The Maunder Minimum - The Little Ice Age - Cosmic Rays, Sunspots and The New Grand Solar Minimum

solarshutdown (62)in #climate • 6 years ago

The Maunder Minimum roughly coincided with the middle part of the Little Ice Age, during which Europe and North America experienced colder than average temperatures. Whether there is a causal relationship, however, is still controversial. Research at the Technical University of Denmark and the Hebrew University of Jerusalem has linked large solar eruptions to changes in the Earth's cloud cover and clouds are known to affect global temperatures. The current best hypothesis for the cause of the Little Ice Age is that it was the result of volcanic action. The onset of the Little Ice Age also occurred well before the beginning of the Maunder minimum.

Sunspot activity waxes and wanes with roughly an 11-year cycle. In 1894 the English astronomer Edward Walter Maunder pointed out that very few sunspots had been observed between 1645 and 1715. Astronomers such as John Flamsteed and Gian Domenico Cassini who did observe sunspots during that period noted that they were the first they had seen in years. However, most of Maunder’s fellow astronomers blamed the lack of sunspots on haphazard and sporadic observations of the Sun by 17th- and 18th-century astronomers. In 1976 American astronomer John Allen Eddy used extensive historical data to show that 17th- and 18th-century astronomers had indeed been careful and diligent observers of the Sun. Eddy also conducted detailed analysis of levels of carbon-14 (a radioactive isotope whose abundance increases during periods of low solar activity) in tree rings to confirm that during two distinct historical periods sunspot activity was greatly decreased. Eddy dubbed the conspicuous solar calm that lasted from 1645 to 1715 the Maunder minimum, after Maunder. (Eddy also examined evidence of an earlier peaceful interval between 1450 and 1540, which he called the Spörer minimum in honour of the 19th-century German scientist Gustav Spörer, another early observer of the irregularities.)

The Maunder minimum coincided with the coldest part of the “Little Ice Age” (c. 1500–1850) in the Northern Hemisphere, when the Thames River in England froze over during winter, Viking settlers abandoned Greenland, and Norwegian farmers demanded that the Danish king recompense them for lands occupied by advancing glaciers. The physical mechanism that explains how a drastic change in solar activity affects Earth’s climate is unknown, and a single episode, however suggestive, does not prove that lower sunspot numbers produce cooling. However, if real, the phenomenon may indicate that the Sun can influence the climate on Earth with even slight fluctuations.

https://en.wikipedia.org/wiki/Maunder_Minimum