International study raises questions about cause of global ice ages
HANOVER, N.H. – A new international study casts doubt on the leading theory of what causes ice ages around the world — changes in the way the Earth orbits the sun.
The researchers found that glacier movement in the Southern Hemisphere is influenced primarily by sea surface temperature and atmospheric carbon dioxide rather than changes in the Earth’s orbit, which are thought to drive the advance and retreat of ice sheets in the Northern Hemisphere.
The findings appear in the journal Geology. A PDF is available on request.
The study raises questions about the Milankovitch theory of climate, which says the expansion and contraction of Northern Hemisphere continental ice sheets are influenced by cyclic fluctuations in solar radiation intensity due to wobbles in the Earth’s orbit; those orbital fluctuations should have an opposite effect on Southern Hemisphere glaciers.
“Records of past climatic changes are the only reason scientists are able to predict how the world will change in the future due to warming. The more we understand about the cause of large climatic changes and how the cooling or warming signals travel around the world, the better we can predict and adapt to future changes,” says lead author Alice Doughty, a glacial geologist at Dartmouth College who studies New Zealand mountain glaciers to understand what causes large-scale global climatic change such as ice ages. “Our results point to the importance of feedbacks — a reaction within the climate system that can amplify the initial climate change, such as cool temperatures leading to larger ice sheets, which reflect more sunlight, which cools the planet further. The more we know about the magnitude and rates of these changes and the better we can explain these connections, the more robust climate models can be in predicting future change.”
The researchers used detailed mapping and beryllium-10 surface exposure dating of ice-age moraines – or rocks deposited when glaciers move — in New Zealand’s Southern Alps, where the glaciers were much bigger in the past. The dating method measures beryllium-10, a nuclide produced in rocks when they are struck by cosmic rays. The researchers identified at least seven episodes of maximum glacier expansion during the last ice age, and they also dated the ages of four sequential moraine ridges. The results showed that New Zealand glaciers were large at the same time that large ice sheets covered Scandinavia and Canada during the last ice age about 20,000 years ago. This makes sense in that the whole world was cold at the same time, but the Milankovitch theory should have opposite effects for the Northern and Southern Hemispheres, and thus cannot explain the synchronous advance of glaciers around the globe. Previous studies have shown that Chilean glaciers in the southern Andes also have been large at the same time as Northern Hemisphere ice sheets.
The ages of the four New Zealand ridges – about 35,500; 27,170; 20,270; and 18,290 years old — instead align with times of cooler sea surface temperatures off the coast of New Zealand based on offshore marine sediment cores. The timing of the Northern Hemisphere’s ice ages and large ice sheets is still paced by how Earth orbits the Sun, but how the cooling and warming signals are transferred around the world has not been fully explained, although ocean currents (flow direction, speed and temperature) play a significant role.
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They only go back 41kyrs — not even half a full glacial/interglacial cycle. The paper is paywalled so it’s hard to know exactly what they did. Projects CLIMAP and SPECMAP used much better dated sediment cores worldwide to establish the theory than beryllium in moraines. And it was recognized way back in the 1980s that continental ice certainly modified the purely orbital-based cycles. It will take a lot more to disprove the Milankovich explanation.
Well let’s see…extended ice coverage in the northern Hemisphere = more sunlight reflected = less heat absorbed by planet = cooler oceans & atmosphere = buildup of ice on poles, mountain tops worldwide = advancing glaciers in both hemispheres. My theory would be that the Milankovitch cycles that are able to warm the northern hemisphere aren’t able to do the same in the southern hemisphere as effectively due to the lack of ocean over the southern pole. A good indicator of this would be to determine the speed at which the ice advances over the northern hemisphere versus the speed it advances over the southern hemisphere. It should be somewhat slower in the southern hemisphere.
Funny how if you study the tail of a dog the dog moves in relation to the tail, ergo, the tail wags the dog. QED.
Dartmouth, home of the Maple Tree Study, (see WUWT Feb 26). They seem to be willing to do any kind of schlock study to try and be relevant to the AGW crowd.
