Talk:Last Glacial Maximum

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Temperature proxies[edit]

What on Earth does that mean? What else do these temperatures supposed to represent but themselves?
Than the time-scale is backward. Why???
What is the unit of the temperature? One can guess it is F. But what level of ignorance is that nor Celsius neither Kelvin was added? — Preceding unsigned comment added by 202.8.39.83 (talk) 02:00, 13 October 2015 (UTC)[reply]

Came here to say the same thing. 8 years later. If nobody knows what the heck the plot is I will go ahead and delete it. Gjxj (talk) 16:29, 14 April 2023 (UTC)[reply]
They are proxies, not temperature. Click on the graph and it will tell you: delta-D or delta_O-18 William M. Connolley (talk) 16:59, 14 April 2023 (UTC)[reply]
well i can spend some time google-ing and figure out that GRIP is Greenland Ice Sheet Project (GRIP) oxygen isotope proxy, and so forth. That info should be in the article with sufficient explanation of what it means. Gjxj (talk) 23:53, 16 April 2023 (UTC)[reply]
I support deleting it. All text and graphs should be comprehensible to readers and this will mean nothing to 99%. I get proxy, although the link in the image text goes to a disambig. Delta_O-18 presumably means ratios of O18 to O16 in ancient air samples as a proxy for direct measurement of temperature. I have no idea what Delta-D means and the term redirects to Cholecalciferol with nothing about it being a proxy. 1x10 power 4 is 10,000, although it is an unnecessarily obscure way of expressing it. The vertical units must be temperature but I have no idea what scale. The graph would be useful with comprehensible and well explained units, although it may be out of date as a lot of work has been done to improve the data since it was created in 2006. Dudley Miles (talk) 10:13, 16 April 2023 (UTC)[reply]

Untitled[edit]

Why isn't the title of this article Pinedale Glaciation...maybe a merge is necessary?--MONGO 18:20, 10 February 2006 (UTC)[reply]

Interesting, I've never seen that name used in the paleoclimatic or paleoecologic literature. You only get a handful of hits for it on Google UK; maybe it's only used widely in the US (or perhaps the UK is perculiar). Must admit, it makes sense to give it a name that won't be out of date by the next glacial maximum ;-) but LGM appears to be the more accepted term at the moment. (Deditos 13:09, 22 February 2006 (UTC))[reply]
It must be a North American term, or applies to North America. Here's a U.S. Geological Survey link that claims it was the period of 15-20,000 years ago. [1]--MONGO 13:13, 22 February 2006 (UTC)[reply]

The Gobi Desert isn't in Africa or the Middle East[edit]

Why is the Gobi Desert mentioned under the section for Africa and the Middle East? The Gobi is in Mongolia and China.

Citations?[edit]

Why aren't there any citations on this wikipage? How do we know that the data is verifiable and altogether true?

Here's a paper that uses a nice new technique (oxygen/nitrogen ratios in ice) to confirm the Milankovitch hypothesis and the overall chronology described in the LGM page: Nature 448, 912-916 (23 August 2007) doi:10.1038
Northern Hemisphere forcing of climatic cycles in Antarctica over the past 360,000 years
Kenji Kawamura, Frédéric Parrenin, Lorraine Lisiecki, Ryu Uemura, Françoise Vimeux, Jeffrey P. Severinghaus, Manuel A. Hutterli, Takakiyo Nakazawa, Shuji Aoki, Jean Jouze, Maureen E. Raymo, Koji Matsumoto, Hisakazu Nakata1, Hideaki Motoyama, Shuji Fujita, Kumiko Goto-Azuma, Yoshiyuki Fujii5 & Okitsugu Watanabe.
The overall chronology of the LGM is in any case mapped out by a myriad of C14 and other radiometric dates. A list of them would be the length of a book in itself. Having said that, the fine details of what happened at the LGM and since is still a matter of keen scientific debate; see eg Science 2 December 2005: Vol. 310. no. 5753, pp. 1469 - 1473 ::DOI: 10.1126 Radiocarbon Variability in the Western North Atlantic During the Last Deglaciation
Laura F. Robinson, Jess F. Adkins, Lloyd D. Keigwin, John Southon, Diego P. Fernandez, S-L Wang, Daniel S. Scheirer
Hope this helps!Orbitalforam (talk) 15:25, 5 September 2008 (UTC)[reply]

Amazonia[edit]

This article states that the Amazonian rainforest was divided in two by savanna during the glacial maximum. However the article on Amazonia states that scientific opinion is divided as to what Amazonia was like at this time. It cites articles from reputable scientific journals that hypothesise that the Amazon rainforest was reduced to a number of relatively small refugia amongst savanna and others that hypothesise that the rainforest remained substantially intact, though covering a smaller area. These would seem to be the two major points of view, with the scientific community not being settled definitively on one or the other. Therefore it seems odd to make this statement as if it was something generally agreed, when in reality it is strongly contested. Booshank 20:05, 4 September 2007 (UTC)[reply]

