Talk:Ice age/Archive 1

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Archive 1 Archive 2

Changes

I think the sentence in the 'variations in solar energy output' section should be changed... "rising temperatures produce more water vapour, water vapour is a greenhouse gas (much weaker than CO2, but there will eventually be vastly more water vapour), the temperature rises, more water vapour is produced, etc." This seems to imply that water vapor is only responsible for a small part of the greenhouse effect, and it also says that their will be vastly more water vapor, when in fact their already is in relation to CO2

Semantics are important, but shouldn't we adress the blatant vandalism found in the overview?

Still in a series of glaciations

'A minor series of glaciations occurred from 460 to 430 million years ago. Two more extensive glaciations were from 350 million years before present to 250 million, and from 4 million years ago to about 10,000 years ago (the Pleistocene period).'

Isn't there general agreement that we're still in a "series of gaciation" - that is, an Ice Age? Glaciations have come and gone regularly for the last 4 million years, and we're in between two now. As long as we're talking about "series of glaciations", I think the "to about 10k years ago" is misleading.

    • I recently saw a show on the subject on the Discovery Channel. The theory is as follows; x number of million yrs ago, during continental shifting, the gap between North and South America was formed, essentially Central America. Until this time, the north pole was very cold but saw no precipitation due to the dry air. However, when Panama was formed, underwater oceanic currents could no longer flow from the Atlantic to the Pacific (or was it the Pac to the Atl?) ansd were thus subsequently diverted towards the North bringing along with it warm air, water and humidity. Only then did the North Pole see snow start to fall, eventually giving birth to the Ice Age. The theory was very well explained and illustrated, and I think it warrants further investigation as I see no mention of it here. - AL

HERES THE LINK [1]

Wait and see, but maybe humans preventing ice age

I'm not sure - it may be impossible to say unless another one actually occured. It seems for the present we have emitted enough CO2 to make it less likely.
According to ONE computer model and a pile of rhetoric. Maybe humans preventing something called scientific rigour and trading it in for something called monkey see monkey do. 59.167.86.232 16:29, 30 October 2007 (UTC)

Warmed humidity can cause more snowfall

A slight increase in temperature could make increased winter snowfall in colder regions. If temperature growth is then terminated this situation will continue indefinetely and thus theoretically hasten the arrival of a new ice age.
I remember reading a news story (I can't remember exactly where, though) that measurements of glaciers in the Alps in Europe have confirmed that we are in a "little Ice Age." However, this trend towards increased glacial action is being offset by the effects of global warming, which is causing many glaciers and much of the Antarctic ice floe to melt. -- Modemac

Arctic Ocean thawing may cause snow bloom

There also is concern that if the Arctic Ocean surface loses its ice, heating will occur for a few years due to the water absorbing much more heat than now. The exposed ocean would probably raise temperatures in this hemisphere. But much more water vapor would also be emitted, which during winter could cause a much larger snow cover than usual. A larger snow cover might not melt off as much as it presently does, causing a cooler summer and colder temperatures the following winter. This could cause feedback with increasingly colder or longer winters, as the glaciers begin to accumulate.
Back to the immediate subject -- It seems unlikely that whatever has been powerful enough to cause glaciations during 4my would happen to stop just when we arrive. It could have happened. Or we might warm our way out of the cycle. Or there is another glaciation in our future.
I think we need a few thousand more years before we have a trend which suggests the glaciation cycle has ended. Put on your calendar to update this article then. -- SEWilco 07:39, 13 Aug 2003 (UTC)

Orbital Obliquity additions

(William M. Connolley 20:01, 20 Jan 2004 (UTC)) SEW added some stuff, including: "Han-Shou Liu[2] and others[3] have pointed out that changes in obliquity seem to be relevant", which are:

http://www.worldscinet.com/fnl/03/0301/S0219477503001099.html

and

http://www.people.virginia.edu/~jba5b/c2.htm

The first of these appears to be about "Orbital Noise of the Earth Causes Intensity Fluctuation in the Geomagnetic Field" and doesn't seem to have any relevance to climate/ice age.

(SEWilco 12:23, 1 Feb 2004 (UTC))
  • It's not a climate reference, it is a reference of obliquity periods: we show that noise spectrum of the obliquity frequency have revealed a series of frequency periods centered at 250-, 100-, 50-, 41-, 30-, and 26-ky. I thought there was little enough text in that summary that it was apparent what is relevant to obliquity. There being many frequencies is of interest.
(William M. Connolley 19:19, 1 Feb 2004 (UTC)) I still don't get it. "Han-Shou Liu[1] and others[2] have pointed out that changes in obliquity seem to be relevant.". Relevant to what? Not climate, you seem to be saying.
  • I was trying to keep it brief, to point out the topic exists. I mentioned the full name of Liu for those wanting to get more information. Liu is referenced by many others, and the above is also of interest because it is recent work of his, and it shows some differences to his earlier work.
I'm not a great historian of Liu's work, and I doubt many other people are. Could we try to keep things closish to Milankovitch/Ice Age stuff? "Han-Shou Liu[1] and others[2] have pointed out that changes in obliquity seem to be relevant." is brief to the point of incomprehensibility: you need to expand this if it is to make any sense.
I point out that AFAIK there is no dispute about the various orbital periods of the earth.
Ah, thats a bit more like it.
He doesn't seem to have been active recently. But thats OK.
Odd, why isn't that listed above?
Didn't find it but I assume you're correct.

(William M. Connolley 19:19, 1 Feb 2004 (UTC)) From what I'm reading above, Liu seems to think there is a problem with the 100 kyr ecc cycle causing ice ages. Thats OK, because everyone knows that: the forcing is too weak. People invoke various geophysical explanations for this, e.g. response times for ice sheets. Jus to be clear: I've no objections to the article talking about Liu's work, but your one-sentence bit just didn't make sense to me.

The second contains useful stuff but some nonsense ("Muller and MacDonald theorize that this narrow peak in this and other data implies an astronomical origin" is true but misleading, implying they originated the idea; "They further suggest that this narrow peak has been missed due to the spectral analysis methods used" is nonsense; the peak in question is the commonplace 100 kyr peak).

  • There are problems with the commonplace 100 kyr peak. Popularity does not determine correctness, particularly when there are oddities which may be major failures. (SEWilco 12:23, 1 Feb 2004 (UTC))
(William M. Connolley 19:19, 1 Feb 2004 (UTC)) Yes yes but you miss my point. The article refed is garbled.
(SEWilco 18:25, 2 Feb 2004 (UTC)) Yes, that paper is not of top quality. The contrasts in it were useful.
I am the author of the paper in question. I was a college student when I wrote it, and any reasonably sophisticated analysis of the same papers I cited would be more helpful than my efforts, which were really only online so that I could turn in the paper without walking to the classroom.
FWIW, the sentence above labeled nonsense should have said "the narrowness of this peak" rather than "this narrow peak". Obviously, everyone has noticed the 100k-year cycle.
The paper is certainly "not of top quality". I have no training in environmental science (outside of a few undergrad classes). The paper should not be cited here. (it isn't now) Jim Apple 04:14, 23 January 2006 (UTC)
This is all moot anyway
But its certainly an interesting postscript! Thanks for the info William M. Connolley 09:48, 23 January 2006 (UTC).

I think the Rial (the pretty colour pic) work *supports* the Milank stuff and opposes Muller etc.

  • Yes, that is what Rial says. I included that link because it refers to several studies, which is useful for those needing more details. You mention *supports* as if only full support of an idea should be provided, but I'm sure you did not intend to imply that. (SEWilco 12:23, 1 Feb 2004 (UTC))
Rial opposing Muller etc is probably worth putting into the article.

"However, Milankovic cycles predict an extremely cold period 400 thousand years ago which seems to have not happened." needs a ref.

I think oyu've misunderstood this. It says stuff about the 400 kyr cycle. Not that Milank predicts cold 400 kyr ago. Could you quote more precisely if you want to support this point.
Yes, I did misunderstand. Theory indicates there is a 400 kyr cycle, which should have happened in the past 400 kyr. But records are not showing anything dramatically unusual in the past 400 kyr. There was an unusually long mild period 400 kyr ago ("Stage 11") which might have been due to the 400 kyr cycle, which implies the Holocene may be similar. (SEWilco 18:25, 2 Feb 2004 (UTC))

"Milankovic patterns also have two peaks near 100 thousand years but not at 100 thousand years." - not sure this is v important - peaks in spectral space don't nec correspond in real time.

  • The issue is that the other methods included a process specifically to remove details. This has benefits, but might have hidden information relevant to the problem because the lost details fit in with other information. (SEWilco 12:23, 1 Feb 2004 (UTC))
Yes, but again: geophysically, there are mechanisms (ice sheet time constants for example) that might reasonably be expected to blur spectral peaks. I get the impression that some of these people are taking their time series a bit too seriously and not doing enough physics.

Para removed to Talk for work

Following the lack of reply to the above comments, the offending para is removed to here, and a v brief summary left behind (William M. Connolley 19:45, 25 Jan 2004 (UTC)).

However, Milankovic cycles predict an extremely cold period 400 thousand years ago which seems to have not happened. Milankovic patterns also have two peaks near 100 thousand years but not at 100 thousand years. Richard A. Muller and Gordon J. MacDonald have pointed out that those calculations are for a two-dimensional orbit of Earth but the orbital inclination in the three-dimensional orbit has a 100 thousand year peak. Earth's movements through and out of the plane of the ecliptic of all planets match the temperature patterns of the past 1 million years. He suggests this might be due to an interstellar dust cloud or increased collisions in the Themis and Koronis asteroid families causing their dust band to increase. The sudden change 1 million years ago from 41 thousand year cycles to 100 thousand cycles is not explained by unchanging two-dimensional Milankovic cycles but is explained by a cause which is affected by the inclination cycle. Han-Shou Liu[2] and others[3] have pointed out that changes in obliquity seem to be relevant.

