Everything about Volcanic Winter totally explained
A
volcanic winter is the reduction in temperature caused by
volcanic ash and droplets of
sulfuric acid obscuring the
sun, usually following a large
volcanic eruption.==Effects on life==
The causes of the
bottleneck phenomenon, for example, a sharp decrease in a
species' population immediately followed by a period of great genetic divergence (
differentiation) among survivors—might be attributed to volcanic winters. According to
anthropologist Stanley Ambrose, such events diminish the population size to "levels low enough for evolutionary changes, which occur much faster in small populations, to produce rapid population differentiation".
Ancient case of volcanic winters
One proposed volcanic winter happened around 71,000–73,000 years ago following the
supereruption of
Lake Toba on
Sumatra island in
Indonesia. In the following 6 years there was the highest amount of volcanic
sulphur deposited in the last 110,000 years, possibly causing significant
deforestation in
Southeast Asia and the cooling of global
temperatures by 1 °C. Some scientists hypothesize the eruption caused an immediate return to a
glacial climate regime by accelerating an ongoing continental glaciation, thereby causing massive population reduction among animals and human beings on
Earth. Others argue that the climatic effects of the eruption were too weak and brief to impact early human populations to the degree proposed.
This, combined with the fact that most human differentiations abruptly occurred at that same period, is a probable case of
bottleneck linked to volcanic winters (see
Toba catastrophe theory). On average, super-eruptions with total eruptive masses of at least 10
15 kg (Toba eruptive mass = 6.9 × 10
15 kg) occur every 1 million years.
Recent cases of volcanic winter
The scales of recent winters are more modest but their effects can be significant. A paper written by
Benjamin Franklin in 1783 blamed the unusually cool summer of 1783 on volcanic dust coming from
Iceland, where the eruption of
Laki volcano had released enormous amounts of
sulfur dioxide, resulting in the death of much of the island's
livestock and a catastrophic
famine which killed a quarter of the population. Temperatures in the
northern hemisphere dropped by about 1 °C in the year following the Laki eruption.
The
extreme weather events of 535-536 are most likely linked to a volcanic eruption.
In
1452 or
1453, a cataclysmic eruption of the
submarine volcano Kuwae caused worldwide disruptions.
In
1600, the
Huaynaputina in
Peru erupted. Tree ring studies show that 1601 was cold.
Russia had its worst famine in 1601 to 1603. From 1600 to 1602,
Switzerland,
Latvia and
Estonia had exceptionally cold winters. The wine harvest was late in 1601 in
France, and in Peru and
Germany wine production collapsed. Peach trees bloomed late in
China, and
Lake Suwa in
Japan froze early .
The 1815 eruption of
Mount Tambora, a
stratovolcano in
Indonesia, occasioned mid-summer frosts in
New York State and June snowfalls in
New England in what came to be known as the "
Year Without a Summer" of 1816.
In 1883, the
explosion of
Krakatoa (Krakatau) also created volcanic winter-like conditions. The next four years after the explosion were unusually cold, and the winter of 1888 was the first time snow fell in the area. Record snowfalls were recorded worldwide.
Most recently, the 1991 explosion of
Mount Pinatubo, another stratovolcano in the
Philippines, cooled global temperatures for about 2–3 years.
Further Information
Get more info on 'Volcanic Winter'.
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