Onset of the Next Glaciation

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:

clip_image002

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.

clip_image004

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

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The next glaciation will wipe out many countries and nothing will stop that from happening.
Luckily, the slide into a glaciation is long and slow, tens of thousands of years, and, of course, the sun has nothing to do with it [Jupiter has].

richard telford

“there are rocks on the beaches of Scotland that got blown over from Norway across a frozen North Sea. As scientists, our task is to predict the onset of the next glaciation.”
But the first task is to stop making things up.

A good paper on Milankovitch’s theory: http://www.leif.org/EOS/2006GL027817-Milankovitch.pdf

davidq

Perhaps we need to widen and deepen the Panama canal. Didn’t the current onset of glaciation start occurring after the Atlantic and Pacific was cut off?
20 Miles wide, 300 feet deep. doable?

With all our revulsion regarding models, it is difficult to say “OK, but this one refutes global warming”. Well, it might, but is it not still a model? And this ice age is how far into the future? No point in being alarmist at all, because the effects of continental glaciation are well known! It’s like running a big scraper across the world. Nothing will stop it.
The Climate alarmists, on the other hand, need to raise alarm to curry support for what is largely a speculative circumstance. They need to invent a bogeyman, and invent a solution, which, like kinetic energy, compounds at the square of its velocity! They can’t define the problem, so how on earth can they propose a solution?

Aussie Luke Warm

This article has spooked me. In fact, I’ve just put on my hawthorn reg grundies.. Can we do anything to avert returning to an ice age?

This post so apes the CAGW meme that I can’t help wondering if it was not written with tongue firmly in cheek Very much, “Back to the Seventies”.

sophocles

Hmm, I don’t think I’ll sell my wool shares just yet .

Christian_J.

This effort turns everything everyone has been told for the last thirty odd years, completely upside down. It puts paid to the increase in warming as those old studies have continually demonstrated, which will not happen and also introduces the fact that the Sun, remember the Sun, will have the last say after all. Meanwhile we pass the popcorn as the lunacy of the CAGW hysterics wanders on it’s already disturbing path. But this time, it’s all downhill.

tallbloke

Or, the 65N insolation may not drop low enough to cause glacial onset this time round and the Holocene may continue for another 50k years.
Nobody knows.

More likely those rocks were embedded in icebergs calved from Norwegian glaciers that got blown across the North Sea. BTW, they are called Drop Stones.

Warm

“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”
I agree,
But… Where are the evidences that it is happenning ?
http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=6
http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=7

OMG, Mann got his hockey stick up side down!
Thanks
JK

Chris in Canada

Just have to ask this:
Given the recent discussion about geo-engineering to combat the alleged AGW (parasol gases and the like):
How much human-generated CO2 would be required to counteract an ice age? If we have 1000 years to pump CO2 into the atmosphere, is it possible to maintain the interglacial indefinitely?
(This, of course, assumes that humanity won’t do itself in, in some other way, in the intervening thousand years.)

tango

Please would somebody tell the Australian prime minister J Gillard what’s around the corner she is hell bent on destroying us with the carbon tax

I guess i won’t be around to notice. Good news then. No more need to worry about our grandchildren’s earth and how we leave it. Bummer for the ecofanatics though.

Kev-in-Uk

Obviously, as a geologist, I find this easy to read – but for those who may find it difficult to comprehend, the net result is we don’t have to worry for a good few centuries yet!
In passing, I’m not keen on the use of the term ‘trigger’ for a glacial event – it implies a ‘non-reversible’ and ‘fixed’ point, kind of like the tipping point scenario that the warmista like to use for earths mean temp (which all geologists know is false!). Lots of factors have to come together, and remain together, for some considerable time for glacial onset to fully take hold (IMHO).
What I mean is that a glacial period could be presented/considered by ‘coolists’ to be initiated by the onset of several cold winters, but this would be a false premise – in the same way as ‘runaway’ thermal heating didn’t occur as per the ‘warmists’ arguments in the 90’s! Obviously. no one ‘knows’ for sure, but I can’t imagine the next glacial period being able to be defined without at least a few centuries of data?
An interesting piece, but to be fair, I think the timescale inferences have been perhaps lost to the general non-geological folk…just saying…

Here is a link to the Rutgers snow extent graphs.
http://climate.rutgers.edu/snowcover/chart_seasonal.php?ui_set=namgnld&ui_season=2
Note the increasing winter snow extent trend, particularly from around 2007. Also the steep decline in spring snow extent.
But perhaps the most interesting thing is the high year to year variability. Given the large albedo difference between snow and bare ground, it looks to me like natural variability plays a significant role in the start of the glacial phase.

