Volcanic winter
As a volcanic winter, the cooling of the lower atmosphere is called after a volcanic eruption. Ash and sulfur dioxide (SO2 ) from which form aerosols of sulfuric, are thrown at a larger eruption into the stratosphere and spread out like a veil over the entire globe. The sun's rays are thus partially absorbed or scattered back. In the stratosphere, this causes warming. At the bottom there is the means to a cooling of the global climate, regional and depend on the time of year it comes at the same time but also to warming. A volcanic winter comparable effect, which would be triggered by a nuclear war, nuclear winter is called.
Geologically significant volcanic activities (z as the formation of the Siberian Traps, the Emeishan Traps and Deccan Traps ) are associated with several mass extinctions in conjunction.
Measure for reducing the radiation transmissivity of the atmosphere is called the turbidity index, which has been set for the eruption of Krakatau from 1883 to 1000. The haze has little connection with the Vulkanexplosivitätsindex. This is due to the very different sulfur releases the same explosive volcanic eruptions. However, the turbidity efficiency of sulfur gases is much stronger than that of ash that reached the stratosphere to a much lesser extent.
So registered meteorologists after the eruption of Pinatubo with a explosiveness of 6 at a turbidity of 1000 on the island of Luzon in 1991, a temperature decrease from an average of 0.5 degrees Celsius.
Past events
Consequences from the eruption of Tambora was on Sumbawa in 1815, of a haze of 3000 reached at a explosiveness of 7 on the Vulkanexplosivitätsindex ( VEI ). He looked through a decline in the average temperature by 2.5 degrees Celsius, and there was frost in Europe in July, which is why the year 1816 is also known as the year without a summer. Until 1819 the cold led to crop failures and thereby waves of emigration from Europe to America.
The climate changes of the " Little Ice Age " from the 15th century could not be determined beyond all doubt, variously, a series of volcanic eruptions, which are due to at least four active volcanoes, suggested as the cause.
Global weather changes with accompanying crop failures occurred after the outbreak of Kuwae in 1453.
The volcanic winter weather similar anomaly of 535/536 could not be assigned to specific volcanic eruptions such as those of Krakatau or Tavurvur.
Around 10,930 BC, volcanic ash and pumice were ejected in an eruption in the volcanic Eifel within a few days about 16 km ³, as a consequence of the caldera of Laacher lake was formed. The finer sediments of the explosion are still to Sweden in Quaternary sediments as a narrow Bimshorizont (known as Laacher See Tephra, LST) to find.
To a cooling of several degrees Celsius and a dramatic climate change also led the last eruption of the volcano Toba Super approximately 74,000 years ago. According to the Toba catastrophe theory, then the population of Homo sapiens should have reduced to a few thousand individuals. This could be the low genetic diversity of modern man declare ( "Genetic bottleneck" called ).
For about 65 million years ago at the Cretaceous - Tertiary boundary ( the same transition from the Mesozoic to Cenozoic ) died out about 50 percent of all animal species, including the dinosaurs. The cause two events are discussed: the impact of a meteorite (KT - Impact; translates to about Cretaceous-Tertiary impact ) near the Yucatán Peninsula and the continental outbreak of a plume in the Deccan Traps in western India. The dust due to the meteorite also corresponds to a volcanic winter, but without release of SO2.
Before about 200 million years ago at the end of the Triassic died from 50 to 80 percent of all species, including almost all land vertebrates. Here is a link with massive magma release is before the breakup of Pangaea suspected (central atlantic eruption ).
Before about 252 million years ago, within a span of 200,000 years at the Permian - Triassic boundary, 95 percent of all meeresbewohnenden species and about 66 % of all terrestrial species ( reptiles and amphibians ) died out. The causes are still unknown, but an association was seen with the then incurred Siberian Trapp, an extremely large magma field that seemed climate -changing.
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Super Volcano Yellowstone in Yellowstone National Park (USA) As is currently the largest threat to trigger a volcanic winter is considered. His outburst could lead to several decades glacial -like climate, which would lead to global crop failures and famines after themselves.