Etna is active again. Can volcanic eruptions affect the climate?
The summer of 1816 went down in the annals as one of the coolest. The cause came to light much later. At that time, in southern Germany and Switzerland, snow still fell down to the lowlands in July. The entire summer, i.e. the months of June, July and August, was around 2.5 degrees colder in Germany than the current average from 1971 to 2000.
That was the coldest summer in Germany since at least 1761, since comprehensive temperature measurements were available. The deviations were greatest in the south of France at that time, as one could reconstruct from tree rings or pollen deposits. The summer temperature there was even more than three degrees below the long-term average.
That sounds moderate, but it wasn’t. The persistently cold and very rainy weather, which incidentally also occurred in North America, led to crop failures and, as a result, especially in southern Germany and Switzerland, to famine, which in turn led to waves of emigration to the new world. Up to 30 cm of fresh snow fell in Quebec, Canada in August 1816. From the New England states in the east of the USA, the then new states Ohio, Illinois and Indiana were settled within just a few years. In the United States, this summer is also known as “Eighteen hundred and froze to death”.
The cause of this extreme weather was long in the dark and was only discovered in 1920 by the American meteorologist William Jackson Humphreys: In the previous year, the Tambora volcano erupted on the island of Sumbawa, now part of Indonesia. It was the largest eruption in the world for over 20,000 years, throwing around 150 cubic kilometers of dust and ash into the atmosphere. In the stratosphere, a sulfur-containing ash cloud spread like a veil around the globe and markedly weakened solar radiation worldwide in the following four years. A similar, but nowhere near as strong, effect was last seen in 1991 when the Pinatubo erupted in the Philippines and the temperature fell by a few tenths of a degree worldwide.
As a result of the famine, an agricultural association was founded in Württemberg in 1817, which has been organizing the folk festival on the Cannstatter Wasen ever since. The university in Stuttgart-Hohenheim, which specializes in agricultural sciences, was also brought into being at that time to be better armed against impending famine in the future.
Friday 19th February 2021
The Staeger Team
ARD weather competence center
Broadcast: “alle wetter!”, Hr television, February 19, 2012 7:15 pm
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