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In Serbian or Croatian, there is no official way to transcribe the letters, so Milankovitch is actually very not correct. Why wouldn't the name of the article be "Milanković cycle"? Beauty of Serbian language is that it also uses the latin script, which is then the same as a Croatian script, so there's no any trivia around this.
Whether the name is or isn't known in a misspelled form, it seems that any self-respecting person would wish to honor Milanković with the correct spelling of his name. There is literally no uncertainty about the correctness of the NAME of this eminent person. The beauty or merits of the language are entirely besides the point. It is rather objectively disrespectful.— Preceding unsigned comment added by 75.150.214.2 ( talk • contribs)
second this
i knew it as milankovic cycle but that was 404 not even disambiguation
and it is spelled that way in the article headed with the alternatic spelling
at least index it right even i fyou redirect it — Preceding unsigned comment added by 24.254.189.92 ( talk • contribs) 22:27, 30 November 2015 (UTC)
Why would the graph at the top of the page show time flowing from right to left? It is unconventional and might appear misleading to some. GBMorris 13:31, 25 July 2007 (UTC)
Image:Earth_axis_tilt_and_precession.jpg has two apparent errors:
The blue box indicates the Minimum, not Maximum, Axial Tilt.
The duration of 21000 years is half of, not twice, 41000 years;
thus there are about two 21000 year periods in a 41000 year period.
Joe Kress 05:34, Aug 26, 2004 (UTC)
I note the orbital forcing content. I thought the explanation of the cycles should be here, as the physical movements are part of this topic while it is possible that the orbital forcing article may be more focused on the effects of movements. Whatever happens in the other article, this seemed like the place to begin explanations. — SEWilco 07:26, 7 Mar 2005 (UTC)
( William M. Connolley 10:04, 7 Mar 2005 (UTC)) I removed this:
I couldn't make sense of it. The orbital periods are all well known, how could it be otherwise? The 413 kyr period is largest (say Imbrie and Imbrie).
( William M. Connolley 22:11, 15 Mar 2005 (UTC)) SEW added:
This seems weird to me. The 100 kyr peak is the largest in the spectral record (Imbrie, Science, 1980; many other places too). Records contain only 10-20% of their energy in the obliquity and precession bands. doesn't seem to be too relevant, except to demonstrate that they are small - but since they are not the 100 kyr signal, that doesn't seem to be relevant to whether there is a 100 kyr signal (except to support it).
1.) I have been studying a book on the Milankovitch cycles (The Dynamic Earth, OU) which suggests that the main effect of the changing shape of the orbit is to change the amount of solar radiation reaching the Earth as a whole, in addition to a subsidiary effect accentuating the seasonal changes in one hemisphere. I don't see any mention of such a total increase in radiation for highly elliptical orbits here, and I would have thought intuitively that the greater time spent further away from the Sun would balance the time spent in close approach. Does this effect exist? Tonderai 18:27, Apr 25, 2005 (UTC)
I'm puzzled by a couple of things. First, the eccentricity effect does change the total solar insolation over a year, wheras the effects axial precession, polar wobble, and orbital precession pretty clearly don't. They can only have an effect through second order effects due to the arrangement of landmasses on the earth. I don't understand the expression of surprise in the article that eccentricity seems to be the dominant effect. Second, if my sums are right, the total insolation is proportional to (1+0.5*e^2) to lowest order in e. So the maximum deflection is about 0.25%, or 3.4 Wm-2. That's about twice the forcing due to greenhouse gasses that everybody is so het up about at the moment. What am I missing? —Preceding unsigned comment added by 79.68.98.200 ( talk) 18:54, 10 September 2008 (UTC)
2.) From the article Due to the eccentricity resembling a circular orbit, there is a 6% difference in the amount of solar radiation during summer in the two hemispheres. (from Present Conditions). I understood that it was the current eccentricity of the orbit that caused the difference in solar radiation between summers in different hemispheres. A circular orbit would mean there was no difference between the hemispheres. Correct? Tonderai 18:27, Apr 25, 2005 (UTC)
Why does the eccentricity change? 84.191.227.100 17:16, 26 January 2006 (UTC)
Please copy the images to Wikimedia Commons. -- Saperaud 5 July 2005 11:30 (UTC)
Perihelion and aphelion are points (in space or time). They occur during a season. Perihelion may occur during summer, but summer cannot occur during perihelion. The mistake occurs several times in the article.
[Above comment by 24.112.15.149 on 8 October 2005]
Good point. I've rewritten two sentences where this occurs. -- JimR 12:28, 27 October 2005 (UTC)
The page needs a bit on how the axial tilt affects the latitude of the Arctic and Antarctic circles, including the distance and degrees latitude they range over. Including the total surface area ranged over would be a good datum for those who don't have the foggiest notion of how to calculate the surface area of a section of a sphere. ;) As the circles move towards the poles, there's less area in 24 hours to six months continous darkness per year, which reduces the net heat radiation of Earth.
The History Channel's recent documentary on the "Little Ice Age (Big Chill)" had nothing on Milankovitch cycles. That was a rather large omission!
It would be nice to see some of the successes of this theory, rather than just the problems! As it stands, it looks like there is very little reason to accept that Milankovitch explains anything. I suggest a figure showing the coherency and power spectra of the 65N insolation and some of the untuned ODP cores. Also the new EPICA Dome C records?
I've added some references on orbital forcing climate effects before the Quaternary (the articles of Zachos are the ones usually cited), and links to the simulation data of Berger (1978 and 1992, 1-5 My BP), Laskar et al. (1993 and 2004, up to ~50-65 My BP) and Varadi et al. (2003, up to ~50 My BP). I had quite some trouble finding actual simulation data and accurate information on longer-term (ie. over more than 1-5 My) orbital forcing elsewhere, so this might be useful for others as well. The article by Varadi et al. might be a bit too technical/astrophysical, but has a very nice introduction on the subject of orbital cycles and climate, and good references. Accurate calculation of planetary orbits seems to be restricted to ~50 million years, because chaos causes errors to accumulate over long time periods. Lvzon 10:45, 23 February 2006 (UTC)
Orbitalforam 8 May 2006
While true there is some overlap, it is not so large as that. The distinction ought to be that orbital forcing is only one of many climate forcings, whereas M. cycles are primarily used in an attempt to explain the paleoclimate record. 134.121.64.253 23:07, 14 February 2007 (UTC)
I'd prefer no merge as well. People will come looking for the article under this name, and will not be able to find it. I was glad to have found it here. Jiminezwaldorf 08:10, 30 August 2007 (UTC)
It seems this merge was suggested long ago, with no proponent arguments surviving on the talk page. Change history indicates previous frustration at the lack of merge discussion, along with previous attempts to remove the merge (29 October 2005). This matter should be considered settled. - Rgrant 00:46, 5 October 2007 (UTC)
For an initial impression of what's going on in this space, i used three separate Google scholar searches. one on "Milankovitch cycles", one on "orbital forcing", and one on both quoted terms. At present, Google found more than twice as many references to "orbital forcing". Only a fraction of articles crossed memespace and referred to both terms. This technique does not tell us what specific climate theories are being discussed.
I did run across a reference indicating that popular understanding ties Milankovitch cycles to a specific mechanism for climate change.