As discussed in our website ozonedepletiontheory.info, prolonged, intense episodes of effusive basaltic volcanism end ice ages by depleting ozone due to erupted chlorine and bromine (as HCl and HBr), resulting in increased high-energy UV-B irradiance, which causes global warming, whereas prolonged, intense episodes of explosive andesitic volcanism plunge Earth into ice ages by loading the stratosphere with dust and sulfate aerosols, thus increasing albedo (andesitic eruptions also produce HCl and HBr, but their warming effect is overwhelmed by the cooling effect of dust and aerosols). Both styles of volcanism are the result of tectonic plate motion (basaltic at divergent plate margins, andesitic at convergent margins). The synchronous tracking of glacial-interglacial cycles by Milankovitch rhythms in both hemispheres is more likely due to the latter’s gravitational effects on plate motion, which are global in scope, than to its effects on insolation, which are hemisphere-dependent.
A long winded method of establishing claims that CO2 causes the Antarctic ice expansion?
Perhaps this theory belongs with the excuses for the pause in temperatures.
CO2. Is there anything it cannot do?
Yes, there are some things it cannot do, but we have good remedies with large quantities of fried fish and a massive amount of cold beer
Both of which are 90%( CO2+H2O – O2 ) + a bit of other stuff and more H2O
Nope. It’s puff the magic dragon.
I’t didn’t cook my breakfast, wash my clothes, or shovel the snow off my walk.
That is because you lack the funding necessary to show the link between CO2 and cooked breakfasts, washed clothing, and shoveled walkways.
All you need to do is get on CO2 AGW grant gravy train and with a $250K/yr senior professor PI salary, you can pay someone else to do those things. It’s simple, it uses someone;s money to make those little life annoyances go away. That’s how the Limousine Liberals do it.
How do papers like this get published, mostly with other peoples money?
Imagine that the US government thought glacier cycles were caused by a giant comet that comes close to earth every 100K years. Particles from the comet’s tail get caught in earths gravitational field for thousands of years, blocking the sun. The particles slowly fall to earth, and just when the planet starts to warm up, here it comes again. Then imagine that government issued several Billion dollars worth of grants to prove it. How many peer-reviewed papers would be produced saying that it could, may, might, possibly, be true?
If the warmist’s objective was to solve a scientific problem rather than to their push CO2 propaganda, then would have considered the logical implications of all of the paleo climatic data and the current temperature data.
Cyclic warming and cooling both poles requires a mechanism that is capable of simultaneously warming and cooling both poles. There is no mechanism to cyclically increase and decrease atmospheric CO2. CO2 does not cyclically increase and decrease when there is Dansgaard-Oeschger warming and cooling both poles. Variation in atmospheric CO2 is not the cause of the Dansgaard-Oeschger warming and cooling and is not the cause of the glacial/interglacial cycle.
There is cyclic warming and cooling in the paleoclimatic record (both poles cyclically warm and cool with the same periodicity 1500 years and 400 years) that correlate with high solar magnetic cycle activity were all followed by a cooling phase when the solar magnetic cycle moves into a like maunder minimum.
P.S. The solar magnetic cycle is moving rapidly into a Maunder like minimum which explains why there is suddenly record sea ice in the Antarctic and the start of high latitude cooling in the Northern hemisphere.
http://wattsupwiththat.com/2012/09/05/is-the-current-global-warming-a-natural-cycle/
Very worrisome.
I suspect that by the time the truth becomes obvious to everyone, the skeptics will have little cause or inclination to gloat, as we will all be in a very bad situation, with crops failing and famines ensuing.
Unlike the warmistas, I hope very much to be wrong, and will be happy if the Grand Solar Minimum and associated cooling turns out not to occur.
But that sunspot trend chart looks an awful lot like real science, and reeks of having not been made up to suit a political agenda.
This paper has 10 authors, with surely many 100’s hours put into this by each author. How can so many people be so ignorant, or so fooled, into wasting their careers?
“The researchers found that glacier movement in the Southern Hemisphere is influenced primarily by sea surface temperature and atmospheric carbon dioxide rather than changes in the Earth’s orbit..”
But we can still be happy for them. It seems good enough to have their CO2 religion work (at random times) only in the Southern Hemisphere.