Truthseeker

So, how long have we got before we are all screwed?

Gerry B

BRRRRRR!!

Andy, Epsom, Surrey, UK

Maybe it is time to have central heating installed (at last)

Atomic Hairdryer

Re Kev-in-Uk says: September 16, 2012 at 1:33 am

Obviously, as a geologist, I find this easy to read – but for those who may find it difficult to com8prehend, the net result is we don’t have to worry for a good few centuries yet!

Obviously as a concerned citizen, I think governments should be applying the precautionary principle and ACT NOW! Together, we can prevent glaciation. We can fight glaciation and the causes of glaciation. The developed western economies obviously have the most to lose, so I suggest a mere 1% of GDP is transferred to building the Atomic Hairdryer fleet. With suitable funding, we can blow that pesky ice back to the holocene optimum, all for a modest management fee.

Brian H

Andy;
What have you been using up till now, campfires in a recess in the wall?

Galvanize

“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 from Norway across a frozen North Sea.”
Are you sure? Sorry, but this looks a bit like model based scare mongering to me.

kadaka (KD Knoebel)

Remember when the cemetery plot salesman is justifying their exorbitant prices by promising perpetual care, that “perpetual” will end once an advancing glacier covers over the graveyard, and your “eternal resting place” gets scraped and ground away to non-existence. Get the “dust to dust” over early and take the cremation.
Although if anyone here feels up to the marketing challenge, there are many abandoned mines available that are suitable for conversion to thousands of glacier-proof burial vaults.

anarchist hate machine

How much human generated CO2 would counteract an ice age? If we burned all of the remaining fossil fuels found in the earth we couldn’t create a greenhouse effect enough to offset the next glaciation.

kwik

davidq says:
September 16, 2012 at 12:18 am
“Perhaps we need to widen and deepen the Panama canal. Didn’t the current onset of glaciation start occurring after the Atlantic and Pacific was cut off?
20 Miles wide, 300 feet deep. doable?”
For modern man, it is doable. We can make huge “Canal Machines”. Just like the tunnel machines.
Just click “Play”…..or “Dig”. But 20 Miles ? Make it 100 Miles wide.

We can al move to central Siberia, that’s usually warmer than today during glacials,
https://dl.dropbox.com/u/22026080/Last%20Glacial%20Maximum%20in%20Siberia.pdf

It’s like running a big scraper across the world. Nothing will stop it.
Black carbon will. Well at least for a few hundred to a few thousand years.
Legally mandated inefficient coal and wood stoves, building the dirtiest coal fired power stations we can, prescribed setting of forest fires, legally mandated field burning of agricultural waste, make sure those peat fires in SE Asia burn every year.
It’s doable.

mwhite

“Earliest evidence for modern humans in Europe identified”
http://planetearth.nerc.ac.uk/news/story.aspx?id=1087
“researchers dated the jawbone to between 41,000 and 44,000 years old”
“The jawbone was first unearthed in 1927, but its significance wasn’t appreciated until now. ‘The site in Devon – Kent’s Cavern ”
With a much lower sea level Devon was a considerable distance from the sea. Things will change but we’ll survive.

Kelvin Vaughan

tango says:
September 16, 2012 at 1:23 am
Please would somebody tell the Australian prime minister J Gillard what’s around the corner she is hell bent on destroying us with the carbon tax
You wait til she introduces glaciation tax. It will be horrendous!