The theory of Milankovitch cycles states that periodic changes in Earth's orbit cause increased summertime sun radiation in the northern hemisphere, which controls ice size.
However, this study suggests that the pace-keeper of ice sheet growth and retreat lies in the southern hemisphere's spring rather than the northern hemisphere's summer.
— Terradaily staff writers, from "Carbon Dioxide Did Not End The Last Ice Age" [4], Oct 04 2007
Confusingly, this recent research seems to suggest that orbital forcing is occurring, that the physical orbital mechanics first described by Milankovitch cycles are its cause, and that the theorized mechanism of climate change associated with Milankovitch cycles (longer summers in the Northern hemisphere) is causally backwards from the details of these newly observed climate changes. I look forward to seeing this topic space well organized. - Rgrant 19:00, 9 October 2007 (UTC)
It is implied that humans cause global warming in this article ("anthropogenic effects (global warming)") when that fact is still hotly debated. This asserts a particular point of view that I don't think is neutral. I think it should be changed to conform to a NPOV. -- Rcronk 20:01, 27 April 2007 (UTC)
Pfvlloyd please explain the changes you are making. You keep citing Berger and Loutre without identifying which one (they've published together several times). Maybe you know of something new, but I don't know of anything that justifies the large scale changes you are making. Dragons flight 17:10, 5 August 2007 (UTC)
Hi ! - Thanks for your interest. I see a note which says I have not replied to your questions, but since this was only placed a few hours ago, I think it's a bit steep to cancel my edits without even seeing my side of the story. Maybe this is just how you do things here!
Firstly, nearly all my comments arise from a sraightforward application of the celestial mechanics calculations of Earth orbital eccentricity which are universally accepted.
Secondly, Berger and Loutre's refinements of 1991 and 2002 provided very clear data over the past 750,000 years showing the timings and extent of eccentricity cycles. I refer you to 1991 Quaternary Science Reviews, 10: 297-397; and to Science, 23/8/02, pp1287-1288.
If you find that any of my statements are not upheld by this rather basic material, L'ld be very pleased to review and discuss.
But I would have preferred to have had the chance to do so before a summary withdrawal of my suggestions with no notice! Pfvlloyd 22:25, 5 August 2007 (UTC)
Reply -
I didn't see your note before I logged off - it was getting late here. But it was still a rather brief time allowed before posting that I had not responded to requests for an explanation. However, that's water under the bridge.
Thanks for your comments on my edits. OK, I see where you have problems with them. I think I can offer you reasonable arguments for most of your comments, but some are just plain differences of interpretation which we may never agree on, but that's science!! And I found some of the text very confused, so obviously so that I did not think an explanation for an edit was necessary in those cases.
However, I have deadlines to meet just now and cannot reply properly. Give me a day or two and I will respond properly. I really look forward to discussing these issues with you - an excellent opportunity to improve insight.
Regards. Pfvlloyd 15:22, 6 August 2007 (UTC)
The axial tilt changes slightly on a short period, less than a year, which moves the circles toward and away from the poles a bit. What would the maximum and minimum latitudes be over the 41,000 year cycle? Now for the math wizard question. What's the total surface area of the two belts the circles wander over? An important thing to remember as this relates to climate change is the very different topography of the north and south poles. The north is water surrounded mostly by land while the south is land surrounded by an unbroken ring of water. In winter, the area above the circle can get heat only via convection and a small amount that comes from the interior of Earth. The north gets heat both from water and air convection while most of the south gets heat only from air convection. the convection can't keep up with the radiant heat loss during the time the sun doesn't rise above the horizon. As the tilt decreases, there's less surface area with 24 hours or more constant darkness to radiate heat. Anyone who remembers the basic science classes they had in school knows that a planet with less axial tilt has an overall more temperate climate than a planet with a greater axial tilt, yet I've talked with several people who are convinced this should make the poles *cooler*, and thus "proof" of anthropogenic "global warming". —Preceding unsigned comment added by Bizzybody ( talk • contribs) 13:30, 20 October 2007 (UTC)
I want to understand the basis for these theories. What is the basis being used for the timeframe estimates used in this article? How did they calculate the 41,000 years and the 100,000 years? Are those numbers calculated based on geological observations tied to assumptions about radiometric dating and stratigraphic principles? Thank you. 68.253.24.169 13:53, 29 October 2007 (UTC)
It is inappropriate to insert personal queries into Wikipedia articles to get attention. It is a form of vandalism. I have removed the query from the article.
Re. "What is the basis being used for the timeframe estimates used in this article? How did they calculate the 41,000 years and the 100,000 years? re those numbers calculated based on geological observations tied to assumptions about radiometric dating and stratigraphic principles?":
I am not a geologist or paleoclimatologist, but since nobody with real credentials has answered the query I will say this: Data about climate variations in the range of tens to hundreds of thousands of years ago are available from a rich range of sources that do not depend on radiometric dating. The study of climate over this time scale depends heavily on ice cores and cores of ocean-floor sediments. These deposits record the yearly layering of snow and sediment from the present time back in unbroken series to, in the case of at least one Antarctic ice core, about 800,000 years ago. Each year adds a new, thin layer like the growth of a tree. Although it is my understanding that the precise dating of these layers is a complex professional matter, to a rough approximation, at least, one dates the layers simply by counting them, exactly like tree rings.
See the Wikipedia articles on Paleoclimatology and Ice Cores for more information. —Preceding unsigned comment added by 72.173.17.89 ( talk) 18:41, 3 November 2007 (UTC)
Ultimately, the timing of Milankovitch cycles is obtained by physical models: precession, nutation, torque, and orbital changes influenced by the moon and other planets, all plugged into simulators. Written history, tree rings, ice cores, sediments, and fossils are all useful to calibrate these models, if you can be confident that each layer represents a uniform time interval, and that migration of gases or particulate does not occur. To gain this confidence, you have to examine and correlate many individual ice cores, sediments, tree rings, and fossils. One such vital calibration is the iridium anomaly at the K-T boundary -- 99.233.186.4 ( talk) 16:39, 23 May 2010 (UTC)
In the October issue (2007) of National Geographic there is a poster called Greenhouse Earth. The bottom graphic line shows how the change in eccentricity, tilt, and wobble of the earth should have impacted global climate changed for the last 400,000 years. What is most cool about this is you can see changes in sea level, temperature, and co2 concentrations at the same time. The graph suggests that we should be in a cooling period for the last 100 thousand years....which is a concern because we are in a one of the most warm periods over the last 400,000 years. Is this correct. I didn't find any citations for this. It strange that the dotted line doesn't have a label. How solid is this evidence. Perhaps it belongs on this page. SoilMan2007 ( talk) January 1, 2008
Hello i have recently proposed the Wikiproject Earth. This Wikiproject`s scope includes this article. This wikiproject will overview the continents, oceans, atsmophere and global warming Please Voice your opinion by clicking anywhere on this comment except for my name. -- Iwilleditu Talk :) Contributions —Preceding comment was added at 15:35, 30 March 2008 (UTC)
The opening paragraph of the article states that the axial tilt varies between 21.5° and 24.5°. However, the section "Axial Tilt (Obliquity)" states that it varies between 22.1° and 24.5°. The article Axial tilt seems to agree with the latter range although it mentions the 21.5° low value in section "Long period variations", but also questions it as a possible one-time overshoot. I just happened to read this article and am not an expert on the subject, so I don't feel comfortable fixing this disparity, but most likely in the same article we should either stick to same numbers or explain the differences. -- Antti Salonen ( talk) 18:35, 4 June 2008 (UTC)
In the same paragraph there's this sentence which refers to a particular time: "It is currently 23.44 degrees and decreasing." What time are we talking about here?
