New study may solve long-standing mystery of what triggered ice age

Posted: June 25, 2022 by oldbrew in Ice ages, modelling, paleo, research, Temperature
Tags: ,

Canadian Arctic archipelago [via Wikipedia]

The clue is in the study title: The importance of Canadian Arctic Archipelago gateways for glacial expansion in Scandinavia.
– – –
A new study led by University of Arizona researchers may have solved two mysteries that have long puzzled paleo-climate experts (says Where did the ice sheets that rang in the last ice age more than 100,000 years ago come from, and how could they grow so quickly?

Understanding what drives Earth’s glacial–interglacial cycles—the periodic advance and retreat of ice sheets in the Northern Hemisphere—is no easy feat, and researchers have devoted substantial effort to explaining the expansion and shrinking of large ice masses over thousands of years.

The new study, published in the journal Nature Geoscience, proposes an explanation for the rapid expansion of the ice sheets that covered much of the Northern Hemisphere during the most recent ice age, and the findings could also apply to other glacial periods throughout Earth’s history.

About 100,000 years ago, when mammoths roamed the Earth, the Northern Hemisphere climate plummeted into a deep freeze that allowed massive ice sheets to form. Over a period of about 10,000 years, local mountain glaciers grew and formed large ice sheets covering much of today’s Canada, Siberia and northern Europe.

While it has been widely accepted that periodic “wobbling” in the Earth’s orbit around the sun triggered cooling in the Northern Hemisphere summer that caused the onset of widespread glaciation, scientists have struggled to explain the extensive ice sheets covering much of Scandinavia and northern Europe, where temperatures are much more mild.

Unlike the cold Canadian Arctic Archipelago where ice readily forms, Scandinavia should have remained largely ice-free due to the North Atlantic Current, which brings warm water to the coasts of northwestern Europe.

Although the two regions are located along similar latitudes, the Scandinavian summer temperatures are well above freezing, while the temperatures in large parts of the Canadian Arctic remain below freezing through the summer, according to the researchers.

Because of this discrepancy, climate models have struggled to account for the extensive glaciers that advanced in northern Europe and marked the beginning of the last ice age, said the study’s lead author, Marcus Lofverstrom.

“The problem is we don’t know where those ice sheets (in Scandinavia) came from and what caused them to expand in such a short amount of time,” said Lofverstrom, an assistant professor of geosciences and head of the UArizona Earth System Dynamics Lab.

Continued here.

  1. […] New study may solve long-standing mystery of what triggered ice age […]

  2. Craig King says:

    Still no talk of the possible effect of interplanetary dust.

  3. Phoenix44 says:

    “…climate models have struggled to account for…”

    Which means climate models CANNOT reproduce what happened. This ought to be relatively straightforward but it’s not because we don’t understand anywhere near enough about how such things work.

    This is clear evidence the models are useless as their “forecast” Ice Age looks nothing like a real Ice Age.

  4. Bloke down the pub says:

    Better not tell the Geo-engineers or they’ll be suggesting damming the Canadian Archipelago as a means to control global temperatures.

  5. brianrlcatt says:

    ‘sme again ;-). I suggest this is not such a great mystery. The supply of precipitation to create this is still coming in the colder BUT a typically warm water reaching the land bordering the NE Atlantic, while the land surface have cooled resolutely to the glacial period floor and the land surface then become tundra, with perma frost. Once you get perma frost the precipitation will accumulate year on year, because the warm water doesn’t stop coming, give or take, from elsewhwre down South, while the ground will stay frozen

    Have they overthunk this? “Gonna need some more modeller guys.”

    I, as you may recall, suggest the ice is melted by the re heating of the oceans by the orbital forcing of the Earth’s structure during the Interglacial event. THat takes a lot less time than it does to form, 17Ka to form, 7Ka to thaw. Neither is fast in terms of deg pa. Like this:

    It’s the (gravitational) Orbital Forcing what does it, under the oceans, with a volcano. I have just, finally, managed to get the presentation of my paper as a less wordy and more direct talk on line, presented to the American Creative Society a few months ago.

    It’s here if anyone cares to watch, do like/dislike, comment if engaged…. skip the bit about me and go to the actual opening slide, I don’t know why they left all that in, but they did the recording in two parts, and I was really talking just to the people in the panel, rather than the final audience.

    lots of interesting comments from Geologist colleagues who are quite persuaded by this, although I need more heat, there is a lot more available from tectonic stresses which will also have similar periodic variability driven by the solid gravitational tides created by orbital forcing, but its simply not possible to quantify. Yet.

  6. Jim says:

    What I like, is how it is always one factor to make a global disaster, like in the movies. Cold, orbital wander, not enough power from the sun, too much insulating power from the earth, you get the idea? Not a blended idea. And there may have been several factors, along happenstance, to get the process going. All those ideas, and none mention, we are near the end of a patch of a warm spell, any forecast on what happens at the end of a warm spell from the models?