Kelvin Vaughan

Truthseeker says:
September 16, 2012 at 1:37 am
So, how long have we got before we are all screwed?
Usually around 80 years or so but with todays fast food diets and obesity it will probably fall to 50 years not too long from now.

aksam@op.pl

Glaciations take place when 65N is less insolated in springs and summers which causes snow not to melt. When snow is not melting most of solar radiation is reflected (instead of being absorbed by dark earth surface) so less energy is provided. Currently there is almost no snow at 65N in summers (despite the low insolation) so no glaciation can take place. And in the near future, because of Earth’s precession decade by decade 65N will be better and better insolated in sprigns and summers so glaciation will be less and less probable.

kadaka (KD Knoebel)

From Aussie Luke Warm on September 16, 2012 at 12:26 am:

Can we do anything to avert returning to an ice age?

Cover the Earth-facing side of the Moon with reflective foil. NASA says the visual geometric albedo is only .12, a third of Earth’s. It only looks so bright because it gets a lot of sunlight. So cover that side in foil and bounce that wasted energy onto the Earth, keep the tipping point away and the glaciation at bay.
Hey, we got people seriously considering fixing CAGW with a “solar shield” placed between us and the Sun. Investigating covering the Moon in foil should easily be worth a few million in research grants, and that’s just for the computer modeling.
And if we do have several centuries of lead time, it’d be pretty cheap to do, as in a few decades we’ll be able to drop onto the Moon some self-replicating solar-powered robots to process the lunar material and do the work. Then whomever’s here just has to sit back and wait for the job to get done…

Kelvin Vaughan

Building An Igloo
amazon.co.uk/Building An Igloo
Low Prices on Building An Igloo. Free UK Delivery on Amazon Orders

DaveF

kwik 2:22am:
“Make it 100 miles wide.”
I’m not sure that the Panamanians would be too keen on losing around a sixth of their country.

DirkH

In the description at “most likely”, I find no test for predictive skill of the optimized model. One would do that by optimizing the model on only a part of the past data and use the remainder of the past data for a validation. So, just as I tell the warmists, I have to tell this modeler: as long as I have not seen such a test, I won’t believe the model until I have seen it get something right that it was not trained on.

David Archibald

Philip Bradley says:
September 16, 2012 at 12:57 am
So much has been forgotten. Fred Hoyle’s book “Ice” has a good description of the Norwegian rocks out of place. Just think for a moment. For the rocks to be dropstones, sea level would have to have been higher than it is now.

Kev-in-Uk

Atomic Hairdryer says:
September 16, 2012 at 2:05 am
Good idea! do you need a PA? LOL

David Archibald

Chris in Canada says:
September 16, 2012 at 1:09 am
All the rocks we can dig up and burn will only get us to 600 ppm at best, good for only another 0.2 of a degree. Then the deep oceans will suck it all down.

Michael Schaefer

Well, normally, Tallbloke’s name in a posted comment appears with a direct link to his own Blog “Tallbloke’s Talkshop” – but not here:
tallbloke says:
September 16, 2012 at 12:39 am
Or, the 65N insolation may not drop low enough to cause glacial onset this time round and the Holocene may continue for another 50k years.
Nobody knows.
—————————————————————————————————————–
Also, the content of this comment makes me wonder, if we may perhaps have a Name Troll among us.
Tallbloke – was that really you?
[Not a Name Troll – IP and email is correct for Tallbloke ~mod]

ExWarmist

Very interesting if you happen to be alive during the transition…

ExWarmist

This is bullish for Australian real estate…

Ian W

Chris in Canada says:
September 16, 2012 at 1:09 am
Just have to ask this:
Given the recent discussion about geo-engineering to combat the alleged AGW (parasol gases and the like):
How much human-generated CO2 would be required to counteract an ice age? If we have 1000 years to pump CO2 into the atmosphere, is it possible to maintain the interglacial indefinitely?
(This, of course, assumes that humanity won’t do itself in, in some other way, in the intervening thousand years.)
anarchist hate machine says:
September 16, 2012 at 2:19 am
How much human generated CO2 would counteract an ice age? If we burned all of the remaining fossil fuels found in the earth we couldn’t create a greenhouse effect enough to offset the next glaciation.