Of course this is somewhat a rhetorical question. More properly put, I suggest a new formulation of this. It might go like "As of 2014, it is ??? degrees and decreasing. [reference]" Cemkay ( talk) 14:34, 4 March 2014 (UTC)
Captions for the images would be nice, especially Orbital_variation.svg. Rtdrury ( talk) 07:19, 12 August 2008 (UTC)
In this section the sets of numbers: (high eccentricity of 0.058) and (variation of −0.03 to +0.02) seem to conflict. Is the high 0.058 or is it 0.02? Rtdrury ( talk) 07:31, 12 August 2008 (UTC)
I propose expanding "the future" section with the images found on my user page. Incredio ( talk) 21:50, 31 May 2009 (UTC)
"The inclination of Earth's orbit drifts up and down relative to its present orbit with a cycle having a period of about 70,000 years....The inclination of the Earth's orbit has a 100,000 year cycle relative to the invariable plane."
Might I suggest that attention be given this apparent discrepancy? The period cannot be both values. I tracked this back to SEWilco way back in 2005 (3/7), and since it's stood for so long without revision and I hold no expertise, I'm hesitant to revise it myself. However I note that the two sources in the paragraph both reference 100k in abstract. Could somebody resolve the discrepancy? —Preceding unsigned comment added by Jjchong ( talk • contribs) 02:57, 19 August 2009 (UTC)
I think it would be nice to have a section on historical development of the theory. It would be a good section; this theory is probably notable for being the best example of a theory disproved multiple times by observations :-) William M. Connolley ( talk) 23:13, 14 December 2009 (UTC)
Yes, the various theories that were knocked down humiliated a lot of people. David Archer's book about the history of climate science ends every other chapter with "and so he died friendless and mocked by the scientific community." I no longer have access to the book ("the long thaw"), but it would make an excellent source for a history section. Would involve lots of cross-linking to ancient scientists like Agassiz. Therealhazel ( talk) 06:31, 29 December 2009 (UTC)
Is there an estimate of solar irradiance in the last glacial minimum? Joseph449008 ( talk) 22:15, 19 December 2009 (UTC)
I just added this section because someone badly needs to update this completely obsolete article. Because of the well-cited 2006 article below, pretty much all the criticisms in this Wikipedia article are out of touch. The readers will be grateful to anyone who will update it - but the amount of required work is nontrivial.
Many of the doubts about the theory disappeared in 2006 when Gerard Roe published a paper, In defense of Milankovitch, in Geophysical Research Letters, Vol. 33, L24703, doi:10.1029/2006GL027817, 2006. [9] He correctly identified the insolation with the time-derivative of the measured ice volume, rather than the ice volume itself, and obtained a spectacular agreement that has solved the 100,000-year problem and other problems below. By taking the derivative, the short-duration, higher-frequency cycles are amplified. Until this text takes Roe's paper into account, you should realize that it is obsolete. -- Lumidek ( talk) 09:37, 6 July 2010 (UTC)
I've added an NPOV tag to this article because the current version tries to hide the most important modern insight about the cycles, included in Roe's 2006 paper. I encourage educated readers to read the paper [10], check its merits and citations, decide whether I am right that it is impossible for the content of this paper to be neglected or denied by this Wikipedia article, and fix all the obsolete information on this page. Many things claimed to be problems of the theory have been resolved. WMC has very "unrelated" reasons why he wants the key paper by Roe to be suppressed - they're much more related to other theories about the climate than the content of this article which is the Milankovitch theory. -- Lumidek ( talk) 13:12, 7 July 2010 (UTC)
The article mentions that changes provoked by the Milankovitch cycles around the north pole are more significant than elsewhere on the planet because the north pole has a big land mass and land reacts quicker to changes than the oceans. This is puzzling because of two reasons. First, land reacts much slower than the oceans to changes in climate and not the other way around: this is because the specific heat of soil is much higher than that of water, making soil change temperature much slower than water under the same conditions. Secondly, the north pole has no land mass unlike the south pole which has an entire continent beneath the ice: this is one of the reasons (in fact, the one described as the most significant in all the sources I've encountered so far) why the south pole is much colder than the north pole. Moreover, the article lacks a few important references as to the source of some statements.
Other posts in this discussion page have mentioned similar errors. Perhaps this article not only lacks neutrality but also scientific basis and should be marked as having a disputable accuracy. The neutrality issue is clear but the references indicated in the article itself show, for the most part, that the subject of this article is considered a hypothesis rather than a generally accepted theory. Perhaps the issue of neutrality could be overcome by simply changing the article's name to mention that it is a hipothesis and by making an accurate assessment of the theory's acceptance among the scientific community in it.
As an example of the validity of this form of resolving such an issue, it might be useful to realize that an article about creationism is as valid as an article about evolutionism as long as it is specifically marked as a hypothesis (and not a scientific fact or accepted theory) and the general scientific opinion about it is mentioned (in this case, that it is considered by the large majority of the scientific community as false).