Orbital mechanics since Kepler have been known more precisely than any other factor determining our insolation and thus temperature . Holding spectral map constant , our temperature varies as the square root of our distance from the Sun . More surely than the flushing of a toilet , this is settled physics . None of this “no such thing as settled … ” crap .
Orbital factors should simply be calculated and subtracted from the data . Then the unexplained variance is left in the residuals .
That’s one reason I found http://wattsupwiththat.com/2015/01/09/two-new-papers-suggest-solar-activity-is-a-climate-pacemaker/ so interesting . It analyses the largest cycle of all ( next to the diurnal ) , the 0.8% +- variation our equilibrium temperature from peri- to ap- -helion . That variation in energy must be accounted for and the fact that some is in subharmonics makes me want to understand PID math better .
I don’t understand why satellite thermal engineers are not more involved in these debates . There’s an awful lot of relevant settled quantitative understanding and algorithms in that field .
How on earth did they seperate the efect of CO² from that of the oceans and milankovic?
“…glacier movement in the Southern Hemisphere is influenced primarily by sea surface temperature …”
well, that’s kind of a given, isn’t it?
And let’s ignore the position of the continents while we are at it… We wouldn’t have a big mountain of ice at the south pole if there wasn’t a land mass down there to catch all that frozen water. A quick trip to the Scotese website will reveal a landmass at the poles is not essential for an iceage, but it sure helps if the Milankovitch cycles are favouring cold times!
Generally, there is always glacier when there is land at one of the poles.
They do have to be above sea level however, and when a 3 or 4 km glacier builds up and lasts for a million years, the landmass tends to get depressed, often below sea level. The ocean floods in and the glaciers break-up. This appears to be common enough, so there can be periods of time when a continent is at one of the poles but remains unglaciated most of the time because it is below sea level.
Land masses can also be configured so that mid-latitude ocean Gyres flow along the western side of the continent(s) and keep it warm enough to stop full glaciation. It is still frigid especially in the six months of darkness but the snow can melt in the summer.
True.
Ordovician/Silurian Ice Age, onset c. 443 Ma: lots of land at the South Pole. Map is from before the onset of glaciation. Look at Silurian map (from after the glaciation) to see how the continents were drifting.
http://www.scotese.com/newpage1.htm
Carboniferous/Permian Ice Age, c. 300 Ma: lots of land near the South Pole.
http://www.scotese.com/newpage4.htm
Jurassic/Cretaceous Ice House, c. 168 Ma: Colder than before and after during the warm Mesozoic Era, but not enough land at either pole for ice sheets to form, hence no “Ice Age”, but there were montane glaciers. During the preceding age of the Middle Jurassic Epoch, sea temperature fluctuated, so hard to date onset of Ice House conditions. Evolution of proto-feathers may have been in response to colder conditions.
Cenozoic Ice Age, c. 38 Ma: Antarctica over the South Pole and separated from South America and Australia by deep ocean channels. Ice sheets on that continent in the Oligocene Epoch, waxing and waning during the Miocene and Pliocene, then joined by NH ice sheets in the Pleistocene, after closure of the Inter-American Seaway.
http://www.scotese.com/lastice.htm
Here’s the perfect explanation for the Ordovician and Carboniferous ice ages (noting the two situations I mentioned above which can stop the glaciers).
You can think of it as Gondwana starting upside down in the South Pacific and migrating across the South Pole, taking 150 million years. It eventually broke up and Africa then ended up rightside up at the equator. Antarctica briefly moved north off the south Pole but then drifted back to end up right on top of it.
Gondwana lasted from 570 Mya to 200 Mya (having also been part of Pangea from 290 Mya to 200 Mya). Before that, they also were part of the super-continent Pannotia which was at the south Pole from 650 Mya to 600 Mya which resulted in the last Snowball Earth episode (basically all the continents were locked together over the South Pole and temperatures on top of the 5 km high glaciers reached -100C).
http://www.ncdc.noaa.gov/paleo/ctl/images/figure05_10.jpg
The high resolution temperature estimates put the peak of Ordovician ice age at -7.5C, 443.4 million years ago which is the exact peak of the extinctions timeline. The ice age started at 458 Mya and ended by 415 Mya.
The Carboniferous ice age stared about 360 Mya and ended about 290 Mya, although there were brief interludes in this ice age.