Carbon dioxide has a minimal effect on atmospheric temperatures and what effect it might have is merely to slow the loss of heat. If the heat is not put there in the first place then sorry it will still get cold however many SUVs you drive chasing flatulent cattle.
From the paper by Gerard Bond – the ‘Bond Event’ drops into glacial temperatures can be rapid:
“As was the case for the glacial events, the Holocene shifts were abrupt, switching on and off within a century or two at least and probably faster, given the likely blurring of event boundaries by bioturbation”
http://rivernet.ncsu.edu/courselocker/PaleoClimate/Bond%20et%20al.,%201997%20Millenial%20Scale%20Holocene%20Change.pdf
So perhaps tell your grandchildren to move to live somewhere warm,

RexAlan

Sorry Kwik no can do!
Only picks and shovels allowed or the environmentalists will have a nanny fit.

steve

of course an ice age would be very easy to put off. just use the greenhouse gases that are 20,000 times as powerful as CO2 but don’t harm the ozone layer. a relatively small industry could do it. it’s probably how we will terraform mars.
http://en.wikipedia.org/wiki/Terraforming_of_Mars#Using_fluorine_compounds

Richard M

If, as it appears, all radiation available to CO2 is already absorbed, then adding more CO2 will do nothing. However, there are other GHGs like N2O that may do the trick. The problem would be to find something that can be easily scrubbed after the fact. Otherwise, it may get too warm after the snow/ice is melted.