Arkaever ( talk) 11:48, 14 July 2010 (UTC)
The section on Apsidal precession needs looking at as it is currently broken. Sapient Homo ( talk) 18:40, 22 November 2010 (UTC)
Venting
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Here come's the newbie, just asking for a sock on the chin (Askaever) from the loser (Lumidek),(by coming in the middle of an argument): while the winner (WMC) sits silently smirking over his recent victory. Gee whiz, what a waste of talent. There are many comments made by brighter minds, so will paraphrase one: Don't open your mouth and remove eventual doubt over your idiocy. Further, citation of scientific consensus does not prove anything other than scientists as a group generally are bullies (bully: a coward who postures as brave man, when he has group backing); ref. scientific consensus on anthropic climate effects. That said, a major problem is lack of references to highly relevant co-factors such as vulcanism feeding oxygen creation in the oceans, and similar non-cyclical disturbances. While this may be a discussion of one theory, there are other factors influencing climate. Similarly, using "the exception to prove the rule" (ie theory, in this case) as one expressed it, seems to me as idiotic. I thought it was the rule you gentlemen were discussing. Lastly, the most important "rule" is that remarking on other people ideas, opinions, etc, by attacking the person, instead reveals a lack of argument. Besides, it is rude and childish. It has been quiet here for almost a year. Are you still exhausted or occupied defending other piles? Now get in line. The pile of stones are there ready. Written by one without credentials, or need of them. Idealist707 ( talk) 20:48, 3 July 2011 (UTC) |
This is discussed above, but it seems to have gone nowhere:
I don't really believe this. I think its albedo feedback from seasonal snow cover. Either way, its stated without refs William M. Connolley ( talk) 22:16, 5 October 2012 (UTC)
Reading about the Milankovitch cycles is beyond my capacity of scientific knowledge. I am reading a website http://www.earthhistory.org.uk/questions-of-age/cyclicity-in-chalk where I believe it is saying that these cycles determine that radioactive dating is incorrect - as proof that the earth is younger. I may be reading both sites incorrectly. Would someone either add a section or a criticism section whether this is true or not? Mylittlezach ( talk) 04:17, 14 October 2012 (UTC)
This is an astronomy topic and the article should be limited to the specifics of the subject, Milankovitch cycles. "Global Warming", "Climate Change", "Greenhouse gasses" and the effects thereof, whether you are certain of them or not, are not astronomy, and are therefore not appropriate for this article. SteveOak ( talk) 08:59, 30 December 2012 (UTC)
"human impact on the environment, anthropogenic effects may modify or even overwhelm orbital effects" as there is no reference cited so this is, at best, speculation, it is not suitable material for a scientific article. SteveOak ( talk) 09:07, 30 December 2012 (UTC)
"You're wrong" is not sufficiently specific. Please cite your objections as I have done. Please cite with specificity how "Global Warming", "Climate Change", "Greenhouse gasses", and human impact on the environment the potential effects thereof are the results of Milankovitch cycles. SteveOak ( talk) 18:59, 30 December 2012 (UTC)
"you could, for example, look at the categories at the bottom" You are attempting to use circular logic to justify the inclusion of non-relevant information. Repeating the same non-sequitor does not make the extraneous material suddenly relevant. SteveOak ( talk) 01:54, 31 December 2012 (UTC)
If you sincerely have no clue what I am "going in about", perhaps you should desist from re-inserting the non-relavant information. SteveOak ( talk) 01:54, 31 December 2012 (UTC)
"Milankovitch theory describes the collective effects of changes in the Earth's movements upon its climate." Since greenhouse gasses are not one of "Earth's movements" they are not relevant to the discussion. If this were an article on the collective possible influences on the Earth's climate, you could then include Milankovitch's theory in that article but that does not justify the reverse. SteveOak ( talk) 01:59, 31 December 2012 (UTC)
Milankovitch developed his theory in the early 1900's and was focused on a correlation between the eccentricity of the Earth's orbit and ice ages. http://earthobservatory.nasa.gov/Features/Milankovitch/milankovitch_3.php Long before 'climate change' was a consideration. SteveOak ( talk) 06:25, 31 December 2012 (UTC)
Is this article about Earth or about Milankovitch cycles in general? Right now it's very Earth focused, but it includes orbital simulations that have nothing to do with Earth, misleading the reader... ~D — Preceding unsigned comment added by 174.28.166.179 ( talk) 02:35, 21 June 2015 (UTC)
Looking here, and at Milutin Milanković, I see that the history of all this needs more work. Broadly, this theory has been got wrong by more people than almost anything else, and MM semi-lucked-out that it ended up with his name on it William M. Connolley ( talk) 21:51, 1 January 2013 (UTC)
OK, notes towards this (from Imbrie and Imbrie) starting from MM starting, with Croll's theory dead:
William M. Connolley ( talk) 22:49, 1 January 2013 (UTC)
My original text:
The Solar system also moves up and down relative to the Galactic Plane, in a cycle of 62 million years, wandering 230 light years out of the plane as a result. According to Richard Muller and Robert Rohde, this cycle closly matches that of marine extinctions in the past 542 million years. The death rate is highest when the solar system is located at a maximum distance from the galactic plane in the direction of galactic north and lowest when it is down south. [1]
An explanation for this has been proposed by Mikhail Medvedev and Adrian Melott. They point out that the galactic halo is not symmetric between north and south. The galaxy emits a wind that consists of protons and other charged particles, creating a cloud that extends into intergalactic space but is lopsided towards the south. These protons make up a large fraction of high energy cosmic rays that impact the Earth. The effect is so great that the Earth receives five times more cosmic radiation at its northernmost point relative to the galactic plane compared to its southernmost point. . [2]
This lopsided effect exists because the Milky Way travels at a speed of 200 kilometres per second in the direction of the Virgo supercluster of galaxies, which lie to the galactic north. The intergalactic medium, consisting mostly of ionized hydrogen gas, serves as an impediment, which has deformed the galactic halo towards the south. When the halo gas meets the interstellar medium, a bow shock is created. The energy in the shock front is transferred via a magnetic process to protons from both the intergalactic medium and the halo. These are the protons which form the cosmic rays. [3]
This edit was undone by William M. Connolley for the reason of wrong timescale. I will not pretend to be an expert in either geology, climatology, or astronomy, but the definition of Milankovitch cycles in the article is: "the collective effects of changes in the Earth's movements upon its climate". The motion of the Earth (or the solar system) relative to the galactic plane is a change in the Earth's movements, and according to my references it does impact the climate. 069952497a ( talk) 21:52, 18 January 2013 (UTC)
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Science Daily
Why an Ice Age Occurs Every 100,000 Years: Climate and Feedback Effects Explained
—
al-Shimoni (
talk)
22:21, 12 August 2013 (UTC)
I just deleted some text and a citation about global warming that was at the end of the section on axial tilt. I think it is laudable to include a reference to anthropogenic climate change in a section discussing how all of these disparate factors add up, but muddying up a section that explicitly is only discussing one of the factors is bad narration. 67.175.146.68 ( talk) 16:29, 28 December 2013 (UTC)
Merge Proposal and / or
Redirect.
Please do not modify it.
The result of the request for the Proposed Merger of {requested article} into this talk page's article was:
There has been a merger proposal back in 2007, without any conclusiveness. Orbital forcing should be merged into this article since the article and literature refer to Milankovitch cycles, when discussing orbital forcing, and because OF appears to be written with a NPOV. prokaryotes ( talk) 15:19, 1 May 2014 (UTC)
Please do not modify it.
Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.
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The picture showing the effects of precession on the seasons (using the Northern Hemisphere terms) is very hard to understand. It's hard to understand which time frames the arrows are pointing to in the future, past and present. Even Malenkovitch explained it in more understandable terms — Preceding unsigned comment added by 2601:540:C001:7708:4E:F3BB:1571:2478 ( talk) 08:45, 21 June 2015 (UTC)
Precession affects the Earth's axial tilt in its rotation, not its orbit. AndroidCat ( talk) 21:42, 12 January 2020 (UTC)
On certain display settings (non-fullscreen on desktop computers) this looks visually awkward: One quite narrow column of intro text next to the big, complicated diagram filling most of the browser window.
For all users the questions should be asked: Isn't this too heavy a dose of information to throw into the reader's face, right at the start? I find it easier to stomach if the first thing a reader sees besides text is something he can more easily relate to. Admittedly, the article subject itself is quite abstract; and a photo of a cliff wall that invites the reader to lock for patterns of strata in it is still a lot brainier, than, say, a picture of a cute-looking animal. But seeing the article's concept directly expressed in nature is much more accessible to me than an abstract diagram.
In short: I find that the suggested start of the article (beginning with a photo) is more approachable and accessible than beginning with a complicated diagram. Got reverted on this issue by SageGreenRider previously; opened discussion as requested. ΟΥΤΙΣ ( talk) 11:09, 21 June 2020 (UTC)
Section 1.1 on Orbital eccentricity states that the "major component of these variations occurs with a period of 413,000 years" but the only cited reference says that this period is 405,000 years. See reference 2:. [1] George Fergus ( talk) 16:42, 21 June 2020 (UTC)
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In Serbian or Croatian, there is no official way to transcribe the letters, so Milankovitch is actually very not correct. Why wouldn't the name of the article be "Milanković cycle"? Beauty of Serbian language is that it also uses the latin script, which is then the same as a Croatian script, so there's no any trivia around this.