Para modified

How does this look? (SEWilco 18:47, 2 Feb 2004 (UTC)) Again? (SEWilco 10:07, 4 Feb 2004 (UTC))

However, Milankovic cycles have periods of 95, 125, and 400 thousand years[4]. Difficulties with Milankovic predictions include that the 400 kyr cycle is not detectable in most records, the major climate cycle has a sharp 100 thousand year peak (instead of 95 and 125 kyr), and some orbital changes which were expected to end an ice age actually took place after the ice age had already ended. Richard A. Muller[5], Gordon J. MacDonald[6], and others have pointed out that those calculations are for a two-dimensional orbit of Earth but the three-dimensional orbit also has a 100 thousand year cycle of orbital inclination. Earth's movements through and out of the plane of the ecliptic of all planets match the temperature patterns of the past 1 million years. Being in the plane of Jupiter's orbit seems to have the greatest effect. Suspected causes include solar radiation or atmospheric effects due to an interstellar dust cloud or a dust band in our solar system. The change 1 million years ago, during the Middle Pleistocene Revolution, from 41 thousand year cycles to 100 thousand cycles is not explained by unchanging two-dimensional Milankovic cycles but is explained by a cause which is related to the orbital inclination cycle, such as increased collisions in the Themis and Koronis asteroid families. J.A. Rial[7] replies with more details for traditional explanations.

(William M. Connolley 21:17, 2 Feb 2004 (UTC)) I don't like the start. The basic point is trying to explain the competing mechanisms for causing the ice ages. Firstly, the 400 kyr stuff isn't very relevant: "tradiational" Milank doesn't predict a 400 kyr period, so the fact that its missing doesn't help much. Err, and then again Muller says: "In contrast, spectral analysis of the coarse component fraction of the sediment (primarily foraminifera) shows a structure characteristic of standard Milankovitch theory, with a triplet of peaks with periods near those expected from the Earth's eccentricity: 95, 125, and 400 k.y.", err, which seems to suggest that 400 kyr period *is* found in the record. The story needs to be straight.
(SEWilco 10:07, 4 Feb 2004 (UTC)) Right, although the 400 ky being sometimes detectable is a confirmation that the 2-D orbital models do have some effect. Muller does say 400 is usually not detectable.
(William M. Connolley 17:36, 4 Feb 2004 (UTC)) This still isn't a straight story. Muller says "Although the spectra of eccentricity and inclination are quite different, they are remarkably easy to confuse for two reasons: First, it has become traditional to ignore the absence of the expected 400 k.y. eccentricity cycle since it is difficult to see in the short records and plausible effects have been postulated that could suppress it.". So I don't see concentrating on the 400 kyr cycle is a good idea.
(WMC) And I must have missed "and some warming changes happen before the orbital causes" as well.
(SEW) Search for "causality" in Muller's Eccentricity is ruled out. But I see my phrasing is not good. Maybe "and some orbital changes which were expected to end an ice age actually took place after the ice age had already ended".
Um yes, its just about there, though not really: just references to other papers. So I don't see exactly what the problem is, just that M thinks there is one.
(WMC)The essential point of Muller, as I take it, is that the insolation modulation is *caused* by dust clouds (and the orbit of the earth carries it into and out of these) unlike the std Milank where the modulation comes directly from orbital variations.
(SEW) Actually, Milank and Muller agree on orbital variations as being related to climate changes.
Yes yes I understand that. The point is, that Milank and Muller predict essentially the same thing - 100 kyr cycles - but have different explanations: Milank is pure insolation (plus feedbacks) forced by orbital var, Muller is the same but orbital var leads to insol var via dust.
Milank uses 2-D orbits and it has been believed that various effects upon solar warming caused climate alterations. Muller et al point out that the motion in the 3rd dimension seems to have a significant effect, but the reason for the effect is only speculation. Maybe Jupiter is dragging dust to form an ecliptic disk. Or maybe Jupiter is capturing incoming interstellar material, so it sometimes is shielding us.
(WMC)Where do you get the shift 1 Myr ago from? From http://muller.lbl.gov/papers/sciencespectra.htm ? In that case you need to omit "sudden", since the period from 1 Myr to 1.5 Myr ago seems to be missing.
(SEW) 0.9 Myr Middle Pleistocene Revolution. Muller thinks an astronomical event caused the shift, while Rial and Milank depend upon subtle orbital movements with a transition period.
Please please get into the habit of quoting text for anything controversial, or interesting, like this. I still don't know where you get the "sudden" shift idea from.
(WMC) As near as I understand it, Liu's theory is not the same as Mullers.
(SEW) Argh. Yeah, Liu was looking at the tilt of the polar axis, not the tilt of the orbital plane. Geology, not astronomy. An alteration of a Milank parameter, not an effect of the present patterns.
(William M. Connolley 17:36, 4 Feb 2004 (UTC)) Errm.

Another try

(William M. Connolley 18:24, 4 Feb 2004 (UTC)) OK, we're getting a bit bogged down in detail here. Instead of nit-picking yours, let me try mine again. But first, a couple of principles...

  • Milank *is* still the dominant explanation, perhaps (who knows) only for reasons of inertia, but nonetheless. So the article ought to reflect that, and not have much more text on competing explanations.
  • I don't think either of us has really read Muller, or Rial, or other literature, in enough detail to explain their ideas really well.
  • So we should avoid details, and mention the ideas, and provide links to the details.

With that in mind, I propose:

The "traditional" Milankovitch explanation struggles to explain the dominance of the 100 kyr cycle over the last 1 Myr. Richard A. Muller and Gordon J. MacDonald [2] [3] [4] and others have pointed out that those calculations are for a two-dimensional orbit of Earth but the three-dimensional orbit also has a 100 thousand year cycle of orbital inclination. They proposed that these variations in orbital inclination lead to variations in insolation, as the earth moves in and out of dust clouds. Although this is a different mechanism to the traditional view, the "predicted" periods over the last 400 kyr are nearly the same. The Muller and MacDonald theory, in turn, has been challenged by Rial [5].

(No room for Liu, because... I don't understand what he is saying).

We also seem to be in some uncertainty as to what the ice age periodicities are, and when. So a list of, last 1 Myr: 100 kyr; 1.5-2.5 Myr: 41 kyr; or whatever; would be useful. Hmm, actually, thats in the article, but the break is set at 0.8 Myr. This should be ref'd.

Meanwhile, I've re-arraned the paras in the Causes section to roughly chronological: ie first ice ages first, and ending with most recent, Milank. This stuff is a touch nusatisfactory at the moment as I think that 9without a good idea in your head already) you are likely to get confused by the article as to which causes fit which periods.

Dates of Ice Ages

All of these dates assume an old earth, just as many pages assume evolution and take it as fact. I think we should get both sides of the issue. That's why I put the young earth stuff in there. Please consider it. - SamE 21:21, 3 May 2004 (UTC)

(William M. Connolley 21:56, 2004 May 3 (UTC)) I'm sure you like the young earth stuff but I have no sympathy with it. Its essentially pollution, when put into science pages. I've just been to a science conference, which discussed - amongst other things - ice cores and ocean sediment cores. No one proposed young earth stuff: there is no scientific support for the idea at all. Scientifically, there is only one side to this.
The only part of that comment that's correct is the last line. Scientifically, the earth is less than 10,000 years old. The Ice Age most likely occured a little over 4000 years ago, from the most modern scientific evidence. The only "pollution in science pages" I see is claiming that an archaic theory that rests upon the earth being far older than scientifically possible is fact. Evolution is the antithesis of science. - MarioFanaticXV

If you want to put together a page entitled something like "ice cores interpreted from a young earth perspective" then feel free. That would be OK. But I very much doubt it can be done.

The debate really belongs on the young earth pages, where it is occurring as we speak... (though of course as DJC commented on the talk pages, wiki is not a debating society).

Seems as though there IS enough of a variation in insolation on a 100KY and 400KY Cycle to expect climate change

The IPCC http://www.grida.no/climate/ipcc_tar/wg1/fig2-22.htm [8] indicate that there has been a major interglacial period every 100ky, including one at 400ky. Is this an error?

Your link doesn't appear to be working at the moment, but this is basically correct. Some were a little earlier than expected, some were a little late, but basically every 100kyr for the last ~800kyr or so. This includes a major glaciation at 400 kyr that cannot be predicted by traditional orbital forcing arguments. This is known as the 400 kyr problem or the "stage-11" problem (in reference the marine isotopic stages).

http://www.museum.state.il.us/exhibits/ice_ages/insolation_graph.html [9] shows particularly strong 400 ky cyclicity and as much as a 25% difference in insolation during one precession cycle during the more high-amplitude 100ky cycles. I would think 25% less solar energy might make a difference.

http://amper.ped.muni.cz/gw/articles/html.format/orb_forc.html[10] shows a similar pattern, though he assumes a different solar constant and therefore gets somewhat higher average fluxes, but the amplitude af the variations is on the order of 25%.