Clearly the article should summarize the major points of view per WP:POV, unless there is no real disagreement. —EncMstr 20:12, 4 September 2007 (UTC)[reply]

Map of Vegetation Patterns[edit]

Could somebody please edit the map of the vegetation patterns? Many of the colors are hard to tell apart. Some colors appear in the map but I don't find them in the key. For example, there are strips of light brown in south and southeastern Asia. Some strips of color would be easier to distinguish if a different, brighter color were used. I'm not sure I could edit it very well. Thanks. 99.9.112.31 (talk) 22:32, 27 January 2011 (UTC)NotWillDecker[reply]

I agree with you and have done exactly that. The picture was cropped vertically as adoption to the landmasses actually shown. Then each of the colours was changed to one I thought fitted better. Some of the differently coloured fields have been given the same colour. This is because I could not tell any clear difference between the vegetation zones. Otherwise, the borders between the different coloured fields are almost identical. Two different versions of the map with legends in Swedish and English have been made. You may excuse my Swedish-influenced English but it should be understandable. Finally, four versions without text have been made. To these four texts in most written language can be added. All can now be found on my website:

Version with Swedish legend.

Version with English legend.

Eurocentric version adopted for languages written from left to right.

Eurocentric version adopted for languages written from right to left.

Sinocentric version adopted for languages written from left to right.

Sinocentric version adopted for languages written from right to left.

All on the same page can be found here. Please note that on this page all maps are clickable. If you click on them you get a pop-up window with the same image in full resolution PNG. I have decided not to claim any copyright on these six images. This because the borders between the climate zones (as shown in the form of vegetation zones) are often depicted as sharper than I find plausible. To my knowledge forests don’t directly border to deserts. Neither does ice sheets directly border to temperate or subarctic climates. There most have been some sort of intermediate climate in between. However, these zones may have been to narrow to be shown on the world map.

2013-12-31 Lena Synnerholm, Märsta, Sweden.

After I posted my inlay I realised that some of the differently coloured areas had been coloured incorrectly. Now I have fixed it. I have tried to make all colours noticeably different. At the same time, I have tried to use the colours I am used to. Of cause, I had to compromise between these. Still, I think it is easier to read than the original one.

2014-01-01 Lena Synnerholm, Märsta, Sweden.

Map of northern Europe[edit]

The map of northern Europe needs an explanation. What dos the arrows mean? Why is the southern part of the present-day Baltic Sea striped? There is one more striped area in northwestern Siberia. What does that one mean? Anyone else who knows?

2013-12-31 Lena Synnerholm, Märsta, Sweden.

2021 Answer : There was no Baltic Sea. Sea level was 120 meters lower. And it was a glacier instead. — Preceding unsigned comment added by 37.166.119.218 (talk) 00:00, 24 February 2021 (UTC)[reply]

Andes and Siberia on the world map[edit]

The worldwide vegetation map really seems to indicate a long strip of glaciation in the central Andes - not Patagonia (grey colouring). Most maps and books I've seen only state the far southern Andes were glaciated. - Discussion of the map further up on this talk page indicates that it was cropped and some of the colours changed out, but I hope this is not a side effect of that.

Also I think the article should state that the extent of glaciation in Siberia is unclear and under discussion. In most older books and maps, and some maps that simply restate old views, the idea is that Siberia was ice free, a cold desert with so little precipitation no ice sheets ever formed. That picture has been reshuffled and challenged over time; many glaciologists now think (supported by field data) that there were major ice sheets in northern and eastern Siberia blocking the flow of the big rivers and stretching out onto the shelf of the Arctic ocean. The simple fact is the area is distant and inhospitable and there's never been near the amount of digging and investigation of paleoclimate on the spot that there has been in Quebec, Britain or Scandinavia (and during the Soviet era, exchange of research data was very limited and western researchers had no chance of getting to Siberia to look for field data). 83.254.154.164 (talk) 01:48, 9 October 2014 (UTC)[reply]

A considerable part of the Central Andes may well have been glaciated. However, to what extent Siberia was ice-covered may well be an area (!) of active research. Which great rivers do you think were blocked by ice sheets? If so, were did their water go? One can compare the situation to merging of the British and Scandinavian ice sheets during the same ice age. The result was the temporary flooding of Doggerland an the formation of the English Channel as an alterative outlet.

2015-01-04 Lena Synnerholm, Märsta, Sweden. — Preceding unsigned comment added by 213.114.158.174 (talk) 16:08, 4 January 2015 (UTC)[reply]

LGM survivability and potential extent of humans?[edit]

Potential extent of human survivability during the last glacial maximum, if we subtract out deserts, tundras, and glacial regions.

I am interested to know more about where humans may have lived during the Ice Ages. Other articles on Wikipedia (e.g. Homo) state that humans migrated out of Africa at least 60,000 years ago, so there may have been human populations scraping out an existence all around the planet through the last several Ice Ages.