Whether the name is or isn't known in a misspelled form, it seems that any self-respecting person would wish to honor Milanković with the correct spelling of his name. There is literally no uncertainty about the correctness of the NAME of this eminent person. The beauty or merits of the language are entirely besides the point. It is rather objectively disrespectful.— Preceding unsigned comment added by 75.150.214.2 ( talk • contribs)
second this
i knew it as milankovic cycle but that was 404 not even disambiguation
and it is spelled that way in the article headed with the alternatic spelling
at least index it right even i fyou redirect it — Preceding unsigned comment added by 24.254.189.92 ( talk • contribs) 22:27, 30 November 2015 (UTC)
Why would the graph at the top of the page show time flowing from right to left? It is unconventional and might appear misleading to some. GBMorris 13:31, 25 July 2007 (UTC)
Image:Earth_axis_tilt_and_precession.jpg has two apparent errors:
The blue box indicates the Minimum, not Maximum, Axial Tilt.
The duration of 21000 years is half of, not twice, 41000 years;
thus there are about two 21000 year periods in a 41000 year period.
Joe Kress 05:34, Aug 26, 2004 (UTC)
I note the orbital forcing content. I thought the explanation of the cycles should be here, as the physical movements are part of this topic while it is possible that the orbital forcing article may be more focused on the effects of movements. Whatever happens in the other article, this seemed like the place to begin explanations. — SEWilco 07:26, 7 Mar 2005 (UTC)
( William M. Connolley 10:04, 7 Mar 2005 (UTC)) I removed this:
I couldn't make sense of it. The orbital periods are all well known, how could it be otherwise? The 413 kyr period is largest (say Imbrie and Imbrie).
( William M. Connolley 22:11, 15 Mar 2005 (UTC)) SEW added:
This seems weird to me. The 100 kyr peak is the largest in the spectral record (Imbrie, Science, 1980; many other places too). Records contain only 10-20% of their energy in the obliquity and precession bands. doesn't seem to be too relevant, except to demonstrate that they are small - but since they are not the 100 kyr signal, that doesn't seem to be relevant to whether there is a 100 kyr signal (except to support it).
1.) I have been studying a book on the Milankovitch cycles (The Dynamic Earth, OU) which suggests that the main effect of the changing shape of the orbit is to change the amount of solar radiation reaching the Earth as a whole, in addition to a subsidiary effect accentuating the seasonal changes in one hemisphere. I don't see any mention of such a total increase in radiation for highly elliptical orbits here, and I would have thought intuitively that the greater time spent further away from the Sun would balance the time spent in close approach. Does this effect exist? Tonderai 18:27, Apr 25, 2005 (UTC)
I'm puzzled by a couple of things. First, the eccentricity effect does change the total solar insolation over a year, wheras the effects axial precession, polar wobble, and orbital precession pretty clearly don't. They can only have an effect through second order effects due to the arrangement of landmasses on the earth. I don't understand the expression of surprise in the article that eccentricity seems to be the dominant effect. Second, if my sums are right, the total insolation is proportional to (1+0.5*e^2) to lowest order in e. So the maximum deflection is about 0.25%, or 3.4 Wm-2. That's about twice the forcing due to greenhouse gasses that everybody is so het up about at the moment. What am I missing? —Preceding unsigned comment added by 79.68.98.200 ( talk) 18:54, 10 September 2008 (UTC)
2.) From the article Due to the eccentricity resembling a circular orbit, there is a 6% difference in the amount of solar radiation during summer in the two hemispheres. (from Present Conditions). I understood that it was the current eccentricity of the orbit that caused the difference in solar radiation between summers in different hemispheres. A circular orbit would mean there was no difference between the hemispheres. Correct? Tonderai 18:27, Apr 25, 2005 (UTC)
Why does the eccentricity change? 84.191.227.100 17:16, 26 January 2006 (UTC)
Please copy the images to Wikimedia Commons. -- Saperaud 5 July 2005 11:30 (UTC)
Perihelion and aphelion are points (in space or time). They occur during a season. Perihelion may occur during summer, but summer cannot occur during perihelion. The mistake occurs several times in the article.
[Above comment by 24.112.15.149 on 8 October 2005]
Good point. I've rewritten two sentences where this occurs. -- JimR 12:28, 27 October 2005 (UTC)
The page needs a bit on how the axial tilt affects the latitude of the Arctic and Antarctic circles, including the distance and degrees latitude they range over. Including the total surface area ranged over would be a good datum for those who don't have the foggiest notion of how to calculate the surface area of a section of a sphere. ;) As the circles move towards the poles, there's less area in 24 hours to six months continous darkness per year, which reduces the net heat radiation of Earth.
The History Channel's recent documentary on the "Little Ice Age (Big Chill)" had nothing on Milankovitch cycles. That was a rather large omission!
It would be nice to see some of the successes of this theory, rather than just the problems! As it stands, it looks like there is very little reason to accept that Milankovitch explains anything. I suggest a figure showing the coherency and power spectra of the 65N insolation and some of the untuned ODP cores. Also the new EPICA Dome C records?
I've added some references on orbital forcing climate effects before the Quaternary (the articles of Zachos are the ones usually cited), and links to the simulation data of Berger (1978 and 1992, 1-5 My BP), Laskar et al. (1993 and 2004, up to ~50-65 My BP) and Varadi et al. (2003, up to ~50 My BP). I had quite some trouble finding actual simulation data and accurate information on longer-term (ie. over more than 1-5 My) orbital forcing elsewhere, so this might be useful for others as well. The article by Varadi et al. might be a bit too technical/astrophysical, but has a very nice introduction on the subject of orbital cycles and climate, and good references. Accurate calculation of planetary orbits seems to be restricted to ~50 million years, because chaos causes errors to accumulate over long time periods. Lvzon 10:45, 23 February 2006 (UTC)
Orbitalforam 8 May 2006
While true there is some overlap, it is not so large as that. The distinction ought to be that orbital forcing is only one of many climate forcings, whereas M. cycles are primarily used in an attempt to explain the paleoclimate record. 134.121.64.253 23:07, 14 February 2007 (UTC)
I'd prefer no merge as well. People will come looking for the article under this name, and will not be able to find it. I was glad to have found it here. Jiminezwaldorf 08:10, 30 August 2007 (UTC)
It seems this merge was suggested long ago, with no proponent arguments surviving on the talk page. Change history indicates previous frustration at the lack of merge discussion, along with previous attempts to remove the merge (29 October 2005). This matter should be considered settled. - Rgrant 00:46, 5 October 2007 (UTC)
For an initial impression of what's going on in this space, i used three separate Google scholar searches. one on "Milankovitch cycles", one on "orbital forcing", and one on both quoted terms. At present, Google found more than twice as many references to "orbital forcing". Only a fraction of articles crossed memespace and referred to both terms. This technique does not tell us what specific climate theories are being discussed.
I did run across a reference indicating that popular understanding ties Milankovitch cycles to a specific mechanism for climate change.