Greg, My comment that your statements were inaccurate was not because insolation changes of this magnitude don't occur, but because you didn't cite the season and the location, and in your first post you made it sound like the changing distance was the controlling factor in changing the insolation. The annual average change in isolation is near 0 (as changes in winter cancel changes in summer), so it is very important that this be referenced as a seasonal thing. Secondly, the main cause of these changes is the precession of the Earth's axis. Eccentricity sets the envelop, but the rapid change in the strength of seasons is basically controlled by precession.
Also, in this article, orbital variability is referenced extensively already. I really feel that the details, such as what you present, belong not here but on the page regarding Milankovitch cycles. Keep in mind that this is a page dealling with ice ages in general (i.e. both the recent ones and those in deep history), so I don't think it is appropriate to create too much detail regarding the recent ice ages. I should also say that I am inclined to move some of the already existing material off of this page as well.
Greg, I will let you have another go at the statements you are making before I make additional changes, but I still am not satisfied in the way you are representing the insolation chart. Dragons flight 12:12, Jul 20, 2004 (UTC)

Capitalization

This article just got moved from "ice age" to "Ice Age" and I don't think that's quite right. The article itself uses lower-case throughout. Furthermore this article is discussing ice ages in general, not a specific ice age which might have the proper name "Ice Age" (as the most recent glacial period is often called). I thought I'd bring it up here first, though, since I'm no expert. Bryan 04:20, 26 Aug 2004 (UTC)

(William M. Connolley 08:49, 26 Aug 2004 (UTC)) I can't see why either. Ice age is more obvious.

I proposed the change a couple weeks ago, and there has been no comment on it, so regarded it as consensus. The talk on that got moved to talk at Ice Age (movie) if you want to see it. Capitalization is not the primary issue. The problem was that people looking for information on continental glaciation first got referred to a B movie about it. In this way the "main event" got the primary page. Pollinator 11:35, Aug 26, 2004 (UTC)

(William M. Connolley 11:57, 26 Aug 2004 (UTC)) Well, people watching Ice age (climate thingy) aren't watching Ice age (movie) so didn't see your note. There is no reason at all why the change in caps to the movie should affect the other page! So I've moved it back.

Ambiguity

The end of the paragraph defining ice ages and glacial ages is very confusing. You have used ice age in two differnt ways and then you try and clarify the issues by defining glacial in terms of ice ages. I'm still not quite sure what you meant so i can't fix it. Logicnazi 05:18, 21 Dec 2004 (UTC)

(William M. Connolley 10:39, 21 Dec 2004 (UTC)) Hmm, fair point. I have attepmted to resolve this ambiguity, which also involved a fair amount of changes-for-consistency elsewhere in the article. If there is a real glacio out there, do feel free to correct.
In my experience, which includes some glaciology, Ice Age refers to periods such as Weichselian / Würm / Wisconsin, etc, and not the entire last 5 million years. It is synonymous to glaciation, and translates to Eiszeit in German and Istid in Swedish. If an author writes 'the last ice age', I would take for granted that he is writing about the last glaciation (i.e., Weichselian / Würm / Wisconsin / Valdaj, etc), and for all the glaciological literature I have read, I have never suspected anything else. If you want to refer to all of them together, the term Pleistocene can be used (the Pleistocene glaciations). I'm just afraid that trying to establish a definition that differs from regular usage will introduce confusion in the future, when articles written today may be misunderstood. --Lindorm 22:42, 19 July 2006 (UTC)

Rationalising glaciation names

The current naming conventions for glaciations and interglacials are a bit of a mess. This is more the fault of the international glaciological community that it is ours. Even so, we have lots of red links for the varying names and some duplicate entries under different regional names. From an archaeological perspective it would make more sense to give each region's name for the same glaciation its own article, each one explicitly linked with its analogues. This would permit better discussion of the relevant cultures and any other local phenomena. From a geologist's or biologist's standpoint and in the name of simplicity though it may be better to merge each name into one article as has been done in Wisconsin glaciation with lots of redirects set up. Any thoughts? adamsan 12:06, 30 Dec 2004 (UTC)

Use redirects unless we're talking about really long articles, or if the linkage would be overly tangled or indirected. In general we want articles to be about the "subject" irrespective of nomenclature, and only raise nomenclature to article level when naming is itself a complicated issue. Redirecting can also be undone later, if the redirected topic begins to get large within the original article. Free links to synonyms have a way of becoming needless dups. Stan 15:31, 30 Dec 2004 (UTC)putos

missing "only"?

"Since the earth has significant continental glaciation in the Arctic and Antarctic, we currently are in a glacial minimum of a glaciation" doesn't quite make sense to me.

Edits by 131.172.4.45

I am reverting the edits by 131.172.4.45. The user gives no citations and the stated science appears to be wrong. Veizer et al.'s strontium isotope measurements do not support a long-term relationship between continental erosion and CO2 changes. The Sr measurements suggests that the Himilayan orogeny has been uniquely profound during the Phanerozoic in it's ability to increase continental erosion (and so might contribute to recent declines in CO2), but previous mountain building events have either been too extented in time or too randomly distributed through time to significantly perturb the continental erosion budget. And as far as I know, the weak perturbations that do occur during most of the record haven't been strongly tied to CO2 changes.

Further, the CO2 declines during the Carboniferous are a biological effect (the result of the evolutionary invention of lignin bearing plants and excess carbon burial) not a geological effect. It is called the Carboniferous because so much carbon ended up in the rocks after all.

Also, while I don't know what qualifies as "extensive" mountain building, there was significant mountain builing in the Rocky Mountain range and Eastern Alps during the Paleogene, which doesn't fit the notion of "absense" of mountain building.

Dragons flight 14:22, Mar 18, 2005 (UTC)

TOCright

Can anybody justify the use of TOCright on an eight item table of contents? This template has only survived deletion on the grounds that it is used sparingly and it really doesn't seem to me to improve the layout of this article at all. Joe D (t) 8 July 2005 23:52 (UTC)

As I said in my edit comment, I think that on most screens the TOC fits next to the introductory paragraph nicely, and placing it there makes it not interrupt the text. (SEWilco 9 July 2005 01:03 (UTC))
That's not what it's for though, it's for preventing very long TOCs from creating excessive whitespace etc. An eight item TOC doesn't cause a problematic interruption of the text, but does look ugly when floating right. Joe D (t) 9 July 2005 13:05 (UTC)
TOCright can be used to good effect in some articles, but I don't think it is necessary for this one. violet/riga (t) 9 July 2005 13:15 (UTC)

periodicity

"During the last few million years there have been many glacial periods, occurring at 40–100,000 year frequencies..."

If this statement is meant to say 40,000 to 100,000 years between glacial periods, this is not the way to write it -- it's too open to confusion, and omitting extra zeroes is not important enough to risk complete misunderstanding. Common sense tells me it's ridiculous to think they can happen every 40 years.DavidH 00:36, July 28, 2005 (UTC)–

I've "fixed" this. 40 - 100 was ambiguous for another reason, ie it imples that 80 kyr is also possible, whereas the periods are 40 *or* 100 kyr. William M. Connolley 09:07:12, 2005-07-28 (UTC).

other continents?

Just wondering, why do we have a special section on glaciation in North America, but not for any other continent? Perhaps knowledgeable folks could add sections for each other continent. This would be a bit of a feather in Wikipedia's cap, since most other resources seem to include a bit about North America and a little about Europe, but very little about South America, Asia, Australia, or Africa. -- Securiger 09:10, 17 February 2006 (UTC)

Not totally sure, but the N A (Laurentide) ice sheet was very big and important. By contrast, the European one doesn't do much. William M. Connolley 09:34, 17 February 2006 (UTC).
The European ice sheets were actually quite large, as was that of Chilean Patagonia and the Altiplano and are of similar significance. It would also be worthwhile to have an article on glaciation in Asia, though the purpose should be to illustrate why it was so limited in extent compared to that of Europe and North America.

Another Cause offered

03-28-2006

I had a dream last night. I don't recall it's parameters. But I was suddenly jolted out of bed at 3 a.m. with a thought that just has to be written down and sent to a few people for their perusal.

Once or twice (or more) in the earth's history a huge rock fell on the earth which devastated life forms at the time. Many species went extinct. This theory has a very solid scientific foundation and is understood by geologists and planetary sciences as THE explanation for the end of the dinosaurs.

My theory of the Ice Ages also involves a very large meteor. But it didn't hit the earth. It actually hit the earth's moon. The massive explosion as the meteor plowed into the moon (this probably happened several times over the millennia) ejected many, many tons of dust and debris into near earth orbit. The dust cloud encapsulated the earth. Direct sunlight was cut off by a huge percentage by the dust cloud that encased the earth. Temperatures plunged. Ice Ages resulted. Over thousands of years the dust and debris were swept up by the moon or simply fell to earth and temperatures moderated.

To test this new theory I suggest that geologists analyze the dust and debris of the period for similarities with the "moon rocks" that NASA recovered . Some large chunks must have been transferred here from an explosion that large.

