Talk:Younger Dryas

message: @Volcano345 The section on causes, as well as in the short description, presents the consensual hypothesis of meltwater flux as apparently a dismissed theory, then proceeds to elevate volcanism to the position of the main cause. This is inaccurate. If the editor is willing to look hard enough, one can always find articles that reject the mainstream theory. If no one objects, I hereby propose to rewrite the section to reflect the mainstream theory, namely the freshwater flux hypothesis. However, I will still retain paragraphs on volcanism for the possible role it played in triggering the Younger Dryas (YD). The mainstream theory on the cause of YD is fairly consensual:
IPCC report (2007) on Palaeoclimate : Freshwater influx is the likely cause for the cold events at the end of the last ice age, i.e. the Younger Dryas (p. 456)
Encyclopedia of Quaternary Science (2013) on Palaeoclimate : The northward retreat of the southern margin of the Laurentide Ice Sheet from the Great Lakes caused a routing of freshwater from the western Canadian Plains from the Mississippi River to the St. Lawrence River, with the increased freshwater discharge to the North Atlantic slowing ocean circulation and ultimately causing the Younger Dryas (abstract)
NOAA on the cause of YD : just prior to the Younger Dryas, meltwater fluxes were rerouted from the Mississippi River to the St. Lawrence River (p. 2)
Annual Review of Marine Science (2017) on AMOC : most of the evidence is consistent with the long-standing hypothesis that the Younger Dryas cold event was caused by the routing of glacial meltwater into the North Atlantic (p. 98) Aleral Wei (talk) 07:22, 12 January 2024 (UTC)
replies: text: I agree. The lead currently cites an article attributing the YD to the moderate Laacher See eruption 200 years earlier. This should not be in the lead. I am not clear about the status of the meltwater theory as it has recently been attacked. Dudley Miles (talk) 09:06, 12 January 2024 (UTC)
replies: text: I think the case for meltwater is even stronger now than it was 20 years ago (, , , ), though so is volcanism. Some people mistakenly interpret Wallace Broecker's statement as an invalidation of the meltwater theory when, in reality, he disagreed with the specific hypothesis that the meltwater came from a catastrophic flood through the eastern outlet of Lake Agassiz. Overall, he still believed that pulses of meltwater resulting from deglaciation were the ultimate trigger for the weakening of the AMOC (). Aleral Wei (talk) 01:04, 13 January 2024 (UTC)
replies: text: If you are familiar with the current state of the debate then I suggest that you take on the revision. Dudley Miles (talk) 22:13, 13 January 2024 (UTC)
thread_title:  On the triggers of YD 

message: A significant issue exists between the Younger Dryas Impact hypothesis article and that of this article regarding the mainstream explanation for the onset of the Younger Dryas as detailed below. This post ends with a proposed set of actions to resolve this issue, and proposes making this article the source of the (current) mainstream explanation(s) and that discussions occur on this talk page.
The first sentence of the second paragraph of the Summary of the YDIH article
"It is an alternative to the long-standing and widely accepted  explanation that it was caused by a significant reduction in, or shutdown of the North Atlantic Conveyor due to a sudden influx of freshwater from Lake Agassiz and deglaciation in North America.: "The prevailing hypothesis is that the cooling and stratification of the North Atlantic Ocean were a consequence of massive ice sheet discharge of meltwater and icebergs and resulted in reduction or cessation of the North Atlantic Conveyor.""
contradicts the first paragraph of the Younger Dryas Cause section
"The Younger Dryas has historically been thought to have been caused by significant reduction or shutdown of the North Atlantic "Conveyor" – which circulates warm tropical waters northward – as the consequence of deglaciation in North America and a sudden influx of fresh water from Lake Agassiz.  ... The lack of geological evidence for such an event stimulated further exploration, but no consensus exists on the precise source of the freshwater, and in fact the freshwater pulse hypothesis has recently been called into question. ... The lack of consensus regarding the origin of the freshwater, combined with the lack of evidence for sea level rise during the Younger Dryas, are problematic for any hypothesis where the Younger Dryas was triggered by floodwater."
(See the Younger Dryas Cause section for the citations and the text indicated by "..." above.)
The Younger Dryas impact hypothesis Other explanations section,  has several issues as well.
* It is duplicative of the Younger Dryas Cause section such that the two articles are inconsistent and may diverge if the topic of YD causes continues to be covered in more than one article.
* Has a non-working link to the Younger Dryas Cause section
The Younger Dryas impact hypothesis Mainstream explanation section also contradicts the first paragraph of the  Younger Dryas Cause section .
The  Younger Dryas impact hypothesis Other alternatives section has the following issues:
* The jet stream explanation is not mentioned in the Younger Dryas Cause section .
* The second paragraph that begins: "Another proposed cause has been volcanic activity. However, this has been challenged recently due to improved dating of the most likely suspect, the Laacher See volcano.  ...."
contradicts the last two paragraphs of Younger Dryas Cause section that contain the following text:
"An increasingly well-supported alternative to the meltwater trigger is that the Younger Dryas was triggered by volcanism. Numerous papers now confidently link volcanism to a variety of cold events across the last two millennia and the Holocene, and in particular several note the ability of volcanic eruptions to trigger climate change lasting for centuries to millennia.  .... Regardless of the ambiguity surrounding the date for the Laacher See eruption, it almost certainly caused substantial cooling either immediately before the Younger Dryas event or as one of the several eruptions which clustered in the ~100 years preceding the event."
"A volcanic trigger for the Younger Dryas event also explains why there was little sea level change at the beginning of the event. ... No consensus exists that a meltwater pulse happened, or that a bolide impact occurred prior to the Younger Dryas, whereas the evidence of anomalously strong volcanism prior to the Younger Dryas event is now very strong. ..."
(See the Younger Dryas Cause section for the citations and the text indicated by "..."
----
----In order to resolve the above issues, I propose the following:
* Merge the material from  Younger Dryas impact hypothesis Other explanations section into the Younger Dryas Cause section. (Some overlap of text and references exists).
* Revise the summary sentence in this article to align with the  Younger Dryas Cause section and use a working Wikilink to that specific section. The mainstream hypothesis for the Younger Dryas cause has changed significantly from the Broecker 2006 hypothesis stated in the YDIH article.
* Delete the  Younger Dryas impact hypothesis Other explanations section
* Make this article the source of the (current) mainstream explanation(s) (could be more than one, e.g., meltwater and vulcanism) with discussions occurring on this talk page regarding reliable sources in support of (or against) specific explanation(s). (Note that the YDIH article states that YDIH IS NOT considered mainstream.) 
Comments? Dmcdysan (talk) 21:11, 16 February 2024 (UTC)
thread_title:  YDIH article contradicts YD article statement of Mainstream Cause