A series of volcanic eruptions in the middle of the 13th century could be one of the triggers of the "little ice age" — the era of strong climate cooling in the Late Middle Ages and in the New Era, say American Geophysics in an article in the journal Geophysical Research Letters.
To date, the exact timing of this cooling period is not defined. According to the official definition of NASA, the Little Ice Age lasted from short warm "breaks" from 1550 to 1850. Most climatologists and geophysicists associate it with the fall of the active phase of the solar activity in the period from 1640 to 1710 years, which was called the Maunder minimum. However, other causes and scope of this era are not excluded.
A team led by Gifford Miller (Gifford Miller) from the University of Colorado at Boulder (USA) has found one of the possible causes of this phenomenon — a series of volcanic eruptions — to study the remains of plants, which were kept in the glaciers of Baffin Island to the present time.
According to researchers, a number of European Middle Ages chronicles contain references to the series of unusually cold autumn and winter, which destroyed crops and brought the "Great Famine" 1315-1317 period. After that, a period of abrupt climate cooling — in the northern Scandinavian glaciers began to advance in Italy, there was snow, and in Scotland and England, the river began to freeze in the winter, which was not seen before.
In their work, scientists studied 94 fragment "fossil" moss, age ranged from 800 to 2000 AD. Most of the plant residue is at the end of 13th century and early 14th century. This points to the fact that at that time the climatic conditions have deteriorated sharply, leading to the almost simultaneous deaths of plants and their burial beneath the glacier.
The researchers then analyzed the mineral content of glacial deposits of this period, caught off the coast of Iceland and the islands of the Canadian Arctic Archipelago. These deposits are referred to the termination of the melting of glaciers and their gradual growth of the next century.
Home sprawl glaciers corresponds in time to occurrence of four layers of volcanic sulfur, which were found in other parts of the Earth's interior. According to calculations of the researchers, these eruptions occurred about 50 years before the start of the cooling in the tropical part of the world. Scientists have suggested that these disasters have caused "little ice age".
To test this hypothesis, the researchers used one of the climate models used for the preparation of reports by the Intergovernmental Panel on Climate Change (IPCC), adapting it to reconstruct the climate of the Middle Ages. An additional factor, the scientists added to her four volcanoes in the second half of the 13th century and followed the developments in the next 500 years.
According to geophysicists, emergence of a large amount of soot particles and the subsequent decrease in average annual air temperatures disrupt the currents in the Atlantic Ocean, which govern the transfer of heat from the tropics to the middle latitudes. Violation of their work was the cause of the gradual extinction of their activity and further falling temperatures.
According to Miller and his colleagues, the next series of eruptions and solar activity decline in the mid-15th century, this effect intensified and prolonged the duration of the "Little Ice Age" to the 19th century.