Solar cycle to cause global natural disasters?

Life on Earth depends on the Sun. It is the solar activity that can show influence on climate changes on Earth. The solar cycle currently moves towards its maximum. Can it cause any problems to humans? Scientists say that it should not lead to global disasters because they have never occurred in 400 years of observations.

The solar activity implies the appearance of spots on the Sun. The number of those spots may reach their maximum and then reduce to minimum during certain periods of time. For the first time in history, sun spots were discovered in 1611. The discovery became a surprise for astronomers: they previously thought that the sun was something unchangeable.

It was later determined that the number of sun sports changes, albeit not chaotically: they multiply at first and then decrease in number. Such a cycle may last from eight to fourteen years, although most often it continues for eleven years.

Solar cycles may differ from each other from the point of view of their intensity. Sometimes, a maximum of such a cycle is very hard to distinguish from its minimum. Such situation was observed from 1645 to 1715 - the so-called Maunder Minimum (after English astronomer Edward Walter Maunder, who discovered the phenomenon). The number of spots on the sun reduced considerably: there were only 50 of them instead of the usual amount of 40-50 thousand spots. The lion's share of sun spots is located in the southern hemisphere of the Sun.

This coincided with the so-called Little Ice Age that lasted from the 14^th to the 19^th centuries. That was the period of unusually cold weather on the territory of Europe and America (average temperatures during the recent 2,000 years were the lowest). The weather was relatively smooth and warm from the 10^th to the 13^th centuries, with mild winters and no droughts. During the 1310s, heavy rains and severe winters destroyed harvests and fruit gardens in England, Scotland, France and Germany.

Frequent ground frosts and snowfalls occurred even in the south of Europe. The weather on the east coast of the USA became a lot colder, whereas in central and western areas the climate conditions were extremely dry, with dust storms.

During the 16^th century, average temperatures raised, winters became milder. In the 17^th century, global temperatures dropped by 1-2 degrees Centigrade. The Thames, the Danube, the Adriatic Sea and the Turkish Straits would freeze in wintertime.

In spite of the fact that the Little Ice Age lasted longer than the Maunder Minimum, it presumably occurred because of the reduction of the solar activity. The theory was subsequently confirmed through the analysis of carbon-14 and other isotopes (beryllium-10, for example) in trees and glaciers. Interestingly enough, the Maunder Minimum coincided with the reign of Louis XIV (1643-1715), who was known as the Sun King.

Thus, according to scientists, 18 minimums of solar activity have occurred during the recent 8,000 years. The Spoerer Minimum (1450-1540) and the Dalton Minimum (1790-1820) were the most notable ones.

The reasons that led to the appearance of sun spots became clear to scientists only in the first half of the 20^th century. It was discovered that the spots were of magnetic nature. The magnetic substance inside the Sun is not stable: it moves and may sometimes come to the surface of the star, which may lead to the displacement of poles. The full cycle, when the poles return to their places, lasts for 22 years. The cycle of eleven years is known to science a lot better because it is easy to detect it with the help of calculations and observations.

Nowadays, the solar cycle moves towards its maximum. The solar activity will reach its peak by the end of 2013 or by the beginning of 2014. Afterwards, the activity will begin to decline. The minimum is to occur in 2020.

The current cycle is special because it is the slowest in the history of space observations. Scientists assumed that there would be a relatively small amount of sun spots during the next solar maximum period. It is not likely to affect planet Earth and humanity, though. 

Irina Shlionskaya

Pravda.Ru

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