Homeric Minimum

The Homeric Minimum is a grand solar minimum that took place between 2,800 and 2,550 years before present (c. 800–600 BC). It appears to coincide with, and have been the cause of, a phase of climate change at that time, which involved a wetter western and drier eastern Europe. This had far-reaching effects on human civilization, some of which may be recorded in Greek mythology and the Old Testament.

Solar phenomenon

The Homeric Minimum is a persistent and deep[1] solar minimum that took place between 2,800 and 2,550 years before present,[2] starting around 830 BC[3] and resembling the Spörer Minimum.[4] This minimum is sometimes considered to be part of a longer "Hallstattzeit" solar minimum between 705–200 BC that also includes a second minimum between 460 and 260 BC.[5] The Homeric Minimum however also coincided with a geomagnetic excursion named "Etrussia-Sterno", which may have altered the climate response to the Homeric Minimum.[6]

Mechanisms of climate effects

Variations in the solar output have effects on climate, less through the usually quite small effects on insolation and more through the relatively large changes of UV radiation and potentially also indirectly through modulation of cosmic ray radiation. The 11-year solar cycle measurably alters the behaviour of weather and atmosphere, but decadal and centennial climate cycles are also attributed to solar variation.[2]

Effects on human populations and climate

Debates on whether a climatic deterioration occurred during that time began already in the late 19th century.[7] The Homeric Minimum has been linked with a phase of climate change,[8] during which the Western United States,[9] Europe and the North Atlantic became colder and wetter[10] although the eastern parts of Europe appear to have become drier.[11] This climate oscillation has been called the "Homeric Climate Oscillation"[8] or the "2.8 kyr event",[12] and it has been associated with the Iron Age Cold Epoch[13] and a cultural interruption in Ireland although its effect there is still debated.[7]

Human cultures at that time underwent changes,[8] which also coincide with the transition from the Bronze Age to the Iron Age.[14] The climate fallout of this prolonged solar minimum may have had substantial impact on human societies at that time.[15]

It has been speculated that some ancient literary references refer to these phenomena. For example, the period saw the growth of a glacier on Mount Olympus, while Greek mythology and Homer refer to ice and storms on the mountain, which may also be reflected in the name "Olympus".[16] Increased activity of the polar lights at the end of the Homeric Minimum may have inspired Ezekiel's vision of God in the Old Testament.[17]

a stormy wind ... out of the north ... with brightness around it, and fire flashing forth ... as it were gleaming metal ... an expanse, shining like awe-inspiring crystal.

— Ezekiel, Ezekiel 1:4–28, Old Testament

Other effects

A variety of phenomena have been linked to the Homeric Minimum:

• Increasingly cold, wet and windy climate recorded from Meerfelder Maar in Germany,[18] where the Homeric Minimum has been associated with a permanent climate transition.[19] A wetter climate was also recognized in a bog in the Netherlands;[20] the present-day Czech Republic, where it also became colder; and in the British Isles.[12]
• A growth in the size of lakes and downward expansion of conifer forests took place in Western North America at the time of the Homeric Minimum.[9]
• Decreased sea levels are recorded from the Homeric Minimum.[21]
• Increased storminess in Scotland and Sweden.[13]
• Increased precipitation in northern Iberia. Such a precipitation increase took place a few decades after the Homeric Minimum and increased wetness has been noted after other solar minima, as well.[22]
• Cold sea surface temperatures in the Santa Barbara Basin of California and a cold interval in the Campito Mountain tree ring record. The Homeric Minimum in general seems to be associated with a cold climate in California.[5]
• Decreased atmospheric pressure differences between Iceland and the subtropics, that is a decreased North Atlantic Oscillation.[23]
• Cooling is also recorded from Asia and the Southern Hemisphere.[24]
• A weaker monsoon in East Asia,[25] India and Tibet.[26]
• A wetter climate is recorded for Central Asia.[27]
• Lake levels in the Caspian Sea rose.[27]
• More frequent floods and storms in the Alps.[28]
• A dry period in the Eastern Mediterranean and the Dead Sea appears to coincide with the Homeric Minimum, although the mechanisms for this are not clear.[29]
• Increased incision along the River Soar.[30]
• Increased production of carbon-14 and beryllium-10 by cosmic rays, recorded in Greenland.[2] The carbon-14 excursion is also recorded elsewhere and constitutes the largest such spike since 2000 BC, exceeding the Maunder Minimum.[14] The so-called Hallstatt plateau, an anomaly in carbon-14 production that creates large imprecisions in radiocarbon dating during that time, has been related to the Homeric Minimum.[31]
• The switch from the Subboreal to the Subatlantic climate epoch in the Blytt-Sernander sequence about 2,800 years before present.[2]
• The "Göschenen I" glacier advance in the Alps relates to the 2.8 kiloyear event.[32]
• A change in storm frequency on the Scotian Shelf.[33]