24.56.162.170 16:23, 31 March 2006 (UTC)

Nice dream :-) - now if you can find a published account of it in a peer reviewed journal, we can include it in the article. Cheers! Vsmith 16:30, 31 March 2006 (UTC)
When they say "the impact of relatively large meteorites", I have thought they were referring to the possibility that their impact would be capable of reducing the Earth's axial tilt. The effect of meteorites is believed to account for the anomalous axial tilt of some other planets in our solar system. Modern computer models demonstrate reduced mean axial tilt (i.e. independent of variation brought about by Milankovitch cycles, which are assumed to be the same) would lower temperatures if all other boundary conditions are equal and continents in their current positions.
The thing here is that there seems little information on whether (and) what changes in the Earth's mean axial tilt have occurred in the past. In the article History of the Earth's Obliquity in Earth-science reviews (volume 34, issue 1, pages 1-45) it is suggested that the Earth's axial tilt has remained stable over Phanerozoic time but was much greater over the Precambrian. However, smaller variations in mean axial tilt brought about by asteroidal or meteoritic collisions could easily cause or end ice ages and are not discussed. Yet, according to the axial tilt article, the level of variation in the Earth's axial tilt is decreasing. This suggests alterations in mean axial tilt must be followed by higher variation that gradually falls as the new tilt stabilises.
If it does not refer to changes in mean axial tilt, what does the phrase "the impact of relatively large meteorites" refer to that would cause ice ages?

luokehao 17:25, 21 December 2006 (UTC)

Causes

I was under the impression that one of the contending theories for ice age causes was related to a cyclic interaction between atmospheric conditions and ocean currents. My understanding was to this effect: the warming of the atmosphere (via heightened carbon dioxide levels or methane, etc.--not sure how this part is explained; possibly by geological activity?) leads to the melting of polar freshwater ice, which in turn disturbs the currents of the saltwater oceans (which are responsible for the distribution of temperate and warm air currents), causing a calming of the oceans and consummate cooling of the atmosphere, thereby lowering the overall temperature and inducing the freezing of an ice age. Is this not a widely held hypothesis, or should it receive mention in the article? --5-23-06

So, has no one seen this research?

http://www.livescience.com/forcesofnature/050330_earth_tilt.html

As far as I can tell, the theory explained at the above link isn't mentioned here. In fact, I don't see any mention of the idea that the 100,000-yr "cycle" is actually just a mixture of 80,000- and 120,000-yr periods (is it really true?). I don't know the subject very well, so maybe I misunderstand, or maybe the stuff in the above article is unworthy of mention. But if so, I would like to know. Thanks. Xezlec 03:27, 10 June 2006 (UTC)

Terminology

What does "the forcing" mean? HMAccount 22:32, 25 June 2006 (UTC)

Copyvio

Copyrighted text from [11] was removed from the article. Conscious 17:11, 15 July 2006 (UTC)

Contributing cause

Since Milankovitch cycles are inadequate to explain an ice age, there must be additional contributing cause. The following, which I believe is consistant with observations, describes how conditions can be brought about by which Milankovitch could then cause the climate to toggle to the opposite climate trend. The strong effect of the incident angle of light on the reflectance of water does not appear to be widely considered in ice age study.

The strong effect of the incident angle of light on the reflectance of water does not appear to be widely considered in ice age study - ah, there you have a problem. Wikipedia does not encourage independent research - in fact it forbids it (WP:OR). If people haven't proposed this mechanism, it doesn't go into the article even if you and I are sure its correct. However, I'm not sure its correct, the most obvious problem being that the sfc area involved is small. But... you don't need to answer that point. You need to find a reputable source making your argument. Note that a series of reputable sources making a chain of arguments that you think you can connect together is not good enough William M. Connolley 20:29, 6 August 2006 (UTC)
sfc area?? == surface area

During the current interglacial period, sea level has risen about 120 meters and water area increased accordingly covering the continental shelves which were exposed at the peak of the last glacial. Water responds differently than land to incident solar radiation. That part of incident solar radiation that is reflected from a body of water is specular and is calculated by the Fresnel equations. A graph showing the reflectivity of water vs. incident angle of light can be seen at[12]. Fresnel reflection is directional and therefore does not contribute significantly to albedo which is primarily diffuse reflection. Therefore, added water area always reduces earth’s albedo but may actually decrease the heat added to the planet.

The real water surface is wavy so reflectance assuming a flat surface as given by the Fresnel equations must be adjusted for waviness. A formula and graph for correction for waviness for two different wave energy spectrum definitions has been published. [1] With the average adjustment for the two spectrums applied for an assumed average wind speed of 5 m/s, the reflectivity of wavy water to unpolarized light increases progressively from 5% at an angle of 49.5 degrees to 20% at 72.8 deg and 50% at 83 deg. The rate of increase of reflectivity with angle then declines rapidly so that the reflectivity of wavy water is 67% at 90 deg (light parallel to surface) where it would be 100% if the water were smooth.

Reflectivity of land and various coverings is also given at [13] and does not vary significantly with the incident angle of sunlight. The reflectivity of land varies substantially depending on cover but appears to average about 0.15. Thus at incident solar radiation angles more than about 69 degrees from nadir, water absorbs less heat from the sun than does land. The effective angle for determining water reflectivity is the compound angle accounting for both latitude and time of day. Accounting for the specular reflection of wavy water and the compound angle of the added water surface to the direction of the sun, added water surface area that is further than about 60 degrees north or south latitude results in reduced heat to the planet. Closer to the equator, low reflectance of water during the day more than offsets the high reflectance near dawn and dusk so there is a net gain of heat at these locations. Thus the change in water surface area as the sea level rises provides either positive or negative feedback to ice age climate change depending on the latitude of the added water surface area.

Added water surface area towards the poles that is exposed late in an interglacial period reduces the heat added to the planet and, in concert with other factors, contributes to the toggle from interglacial to glacial. As a glacial period proceeds, lower temperatures and less exposed water area lead to less evaporation and a dryer climate with less cloudiness. The decline in cloud cover allows more solar energy to reach and be absorbed by all surfaces. The largest increase in the heat being absorbed takes place at ocean areas remote from the poles. Water areas at the equator with no cloud cover absorb about 95% of incident solar energy. The resulting net heat gain by the planet, in concert with other factors, may cause the climate to toggle from glacial to interglacial.

Acceptance of Milanković

I think it would be an interesting (and cautionary) point to mention that the Milanković theory was dismissed as "pseudoscience" until being proven likely in recent years (and we still find some people downplaying it if I'm not mistaken?).

Glaciation other than in N. America

Obviously a section on the extent of glaciation in Europe is needed alongside the N. American treatment -- mentioning the interesting connection of Britain to continent.

Also the general issue of sea level change doesn't seem to have been dealt with in depth if I'm not forgetting something I just read. Map of coastlines at glacial maximum would be great with features like Sundaland pointed out.

The articles on sea level change and continental shelf address this. I suggest a new section as follows:

Sea Level Change

Glaciation moves water from ocean to glacier resulting in sea level decline. Glacial melt during an intergalcial period moves water to the oceans producing sea level rise that covers the continental shelf. 4.232.0.79 18:53, 16 August 2006 (UTC)

Context with Great Flood and Atlantis myths

I've just added a huge section discussing the Ice Ages and the myths of the Great Flood and Atlantis. I'm not really sure how to handle inclusion of this into Wikipedia, but since this is the scientific view of the myths it seems more appropriate for this to be attached to this article. I ask the more experienced editors... would this be more appropriate as a separate article?

Rursus 21:17, 27 December 2006 (UTC) says from here:

I opinionate thusly: it would be more appropriate as a separate article, since the text is off-topic from Ice Age and far too long - however: making a short 'Myth interpretation section linking from Ice Age to that article may be OK. You may do it by the following steps:
1. add a link text to the section just below the heading, such as for example:
Main Article: Ice Age Myth Interpretations,
2. create a new web browser window/tab, and there go to wikipedia:Ice Age,
3. edit Ice Age Myth Interpretations in the old window by looking up Ice Age Myth Interpretations and creating it when reaching the page "No page with that title exists."
4. in the other window edit Ice Age,
5. cut and paste as you feel is appropriate.

Rursus 21:17, 27 December 2006 (UTC) said to here. STOP.

Wikipedia logged me out because I took so long posting that. So no attribution and you don't know who to blame. Oh well. :) DMahalko 19:40, 23 December 2006 (UTC)

It should be a separate article, for the reasons already listed. Also the material must be supported with references - especially given that it all seems extraordinarily speculative. There are more widely-accepted explanations for the Great Flood myth (presumably you mean the Noah/Gilgamesh flood story). Raymond Arritt 22:13, 27 December 2006 (UTC)

List of doomsday scenarios

Could use votes to save this article, thanks MapleTree 22:28, 28 September 2006 (UTC)

Pleistocene

added section on T changes and an external link to more detailed discussion KonaScout 14:58, 16 November 2006 (UTC)

Vicious and virtuous cycles in ice ages

Can any one please explain why this was removed? It covered: (A) the increase in albedo initially accelerates the advance of the ice; (B) the advancing ice decreases weathering and thus causes an increase in the greenhouse effect, which brakes the advance of the ice; (C) during the Cryogenian Ice Age the unusual position of the continents (equatorial super-continent Rodinia) delayed the operation of mechanism (B) and therefore made both the ice age and the eventual increase in greenhouse effect much more severe than usual.Philcha 19:09, 5 December 2006 (UTC)

The only person who can say for certain why it was removed is the person who removed it (which was not me). But it's partially redundant with material that's already in the article. If you can find a way to weave it in so that it doesn't repeat what's already there, give it a shot. By the way, I suggest more specific terminology than "vicious and virtuous cycles" -- you probably want "positive and negative feedbacks." Raymond Arritt 01:36, 6 December 2006 (UTC)

Better picture

I wish there was a better picture for this article. How about a map of the world showing the areas covered by ice? I couldn't find anything on Wikicommons. Steve Dufour 04:49, 14 March 2007 (UTC)

expanding/clarifying Evidence for Ice Age section

A little background on me: I'm not an expert or anything, but I love history and although I'm only a freshman in college I have read/studied alot of subjects on my own so I have a good base knoweldge of this subject. Even though I'm not able to contribute new evidence, material or studies I feel I can contribute by pointing out what I feel are weak points in the article, in hopes someone who really knows this stuff can come in and beef them up. Anyway, I was struck by a few key points while reading this section.

Three types of evidence were discussed: geological, chemical and paleontological. Evidence is intented to convince someone of a fact, but some of the phrasing within this section seemed self defeating and unnecessary to me.