So something kept Gondwana relatively ice free from 415 Mya to 360 Mya. The best guess would be that all the land near the pole was pushed down below sea level by all that glacier and when it eventually rebounded back above sea level, the glaciers rapidly returned and the land was pushed down again. (we know north Africa went below sea level not long after the Ordovician ice age started but there isn’t much data for the non-glaciated interval).
Note how many times I mentioned land at the South Pole and resulting ice ages.
Alice is in climate wonderland.
The Milankovich theory (scary east-European sounding name so it must be wrong – Gaad bless America!) states that since the MPR interglacials are spaced by about 100,000 years corresponding to the eccentricity cycle.
So they study the glacial dynamics of four New Zealand ridges – about 35,500; 27,170; 20,270; and 18,290 years old.
This is all within less than quarter of a SINGLE ONE glaciation – the most recent Wisconsin glaciation.
Can someone tell me how this is supposed to test a theory about glacial-interglacial spacing with a 100,000 year interval?
Does dear little Alice even understand what the Milankovitch theory is?
One year ago she probably didn’t even know what an ice age is, before getting drafted from political science to “climate science”.
Perhaps they’re studying the shorter term Milankovitch Cycles, those not derived from eccentricity, but obliquity, precession, etc.
Steven Mosher is standing on his head and so all the evidence, for him, points to the verification of CAGW by any event.
true.
sorry I dont agree that climate change will be catastrophic. you fail
Must be the BAGW then Beneficial Anthropogenic Global Warming
or perhaps the
DMAGW; Doesn’t Matter Anthropogenic Global Warming
Regardless, what is debatable is the “Anthropogenic” and “degree and duration of Global Warming” parts of AGW, leaving only the it is either Beneficial, Catastrophic or Doesn’t Matter parts.
Which sounds about right
Steve M, do you actively criticize the disparate world wide attempts at CO2 mitigation and tax? If so where have you done this?
ls it known if the ice sheets expanded over North America before the same thing happened in Europe during the last ice age.?
Because if that was the case, than l can understand how that would have helped to expand the ice sheets across Europe later on.
Is anybody going to question how a combination of orbital eccentricity, axial wobble and precession could cause one pole of the earth to be cooled and the other pole warmed simultaneously? The “opposite effect. Does this require the earth to be stopped in its orbit for 100,000 years? How can they possibly make such a claim?
Pedantic old Fart “Is anybody going to question how a combination of orbital eccentricity, axial wobble and precession could cause one pole of the earth to be cooled and the other pole warmed simultaneously?”
No, not yet anyway. Past performance is not an indicator of future performance.
Orbital eccentricity affects the whole planet equally. No need for stoppage.
Axial tilt and precession do lead to different insolation in the two hemispheres, but that doesn’t matter. In the present configuration of the continents, the effect of lower insolation at high latitudes in the NH is much greater than the effect of of greater insolation at high SH latitudes, where there is going to be ice no matter possible range in variation.
During the Ordovician and Carboniferous Ice Ages, the reverse was true. The preponderance of land was in the SH rather than the NH.
This research might exclude Milankovitch cycles as main driver of the glacial->interglacial transition, but does not exclude them as a primer.
It’s actually not necessary to study New Zealand glaciers to come to the same conclusion, it is apparent from temperature proxies that show that by the time when the interglacial actually starts, the Milankovitch cycle is already back at its minimum. There’s something else driving the change of the climate. But again, “if we don’t see any other reason it must be CO2” is a bad argument here.
My opinion is that it is sea temperature/albedo cycle actually. During glaciation, Earth’s albedo is high thanks to all the surface/sea ice but the atmosphere is dry. All it takes is some thawing to reduce albedo and start the transition to interglacial. Once it’s warm and Earth’s albedo is low, the sea water gradually warms up and drives atmospheric humidity along. When the humidity is high enough, clouds increase albedo again and the Earth starts descent towards another glaciation. As soon as there is enough surface ice and sea water cools down sufficiently, atmosphere dries out again and is primed for another transition to interglacial.
Astrology can also be really complicated and take years to study all the associated BS.
If you think climate and astrology are difficult, then just have a crack at alienology.
It could be the new science to replace climatology if the climate research grants dry up.