  7. JB says:

    “…Agassiz’s hypothesis won rapid acceptance in geological circles – one suspects because, to at least some degree, it followed so closely upon the heels of Lyell’s by then fashionable and beguilingly logical theory of uniformity. Indeed, it was soon widely held that huge slow-moving glaciers and ice-sheets were sufficient to account for all observable ‘drift’ phenomena. That extensive, enormously thick, ice-sheets formerly lay across vast tracts of the northern hemisphere during Pleistocene times began to be accepted as having actually occurred. Theory was beginning to be converted into fact.” p24 CATACLYSM! D. S. ALLAN & J.B. DELAIR

    “…through an uneasy mixture of field discoveries, inferences and presumptions, was born the concept of an Ice Age occupying an ever-lengthening Pleistocene period. By now, of course, it will be evident that the
    whole edifice of the Ice Age of orthodoxy rests upon very shaky ground. That is not to assert that the Ice Age did not exist, but does indicate that it occurred in a form and by a means not properly accommodated by conventional dogma. Moreover, a serious error down the years has been the general acceptance by most older (and many present) glaciologists that the Ice Age, whatever its origin, character and duration, developed and ran its course in a world topographically similar to that of today. As we shall now see, that too was a fallacy, and that the implications of that conclusion are huge and very far reaching.”p25 CATACLYSM! D. S. ALLAN & J.B. DELAIR

    Its never been properly demonstrated there were any ice nor glacial ages. Periods where glaciers waxed and waned, periods that were much colder than the last 10K years, yes. The whole picture is not in, and probably never will be, because no one knows definitively what upheavals the earth has been through. This just more speculative bunkum built on a house of cards of speculation assumed to be fact.

  8. Gamecock says:

    ‘A new study led by University of Arizona researchers may have solved two mysteries that have long puzzled paleo-climate experts’

    ‘Puzzled’ ‘experts’ in the same sentence.

  9. Ned Nikolov, Ph.D. says:

    This study identified the weakening of deep ocean circulation and the slowdown of heat transport to Northern Europe as the immediate causes of European and Asian continental glaciation during the last Ice Age. However, the study did not address why the deep ocean circulation was weakened?

    Our research has shown that the ultimate cause of Ice Ages is the depressurization of the Erath surface, i.e. the net loss of atmospheric mass and the resulting decrease of surface air pressure. Lower air pressure cools the surface and increases the meridional (Equator-to-Pole) temperature gradient forcing Polar temperatures to drop much more than tropical temperatures (a phenomenon observed in the geological record known as Polar Amplification). This is all explained in our paleo-climate video:

  10. brianrlcatt says:

    “About 100,000 years ago, when mammoths roamed the Earth, the Northern Hemisphere climate plummeted into a deep freeze that allowed massive ice sheets to form. Over a period of about 10,000 years, local mountain glaciers grew and formed large ice sheets covering much of today’s Canada, Siberia and northern Europe.” REALLY?

    First of all, the dominant stable condition on Earth is the glacial phase of the current ice age floor temperature. THis is perturbed every c100Ka by the combined effect of the Milankovitch cycles, well established by the spectral analysis of proxy measurement. As this heat perturbation is dissipated to space, temperatures return to the glacial base line in a typical exponential cooling curve, self evidently.

    And, the ice does not and cannot form for some time on land as it slowly cools, because it is still too warm.

    Per the ice record, which I already provided the gif of, the statements made in the article above are just wrong. The period after the interglacial did not “plunge” into the ice sheet phase of the last knockings of the glacial period. In fact the cooling recorded in the ice core records is effectively exponential cooling curve following the interglacial perturbations, once the energy to maintain a saturated tropical climate has dissipated and the interglacial effectively ends, and that cooling is interrupted but not terminated by the 41Ka and 23Ka Milankovitch cyclic peaks as it cools. In the case of the Eemian for about 70Ka after the end of the last interglacial before the ice sheets formed.

    But only as the records show. Other scenarios can be made up for Nature, whose peer review is non existent as far as any basic rigor or quality goes. Or perhaps the records the active gif was built from were wrong? Whatever the interglacial cause is proven to be eventually, I did crude schematic from the data to illustrate the basics. Hope you like it.

    SO: Either the gif I submitted above is nonsense and the ice sheets did not start to form until 34Ka BP at the end of the last glacial phase, but formed immediatly after the last interglacial, as stated. But I don’t think this makes any sense, any way. beginning, OR the above paper is baseless speculative Bullshit, it took a long time to cool enough to suport the accumulation of ice, as the record shows, and the Nature article is totally denied by observations. But which……. ? Typos interuptus….