For example at the end of the paragraph explaining the geological evidence it says "Successive glaciations tend to distort and erase the geological evidence, making it difficult to interpret. It took some time for the current theory to be worked out." Is it necessary to add this? Seen from the view point of a student who is learning about ice ages for the first time, I would say this student would be confused somewhat because this statement seems to discredit the previously presented evidence.

Also, in the paragraph concerning chemical evidence: Rather than information supporting ice ages and their documentation/dating (ice cores were mentioned) here it seems this paragraph actually presents negative evidence that is not expedient towards a credible base of pro-IA evidence. "This evidence is also difficult to interpret since other factors can change isotope ratios." It basically talks about how chemical evidence is unreliable because too many other factors affect the isotopes that are studied. We should replace this paragraph with firm evidence/statistics and studies from a credible source with citations. (I would if I had the knoweledge myself)

My tertiary quibble is this: The paragraph on paleontological evidence was just as disapointing as the paragraph about chemical evidence. This paragraph states what paleontological evidence is and how it relates to glacial periods but goes no farther. Instead of bolstering the argument with successive supporting material it is followed by material that once again explains how this particular evidence is not reliable!

The last paragraph goes on to say "Despite the difficulties, analyses of ice cores and ocean sediment cores unambiguously show the record of glacials and interglacials over the past few million years." As an impartial observer I would see that and say "Hey, they just talked about how all the evidence that is used to document ice ages/glacial periods is difficult to interpret or is potentially affected by other factors, but then they say they have unambiguous records? Since this is wikipedia I have to be mindful about the legitimacy of information I find, so I think this may be fake." Come on! Beef this thing up! I don't have the knoweledge to do it myself so like I said I'm pointing out what I think are weaknesses and points that should be expounded upon and added to in order to make this article better!

You seem to be asking for a simple straightforward story, irrespective of reality. The evidence *is* difficult to interpret. But nonetheless the evidence does "unambiguously show the record of glacials...". This is not to say that the article can't be improved William M. Connolley 10:13, 15 January 2007 (UTC)

Merger done

The old Glaciation article has been merged in. Cleanup is now necessary. The way, the truth, and the light 10:18, 27 April 2007 (UTC)

'Processes which mitigate glaciation'

I removed the old contents of this section because they specifically applied to Snowball Earth only and would be misleading in the context of ice ages in general; also, the information was all already found in Snowball Earth. The way, the truth, and the light 04:13, 2 May 2007 (UTC)

Weathering

In the section "Causes of ice ages", the leading summary paragraph states "climate change itself can change the atmospheric composition (for example by changing the rate at which weathering removes CO2)."

Some explanation or reference on how "weathering removes CO2" from the atmosphere would be appreciated. Thank you. —The preceding unsigned comment was added by 207.7.185.129 (talk) 03:15, 13 May 2007 (UTC).

Ice age was more recent?

Today's New York Times has an article on the modern ice age, which the article says was some odd years more than 8,000 years ago, but still more recently than the 10,000 year figure usually cited in places like this article. Could someone with greater experience in the hard sciences please shed light on this discrepancy? Dogru144 04:22, 16 May 2007 (UTC)

I haven't seen the NYT article but 8000 years ago is very wrong. Even 10000 years ago is a little too short. The last glacial maximum (Wisconsonian) is generally held to have ended around 12000 years ago (note also Younger Dryas). This would have been 10000 BC, so maybe somebody mixed up "BC" with "years ago." Raymond Arritt 04:37, 16 May 2007 (UTC)
Thanks for the input, Raymond. The Times article location is http://www.nytimes.com/2007/05/15/science/earth/15cold.html?_r=1&oref=slogin for anyone interested in checking it out. Dogru144 07:58, 16 May 2007 (UTC)
Its the 8.2kyr event stuff William M. Connolley 09:00, 16 May 2007 (UTC)
OK. Thanks to Dogru144 for the article link. You may also want to see Lake Agassiz. Raymond Arritt 14:07, 16 May 2007 (UTC)

labeling and colors of the dust-CO2-temp graph

I found the primary graph to be confusing. It would not take much effort to reverse the axis, so time proceeds left to right.

But it is essential that the graph be labeled properly and the color error corrected in the text, where CO2 is printed in blue, and Temperature in red, which is manifestly incorrect.

The graph properly shows axis labels that correspond to the median value of the variable, but PLEASE label the curves redundantly anyway.

the article is excellent, and much appreciated.

Ignorant in Ottawa

Glaciation toggle

The difference in water surface area between the peak of glaciation and the end of an interglacial period can exceed 7%. This difference in evaporative area would have a significant effect on atmospheric water vapor quantity, average cloud cover and average cloud altitude (thus average cloud temperature). This cloud change could be a major contributor in toggling between glaciation and interglacial climates. Has this been considered? Dan Pangburn 00:21, 26 August 2007 (UTC)

The question is whether someone published a study which considers this. We here don't experiment with glaciers and changing the Earth's surface area because the Environmental Impact Statements are too unwieldy. (SEWilco 04:11, 26 August 2007 (UTC))

Dates for Ice Ages conflict with other article

Timeline of glaciation gives alternate dates for earliest hypothesized ice ages. Those dates appear to be sourced. JP 01:40, 21 September 2007 (UTC)

Bad reference

Hello-

I noitced that one of the references is wrong. Should be: "Frozen Earth: The Once and Future Story of Ice Ages" -- I would have corrected it, but I don't know how to change reference lists. —Preceding unsigned comment added by 129.79.184.227 (talk) 18:17, 7 November 2007 (UTC)

Mitigations confused with causation

In the section on mitigating factors that can lead to a worsening Ice Age, several of the items included are the prospective effects of global warming (either manmade or natural) cycles. Since global warming itself is either a mitigating factor to alleviate glaciation or is a factor to either prolong or end an interglacial period, if it can be argued to cause increased glaciation at all it should be treated as a cause of glaciation and not a mitigating factor to worsen it. It's not logical to argue that warming would worsen glaciation, only that it could trigger it, which is actually what the argument says. It's just been placed in the wrong part of the article. Anytime we get into global warming, I start to smell a rat with regard to the quality of the discussion. Too much junk science and politics (and I mean on both sides of the discussion) mixed up with a legitimate scientific concern. In the context of cause and effect in relation to glaciation cycles, a good litmus test for whether global warming is being discussed fairly and logically is to ask whether the proposed effects of global warming held true during the most severe global warming recorded, which was following the Younger Dryas period and not (at least so far, or even by the suggestions of most scientists) during the global warming uptick currently being experienced and widely attributed to the use of fossil fuels. If the earlier and more severe global warming cycle did not cause these things, it's not likely the less severe global warming forecast as a result of human activity will have a more dire effect.Ftjrwrites (talk) 20:40, 10 December 2007 (UTC)

Recent glacial and interglacial phases + Glaciation in North America

The section Recent glacial and interglacial phases points to Timeline of glaciation as main article, a somewhat mixed article, one half about all major episodes of glaciations in Earth's history, and the other to the Quaternary glaciation timeline. So something's wrong, the article should be Timeline of last glaciation or similar ... and there should be at least a bit of text in the corresponding section here. The section Glaciation in North America is about the Wisconsin Glaciation, which is a glacial phase of the Quaternary glaciation. This topic should be a sub-section of the preceding section as long as the other stages of the Quaternary glaciation are missing.

I renamed and moved it accordingly to third level, adding the names of all major NA glacial stages according to the Timeline-article.--Jo (talk) 20:49, 30 January 2008 (UTC)

Edited this section for clarity, so that it wouldn't appear to be concerned with fossil fuel use in fifty thousand years, and to dispel the notion that the idea of a 12,000-year interglacial period can be "widely contradicted" by one article which only asserts that it may be contradicted. —Preceding unsigned comment added by 0nullbinary0 (talk • contribs) 04:51, 25 April 2008 (UTC)

Fictional Ice Age

I'm working on a fiction that involves the beginning of a new Ice Age, over several hundred years, and am contemplating potential causes. I was considering atmospheric change: specifically, gases released by decomposition of 9/10th (or so) of the world population, and a goodly chunk of it's non-human life, after an extinction level event like a super virus. Could such massive decomposition be enough to kick start an ice age?

--Rencheple (talk) 17:58, 11 April 2008 (UTC)

It is not known exactly what processes trigger an ice age. However, decomposition is known to release methane which is a global warming gas. Also, do the math on how much meat you're thinking about; there probably isn't enough meat to affect the planet unless the insects also die. And the most significant effect of the insects dying would probably be a lack of pollination of the last generation of flowering plants. But I don't know if that would affect ice processes. -- SEWilco (talk) 19:06, 11 April 2008 (UTC)

Shouldn't this say "glacials"?

Ice ages can be further divided by location and time;... The examples given are glacials not ice ages. Could s.o. check and correct, please. 71.236.23.111 (talk) 15:56, 20 May 2008 (UTC)

Pole Shift

I removed this section which was under Volcanism:

    • It is possible that the ice age never occured at all. Rather, that a phenomenon known as pole shift is responsible for the glaciation in north america and northern europe. Pole shift is an event where the earth's crust rotates over the mantle. Pole shift is described in detail in another article.

Relatively intact wooley mammoth carcasses have been recovered from the Siberian permafrost. For this to occur freezing would have to have happened in days or perhaps even hours. Some even have been found to have undigested daisies in their stomachs, flowers that do not grow in such northern climbs. Pole shift presents a possible explaination of how this might have occured.

A review of various maps depicting the ice age depict Siberia and northern Alaska to be free of ice sheets. A possible explanation could be that the north pole had originally existed 30 degrees to the south towards greenland. In other words, possibly there was no extensive ice age, but rather a shift of the ice cap itself.

