Last Glacial Maximum

A map of sea surface temperature changes and glacial extent during the last glacial maximum, according to Climate: Long range Investigation, Mapping, and Prediction, a mapping project conducted by the National Science Foundation in the 1970s and 1980s

The Last Glacial Maximum (LGM), also referred to as the Last Glacial Coldest Period,[1] was the most recent time during the Last Glacial Period where ice sheets were at their greatest extent 26,000 and 20,000 years ago.[2] Ice sheets covered much of Northern North America, Northern Europe, and Asia and profoundly affected Earth's climate by causing a major expansion of deserts,[3] along with a large drop in sea levels.[4]

Based on changes in position of ice sheet margins dated via terrestrial cosmogenic nuclides and radiocarbon dating, growth of ice sheets in the southern hemisphere commenced 33,000 years ago and maximum coverage has been estimated to have occurred sometime between 26,500 years ago[1] and 20,000 years ago.[5] After this, deglaciation caused an abrupt rise in sea level. Decline of the West Antarctica ice sheet occurred between 14,000 and 15,000 years ago, consistent with evidence for another abrupt rise in the sea level about 14,500 years ago.[6][7] Glacier fluctuations around the Strait of Magellan suggest the peak in glacial surface area was constrained to between 25,200 and 23,100 years ago.[8]

There are no agreed dates for the beginning and end of the LGM, and researchers select dates depending on their criteria and the data set consulted. Jennifer French, an archeologist specialising in the European Palaeolithic, dates its onset at 27,500 years ago, with ice sheets at their maximum by around 26,000 years ago and deglaciation commencing between 20,000 and 19,000 years ago.[9] The LGM is referred to in Britain as the Dimlington Stadial, dated to between 31,000 and 16,000 years ago.[10][11]

  1. ^ a b Barrell, David J. A.; Almond, Peter C.; Vandergoes, Marcus J.; Lowe, David J.; Newnham, Rewi M. (15 August 2013). "A composite pollen-based stratotype for inter-regional evaluation of climatic events in New Zealand over the past 30,000 years (NZ-Intimate project)". Quaternary Science Reviews. 74: 4–20. Bibcode:2013QSRv...74....4B. doi:10.1016/j.quascirev.2013.04.002. Retrieved 9 May 2023.
  2. ^ Armstrong, Edward; Hopcroft, Peter O.; Valdes, Paul J. (7 November 2019). "A simulated Northern Hemisphere terrestrial climate dataset for the past 60,000 years". Scientific Data. 6 (1): 265. Bibcode:2019NatSD...6..265A. doi:10.1038/s41597-019-0277-1. PMC 6838074. PMID 31700065.
  3. ^ Beyer, Robert M.; Krapp, Mario; Manica, Andrea (14 July 2020). "High-resolution terrestrial climate, bioclimate and vegetation for the last 120,000 years". Scientific Data. 7 (1): 236. Bibcode:2020NatSD...7..236B. doi:10.1038/s41597-020-0552-1. PMC 7360617. PMID 32665576.
  4. ^ Mithen, Steven (2004). After the Ice: a global human history, 20.000–5.000 BC. Cambridge MA: Harvard University Press. p. 3. ISBN 978-0-674-01570-8.
  5. ^ Anonymous (22 February 1994). "Reconstructing the last glacial and deglacial ice sheets". Eos, Transactions American Geophysical Union. 75 (8): 82–84. Bibcode:1994EOSTr..75...82.. doi:10.1029/94EO00492. Retrieved 10 May 2023.
  6. ^ Clark, Peter U.; Dyke, Arthur S.; Shakun, Jeremy D.; Carlson, Anders E.; Clark, Jorie; Wohlfarth, Barbara; Mitrovica, Jerry X.; Hostetler, Steven W. & McCabe, A. Marshall (2009). "The Last Glacial Maximum". Science. 325 (5941): 710–4. Bibcode:2009Sci...325..710C. doi:10.1126/science.1172873. PMID 19661421. S2CID 1324559.
  7. ^ Evans, Amanda M.; Flatman, Joseph C.; Flemming, Nicholas C. (5 May 2014). Prehistoric Archaeology on the Continental Shelf: A Global Review. Springer. ISBN 978-1-46149635-9 – via Google books.
  8. ^ Fernández, Marilén; Ponce, Juan Federico; Mercau, Josefina Ramón; Coronato, Andrea; Laprida, Cecilia; Maidana, Nora; Quiroga, Diego; Magneres, Ignacio (15 July 2020). "Paleolimnological response to climate variability during Late Glacial and Holocene times: A record from Lake Arturo, located in the Fuegian steppe, southern Argentina". Palaeogeography, Palaeoclimatology, Palaeoecology. 550: 109737. Bibcode:2020PPP...55009737F. doi:10.1016/j.palaeo.2020.109737. S2CID 216352827. Retrieved 5 November 2022.
  9. ^ French, Jennifer (2021). Palaeolithic Europe: A Demographic and Social Prehistory. Cambridge, UK: Cambridge University Press. p. 226. ISBN 978-1-108-49206-5.
  10. ^ Ashton, Nick (2017). Early Humans. William Collins. p. 241. ISBN 978-0-00-815035-8.
  11. ^ Pettitt, Paul; White, Mark (2012). The British Palaeolithic: hominin societies at the edge of the Pleistocene world. London: Routledge. pp. 424–426. ISBN 978-0415674546.