If I take the SVG climate map and subtract out the deserts and glacial/tundra regions, I get the following result. But I'd like to find more formal studies with citations.

-- DMahalko (talk) 08:47, 27 August 2015 (UTC)[reply]

I don’t think the areas inhabited at the time were quite as limited as your map suggests. Tundra is very much inhabitable to human hunter-gatherers and deserts at least partially so. The only areas uninhabitable 26,500 − 19,000 would have been either ice-covered or polar deserts. These are marked in white and grey on this map found on my website.

That a landmass was habitable does not mean it was inhabited, however. It is unclear when humans first set foot in the New World as this is an areas of active research. My educated guess is that the Falkland Islands and the Caribbean were still uninhabited. Madagascar and New Zealand definitely were.

2015-12-29 Lena Synnerholm, Märsta, Sweden.

Believe it or not, steppe-tundra was occupied by our ancestors. Thank to their great hunting abilities. First migration out of Africa is dated 1.9 million BP, by Homo Ergaster/Erectus. Oldest known sites in Europe are in actual Spain, around 1.2 million BP (Atapuerca, Orce) There is Happisburgh in England, dated 900,000 BP. It was during an Ice Age. "people" there (Homo Heidelbergensis?) lived right below the glacier. Then there is Homo Sapiens migration. Oldest european sites dated 45,000 BP. During the last glacial maximum, there were many human sites. There were many reindeers in tundra (like in actual siberia) and bison in the steppes. The Lascaux caves are dated 15,000 BP, and guess what they drew ? Banana trees. Just kidding. I heard that from conferences of Musee De L'Homme. On youtube but it's in French. There are many maps showing locations of human sites. I cant post them here.

As of the New World, french prehistorian François Djindjian said probably 30,000 BP. Then the glacier grew and they could not go back (to russia) and had to go South. The glacier grew and destroyed every archaeological sites in North America, that's why we dont find anything. And during Holocene (11700 BP), they went back to North.

2021-02-23 Sébastien, Paris, France

dates[edit]

Given the increasing quality in radiocarbon dating and calibrations even for these periods, times given as "ago" become outdated and may only be used for eras not accessable to better dating. Momentarily, the millennia are simply but incorrectly referring to the year 2000 CE/CC. Correctly spoken, we then would now live in the year 16 after that. For what do we have a common chronology, known to everybody? HJJHolm (talk) 17:17, 21 February 2016 (UTC)[reply]

Whoever uses this ambiguous "ago" nonsense has at least to define it!!!HJJHolm (talk) 14:10, 5 September 2023 (UTC)[reply]

Irish Sea Glacier[edit]

The map of the ice sheet coverage in Europe seems quite inaccurate, and grossly underestimates the extent of the ice sheet, as I've always read that all of Ireland, 100% of it, was covered in a very thick ice sheet, during height of the last ice age. Even the Southern edge of Ireland was under at least 2000 metres, a mile or so, of ice sheet.

See the Irish Sea Glacier Wikipedia article and this 2012, Irish Times article, and this scientific paper published in 2014, "Flow-pattern evolution of the last British Ice Sheet" (figure 1 in particular), as just a few examples of how the ice sheet did not just cover all of Ireland, but much further out than that, onto the continental shelf beyond, to the point of almost reaching South West England! — Preceding unsigned comment added by 86.155.3.207 (talk) 14:38, 18 November 2016 (UTC)[reply]

To be honest, I've also understood, completely contrary to what this article claims, that most of South West England at the very height of the last Ice Age was covered in thick boreal forest with temperate deciduous forest in the lowest areas (though without Beech trees), the polar tundra zone only beginning towards South East England and extending into the North Sea. — Preceding unsigned comment added by 86.155.3.207 (talk) 14:46, 18 November 2016 (UTC)[reply]

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Hawaii[edit]

Hawaii is part of the modern country America, but is not in North America. It is in the Pacific Ocean. There is currently no section for any oceans. Danielklein (talk) 03:47, 5 January 2019 (UTC)[reply]

A Commons file used on this page has been nominated for deletion[edit]

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Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 08:51, 26 May 2019 (UTC)[reply]

Exemplary Graphic[edit]

"Evolution of temperatures in the Post-Glacial period according to Greenland ice cores.[6]": Thanks to the scientist who eventually and - against many other not capable ones - to tell his computer how to plot the correct direction of the data! Tip: the PC automatically plots from lower numbers at left hand to higher ones to the right. If the older ones are BC, you "simply" have to mark them as "minus". Thank you again" 95.90.202.165 (talk) 09:54, 29 October 2020 (UTC)[reply]

Note:I moved this section down from above; it had been posted in the middle of the page. Mike Christie (talk - contribs - library) 10:12, 29 October 2020 (UTC)[reply]

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Graph off-topic[edit]

The former greyscaled graph in the middle had to be removed because it roughly starts when the LGM ended - taking the definition in this article, and thus has nothing to do with the topic.HJHolm (talk) 14:21, 20 February 2022 (UTC)[reply]

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