The theory of Milankovitch cycles states that periodic changes in Earth's orbit cause increased summertime sun radiation in the northern hemisphere, which controls ice size.
However, this study suggests that the pace-keeper of ice sheet growth and retreat lies in the southern hemisphere's spring rather than the northern hemisphere's summer.
— Terradaily staff writers, from "Carbon Dioxide Did Not End The Last Ice Age" [4], Oct 04 2007
Confusingly, this recent research seems to suggest that orbital forcing is occurring, that the physical orbital mechanics first described by Milankovitch cycles are its cause, and that the theorized mechanism of climate change associated with Milankovitch cycles (longer summers in the Northern hemisphere) is causally backwards from the details of these newly observed climate changes. I look forward to seeing this topic space well organized. - Rgrant 19:00, 9 October 2007 (UTC)
It is implied that humans cause global warming in this article ("anthropogenic effects (global warming)") when that fact is still hotly debated. This asserts a particular point of view that I don't think is neutral. I think it should be changed to conform to a NPOV. -- Rcronk 20:01, 27 April 2007 (UTC)
Pfvlloyd please explain the changes you are making. You keep citing Berger and Loutre without identifying which one (they've published together several times). Maybe you know of something new, but I don't know of anything that justifies the large scale changes you are making. Dragons flight 17:10, 5 August 2007 (UTC)
Hi ! - Thanks for your interest. I see a note which says I have not replied to your questions, but since this was only placed a few hours ago, I think it's a bit steep to cancel my edits without even seeing my side of the story. Maybe this is just how you do things here!
Firstly, nearly all my comments arise from a sraightforward application of the celestial mechanics calculations of Earth orbital eccentricity which are universally accepted.
Secondly, Berger and Loutre's refinements of 1991 and 2002 provided very clear data over the past 750,000 years showing the timings and extent of eccentricity cycles. I refer you to 1991 Quaternary Science Reviews, 10: 297-397; and to Science, 23/8/02, pp1287-1288.
If you find that any of my statements are not upheld by this rather basic material, L'ld be very pleased to review and discuss.
But I would have preferred to have had the chance to do so before a summary withdrawal of my suggestions with no notice! Pfvlloyd 22:25, 5 August 2007 (UTC)
Reply -
I didn't see your note before I logged off - it was getting late here. But it was still a rather brief time allowed before posting that I had not responded to requests for an explanation. However, that's water under the bridge.
Thanks for your comments on my edits. OK, I see where you have problems with them. I think I can offer you reasonable arguments for most of your comments, but some are just plain differences of interpretation which we may never agree on, but that's science!! And I found some of the text very confused, so obviously so that I did not think an explanation for an edit was necessary in those cases.
However, I have deadlines to meet just now and cannot reply properly. Give me a day or two and I will respond properly. I really look forward to discussing these issues with you - an excellent opportunity to improve insight.
Regards. Pfvlloyd 15:22, 6 August 2007 (UTC)
The axial tilt changes slightly on a short period, less than a year, which moves the circles toward and away from the poles a bit. What would the maximum and minimum latitudes be over the 41,000 year cycle? Now for the math wizard question. What's the total surface area of the two belts the circles wander over? An important thing to remember as this relates to climate change is the very different topography of the north and south poles. The north is water surrounded mostly by land while the south is land surrounded by an unbroken ring of water. In winter, the area above the circle can get heat only via convection and a small amount that comes from the interior of Earth. The north gets heat both from water and air convection while most of the south gets heat only from air convection. the convection can't keep up with the radiant heat loss during the time the sun doesn't rise above the horizon. As the tilt decreases, there's less surface area with 24 hours or more constant darkness to radiate heat. Anyone who remembers the basic science classes they had in school knows that a planet with less axial tilt has an overall more temperate climate than a planet with a greater axial tilt, yet I've talked with several people who are convinced this should make the poles *cooler*, and thus "proof" of anthropogenic "global warming". —Preceding unsigned comment added by Bizzybody ( talk • contribs) 13:30, 20 October 2007 (UTC)
I want to understand the basis for these theories. What is the basis being used for the timeframe estimates used in this article? How did they calculate the 41,000 years and the 100,000 years? Are those numbers calculated based on geological observations tied to assumptions about radiometric dating and stratigraphic principles? Thank you. 68.253.24.169 13:53, 29 October 2007 (UTC)
It is inappropriate to insert personal queries into Wikipedia articles to get attention. It is a form of vandalism. I have removed the query from the article.
Re. "What is the basis being used for the timeframe estimates used in this article? How did they calculate the 41,000 years and the 100,000 years? re those numbers calculated based on geological observations tied to assumptions about radiometric dating and stratigraphic principles?":
I am not a geologist or paleoclimatologist, but since nobody with real credentials has answered the query I will say this: Data about climate variations in the range of tens to hundreds of thousands of years ago are available from a rich range of sources that do not depend on radiometric dating. The study of climate over this time scale depends heavily on ice cores and cores of ocean-floor sediments. These deposits record the yearly layering of snow and sediment from the present time back in unbroken series to, in the case of at least one Antarctic ice core, about 800,000 years ago. Each year adds a new, thin layer like the growth of a tree. Although it is my understanding that the precise dating of these layers is a complex professional matter, to a rough approximation, at least, one dates the layers simply by counting them, exactly like tree rings.
See the Wikipedia articles on Paleoclimatology and Ice Cores for more information. —Preceding unsigned comment added by 72.173.17.89 ( talk) 18:41, 3 November 2007 (UTC)
Ultimately, the timing of Milankovitch cycles is obtained by physical models: precession, nutation, torque, and orbital changes influenced by the moon and other planets, all plugged into simulators. Written history, tree rings, ice cores, sediments, and fossils are all useful to calibrate these models, if you can be confident that each layer represents a uniform time interval, and that migration of gases or particulate does not occur. To gain this confidence, you have to examine and correlate many individual ice cores, sediments, tree rings, and fossils. One such vital calibration is the iridium anomaly at the K-T boundary -- 99.233.186.4 ( talk) 16:39, 23 May 2010 (UTC)
In the October issue (2007) of National Geographic there is a poster called Greenhouse Earth. The bottom graphic line shows how the change in eccentricity, tilt, and wobble of the earth should have impacted global climate changed for the last 400,000 years. What is most cool about this is you can see changes in sea level, temperature, and co2 concentrations at the same time. The graph suggests that we should be in a cooling period for the last 100 thousand years....which is a concern because we are in a one of the most warm periods over the last 400,000 years. Is this correct. I didn't find any citations for this. It strange that the dotted line doesn't have a label. How solid is this evidence. Perhaps it belongs on this page. SoilMan2007 ( talk) January 1, 2008
Hello i have recently proposed the Wikiproject Earth. This Wikiproject`s scope includes this article. This wikiproject will overview the continents, oceans, atsmophere and global warming Please Voice your opinion by clicking anywhere on this comment except for my name. -- Iwilleditu Talk :) Contributions —Preceding comment was added at 15:35, 30 March 2008 (UTC)
The opening paragraph of the article states that the axial tilt varies between 21.5° and 24.5°. However, the section "Axial Tilt (Obliquity)" states that it varies between 22.1° and 24.5°. The article Axial tilt seems to agree with the latter range although it mentions the 21.5° low value in section "Long period variations", but also questions it as a possible one-time overshoot. I just happened to read this article and am not an expert on the subject, so I don't feel comfortable fixing this disparity, but most likely in the same article we should either stick to same numbers or explain the differences. -- Antti Salonen ( talk) 18:35, 4 June 2008 (UTC)
In the same paragraph there's this sentence which refers to a particular time: "It is currently 23.44 degrees and decreasing." What time are we talking about here?