The rapid climatic change suggested by pole shift theory has many implications that need to be explored, such as the length and extent of sea level changes and if and when ice sheets existed in Panagonia. Other possible implications include the disapearance of Atlantis, worldwide peridic dinosaur extinctions, and even Noah's Ark.**

Unless there is some source cited which would pass muster at any university, this section seemed out of place here. If I'm out of line, please restore it.

209.130.192.20 (talk) 18:12, 21 May 2008 (UTC)

Re-removed. Seems this bit of WP:OR or WP:Fringe was added just prior to a bunch of ip vandalism. It is fringe nonsense and totally unsourced. Out with it. Vsmith (talk) 01:06, 22 May 2008 (UTC)

The next one

If the average length of an interglacial (warm period like today), is around 10,000 years, then should our future generations start preparing to head south, or will global warming balance things out for us?

As well, if an ice age were to happen in say, 300 years from now (2308), would northern cities like Moscow, London, and Toronto expect a towering wall of ice advancing forward, scraping rocks and pushing the skyscrapers southwards, or would they be entombed in ice and snow from winter snowfalls that don't end? RingtailedFox • Talk • Contribs 03:05, 18 June 2008 (UTC)

I don't know. To improve the article we need WP:V information. What material have you found? And are the effects on the cities relevant to this article about the ice age, or would that belong in articles about architecture and civil engineering? -- SEWilco (talk) 03:28, 18 June 2008 (UTC)
I would say it is relevant, as they are large cities (with over 2 million inhabitants each), and are very important contributors to global culture. Not to mention they are also far north, and are in places that have been covered with ice to a depth of 3 km (9000 feet) during each past glaciation. I know the Oak Ridges Moraine near Toronto was caused by glaciers pushing a great deal of soil, trees, and whatever else into that big long hill when they were advancing, and then rolled back over it upon retreating. Being roughly 4 hours from Toronto, i've always admired its office towers gleaming in the sky, and wondered if their top dozen or so floors would be poking up from an endless sea of ice in a few hundred years... a bit of a sombering legacy of human civilization to leave for the future, if you ask me. RingtailedFox • Talk • Contribs 05:05, 18 June 2008 (UTC)

Ice Age ended 10,000 or 11,000 years ago?

In this article it says that the last Ice age ended 11,000 years ago in the beginning of the article but it also says at the end of the article that it ended 10,000 years ago. Which number is correct? Thank You.Maldek (talk) 03:55, 8 July 2008 (UTC)

Does an ice age have a clearly defined end point? William M. Connolley (talk) 22:14, 9 September 2008 (UTC)
The end of the Younger Dryas at 11.784 ka is convention that is used by some stratigraphers. Dragons flight (talk) 07:13, 2 October 2008 (UTC)
According to The Niels Bohr Institute at the University of Copenhagen the latest glacial age ended 11711 years ago. The website states that this date is now the international standard reference. -80.163.93.206 (talk) 09:05, 11 December 2008 (UTC)

Kuhle?

This Ice_age#The_Uplift_of_the_Tibetan_Plateau_and_surrounding_Mountain Areas_above_the_Snowline seems dodgy to me William M. Connolley (talk) 22:10, 1 October 2008 (UTC)

It looks like self-promotion or a work of a loving fan. The papers themselves were published in second rate climatology journals and do not have (yet?) enough resonance to make them enyclopedic. I would vote for removing the section or at least to reducing it a one sentence mentioning this hypothesis exists. --Friendly Neighbour (talk) 07:01, 2 October 2008 (UTC)

Companion article requested

In a few words, literally: List of ice ages...

  • Trigger desire is documentary that implied "The Ice Ages", the proto-humans in Africa, and joining of south-north America more or less contemporaneously. Clearly the article has given a different meaning to "Major Ice Ages"... since there existed some big ones previous to 2- 3 million years ago. (Scripts' inaccuracy out of context, no doubt!) Hence, listing a table of advances and perhaps keyed to locales where advances have been shown, strikes me as a good thing to have around. // FrankB 04:55, 23 November 2008 (UTC)

use of word "worker[s]"

I am not a native speaker, still -- shouldn't it rather be 'researcher' or 'scientist' ? 136.173.162.129 (talk) 11:52, 27 November 2008 (UTC)

-Worker is common usage in the field. -Tom Bishop

Study of permafrost, & an alternative view of the ice age

"An extraordinary testimony to the widespread watery destruction of animal life...They are sometimes found in a near-perfect state of preservation, with undigested tropical vegetation in their stomachs." - Earth’s Most Challenging Mysteries.--Standforder (talk) 00:08, 10 December 2008 (UTC)

The "ice age" wasn't a long period, the term is misleading. The earth previous to this brief "ice age" was tropical-like. This rapid freezing put the earth in freezing [temperature]]s. The "ice age" occured nearly 4,400 years, (Compare Genesis 7:18, 21).--Standforder (talk) 00:08, 10 December 2008 (UTC)

"A sinking of the sea basins would cause the waters to collect there, allowing dry land to appear again. Compare Psalm 104:8. In the oceans today there is more than enough water to have accomplished what the Bible describes; 71 percent of the earth’s surface is water, with an average depth of two and a half miles."--Standforder (talk) 00:08, 10 December 2008 (UTC)

Not sure what you are getting at... None of this seems relevant to the article. Richard New Forest (talk) 14:40, 10 December 2008 (UTC)

It does too relate to the article.--Standforder (talk) 23:30, 21 December 2008 (UTC)

Biblical interpretations are not relevant to the scientific understanding of the ice age. (Especially since the ice age did not occur 4400 years ago and was in the last example 100,000 years long, hence not "brief".) Dragons flight (talk) 00:01, 22 December 2008 (UTC)

In addition, the claim that "animal life", specifically the mummified mammoths, and horses, and other animals (in either Alaska or Siberia) are "...sometimes found in a near-perfect state of preservation, with undigested tropical vegetation in their stomachs" is a complete and utter falsehood. These mummified animals were neither in a near perfect state of preservation nor did they have tropical vegetation in their stomachs when they were found. This is discussed in Woolly Mammoths: Evidence of Catastrophe?, MOM and Atlantis, Mammoths, and Crustal Shift, and CC361.2: Quick-frozen mammoths.

Published articles that discuss the imaginary nature of claims about the "near-perfect preservation" of these animals and tropical plants being found in their stomachs are:

Brass, M., 2002, Tracing Graham Hancock's Shifting Cataclysm. Skeptical Inquirer. vol. 26, no. 4, p. 45-49. and

Farrand, W. R., 1961, Frozen Mammoths and Modern Geology: The death of the giants can be explained as a hazard of tundra life, without evoking catastrophic events. Science. vol. 133. no. 3455, p. 729-735. Paul H. (talk) 05:37, 23 December 2008 (UTC)

Vulcanism

The author of this section seems to rule out the possibility that volcanoes can contribute to ice ages, yet there is some evidence that reflective aerosols cause a net cooling effect on the short term (eg. mt. pinatubo). Conflicting evidence (Tuba eruption 70ka) suggests that volcanism has nothing to do with it. I am not familiar with research into the effects of supervolcanoes on climate change, but there was supposedly a massive sea level fall associated with the siberian traps volcanism 251 million years ago that could indicate the initiation of an ice age. The long term net effect of volcanism may be heating, yet that doesn't rule out it's role in the initiation of an ice age. —The preceding unsigned comment was added by Luokehao (talk • contribs) 17:29, 21 December 2006.

If you can find a reference for it, go ahead and add a sentence or so. By the way, please sign your comments by putting four tildes at the end, like this: ~~~~ Thanks. Raymond Arritt 18:59, 21 December 2006 (UTC)
Ice ages are periodic - this is the main evidence linking them to orbital variations. Volcanoes, as far as we know, aren't. QED. You are talking about the current 100 kyr ice age cycle, aren't you? William M. Connolley 19:49, 21 December 2006 (UTC)

I thought undersea volcanism could trigger an ice age by warming the oceans, thereby increasing precipitation. If this happens at the right part of the Milenkovich cycle, increased snowfall at high latitudes would increase albedo, and therefor cooling. —Preceding unsigned comment added by 150.195.11.24 (talk) 19:29, 10 March 2009 (UTC)

Does anyone know what happened to the sun durning the ice age?

I am an Activities Assistant at a nursing home and one of my resident would like to know, so if anyone has an answer would you please email it to me at <address removed to prevent spam>, thanks for your help—The preceding unsigned comment was added by 72.135.25.85 (talk • contribs).