William

Variations of insolation at 60N does not pace or cause the glacial/interglacial cycle.
The glacial/interglacial cycle and the cycle abrupt climate events are caused by the solar magnetic cycle restarting. I will as I have noted previously provide a detailed explanation with supporting papers of the entire mechanism if and when there is unequivocal observational evidence that the solar magnetic cycle has been interrupted as well the observational evidence of the expected earth anomalies.
The Milankovitch theory cannot explain abrupt climate change which is the cause of the glacial/interglacial cycle. The Milankovitch theory cannot explain why the glacial/interglacial cycle followed a 41 kyr cycle from roughly 3 million BP to roughly 800 kyr BP and then changed to a 100 kyr cycle. The Milankovitch theory cannot explain why the Southern Hemisphere abrupt cools when the Northern Hemisphere cools. (The seasonal variance in insolation is of course opposite in the Southern Hemisphere so the ice sheets should not expand as the summers are warmer and the winters cooler. i.e Opposite to the Northern Hemisphere.)
Interglacial periods end abruptly, rather than gradually and there is evidence of cycle “RICKIES” – Rapid Climate Change Events, through the interglacial period and the glacial period. The finding of RCCEs “RICKIES” has one of the big surprises of the Greenland Ice sheet core analysis. At first the researchers did not believe the data and a second Greenland Ice sheet core was drilled a location where there was no ice sheet movement for the entire core period.
This paper notes Milankovitch hypothesis cannot explain what is observed.
http://www.leif.org/EOS/2006GL027817-Milankovitch.pdf
The Milankovitch hypothesis as formulated here does not explain the large rapid deglaciations that occurred at the end of some of the ice age cycles (i.e., the several large negative excursions in Figure 2): many studies point to the need to invoke internal dynamics of ice sheets as a mechanism for occasional rapid collapses if a threshold size is exceeded [e.g., Imbrie and Imbrie, 1980; Paillard, 2001] …. ….Nor do the results explain the mid-Pleistocene transition between an earlier interval characterized by 40 kyr durations of ice ages and a later interval with 80 kyr to 120 kyr durations: it has been suggested that this transition may have been due to changes in basal conditions under the ice sheet or perhaps chaotic ice sheet dynamics [Clark and Pollard, 1998; Huybers and Wunsch, 2005]
This paper discusses the cyclic abrupt climate change events that correlate with a solar change. There is smoking gun the sun is the serial abrupt climate changer – the question is how does the sun cause what is observed.
http://www.esd.ornl.gov/projects/qen/transit.html
Until a few decades ago it was generally thought that all large-scale global and regional climate changes occurred gradually over a timescale of many centuries or millennia, scarcely perceptible during a human lifetime. The tendency of climate to change relatively suddenly has been one of the most suprising outcomes of the study of earth history, specifically the last 150,000 years (e.g., Taylor et al., 1993). Some and possibly most large climate changes (involving, for example, a regional change in mean annual temperature of several degrees celsius) occurred at most on a timescale of a few centuries, sometimes decades, and perhaps even just a few years. The decadal-timescale transitions would presumably have been quite noticeable to humans living at such times, and may have created difficulties or oppor
The time span of the past few million years has been punctuated by many rapid climate transitions, most of them on time scales of centuries to decades or even less. The most detailed information is available for the Younger Dryas-to-Holocene stepwise change around 11,500 years ago, which seems to have occurred over a few decades. The speed of this change is probably representative of similar but less well-studied climate transitions during the last few hundred thousand years. These include sudden cold events (Heinrich events/stadials), warm events (Interstadials) and the beginning and ending of long warm phases, such as the Eemian interglacial. Detailed analysis of terrestrial and marine records of climate change will, however, be necessary before we can say confidently on what timescale these events occurred; they almost certainly did not take longer than a few centuries.
According to the marine records, the Eemian interglacial ended with a rapid cooling event about 110,000 years ago (e.g., Imbrie et al., 1984; Martinson et al., 1987), which also shows up in ice cores and pollen records from across Eurasia. From a relatively high resolution core in the North Atlantic. Adkins et al. (1997) suggested that the final cooling event took less than 400 years, and it might have been much more rapid.
The event at 8200 ka is the most striking sudden cooling event during the Holocene, giving widespread cool, dry conditions lasting perhaps 200 years before a rapid return to climates warmer and generally moister than the present. This event is clearly detectable in the Greenland ice cores, where the cooling seems to have been about half-way as severe as the Younger Dryas-to-Holocene difference (Alley et al., 1997; Mayewski et al., 1997). No detailed assessment of the speed of change involved seems to have been made within the literature (though it should be possible to make such assessments from the ice core record), but the short duration of these events at least suggests changes that took only a few decades or less to occur.
The Younger Dryas cold event at about 12,900-11,500 years ago seems to have had the general features of a Heinrich Event, and may in fact be regarded as the most recent of these (Severinghaus et al. 1998). The sudden onset and ending of the Younger Dryas has been studied in particular detail in the ice core and sediment records on land and in the sea (e.g., Bjoerck et al., 1996), and it might be representative of other Heinrich events.
The 41 kyr world: Milankovitch’s other unsolved mystery by Maureen E. Raymo et al.
http://rsai.geography.ohio-state.edu/courses/G820.01/WI05%20climate%20history/2002PA000791.pdf