Of course this is somewhat a rhetorical question. More properly put, I suggest a new formulation of this. It might go like "As of 2014, it is ??? degrees and decreasing. [reference]" Cemkay ( talk) 14:34, 4 March 2014 (UTC)
Captions for the images would be nice, especially Orbital_variation.svg. Rtdrury ( talk) 07:19, 12 August 2008 (UTC)
In this section the sets of numbers: (high eccentricity of 0.058) and (variation of −0.03 to +0.02) seem to conflict. Is the high 0.058 or is it 0.02? Rtdrury ( talk) 07:31, 12 August 2008 (UTC)
I propose expanding "the future" section with the images found on my user page. Incredio ( talk) 21:50, 31 May 2009 (UTC)
"The inclination of Earth's orbit drifts up and down relative to its present orbit with a cycle having a period of about 70,000 years....The inclination of the Earth's orbit has a 100,000 year cycle relative to the invariable plane."
Might I suggest that attention be given this apparent discrepancy? The period cannot be both values. I tracked this back to SEWilco way back in 2005 (3/7), and since it's stood for so long without revision and I hold no expertise, I'm hesitant to revise it myself. However I note that the two sources in the paragraph both reference 100k in abstract. Could somebody resolve the discrepancy? —Preceding unsigned comment added by Jjchong ( talk • contribs) 02:57, 19 August 2009 (UTC)
I think it would be nice to have a section on historical development of the theory. It would be a good section; this theory is probably notable for being the best example of a theory disproved multiple times by observations :-) William M. Connolley ( talk) 23:13, 14 December 2009 (UTC)
Yes, the various theories that were knocked down humiliated a lot of people. David Archer's book about the history of climate science ends every other chapter with "and so he died friendless and mocked by the scientific community." I no longer have access to the book ("the long thaw"), but it would make an excellent source for a history section. Would involve lots of cross-linking to ancient scientists like Agassiz. Therealhazel ( talk) 06:31, 29 December 2009 (UTC)
Is there an estimate of solar irradiance in the last glacial minimum? Joseph449008 ( talk) 22:15, 19 December 2009 (UTC)
I just added this section because someone badly needs to update this completely obsolete article. Because of the well-cited 2006 article below, pretty much all the criticisms in this Wikipedia article are out of touch. The readers will be grateful to anyone who will update it - but the amount of required work is nontrivial.
Many of the doubts about the theory disappeared in 2006 when Gerard Roe published a paper, In defense of Milankovitch, in Geophysical Research Letters, Vol. 33, L24703, doi:10.1029/2006GL027817, 2006. [9] He correctly identified the insolation with the time-derivative of the measured ice volume, rather than the ice volume itself, and obtained a spectacular agreement that has solved the 100,000-year problem and other problems below. By taking the derivative, the short-duration, higher-frequency cycles are amplified. Until this text takes Roe's paper into account, you should realize that it is obsolete. -- Lumidek ( talk) 09:37, 6 July 2010 (UTC)
I've added an NPOV tag to this article because the current version tries to hide the most important modern insight about the cycles, included in Roe's 2006 paper. I encourage educated readers to read the paper [10], check its merits and citations, decide whether I am right that it is impossible for the content of this paper to be neglected or denied by this Wikipedia article, and fix all the obsolete information on this page. Many things claimed to be problems of the theory have been resolved. WMC has very "unrelated" reasons why he wants the key paper by Roe to be suppressed - they're much more related to other theories about the climate than the content of this article which is the Milankovitch theory. -- Lumidek ( talk) 13:12, 7 July 2010 (UTC)
The article mentions that changes provoked by the Milankovitch cycles around the north pole are more significant than elsewhere on the planet because the north pole has a big land mass and land reacts quicker to changes than the oceans. This is puzzling because of two reasons. First, land reacts much slower than the oceans to changes in climate and not the other way around: this is because the specific heat of soil is much higher than that of water, making soil change temperature much slower than water under the same conditions. Secondly, the north pole has no land mass unlike the south pole which has an entire continent beneath the ice: this is one of the reasons (in fact, the one described as the most significant in all the sources I've encountered so far) why the south pole is much colder than the north pole. Moreover, the article lacks a few important references as to the source of some statements.
Other posts in this discussion page have mentioned similar errors. Perhaps this article not only lacks neutrality but also scientific basis and should be marked as having a disputable accuracy. The neutrality issue is clear but the references indicated in the article itself show, for the most part, that the subject of this article is considered a hypothesis rather than a generally accepted theory. Perhaps the issue of neutrality could be overcome by simply changing the article's name to mention that it is a hipothesis and by making an accurate assessment of the theory's acceptance among the scientific community in it.
As an example of the validity of this form of resolving such an issue, it might be useful to realize that an article about creationism is as valid as an article about evolutionism as long as it is specifically marked as a hypothesis (and not a scientific fact or accepted theory) and the general scientific opinion about it is mentioned (in this case, that it is considered by the large majority of the scientific community as false).