Wikipedia is no question and answer website. However I will give a short reply.
Nothing happened to the sun. It is the Earth orbit that changes in ways that causes polar regions to have more or less sun irradiance in summer from time to time (I speak about cycles of tens of thousands years). When summers far north (North Canada but also the mountains of Norway) are too cold to melt all the winter snow, an ice age starts. That's the simplest explanation (of course more factors play role in real word but the talk page is no place for a lecture). --Friendly Neighbour 06:04, 29 June 2007 (UTC)
How do we know that nothing happens to the Sun? Records of solar variations don't go anywhere near far enough back. Since there is still doubt about the mechanism behind ice ages, excluding changes in the Sun from consideration seems arbitrary.0nullbinary0 (talk) 03:53, 25 April 2008 (UTC)
Solar output variations have an 11 year cyclicity which can be detected in tree rings, varved lake records and ice core records. There may also be longer-term solar variations, but it would be quite a coincidence if they happened to coincide with the orbital periodicities of a minor planet like ours! There is also more direct evidence from N/O ratios in ice cores which are sensitive to local incoming sunlight (as opposed to global climate variation) - the technique is described here:
http://www.ncdc.noaa.gov/paleo/pubs/kawamura2007/kawamura2007.html
These studies indicate that incoming sunlight to Antarctica varied as expected in line with Earth's orbital periodicities, and did not include other major components of comparable magnitude (eg large scale solar output variations). This is consistent with the overall geological record of global climate change which indicates major variation at orbital periodicities (including, of course, annual!) and not much at other periodicities, except very long term (possibly tectonic) trends of the order of millions of years (which aren't really periodicities anyway). Cf the Wikipedia article on solar variation. So the answer to the question  : What did the sun do during ice ages? is probably: "pretty much what it does now". It was the orbital geometry of the Earth that "changed" (ie continued to vary) and that appears to have paced past climate change.Orbitalforam (talk) 13:56, 12 June 2009 (UTC)

Ice-albedo feedback

This description of the ice-albedo feedback under "Processes which make glacial periods more severe" is unclear. The use of the word "equilibrium" seems to imply that this positive feedback loop equilibrates _on its own_, which is clearly false. I suggest changing the wording to something like, "Hence, when the air temperature decreases, ice and snow fields grow, and this continues until [competition with a negative feedback mechanism forces the system to an equilibrium]."

Bradweir (talk) 23:25, 7 May 2009 (UTC)

Major ice ages

The CO2 reference below is conjecture and should be removed, unless someone can provide peer review substantiation for this speculation.

"The earliest well-documented ice age, and probably the most severe of the last 1 billion years, occurred from 850 to 630 million years ago (the Cryogenian period) and may have produced a Snowball Earth in which permanent ice covered the entire globe and was ended by the effects of the accumulation of greenhouse gases such as CO2 produced by volcanoes." —Preceding unsigned comment added by 99.241.247.201 (talk) 23:32, 7 May 2009 (UTC)

Actually that is a pretty standard argument for the "Snowball Earth" theory (see Hoffman, Kauffman, Halverson and Shrag, Science 1998281,1342-1346), or a review paper here:
http://www.ias.ac.in/currsci/apr102003/871.pdf


A mechanism such as this (ie Greenhouse gas increase) is required to explain how the planet could escape from a "Snowball state" if it entered one, since the high albedo of an ice-covered world would otherwise be expected to maintain its chilly state.Orbitalforam (talk) 12:16, 12 June 2009 (UTC)

Article probation

Please note that, by a decision of the Wikipedia community, this article and others relating to climate change (broadly construed) has been placed under article probation. Editors making disruptive edits may be blocked temporarily from editing the encyclopedia, or subject to other administrative remedies, according to standards that may be higher than elsewhere on Wikipedia. Please see Wikipedia:General sanctions/Climate change probation for full information and to review the decision. -- ChrisO (talk) 19:38, 2 January 2010 (UTC)

Variations in the Sun's energy output

In the section: Variations in the Sun's energy output

The phrase: "The long-term increase in the Sun's output cannot be a cause of ice ages." needs some improvement. Oh, I see that is discussing an overall increase in the sun's energy, and not a cyclical phenomenon.

The whole section, however, needs to be updated.

Also, refer to the Wikipedia article: http://en.wikipedia.org/wiki/Sun#Possible_long-term_cycle

This Wikipedia article lists a couple of sources: http://www.newscientist.com/article/mg19325884.500-suns-fickle-heart-may-leave-us-cold.html and http://arxiv.org/abs/astro-ph/0701117

Which indicate a hypothesis that there may be long-term cycles in the sun's output energy that would generate either 41K year or 100K year (on average) cycles of the sun's output leading to the the cyclic glacial / interglacial periods, and these solar cycles may better explain the temperature variations than Milankovitch cycles.--Keelec (talk) 04:43, 17 January 2010 (UTC)

For the moment, I'd say this theory is too fringe to be worth including - it seems to have *no* published papers at all supporting it. My immeadiate reaction is that it is a bizarre co-incidence that the sun's core should just happen to have temperature cycles that match not one but two of the important cycles of the earths orbit. This, I think, is stretching things just a bit too far: without having read the arXiv stuff, I think it is fairly obvious that the author has tuned his model to produce these numbers William M. Connolley (talk) 11:07, 17 January 2010 (UTC)
Endorse the position that references should be papers in peer-reviewed/refereed journals for a topic that has political potential (and anything that relates to global warming has a political potential). Williamborg (Bill) 23:43, 17 January 2010 (UTC)

Interglacial Duration

Shouldn't the article provide more sources for the average durations of interglacials? It appears that several sources indicate that interglacials have an average duration of 10K to 12K years. For example, this says an average of 10K years. And this says: "Over the last one million years there have been about eight Major Ice ages of about 115 kiloyears duration." Now 8 x 115K equals 920,000 and 1,000,000 - 920,000 = 80,000. 80,000/8 = 10,000 so I can see where the average is coming from. I think there are a large number of valid (e.g. actual science) sources that provide these numbers. Shouldn't we be providing that information in the article (with appropriate references of course)? Comments? (And please -- this has nothing to do with global warming etc. -- this has to do with evidence related to the past, not the present.) SunSw0rd (talk) 14:39, 9 February 2010 (UTC)

People bandy numbers around for interglacial duration a bit carelessly - [14] certainly does. Look at the graphs - it isn't even obvous which bit you measure William M. Connolley (talk) 11:00, 18 February 2010 (UTC)

SVG versus PNG plot

Zeog -- what do you prefer in File:Vostok-ice-core-petit.png compared to File:Vostok Petit data.svg? I'd like to incorporate your suggestions to improve it so that we can replace the bitmap image with a vector one as part of WP:SVG. Personally I found the three separate, overlapping Y axis scales in the bitmap very difficult to read since they did not immediately appear to correspond to the different lines. -- Autopilot (talk) 23:04, 21 June 2010 (UTC)

No response for a month; I'll change it back to the svg file. Zeog -- if you have a problem please discuss it here before reverting again. -- Autopilot (talk) 03:23, 16 July 2010 (UTC)
Because it is actually possible to read the text on the non-svg version? --Kim D. Petersen (talk) 20:29, 26 August 2010 (UTC)

Non-Ice Age

I see that WP has articles on Ice ages and the shorter period glacial and interglacial periods between ice ages. But what are the long-term intervals called between Ice Ages? Non-Ice Ages? Warm Ages? I can't find any research or references to these long-period intervals and what the climate, fauna, etc was like. I imagine that these "Warm Ages" also had shorter-period variations analogous to glacial and interglacial periods. Anyone want to address this? —Preceding unsigned comment added by 66.162.130.210 (talk • contribs) 00:09, 24 October 2009

Don't know about the WP article. I have always called the 'non-ice age' as "earth normal." Since we technically live in an ice age even with the interglacial period we live in the earths average temperature is between 5 to 8 deg C warming then what it is today. --OxAO (talk) 00:24, 15 September 2010 (UTC)

Do you mean the kind of "norm" that existed before the present series of Ice Ages began? I don't think it has an official name but I always called it "Pre-Himalayan" and "Pre-Panamanian". Have you seen the Article's Vostok graph of temperature-v-time? That is a very repetitious graph, with time on the horizontal axis and temperature on the vertical axis, of how earth temperature varies as the planets all heave and tug on each other and the sun goes through its variability cycles. Now that curve has always been there, for as long as the solar system has been there, but in ancient times, millions of years ago, the entire graph was "higher up the page", so that we went from Very Warm to Warm, and back again. Then around 40 million years ago, the Himalayas happened. This was an unusually lofty and extensive mountain range by earthly standards and the air moving over it cooled, then condensed as it came down the other side, causing monsoons which washed the CO2 out of the atmosphere and cooled the entire planet. At that point, the whole graph, without changing its shape, just slid vertically right down the page, so that instead of going from Very Warm to Warm and back again, we were now going from Warm to Cool and back again. Next, about 2.5 million years ago, the Panama land bridge was formed, joining North and South America, and this diverted the Gulf Stream. At that point the graph, without changing its shape, again slid right down the page, so that we're now going from Cool to Freezing and back again -- the present Ice Age sequence. So I guess an appropriate answer would be that in the dinosaurs' days we had a "Pre-Himayalan" temperature norm, then after the Himayalas were formed we had a "Pre-Panamanian " temperature norm, and now we have a "Glacial/Interglacial" norm. But these are my names; they are not official. I'm not sure there are any official names. (204.112.57.130 (talk) 21:16, 26 March 2011 (UTC))

173.165.228.33 (talk) 15:59, 25 May 2011 (UTC) I also would like to see more definition as to the length and temperature between ice ages. Water vapor content of early atmos is essential for accurate description of ice ages. If the Med was dry until 5 mya before now, how long was it dry. Science says in order to have ice ages there must be the water vapor in the atmos to fall as snow.

AGW editing

This article is a load of bull, I have a pdf containing a graph that has a chart with references, please look at figure 6 on page 11 of the following pdf: http://spinonthat.com/CO2_files/CO2tdino.pdf

I have read some of the articles myself, and I feel that while wikipedia was once good, I have observed articles changing for the worse over the past couple of years. This especially includes articles which once represented skepticism towards AGW fairly, which now after having looked at them again, do not.

Wikipedia has lost alot of useful information. Indeed it is censored. I remember reading the "ammonium nitrate" article where a recipe for making it into a military grade explosive was in the article, which is now gone (and in fact, much of the rest of the information that was in the article is gone, including the synthesis of ammonium nitrate).

