which could pass for an average. Current ice extent/albedo is exceptionally low, roughly 5% of the last 400ky. Current ice volume is also anomalously low. –AGF
Poorly stated, I mean only about 5% of the last 400ky have T (as governed by albedo or ice extent) as low as at present. And if ice volume is linearly related to surface area rather than related to its square, as might be expected if it freezes from south to north, then even by volume the average situation is an ice age, else you must explain the typically low average T some other way. –AGF
Leif
So suddenly eccentricity is not the important paramenter, now it’s the precession. Just as silly, the glaciations started ‘now’ 400 kyr and 775 kyr ago with the same precession pattern.
http://virakkraft.com/Milankovitch4.png
Bet your next jump will be back to the 65N insolation, also wrong because it’s the integral that matters.
lgl says:
September 25, 2012 at 12:28 pm
So suddenly eccentricity is not the important paramenter, now it’s the precession.
It should have been clear to even the dimmest among us that it is the combination of eccentricity and the precession that is important [you need to be farthest from the Sun in January] that is important. But, apparently, I was wrong on that assumption.
The longest Interglacial:
http://theinconvenientskeptic.com/wp-content/uploads/2012/01/Chap_6-Illustration_47-550×542.png
Chapter 6&7:
http://theinconvenientskeptic.com/chapters-6-7/
We are ALREADY in negative insolation territory and still going down.
sunsettommy says:
September 25, 2012 at 5:25 pm
We are ALREADY in negative insolation territory and still going down.
getting ready for the rapid warming the next 35,000 years before the next mild glaciation 63,000 years from now.
Hi Leif,
So are you saying that the global cooling observed during the Maunder Minimum (circa 1645 to 1715) had nothing to do with reduced solar activity?
Do you have an opinion as to the cause of the observed cooling during the Little Ice Age?
Allan MacRae says:
September 26, 2012 at 3:32 am
So are you saying that the global cooling observed during the Maunder Minimum (circa 1645 to 1715) had nothing to do with reduced solar activity?
Essentially, yes. As the Sun does not vary enough
Do you have an opinion as to the cause of the observed cooling during the Little Ice Age?
No, as they could be many causes, and any complex system has natural variations on its own.
The Maunder minimum is almost certainly the result of reduced solar activity – specifically reduced solar magnetic field strength which leads to an increase in incoming GCRs and the resulting increase in cloudiness and albedo.Check Livingston and Penn and check the Oulu NM count – plot from 2/15/1998 to today to see whats going on.and where we are headed.
Leif
“the combination of eccentricity and the precession” is nonsense because the precession is a ‘combination’ of eccentricity and the longitude of perihelion.
If you had said what’s important is the combination of precession and obliquity, you would have been close but still wrong because of the integral.
lgl says:
September 26, 2012 at 9:14 am
“the combination of eccentricity and the precession” is nonsense because the
Yes, indeed I added my nonsense to your nonsense. It is clear that one has to do it right by combining all of the factors involved. I have in the meantime forgotten what your point is, perhaps you are saying that the next ice age will happen in our lifetime, while I think it is still 63,000 years in the future. At any rate that is the topic of this thread.
Allan MacRae says: September 26, 2012 at 3:32 am
So are you saying that the global cooling observed during the Maunder Minimum (circa 1645 to 1715) had nothing to do with reduced solar activity?
Leif Svalgaard says: September 26, 2012 at 5:09 am
Essentially, yes. As the Sun does not vary enough.
Dr Norman Page says: September 26, 2012 at 7:32 am
The Maunder minimum is almost certainly the result of reduced solar activity – specifically reduced solar magnetic field strength which leads to an increase in incoming GCRs and the resulting increase in cloudiness and albedo.
Allan says:
OK…… Glad we cleared that up.
Could possibly resolve this question through a scintillating game of rock, paper, scissors?
🙂
Here you go Allan,
New paper shows dimming of sunshine during the 1970’s ice age scare, and brightening since the 1980’s
http://hockeyschtick.blogspot.com/2012/09/new-paper-shows-dimming-of-sunshine.html
Leif,
If we are farthest from the sun in January in the northern hemisphere, winter ice will increase, but in July the ice will melt faster because we will be unusually close to the sun. We can also be closest in March and furthest in September. It’s pretty much academic in our lifetimes because we are in a phase of minimum eccentricity where earth’s orbit is nearly circular.