Arkaever ( talk) 11:48, 14 July 2010 (UTC)
The section on Apsidal precession needs looking at as it is currently broken. Sapient Homo ( talk) 18:40, 22 November 2010 (UTC)
Venting
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Here come's the newbie, just asking for a sock on the chin (Askaever) from the loser (Lumidek),(by coming in the middle of an argument): while the winner (WMC) sits silently smirking over his recent victory. Gee whiz, what a waste of talent. There are many comments made by brighter minds, so will paraphrase one: Don't open your mouth and remove eventual doubt over your idiocy. Further, citation of scientific consensus does not prove anything other than scientists as a group generally are bullies (bully: a coward who postures as brave man, when he has group backing); ref. scientific consensus on anthropic climate effects. That said, a major problem is lack of references to highly relevant co-factors such as vulcanism feeding oxygen creation in the oceans, and similar non-cyclical disturbances. While this may be a discussion of one theory, there are other factors influencing climate. Similarly, using "the exception to prove the rule" (ie theory, in this case) as one expressed it, seems to me as idiotic. I thought it was the rule you gentlemen were discussing. Lastly, the most important "rule" is that remarking on other people ideas, opinions, etc, by attacking the person, instead reveals a lack of argument. Besides, it is rude and childish. It has been quiet here for almost a year. Are you still exhausted or occupied defending other piles? Now get in line. The pile of stones are there ready. Written by one without credentials, or need of them. Idealist707 ( talk) 20:48, 3 July 2011 (UTC) |
This is discussed above, but it seems to have gone nowhere:
I don't really believe this. I think its albedo feedback from seasonal snow cover. Either way, its stated without refs William M. Connolley ( talk) 22:16, 5 October 2012 (UTC)
Reading about the Milankovitch cycles is beyond my capacity of scientific knowledge. I am reading a website http://www.earthhistory.org.uk/questions-of-age/cyclicity-in-chalk where I believe it is saying that these cycles determine that radioactive dating is incorrect - as proof that the earth is younger. I may be reading both sites incorrectly. Would someone either add a section or a criticism section whether this is true or not? Mylittlezach ( talk) 04:17, 14 October 2012 (UTC)
This is an astronomy topic and the article should be limited to the specifics of the subject, Milankovitch cycles. "Global Warming", "Climate Change", "Greenhouse gasses" and the effects thereof, whether you are certain of them or not, are not astronomy, and are therefore not appropriate for this article. SteveOak ( talk) 08:59, 30 December 2012 (UTC)
"human impact on the environment, anthropogenic effects may modify or even overwhelm orbital effects" as there is no reference cited so this is, at best, speculation, it is not suitable material for a scientific article. SteveOak ( talk) 09:07, 30 December 2012 (UTC)
"You're wrong" is not sufficiently specific. Please cite your objections as I have done. Please cite with specificity how "Global Warming", "Climate Change", "Greenhouse gasses", and human impact on the environment the potential effects thereof are the results of Milankovitch cycles. SteveOak ( talk) 18:59, 30 December 2012 (UTC)
"you could, for example, look at the categories at the bottom" You are attempting to use circular logic to justify the inclusion of non-relevant information. Repeating the same non-sequitor does not make the extraneous material suddenly relevant. SteveOak ( talk) 01:54, 31 December 2012 (UTC)
If you sincerely have no clue what I am "going in about", perhaps you should desist from re-inserting the non-relavant information. SteveOak ( talk) 01:54, 31 December 2012 (UTC)
"Milankovitch theory describes the collective effects of changes in the Earth's movements upon its climate." Since greenhouse gasses are not one of "Earth's movements" they are not relevant to the discussion. If this were an article on the collective possible influences on the Earth's climate, you could then include Milankovitch's theory in that article but that does not justify the reverse. SteveOak ( talk) 01:59, 31 December 2012 (UTC)
Milankovitch developed his theory in the early 1900's and was focused on a correlation between the eccentricity of the Earth's orbit and ice ages. http://earthobservatory.nasa.gov/Features/Milankovitch/milankovitch_3.php Long before 'climate change' was a consideration. SteveOak ( talk) 06:25, 31 December 2012 (UTC)
Is this article about Earth or about Milankovitch cycles in general? Right now it's very Earth focused, but it includes orbital simulations that have nothing to do with Earth, misleading the reader... ~D — Preceding unsigned comment added by 174.28.166.179 ( talk) 02:35, 21 June 2015 (UTC)
Looking here, and at Milutin Milanković, I see that the history of all this needs more work. Broadly, this theory has been got wrong by more people than almost anything else, and MM semi-lucked-out that it ended up with his name on it William M. Connolley ( talk) 21:51, 1 January 2013 (UTC)
OK, notes towards this (from Imbrie and Imbrie) starting from MM starting, with Croll's theory dead:
William M. Connolley ( talk) 22:49, 1 January 2013 (UTC)
My original text:
The Solar system also moves up and down relative to the Galactic Plane, in a cycle of 62 million years, wandering 230 light years out of the plane as a result. According to Richard Muller and Robert Rohde, this cycle closly matches that of marine extinctions in the past 542 million years. The death rate is highest when the solar system is located at a maximum distance from the galactic plane in the direction of galactic north and lowest when it is down south. [1]
An explanation for this has been proposed by Mikhail Medvedev and Adrian Melott. They point out that the galactic halo is not symmetric between north and south. The galaxy emits a wind that consists of protons and other charged particles, creating a cloud that extends into intergalactic space but is lopsided towards the south. These protons make up a large fraction of high energy cosmic rays that impact the Earth. The effect is so great that the Earth receives five times more cosmic radiation at its northernmost point relative to the galactic plane compared to its southernmost point. . [2]
This lopsided effect exists because the Milky Way travels at a speed of 200 kilometres per second in the direction of the Virgo supercluster of galaxies, which lie to the galactic north. The intergalactic medium, consisting mostly of ionized hydrogen gas, serves as an impediment, which has deformed the galactic halo towards the south. When the halo gas meets the interstellar medium, a bow shock is created. The energy in the shock front is transferred via a magnetic process to protons from both the intergalactic medium and the halo. These are the protons which form the cosmic rays. [3]
This edit was undone by William M. Connolley for the reason of wrong timescale. I will not pretend to be an expert in either geology, climatology, or astronomy, but the definition of Milankovitch cycles in the article is: "the collective effects of changes in the Earth's movements upon its climate". The motion of the Earth (or the solar system) relative to the galactic plane is a change in the Earth's movements, and according to my references it does impact the climate. 069952497a ( talk) 21:52, 18 January 2013 (UTC)
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Science Daily
Why an Ice Age Occurs Every 100,000 Years: Climate and Feedback Effects Explained
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al-Shimoni (
talk)
22:21, 12 August 2013 (UTC)
I just deleted some text and a citation about global warming that was at the end of the section on axial tilt. I think it is laudable to include a reference to anthropogenic climate change in a section discussing how all of these disparate factors add up, but muddying up a section that explicitly is only discussing one of the factors is bad narration. 67.175.146.68 ( talk) 16:29, 28 December 2013 (UTC)
Merge Proposal and / or
Redirect.
Please do not modify it.
The result of the request for the Proposed Merger of {requested article} into this talk page's article was:
There has been a merger proposal back in 2007, without any conclusiveness. Orbital forcing should be merged into this article since the article and literature refer to Milankovitch cycles, when discussing orbital forcing, and because OF appears to be written with a NPOV. prokaryotes ( talk) 15:19, 1 May 2014 (UTC)
Please do not modify it.
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The picture showing the effects of precession on the seasons (using the Northern Hemisphere terms) is very hard to understand. It's hard to understand which time frames the arrows are pointing to in the future, past and present. Even Malenkovitch explained it in more understandable terms — Preceding unsigned comment added by 2601:540:C001:7708:4E:F3BB:1571:2478 ( talk) 08:45, 21 June 2015 (UTC)
Precession affects the Earth's axial tilt in its rotation, not its orbit. AndroidCat ( talk) 21:42, 12 January 2020 (UTC)
On certain display settings (non-fullscreen on desktop computers) this looks visually awkward: One quite narrow column of intro text next to the big, complicated diagram filling most of the browser window.
For all users the questions should be asked: Isn't this too heavy a dose of information to throw into the reader's face, right at the start? I find it easier to stomach if the first thing a reader sees besides text is something he can more easily relate to. Admittedly, the article subject itself is quite abstract; and a photo of a cliff wall that invites the reader to lock for patterns of strata in it is still a lot brainier, than, say, a picture of a cute-looking animal. But seeing the article's concept directly expressed in nature is much more accessible to me than an abstract diagram.
In short: I find that the suggested start of the article (beginning with a photo) is more approachable and accessible than beginning with a complicated diagram. Got reverted on this issue by SageGreenRider previously; opened discussion as requested. ΟΥΤΙΣ ( talk) 11:09, 21 June 2020 (UTC)
Section 1.1 on Orbital eccentricity states that the "major component of these variations occurs with a period of 413,000 years" but the only cited reference says that this period is 405,000 years. See reference 2:. [1] George Fergus ( talk) 16:42, 21 June 2020 (UTC)