Then we will in our lifetime have seen Y2K, CAGW and then aliens.
toorightmate
Undocumented not-yet-arrived immigrants.
CAGW forecasting is like driving a car using the rear view mirrors.
I did that once after hitting a deer (dark night) and the air bags deployed. One head light, van absolutely full of smoke, but fortunately heavy traffic so I could steer by the drivers side rear view mirror (driving by the other drivers headlights behind me only to tell from the lines in the road in the mirror if I was still in the road) for over a quarter of a mile.
Air bags create a load of smoke. EPA regulation?
Forgot to add: 60 mph, smashed glasses, bruised arms and chest.
[Good, quick thinking. Glad you survived with no further injuries to yourself, your passengers, or your fellow drivers.
Was the deer OK? .mod]
It might be nice if Mosh provided some proof for the stuff he posts. But that would be too much to ask of him.
read the paper.
So what if the research discussed in the head article gave an obligatory nod to CO2. Thousands of other research papers do the same. It happens without the authors even being aware of what they are doing. What is notable is that the timing of the glacial events that have been identified in this study ties in nicely with a number of other modern studies on glaciation in the Southern Alps (South Island, New Zealand). Interestingly it also ties in with the timing of several cold events identified in the various Antarctic ice cores. These cold events occur at times when there are modest warming events in the Northern Hemisphere. So the work probably confirms something that has been suspected for nearly 20 years. This is a see-saw relationship between Northern and Southern Hemisphere climatic events. The see-saw operates at a sub-Milankovitch scale (i.e. on the scale of Bond and DO events). The work indicates that the climate at 40 to 45 deg south of the equator (South Island, NZ) has direct linkages to events in Antarctica. So Southern Hemisphere climate is not a simple slave to that in the Northern Hemisphere, which is what had been thought until relatively recently.
There is discussion above about Antarctic ice volume. Please note that the extent of the Antarctic ice shelves and the grounding of the ice is dependent on sea level. As sea level rises and falls due to Northern Hemisphere ice sheets accumulating and then melting, the Antarctic ice shelves couple or decouple from bedrock. This changes the way the Antarctic ice is braced and lets ice either accumulate on land or flow to sea faster. So in some ways there is direct coupling between the Hemispheres and in other ways there is not.
Cosmogenic radionucleotide dating such as beryllium-10 can be used to date exposed surfaces perhaps to 30 million years BP with a half-life of 1.387 million years. Milankovitch cycles (from Wikipedia), “The major component of these variations occurs on a period of 413,000 years (eccentricity variation of ±0.012). A number of other terms vary between components 95,000 and 125,000 years (with a beat period 400,000 years), and loosely combine into a 100,000-year cycle.”
The critical data from this study comes from “The ages of the four New Zealand ridges – about 35,500; 27,170; 20,270; and 18,290 years old”.
These “critical data” have nothing to do with Milankovitch cycles!
About 2 decades ago I found myself with a group of Geologists as we were examining an exposure of a diamicton with apparent drop-stones (i.e. a marine ice sheet of a Precambrian Glaciation, more than one) in the footwall of the Wasatch Fault adjacent to the campus of the Brigham Young University.
About a year ago I, as a reviewer, recommended rejection of a paper based on its Abstract.
I am sure that the “collections department representative” of the magazine Geology ‘tip-toed the light fantastic’ waving the Cheque above his head for all to see down the street to the bank that holds the accounts receivable of the magazine Geology.
Science is not served with papers like this.
They are right about Milankovitch, wrong about CO2. Sure there is a Milankovitch forcing layer, just look at OCO-2 to see why plankton just love him, but his only cycle that produces a net insolation variation at planetary scale is eccentricity. Eccentricity has periods of 100k and 400k years. Neither period is evident in the first half of the Pleistocene. At the mid P transition an unsatisfying 100kyr period emerges, but the 400kyr signal is absent from the entire Pleistocene. Many, including Richard Muller, have suggested the apparent 100kyr signal in the late P is built up.
We might hazard a WAG about how many pertinent forcing layers Milankovitch must share his mojo with. There is probably some BS statistical regression for this. OR, we could quit dithering with epicycles and just admit we don’t know Jack.