References

1. Geel et al. 2012, p. 401.
2. Geel et al. 2012, p. 397.
3. Kilian, Van der Plicht & Van Geel 1995, p. 962.
4. Kilian, Van der Plicht & Van Geel 1995, p. 959.
5. Davis, Jirikowic & Kalin 1992, p. 23.
6. Raspopov, O. M.; Dergachev, V. A.; Gus'kova, E. G.; Kolstrom, T. (2004-12-01). "Development of the Maunder Type of Solar Activity and Their Climatic Response". AGU Fall Meeting Abstracts. 43: U43A–0739. Bibcode:2004AGUFM.U43A0739R.
7. Gearey et al. 2020, p. 2.
8. Rach et al. 2017, p. 45.
9. Davis, Jirikowic & Kalin 1992, pp. 27-28.
10. Rach et al. 2017, p. 44.
11. Słowiński, Michał; Marcisz, Katarzyna; Płóciennik, Mateusz; Obremska, Milena; Pawłowski, Dominik; Okupny, Daniel; Słowińska, Sandra; Borówka, Ryszard; Kittel, Piotr; Forysiak, Jacek; Michczyńska, Danuta J.; Lamentowicz, Mariusz (November 2016). "Drought as a stress driver of ecological changes in peatland – A palaeoecological study of peatland development between 3500 BCE and 200 BCE in central Poland". Palaeogeography, Palaeoclimatology, Palaeoecology. 461: 287. Bibcode:2016PPP...461..272S. doi:10.1016/j.palaeo.2016.08.038. ISSN 0031-0182.
12. Laurenz, Ludger; Lüdecke, Horst-Joachim; Lüning, Sebastian (1 April 2019). "Influence of solar activity changes on European rainfall". Journal of Atmospheric and Solar-Terrestrial Physics. 185: 30. Bibcode:2019JASTP.185...29L. doi:10.1016/j.jastp.2019.01.012. ISSN 1364-6826.
13. Kylander, Malin E.; Söderlindh, Jenny; Schenk, Frederik; Gyllencreutz, Richard; Rydberg, Johan; Bindler, Richard; Martínez Cortizas, Antonio; Skelton, Alasdair (30 August 2019). "It's in your glass: a history of sea level and storminess from the Laphroaig bog, Islay (southwestern Scotland)". Boreas. 49: 12. doi:10.1111/bor.12409.
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17. Siscoe, George L.; Silverman, Samuel M.; Siebert, Keith D. (2002). "Ezekiel and the Northern Lights: Biblical aurora seems plausible". Eos, Transactions American Geophysical Union. 83 (16): 3. Bibcode:2002EOSTr..83..173S. doi:10.1029/2002eo000113. ISSN 0096-3941.
18. Geel et al. 2012, p. 398.
19. Rach et al. 2017, p. 52.
20. Kilian, Van der Plicht & Van Geel 1995, p. 965.
21. Lampe, Matthias; Lampe, Reinhard (2018). "Evolution of a large Baltic beach ridge plain (Neudarss, NE Germany): A continuous record of sea-level and wind-field variation since the Homeric Minimum". Earth Surface Processes and Landforms. 43 (15): 3049. Bibcode:2018ESPL...43.3042L. doi:10.1002/esp.4468. ISSN 1096-9837. S2CID 134663052.
22. Martín-Chivelet, J.; Edwards, R. L.; Muñoz-García, M. B.; Gómez, P.; Sánchez, L.; Garralón, A.; Ortega, A. I.; Marín-Roldán, A.; Cáceres, J. O.; Turrero, M. J.; Cruz, J. A. (1 December 2015). "Long-term hydrological changes in northern Iberia (4.9–0.9 ky BP) from speleothem Mg/Ca ratios and cave monitoring (Ojo Guareña Karst Complex, Spain)" (PDF). Environmental Earth Sciences. 74 (12): 7751. doi:10.1007/s12665-015-4687-x. hdl:10261/118315. ISSN 1866-6299. S2CID 127349575.
23. Rach et al. 2017, p. 50.
24. Davis, Jirikowic & Kalin 1992, p. 29.
25. Tan, Liangcheng; Li, Yanzhen; Wang, Xiqian; Cai, Yanjun; Lin, Fangyuan; Cheng, Hai; Ma, Le; Sinha, Ashish; Edwards, R. Lawrence (2020). "Holocene Monsoon Change and Abrupt Events on the Western Chinese Loess Plateau as Revealed by Accurately Dated Stalagmites". Geophysical Research Letters. 47 (21): 1. doi:10.1029/2020GL090273. ISSN 1944-8007.
26. Sun, Zhe; Yuan, Kan; Hou, Xiaohuan; Ji, Kejia; Li, Can-Ge; Wang, Mingda; Hou, Juzhi (1 August 2020). "Centennial-scale interplay between the Indian Summer Monsoon and the Westerlies revealed from Ngamring Co, southern Tibetan Plateau". The Holocene. 30 (8): 1169. doi:10.1177/0959683620913930. ISSN 0959-6836.
27. Neugebauer et al. 2015, p. 1358.
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29. Neugebauer et al. 2015, p. 1368.
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31. Gearey et al. 2020, p. 17.
32. Kronig, Olivia; Ivy-Ochs, Susan; Hajdas, Irka; Christl, Marcus; Wirsig, Christian; Schlüchter, Christian (1 April 2018). "Holocene evolution of the Triftje- and the Oberseegletscher (Swiss Alps) constrained with 10Be exposure and radiocarbon dating". Swiss Journal of Geosciences. 111 (1): 127. doi:10.1007/s00015-017-0288-x. ISSN 1661-8734. S2CID 134721101.
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• Gearey, Benjamin; Becker, Katharina; Everett, Rosie; Griffiths, Seren (2020). "On the brink of Armageddon? Climate change, the archaeological record and human activity across the Bronze Age–Iron Age transition in Ireland". Proceedings of the Royal Irish Academy: Archaeology, Culture, History, Literature: 1–24. doi:10.3318/priac.2020.120.06. ISSN 0035-8991.
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