Milankovitch is a zero sum game.
The about 40,000 year obliquity cycle SHOULD be a player because it amounts to a several degree poleward shift in the solstices, but both the 40,000year obliquity and the longest and most stable 400,000 year eccentricity cycle have no statistical power in the Pleistocene.
Gymnospern it was discovered that there is a 41,000 year pulse in the 100,000 year cycle way back in the 1970’s when Dr. Imbrie et al pointed it out in a paper.He also explained in the book he wrote for the public about 1978.
Here is a nice chart showing the obvious 100,000 year cycle in it:
http://theinconvenientskeptic.com/wp-content/uploads/2012/01/Chap_4-Illustration_24-550×261.png
http://theinconvenientskeptic.com/chapters-4-5/
Here is the 41,000 glacial cycle and then the 100,000 year glacial cycle:
http://theinconvenientskeptic.com/wp-content/uploads/2012/01/Chap_3-Illustration_20-550×344.png
http://theinconvenientskeptic.com/chapters-1-3/
Thank you Tommy – an interesting paper – full paper at
http://www.atmos-chem-phys.net/12/8635/2012/acp-12-8635-2012.pdf
See also earlier work by Svensmark and Friis-Christensen and others.
This hypothesis, as described above by Dr. Page, has been around for quite a while.
We referred to it in our 2002 paper (see Fig.2) at
http://www.apegga.org/Members/Publications/peggs/WEB11_02/kyoto_pt.htm
This factor and paleoclimatological data led me (us) to predict global cooling, commencing by about 2020-2030, in another article written in 2002.
Leif obviously disagrees with this prediction based on his own work, and Leif has been more correct in his prediction of SC24 solar activity (low) than his colleague Hathaway (high).
My predictive track record is good enough – see the Rebuttal of Point in our APEGGA paper above. I sincerely hope I am wrong about imminent global cooling. Severe global cooling could be catastrophic for humanity and the environment.
For clarity, especially for global warming alarmists, who have exhibited clear evidence of intellectual dimming:
“Warm=good; Cold=bad’.
Allan,
I find this last paragraph very amusing because the last ten years after they wrote it has shown them to be massively incorrect:
“In our opening article, we did not spend much time on the science of climate change because the IPCC picture of the subject is almost universally accepted, not just among professional
climate scientists but among the broader community engaged in the climate change issue, including most of the largest GHG-emitting corporations. The climate change debate has now moved on to economic and political issues. In this area, the authors did make one important point, with which we agree: Kyoto is only a small first step and many further ones will be needed. Let’s get on with the job.”
The IPCC since then has lost a lot of credibility and the Kyoto treaty is dying even in the eyes of its many former supporters.
Ouch!
The near future cooling WILL commence because the past 150 years indicate that it will happen and my my would that smash the CAGW hypothesis for good.
I really do not understand Lief’s inconsistency because David says this “The next glaciation is fully developed between 55,000 and 60,000 AD, with the next interglacial 20,000 years after that.” and Lief says this “getting ready for the rapid warming the next 35,000 years before the next mild glaciation 63,000 years from now.”
When the Insolation is always below 0 the entire time.I fail to see how there can be rapid warming for the next 35,000 years while the insolation is always below the 0 point and still declining.Not only that each of the past 1,000 years has been cooler than the previous and that has been going on around 5,000 years now.Glaciers have been showing up that did not exist 4,000 years and some are quite big now.
I also posted a number of charts and they are based on the published data and yet completely ignored and that to me indicate that he is pursuing a rather narrowminded path on this topic.
I for one believe that we are in climate Autumn and slowly heading to a full blown climate winter that will be obvious in a few thousand years.The cooling will continue in all that time to just before the next huge warming pule that signifies the ending of the climate winter phase.
sunsettommy says:
September 27, 2012 at 6:42 am
When the Insolation is always below 0 the entire time.I fail to see how there can be rapid warming for the next 35,000 years while the insolation is always below the 0 point and still declining
The insolation is, obviously, NEVER below zero [the sun is shining every day, isn’t it?]and is calculated to increase from its current level the next 35,000 years before decreasing again causing the next glaciation ~60,000 years from now.
The insolation is, obviously, NEVER below zero
Jeez Leif
Slide 20 and 25.
http://physics.ucf.edu/~britt/Climate/L6-Temperature.ppt