Ecology
The mysterious cooling that lasted several hundred years and called the Little Ice Age turned out to be caused by a series of volcanic eruptions and was supported by sea ice, it is believed scientists.
Scientists who studied the chemical composition preserved in Arctic vegetation, as well as other data, found that the Little Ice Age began at the end of the 13th century.
During a period of global cooling that lasted until the end of the 19th century, moving glaciers destroyed cities in northern Europe, froze the Thames River in London and canals in Holland. Today, these areas do not experience such low temperatures. There is also evidence that it was relatively cold on other continents.
“For the first time, these studies have helped pinpoint the onset of cold weather that marked the arrival of the Little Ice Age,” said Gifford Miller, a geology professor at University of Colorado. “We also found out what caused the low temperatures to last so long.”
Scientists believe that the reason for the cooling was massive volcanic eruptions in the tropics, as a result of which tiny particles — aerosols — were released into the atmosphere. While in the air, these particles reflected solar radiation into space, preventing the Earth from heating properly.
After the aerosol left the atmosphere, the ice in the North Atlantic Ocean kept the cold. The increased ice thickness slowly melted, affecting the temperature of the ocean water. The ice in the Arctic lasted quite a long time, reflecting the sun's rays back into the atmosphere.
Miller and his colleagues came to these conclusions by analyzing radioactive carbon in dead plants based on Baffin Earth in the Canadian Arctic Archipelago. They looked at how much radioactive form of carbon these plants contained. The analysis showed that many plants at high and low latitudes died between 1275 and 1300, which suggests that Baffin Island was covered with ice rather quickly. Many plants were found to have died around 1450, marking a second period of severe cooling.
These two periods coincide with two periods of serious volcanic activity in the past millennium. Scientists also found that the annual layers of glacier lake sediment, which are associated with the ice cap in Iceland, have suddenly become thicker, which indicates increased erosion caused by increased ice in late 13th and 15th century.
Simulation using a computer climate model has shown that several large eruptions located close to each other can cool the Northern Hemisphere and lead to the growth of the ice crust, which which in turn will lead to a longer cooling period.