[1] For most of the Northern Hemisphere Ice Ages, from approx. 3.0 to 0.8 m.y., global ice volume varied predominantly at the 41,000 year period of Earth’s orbital obliquity. However, summer (or summer caloric half year) insolation at high latitudes, which is widely believed to be the major influence on high-latitude climate and ice volume, is dominated by the 23,000 year precessional period. Thus the geologic record poses a challenge to our understanding of climate dynamics.
The solution to what causes abrupt climate change and the glacial/interglacial cycle is not the thermohaline conveyor.
http://www.sciencedaily.com/releases/2009/05/090513130942.htm
Cold Water Ocean Circulation Doesn’t Work As Expected
The familiar model of Atlantic ocean currents that shows a discrete “conveyor belt” of deep, cold water flowing southward from the Labrador Sea is probably all wet.
A 50-year-old model of ocean currents had shown this southbound subsurface flow of cold water forming a continuous loop with the familiar northbound flow of warm water on the surface, called the Gulf Stream.
“Everybody always thought this deep flow operated like a conveyor belt, but what we are saying is that concept doesn’t hold anymore,” said Duke oceanographer Susan Lozier. “So it’s going to be more difficult to measure these climate change signals in the deep ocean.”
http://www.americanscientist.org/issues/id.999,y.0,no.,content.true,page.1,css.print/issue.aspx
If you grow up in England, as I did, a few items of unquestioned wisdom are passed down to you from the preceding generation. Along with stories of a plucky island race with a glorious past and the benefits of drinking unbelievable quantities of milky tea, you will be told that England is blessed with its pleasant climate courtesy of the Gulf Stream, that huge current of warm water that flows northeast across the Atlantic from its source in the Gulf of Mexico. That the Gulf Stream is responsible for Europe’s mild winters is widely known and accepted, but, as I will show, it is nothing more than the earth-science equivalent of an urban legend.
But from what specialists have long known, I would expect that any slowdown in thermohaline circulation would have a noticeable but not catastrophic effect on climate. The temperature difference between Europe and Labrador should remain. Temperatures will not drop to ice-age levels, not even to the levels of the Little Ice Age, the relatively cold period that Europe suffered a few centuries ago. The North Atlantic will not freeze over, and English Channel ferries will not have to plow their way through sea ice. A slowdown in thermohaline circulation should bring on a cooling tendency of at most a few degrees across the North Atlantic …. When Battisti and I had finished our study of the influence of the Gulf Stream, we were left with a certain sense of deflation: Pretty much everything we had found could have been concluded on the basis of results that were already available
The following is an abbreviated list of paradoxes associated with Milankovitch’s theory.
http://en.wikipedia.org/wiki/Milankovitch_cycles
100,000-year problem
The 100,000-year problem is that the eccentricity variations have a significantly smaller impact on solar forcing than precession or obliquity and hence might be expected to produce the weakest effects. However, observations show that during the last 1 million years, the strongest climate signal is the 100,000-year cycle. In addition, despite the relatively great 100,000-year cycle, some have argued that the length of the climate record is insufficient to establish a statistically significant relationship between climate and eccentricity variations.[8] Some models can however reproduce the 100,000 year cycles as a result of non-linear interactions between small changes in the Earth’s orbit and internal oscillations of the climate system.[9][10]
400,000-year problem
The 400,000-year problem is that the eccentricity variations have a strong 400,000-year cycle. That cycle is only clearly present in climate records older than the last million years. If the 100ka variations are having such a strong effect, the 400ka variations might also be expected to be apparent. This is also known as the stage 11 problem, after the interglacial in marine isotopic stage 11 which would be unexpected if the 400,000-year cycle has an impact on climate. The relative absence of this periodicity in the marine isotopic record may be due, at least in part, to the response times of the climate system components involved—in particular, the carbon cycle.
Stage 5 problem
The stage 5 problem refers to the timing of the penultimate interglacial (in marine isotopic stage 5) which appears to have begun ten thousand years in advance of the solar forcing hypothesized to have been causing it. This is also referred to as the causality problem.
Effect exceeds cause
See also: Climate change feedback 420,000 years of ice core data from Vostok, Antarctica research station.
The effects of these variations are primarily believed to be due to variations in the intensity of solar radiation upon various parts of the globe. Observations show climate behavior is much more intense than the calculated variations. Various internal characteristics of climate systems are believed to be sensitive to the insolation changes, causing amplification (positive feedback) and damping responses (negative feedback).

Rob L

Fortunately we are more than capable of preventing the onset of an iceage, with seabed propellers to drive ocean heat circulation, balloons, space mirrors, fusion, fission, dust on icesheets. The most cost effective methods might only cost a couple of percent of global GDP.
What’s the bet that the trigger for onset of a glaciation is a suitable large volcanic event? Drop the earth’s temp by 1°C and wham!

<i.David Archibald says:
September 16, 2012 at 3:23 am
Philip Bradley says:
September 16, 2012 at 12:57 am
So much has been forgotten. Fred Hoyle’s book “Ice” has a good description of the Norwegian rocks out of place. Just think for a moment. For the rocks to be dropstones, sea level would have to have been higher than it is now.
If the rocks are well above sea level then they will have been transported by Norwegian glaciers that spread to Scotland during the last glacial maximum.
http://donsmaps.com/icemaps.html
A rock sliding across the frozen North Sea is completely implausible. Have you ever seen a frozen ocean? Its one ridge of ice after another. And a rock would be an albedo hotspot and would freeze into the ice after a couple of hours of sunshine.