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 Europe 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.
The Homeric Minimum is a persistent and deep[1][2] solar minimum that took place between 2,800 and 2,550 years Before Present,[3] starting around 830 BCE[4] and resembling the Spörer Minimum.[5] It is sometimes named "Great Solar Minimum".[6] It has been subdivided into a stronger minimum at 2,750-2,635 years before present and a secondary minimum 2,614-2,594 years before present.[7] The Homeric 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.[8] The Homeric Minimum however also coincided with a geomagnetic excursion named "Etrussia-Sterno", which may have altered the climate response to the Homeric Minimum.[9] The name "Homeric Minimum" however is not widely accepted in solar physics.[10]
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.[3] It is possible that cooling in the North Atlantic predated the Homeric Minimum.[11]
Debates on whether a climatic deterioration occurred during that time began already in the late 19th century.[12] The Homeric Minimum has been linked with a phase of climate change,[13] during which the Western United States [14] and Europe became colder[15] but whether it became drier or wetter is under debate;[16] the western parts and the North Atlantic may have become wetter[17] and the eastern parts of Europe drier.[18] This climate oscillation has been called the "Homeric Climate Oscillation"[13] or the "2.8 kyr event",[19][20] and it has been associated with the Iron Age Cold Epoch,[21] the decline of the Urartu kingdom in Armenia[22] and a cultural interruption in Ireland although its effect there is still debated.[12]
Human cultures at that time underwent changes,[13] which also coincide with the transition from the Bronze Age to the Iron Age.[23] The climate fallout of this prolonged solar minimum may have had substantial impact on human societies at that time,[24] with a recovery of societies after its end.[25] Increased precipitation over the Eurasian steppes during the Homeric Minimum may have benefitted the Skythes there, however.[26]
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".[27] 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.[28]
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.
A variety of phenomena have been linked to the Homeric Minimum: