Talk:Late Cenozoic Ice Age

Scope

It is very good that Appple has created an article on this topic, despite the problems naming the article. However, I believe the section on climate change from human activities goes a bit beyond natural topics for the article. This subject is covered by the article Global warming. 216Kleopatra (talk) 10:24, 13 October 2018 (UTC)

The climate change section has been removed. Appple (talk) 20:10, 23 October 2018 (UTC)

lead off topic text

Thanks for working on this Apple. I just removed the following text from the WP:LEAD because it is all about earlier times in earth's history. This material might merit merging into our other articles about those time periods, or articles spanning a wider period than than this article, but here the text should really be about the late Cenozoic.

Throughout the [[Phanerozoic|Phanerozoic Æon]] (everything after the [[Precambrian]]), the [[Earth]] has altered between two phases, [[Greenhouse and icehouse Earth|greenhouse earth]] and [[Greenhouse and icehouse Earth|icehouse Earth]]. During the greenhouse phase, the Earth's polar ice caps do not reach the ocean or calve ice bergs.<ref name="induced">UMass Lowell - A human-induced hothouse climate? http://faculty.uml.edu/lweeden/documents/HumaninducedhothouseGSAToday.pdf</ref> Most of the planet's history has been spent in the greenhouse phase. Times like now in which the Earth has ice bergs is the less common climate.

Ice ages account for only about 13.8% of Earth's history. Ice ages did not happen much during the Precambrian, only about 11.6% of the time. They have happened more frequently during the current Phanerozoic Æon, but still only about 30.3% of the time.

'''List of Icehouse and Greenhouse Periods ‘’‘

{{Main|Timeline of glaciation}}

* A greenhouse period ran from 4.6 to 2.9 billion years ago.

* [[Pongola glaciation]] - an icehouse period that ran from 2.9 to 2.78 billion years ago

* A greenhouse period ran from 2.78 billion years ago to 2.4 billion years ago

* [[Huronian|Huronian glaciation]] - an icehouse period that ran from 2.4 billion years ago to 2.1 billion years ago

* A greenhouse period ran from 2.1 billion to 715 million years ago.

* [[Sturtian glaciation]] - a [[Snowball Earth|snowball Earth episode]] (a time period in which the entire Earth is frozen over) :that ran from 715 to 680 million years ago

* A greenhouse period ran from 680 to 650 million years ago.

* [[Marinoan glaciation]] - a snowball Earth episode that ran from 650 to 635 million years ago

* A greenhouse period ran from 635 million years ago to 579.88 million years ago.

* [[Gaskiers glaciation]] - a snowball Earth episode that ran from 579.88 to 579.63 million years ago

* A greenhouse period ran from 579.63 to 547 million years ago

* [[Baykonurian glaciation]] - a snowball Earth episode around 547 million years ago

* A greenhouse period ran from around 547 to 450 million years ago

* [[Andean-Saharan glaciation]] - an icehouse period that ran from 450 to 420 million years ago

* A greenhouse period ran from 420 million years ago to 360 million years ago.

* [[Karoo Ice Age|Late Paleozoic Ice Age/Karoo Ice Age]] - an icehouse period that ran from 360 to 260 million years ago

* A greenhouse period ran from 260 million years ago to 33.9 million years ago. This period includes the Late Paleocene - :Early Eocene Torrid Age, a hothouse period that lasted from 65 to 55 million years ago.<ref name="UHCL"/>

* '''Late Cenozoic Ice Age''' - The current icehouse period which began 33.9 million years ago

NewsAndEventsGuy (talk) 00:54, 18 February 2019 (UTC)

Dubious

"During times when the tilt is less (low obliquity), the seasons are less extreme"

Greater tilt means a more even distribution of light energy. Perhaps the word should be, "differentiated", as extreme can imply a singular. Eg, less tilt would make the Arctic cold more extreme. Anarchangel (talk) 20:07, 10 April 2019 (UTC)

Holocene

As it previously stood this article treated the Holocene as invalid, instead including it as part of the Pleistocene, stating that "there is no evidence that it is actually separate" and that the Pleistocene lasts from 2.58 Mya to present. This is justified with two citations: the "Holocene Humanity" section of Why Geography Matters: More Than Ever by Harm de Blij and overview of the Neogene from Humboldt State University's Natural History Museum.