    Your climate may change. B

  11. Ned Nikolov, Ph.D. says:


    Let’s not continue to fool ourselves that Milankovitch cycles controlled the Ice Ages. I have shown numerically that Milankovitch cycles are unrelated to glacial cycles using the best available data to date in a blog article last December:

    Ned Nikolov: Dispelling the Milankovitch Myth

    The spectral analysis you mentioned above only established a weak association between glacial cycles and components of the orbital cycles (such as eccentricity, obliquity, and the TOA insolation at 65 deg. Northern Latitude). However, spectral analysis being in the frequency domain cannot and does not show any cause-and-effect relationship. When analyzed in the time domain, the records of global temperature and Milankovitch parameters show NO correlation (or relationship) with each other. The available data clearly indicate that the Ice Ages were NOT caused by changes of solar radiation reaching the Erath either globally or latitudinally. In short, radiation is NOT the driver of glacial cycles! Variations in the atmospheric adiabatic heating of the surface due to global pressure changes is the actual driver, and it has nothing to do with Milankovitch cycles.

  12. oldbrew says:

    Richard Muller, 2001:

    Limitations and Failures of the Milankovitch Theory

    Although variations of the Milankovitch theory can account for some aspects of climate change, there are serious failures that require attention. In particular, we will discuss the status of the “causality problem”, the apparent fact that major shifts in climate occur prior to the Milankovitch driving force, and the spectral peak problem, in which the spectral shapes predicted by the Milankovitch theory do not match those in the spectrum and the bispectrum of the data. The standard Milankovitch theory ascribes all climate change to the same mechanism: summer insolation in the northern hemisphere. Variations in cloud cover are ignored, even though the net forcing of clouds is (at the present time) approximately 30 Watts per square meter — substantially greater than the rms variations in insolation (18 Watts per square meter). Thus changes in cloud cover could be more important than changes in the standard Milankovitch parameters. We will discuss mechanisms that link variations in the orbital inclination of the Earth to changes in cloud cover, and how these address the causality problem, the spectral problems, and several other failures of the Milakovitch theory. How can we reconcile the failures of the Milankovitch approach with its obvious successes (e.g. in accounting for the 23 kyr cycle in sapropels, and the atmospheric oxygen variations in the Vostok data)? The answer is that climate is multi-dimensional. Insolation certainly affects climate. But we should not make the logical mistake of therefore assuming it accounts for the 100 kyr cycle of glaciation that has dominated for the past 800 kyr. [bold added]
    – – –
    Also by Muller:

    A Causality Problem for Milankovitch
    Daniel B. Karner and Richard A. Muller

    In 1992, Wallace Broecker wrote a comment titled “Upset for Milankovitch Theory” (1) in
    which he discussed what was then a troublesome new measurement. Oxygen isotope data
    (δ18O) from a cave in Nevada called Devils Hole appeared to show that the timing of the
    penultimate termination of the ice ages, called Termination II, was incompatible with the
    standard Milankovitch theory (2, 3). The data indicated a shift in δ18Ο to interglacial values
    that was essentially complete by 135 thousand years ago (ka). But at this time, the Northern
    Hemisphere summer insolation had not yet warmed to the point at which it should have
    triggered anything extraordinary, let alone a glacial termination. The termination event
    appeared to precede its cause. We call this discrepancy the “causality problem

    [bold added]

  13. brianrlcatt says:

    Ned, you should read what I propose as causal as a result of MIlankovitch cycles rather than make up what you think I might have said. And didn’t. I even agree solar insolation from these cycles cannot be causal, especially now the driving cycle is eccentricity rather than obliquity, which is overtly a net zero effect as regards radiation over a year. But I suggest another MIlankovitch effect, that you seem to have missed.

    Look again? I suggest the interglacial warming is driven by the maximum gravitational solid tides driven by MIlankovitch cycles that must substantially increase the heating of the oceans by the much underestimated heat input of submarine volcanicity. And volcanism is observed to have peak activity at the Milankovitch solid tidal peaks, the convolved effect on the c100Ka cycle and lesser peaks in solid tides at the 41Ka and 23Ka. All these effects are fundamentally orbital forcing, but gravitational, not radiative.

    I even suggest solar insolation at the surface is not varied much by changes in absolute radiation levels. Because oceans regulate varying solar input by changing the cloud cover to cahnge surface insolation to negate surface temperature changes, also adjusting the heat balance by changing the rate of heat loss from the surface in the process. Serious negative feedback control with attitude. Why tipping points within a wide range are a nonsense idea to any controlengineer who considers the joined up system not the detail of smallerturbations within the system in isolation, without the context of the dominant oceanic control

    So your response sails straight past my very clear and basic physics suggestion without trying to understand or address it on the way. Denial of the already well debated physics of what I have said by assuming I said something quite different is hardly a considered response. The references in my paper refer to prior qualaitaive descriptions by eminent Earth scientists (Wahr and House). I have tried some early quantification.