I don't care if this information can be used for bad things. We have a right to free learning and free information on the web and this bending over to homeland security and the UN to omit information against their global warming scam is a complete joke, and honestly, wikipedia is becoming a joke for having censored information. I deeply resent your site and I think since alex jones reported the changes to your page, who did it, and how wikipedia responded. The lack of a note on these pages about the issue that people have is offensive and I feel that people deserve to be made aware of the controversy involved. If you cannot ensure that your editors present information in a fair and unbiased way, then what good is your site? I can't learn anything about the world when so much disinformation is being given out, so much information is now omitted from your articles.

I'm not the only one that feels this way. I am personally going to lobby people to boycott your site until your site takes a more impartial presentation of information for learning purposes. Clearly the angle given on AGW and ice age, climate change, etc, is spun to such a degree as to support the UN's perspective that AGW exists. A recent article on physorg.com supports the following:

Climate change models are not accurate (aside from climategate and IPCC fraud) due to the lack of knowledge regarding the behavior of airborne particulates (and any associated reactions which may take place that we do not know about).

It can be found here: http://www.physorg.com/news180628222.html

Your articles do not state much about the "unknowns" and "alternate viewpoints", and therefore come across as heavily biased towards supporting AGW. Cherry picking the weakest counter-arguments against AGW is just as fraudulant as the IPCC doing climategate, and to be honest nobody here believes that it didn't happen considering the statements made by IPCC scientists that support the notion that they committed fraud (as some let this information slip out in video interviews which can be found on prisonplanet.com).

Can wikipedia start presenting factual information or are we supposed to accept this fraud from you as well? Should Alex Jones and I start a wiki about wikipedia articles being inaccurate? Because I am about to make a serious proposal to him to develop software to counter the disinformation your site spews out to people, starting with AGW, and anything else homeland security is paid to bully your site into making things disappear (weather the owner gets paid to allow it, or is forced to do it, or if it's hundreds of homeland security members who actually are the editors, or bribing your editors). Either way we know what's going on and we aren't dumb and you ought to present the medieval warming period information, as well as the fact that we are currently in the middle of an ice age, and that historically, 545 million years ago the co2 levels were near 8000 ppm. Start presenting some real facts, or we will start a site that will. —Preceding unsigned comment added by Stealthc (talk • contribs) 03:04, 24 December 2009 (UTC)

Go for it, can't wait to see en.truthpedia.org/list_of_Lizard_people_in_politics70.226.116.134 (talk) 23:42, 18 November 2010 (UTC)
Dear user talk poster above:
what do lizard people have to do with this? We are talking about greedy people using words to deceive us. That sort of stuff happens all the time. Speak for yourself, you cannot deny the basis of AGW revisionism by claiming the tin foil hat argument, this article's viewers can see for themselves how it is clearly biased towards AGW. It does not present both sides of the story, therefore it is entirely erroneous.. — Preceding unsigned comment added by Stealthc (talk • contribs) 08:27, 27 January 2011 (UTC)


It is disappointing but to be expected. Himilayas increase rainfall which must leave water vapor unaffected because the magic of CO2 ... what a load of bull. Anyway, there are some useful references in material like this in wiki if the general content is useless. —Preceding unsigned comment added by 66.38.159.33 (talk) 03:14, 18 February 2010 (UTC)

Precise Definition of Ice Age

This article describes an Ice Age as "a geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in an expansion of continental ice sheets, polar ice sheets and alpine glaciers.". I am not a scientist but to mee this definition seems a bit "wooly". What counts as long term? How far should temperatures fall below their "long term" levels before an ice age is identified? What percentage of the earth should be covered in glaciation? etc etc

I was unable to find anything better on the web so it may be that the above description is the scientific consensus, does anyone know? Alternatively perhaps people think this issue is too esoteric for an encyclopedia?

Zanzare (talk) 14:10, 30 December 2009 (UTC)

I don't think there is any need for a precise definition, from a scientific POV. It is just a label (analogy: there was no need for a precise defn of "planet" from a science POV) William M. Connolley (talk) 22:49, 30 December 2009 (UTC)
It is a fuzzy term, though the time-spans are typically millions of years or more. I just made some changes to the lede that will hopefully improve some clarity. Awickert (talk) 23:04, 30 December 2009 (UTC)
While I agree that neither "age ice" nor "planet" would necessarily need a strict definition, we should beware the fate of Pluto.94.220.254.157 (talk) 04:27, 1 March 2010 (UTC)

Pluto is still there. That's the thing about labels, they don't change the facts, they're just useful handles for describing them. Tasty monster (=TS ) 18:49, 20 September 2010 (UTC)

New version

I think it is better and more correct the new version of "Ice age",this one:

"An "Ice Age" or, more precisely, "Glacial Age" is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in an existence of continental ice sheets, polar ice sheets and alpine glaciers.

The Earth's climatic history has been divided, in intervals of millions of years, into Ice Ages and Interglacial Ages. The term Ice Age refers to a long interval of time (millions years) where the Earth's poles are covered with ice sheets more or less extensive and where the average temperature of the poles remains below 0 °C) [2]. The Ice Ages are considered the Earth's climate history "seasons" and they are divided into Glacial periods (or alternatively "glacials") and Interglacial periods (or "Interglacials"). The Glacials are the stages of advancement of the ice sheets (called glaciations) and the Interglacials are the stages of retreat (these periods last for thousand years).

Interglacial Ages last millions of years, when the ice sheets have retreated to a minimum extent at the poles, and they separate two successive Ice Ages."

We should vote to choose the best one.--93.151.235.163 (talk) 10:39, 20 September 2010 (UTC)

No we shouldn't. We should discuss how to improve the article. Tasty monster (=TS ) 18:54, 20 September 2010 (UTC)

Main image of the globe during the ice age

Anyone agree the heading image of the earth seen from space at the height of the last glaciation is not very helpful? I've been trying for fifteen minutes to match it to ordinary geography, that is to grasp from what angle it's supposed to show the earth. I supppose the N Atlantic is at the centre, but the rest? If northern Europe is the big hump on the top right, then what are the big white spots at right centre of the picture? Ethiopia and east Africa? That won't do: those ice sheets were relatively small in extent compared to those in the north. The edge outline of the ice to the left looks strange too. The lack of differentiation between non-glaciated continents and sea is a big drawback - both are shown as simply dark! I've seen much better pictures using the same idea, at the very least this one needs some captioning. Strausszek (talk) 10:03, 20 October 2010 (UTC)

I must say I had the same difficulty, but it became much clearer as soon as I blew it up a bit, when cloud over the oceans seems to become less obtrusive. The image has N at the top; the west coast of West Africa is at the centre, with Europe at upper right, S America creeping into the lower left, N Am upper L, the whole of Africa lower R. The smaller white area I think you mean at about 2 o'clock is I think the Caucasian mountains. The only white in Africa looks like cloud from the original image. More contrast for continents would certainly help at the image size WP users are likely to see it. Richard New Forest (talk) 22:50, 20 October 2010 (UTC)

Overly long paragraphs

Some of the paragraphs in the article are way too long, which adversely affects readability. That's bad writing for for all but very advanced literary writers, who can sometimes pull it off. Most writers should instead break larger paragraphs into smaller ones. Especially in articles for wide public consumption.

69.171.160.110 (talk) 02:24, 27 September 2011 (UTC)

Positve and negative feedbacks

Whoever wrote the POV push about global warming and specifically about positive and negative feedbacks seems to have very little idea what they mean. Positive feedback both warms and cools as does negative feedback. The difference is not the direction of effect but whether they increase of diminish the effect of a stimulus. Positive feedback creates a greater change than would be expected by the stimulus alone. Negative feedback reduces the effect. Although... it's more complicated in the real world due to phase changes. — Preceding unsigned comment added by 81.106.237.60 (talk) 18:38, 18 April 2012 (UTC)

Does this section have anything to do with [15]? I've reverted that, because the sentence in question (a) makes sense, (b) adds to the article and (c) isn't a POV push. However, if you don't understand it, please say so and I can try to explain William M. Connolley (talk) 18:43, 18 April 2012 (UTC)

Volcanism

"There appears to be no geological evidence for such eruptions at the right time, but this does not prove they did not happen." That's an incredibly unscientific statement. Should it be reworded? Or eliminated? 167.206.122.66 (talk) 17:17, 24 September 2012 (UTC)

No mention of "Icehouse"

This article surely needs to talk about, or at least link to the article on Greenhouse and icehouse Earth, since an "Ice Age" is only a period within an "Ice House", etc. --Hibernian (talk) 01:45, 11 March 2013 (UTC)

Megafauna Paradox Not Mentioned

The latest BBC tv series Ice Age Beasts features the "elephant in the room" (pun intended) which is the conundrum of how millions of mammoths and other megafauna managed to survive the colder ice age period compared to the interglacial conditions of today. How did grass manage to grow in Siberia where it doesn't grow today? This paradox needs a mention at least, due to it putting the whole ice age theory into question. (P.S. A more common sense idea imv is that Jupiter's 100,000yr cycle increases the Earth's equatorial tidal strength which can even push warm water into the Arctic Basin). 176.24.226.120 (talk) 21:08, 31 May 2013 (UTC) Alan Lowey

  1. ^ V. I. Haltrin, W. E. McBride III, and R. A. Arnone (2001). "SPECTRAL APPROACH TO CALCULATE SPECULAR REFLECTION OF LIGHT FROM WAVY WATER SURFACE" (PDF). Proceedings of D. S. Rozhdestvensky Optical Society. pp. 133 to 138. {{cite journal}}: Check date values in: |date= (help); line feed character in |title= at position 51 (help)CS1 maint: multiple names: authors list (link)
  2. ^ J. Imbrie and K.P.Imbrie, Ice Ages: Solving the Mystery (Short Hills NJ: Enslow Publishers) 1979.
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