The first source (de Blij) is not freely available online. There is a preview available on Google Books but the citation is too vague to check it properly. (The chapters page is available and "Holocene Humanity" does not refer to any of the chapters of the book, so presumably it is a section of one of them.) Using the Google Books search function does however turn up the snippet "The postYoungerDryas warm period that has now lasted some 10,000 years is referred to by geologists as the Holocene Epoch, but of course there is no evidence as yet that this is geologically a new epoch, that is,...".

The second citation (HSU) does not support the claim, stating that the Pleistocene ended 11,700 years ago (or rather 0.0117 million years ago). It does however state that "Though traditionally the Holocene is treated separately, it may in fact just be the latest interglacial of the Pleistocene." (This is a weaker claim than "it is part of the Pleistocene".)

My understanding is that while there is indeed some debate as to whether the Pleistocene and Holocene are actually separate epochs, that there is no scientific consensus on the matter and so they are still treated as separate. Certainly the ICS treats them as separate as of at least 2018 (see the citation given for the 2.58 Mya start of the Pleistocene: http://www.stratigraphy.org/ICSchart/ChronostratChart2018-08.jpg), six years after the book's publication. As such their merger is likely no more "valid" than the Anthropocene (which is also not currently "official") and should not therefore be treated as if it is the "official" designation. To claim that the Holocene is actually part of the Pleistocene (rather than "is considered by some" or similar) therefore seems to fall foul of WP:FRINGE and/or WP:OR. Indeed, the Holocene article cites the same de Blij book (using the same vague description) to make the much weaker claim "It is considered by some to be an interglacial period within the Pleistocene Epoch." It is also worth noting that the snippet I included above explicitly states that "Holocene" is the standard which Geologists use (and so to deviate from it requires more justification than a single book, regardless of the author's credentials).

It is probably also worth mentioning that even if the Pleistocene and Holocene were merged there is no reason I am aware of (there may well be) that the new combined epoch would necessarily be called the "Pleistocene" and not the "Holocene". Indeed, going by the Greek meanings of the names ("most new" and "wholly/entirely new" respectively, along with "more new"/"newer" for the Pliocene, "less new" for the Miocene etc) I suspect that "Holocene" might be used preferentially to "Pleistocene".

It is also claimed (presumably on the same premise) that the Calabrian (has) lasted from 1.8 Mya until present, with the corresponding Britannica article used as the source. This also does not hold up as that article gives its span as 1,800,000 to 781,000 ya (which corresponds to its ICS definition). This seems to be an even bolder claim, as even if the Holocene is an interglacial of the Pleistocene, that in itself does not mean that the Holocene, Late Pleistocene and Middle Pleistocene should be merged into it, so definitely seems to be OR. The Holocene article suggests that those who treat the Holocene as part of the Pleistocene treat it as its own stage under the name Flandrian.

I certainly think that it is worth mentioning, particularly in relation to other glacial/interglacial periods, but to take a position counter to the "official" one (i.e. treat it as "fact") is against Wikipedia's rules. As such I have been bold and changed the infobox-like table at the head of the article to reflect the standard nomenclature with a footnote explaining the alternative (non-standard) view, and changed the wording of the "Current Interglacial Period" section's opening paragraph slightly.

P.S. Since it follows the ICS definition (and other articles on Wikipedia) it may also be worth splitting the "Neogene" into "Neogene" and "Quaternary" in the infobox-like table, I'm not sure.

Alphathon /'æɫ.fə.θɒn/ ^(talk) 03:02, 14 May 2019 (UTC)

Commons files used on this page have been nominated for deletion

The following Wikimedia Commons files used on this page have been nominated for deletion:

• Miocene.jpg
• Pliocene.jpg

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 16:29, 8 November 2019 (UTC)