    But I forgive you as you taught me the Barometric Formulae that nobody else seemed to understand, and I can still write down the barometric equation from memory. Nobody else had told me the lapse rate had little to do with GHE, which is a perturbation to it caused by solar radiation and gravity, But I suggest you reconsider the changing effects of gravitational forcing the MIlankovitch cycles self evidently create, rather than spurious denial.

    Ego te absolvo 😉

  14. Stephen Richards says:

    Does that also explain the little ice age ?

  15. Phil Salmon says:

    What triggered which of the 20-30 ice ages in the last 2.6 million years of the Pleistocene? All of them? One of them in particular?

  16. oldbrew says:

    The article ends with:

    “It is possible that the mechanisms we identified here apply to every glacial period, not just the most recent one,” he said. “It may even help explain more short-lived cold periods such as the Younger Dryas cold reversal (12,900 to 11,700 years ago) that punctuated the general warming at the end of the last ice age.”

  17. Ned Nikolov, Ph.D. says:


    Thank you for giving me an opportunity to address your hypothesis. You basically state that the Milankovitch cycles control the Ice Ages not by affecting incoming solar radiation (which is the conventional view), but by regulating the geothermal flux through volcanic activity. In your own words “interglacial warming is driven by the maximum gravitational solid tides driven by Milankovitch cycles“.

    If what you say is true, then one should still observe a strong correlation between changes of global temperature as inferred from proxies in the geological record and elements of the Milankovitch cycles (i.e. eccentricity, obliquity, precession or a some combination of them). However, as I have shown, the best available data indicate a very poor (insignificant) correlation between these variables. Milankovitch cycles simply show no statistically meaningful relationship with glacial-interglacial cycles of the past 800 ky.

    Another problem with your hypothesis is that it provides no explanation for the observed Polar Amplifications in the geological records of the past 800 ky. This is the fact that, during the glacial-interglacial cycles, Polar temperatures have consistently varied more than twice as much as Equatorial temperatures. No climate model can satisfactorily reproduce this phenomenon. The only model that simulates the observed Polar Amplifications correctly & accurately is ours, which assumes that changes of total atmospheric pressure and related adiabatic heating of the surface is the actual driver of Ice Ages. Watch this video for details:

    Implications of a Semi-empirical Planetary Temperature Model for a New Understanding of Earth’s Paleoclimate History and Polar Amplification

    In addition, if your hypothesis were correct, we should be seeing now a significant geothermal heating of the Erath surface, since we are in an Interglacial period. However, modern measurements and models show that the geothermal heat flux is currently in the order of 0.091 W m-2 as a global average. This is insignificant compared to the 240 W m-2 absorbed solar radiation by the Planet and the observed 342 W m-2 downwelling IR radiation from the atmosphere.

    Hence, your hypothesis is not supported by either paleoclimatic records or modern observations.

  18. oldbrew says:

    Re. Little Ice Age type of events, here’s what one research team (Gerard Bond et al) say…

    A Pervasive Millennial-Scale Cycle in North Atlantic Holocene and Glacial Climates


    Evidence from North Atlantic deep sea cores reveals that abrupt shifts punctuated what is conventionally thought to have been a relatively stable Holocene climate. During each of these episodes, cool, ice-bearing waters from north of Iceland were advected as far south as the latitude of Britain. At about the same times, the atmospheric circulation above Greenland changed abruptly. Pacings of the Holocene events and of abrupt climate shifts during the last glaciation are statistically the same; together, they make up a series of climate shifts with a cyclicity close to 1470 ± 500 years. The Holocene events, therefore, appear to be the most recent manifestation of a pervasive millennial-scale climate cycle operating independently of the glacial-interglacial climate state. Amplification of the cycle during the last glaciation may have been linked to the North Atlantic’s thermohaline circulation.

  19. oldbrew says:

    Univ. of Arizona:

    “Using both climate model simulations and marine sediment analysis, we show that ice forming in northern Canada can obstruct ocean gateways and divert water transport from the Arctic into the North Atlantic,” Lofverstrom said, “and that in turn leads to a weakened ocean circulation and cold conditions off the coast of Scandinavia, which is sufficient to start growing ice in that region.”
    . . .
    Together, the experiments suggest that the formation of marine ice in northern Canada may be a necessary precursor to glaciation in Scandinavia, the authors write.
    – – –
    Bond et al:

    Hence, contrary to the conventional view, the North Atlantic’s Holocene climate must have undergone a series of abrupt reorganizations, each with sufficient impact to force concurrent increases in debris-bearing drift ice at sites more than 1000 km apart and overlain today by warm, largely ice-free surface waters of the North Atlantic and Irminger currents.
    – – –
    Could these two statements be referring to the same process?

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