Volcanic winter

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The cooling of the lower earth atmosphere after a volcanic eruption is called volcanic winter . Ashes and sulfur dioxide (SO 2 ), from which aerosols from sulfuric acid are formed, are hurled into the stratosphere during a major eruption , where they spread like a veil over the entire globe . The sun's rays are partially absorbed or scattered back. This causes warming in the stratosphere. On average, the global climate cools down on the ground, but regionally and depending on the time of year, it also warms up at the same time. An effect comparable to the volcanic winter that would be triggered by a nuclear war is called the nuclear winter .

Geographically, large-scale and long-lasting volcanic activities (e.g. the formations of the Siberian trap , the Emeishan trap and the Dekkan trap ) are associated with various mass extinctions .

The measure of the reduction in the radiation permeability of the atmosphere is the so-called turbidity index , which was set at 1000 for the Krakatau eruption in 1883. The turbidity index has only a small connection with the volcanic explosion index . The reason for this is the very different sulfur releases of the same explosive volcanic eruptions. The clouding effect of the sulfur gases is much stronger than that of the ash, which only reaches the stratosphere to a much lesser extent.

Past events

Holocene

Reconstructed climatic effects of volcanic eruptions in the late Holocene

After the eruption of Pinatubo with an explosiveness of 6 and a turbidity of 1000 on the island of Luzon in 1991, meteorologists recorded an average temperature decrease of 0.5 K ( Kelvin ). The entry of aerosols into the stratosphere by the Pinatubo was unmatched by any other event in the 20th century.

Serious consequences were the eruption of Tambora on Sumbawa in 1815, which reached a turbidity index of 3000 at strength 7 on the volcanic explosion index (VEI) . It resulted in a drop in the average temperature of 2.5 K, and in Europe there was frost in July, which is why the year 1816 is also called the year without a summer . Until 1819, the cold led to bad harvests and thus waves of emigration from Europe to America .

The reasons for the climatic peak of the " Little Ice Age " from the beginning of the 15th to the 1st half of the 19th century are still partly unclear. In addition to decreased solar activity and a weakening of the Gulf Stream, a number of volcanic eruptions have been suspected as contributing causes.

Worldwide weather changes with accompanying poor harvests occurred after the eruption of the Kuwae in 1453 and after the eruption of the Samala in 1257 .

The climate anomaly from 536 , comparable to the volcanic winter , was probably caused by two volcanic eruptions in close succession, one in high latitudes in the northern hemisphere, followed four years later by an eruption in the tropics. The tropical volcano could have been the Ilopango in El Salvador .

Around the year 10,930 BC During an eruption in the Vulkaneifel , around 16 km³ of volcanic ash and pumice were thrown out within a few days , as a result of which the caldera of the Laacher See was created. The finer deposits of the explosion can still be found as far as Sweden in Quaternary sediments as a narrow pumice horizon (known as Laacher-See-Tephra, LST ).

Pleistocene and earlier

The last eruption of the Toba super volcano on Sumatra during the last glacial period about 74,000 years ago also led to a cooling of several Kelvin and a dramatic change in the climate . According to the controversially discussed Toba catastrophe theory, this is said to have reduced the population of Homo sapiens to a few thousand individuals. This could explain the low genetic diversity of people today (called the “ genetic bottleneck ”). In recent geological history since the Oligocene , more than forty supervolcano eruptions have been proven.

About 66 million years ago on the Cretaceous-Paleogene border (at the same time the transition from the Mesozoic to the New Earth Age ), up to 75 percent of all animal species died out, including the dinosaurs . There are two possible causes: the impact of an asteroid (KP impact; translated as Chalk-Paleogene impact ) near the Yucatán peninsula and the continental eruption of a plume in the Dekkan-Trapp in the Indian suburbs. The dust turbulence caused by the asteroid impact also corresponds to that of a volcanic winter, possibly reinforced by an atmospheric layer of sulfate aerosols in connection with a global permafrost climate over several years.

The mass extinction at the end of the Triassic 201 million years ago led to a species loss of around 70 percent and also affected many terrestrial vertebrates to a considerable extent . A direct connection with the extensive magma releases of the Central Atlantic Magmatic Province before the breakup of the supercontinent Pangea is considered very likely in science.

About 252 million years ago, 95 percent of all marine species and about 66 percent of the terrestrial fauna died out within a maximum period of 30,000 years. The trigger and main cause of the collapse of the ecosystems is the large-scale flood basalt emissions of the Siberian trap , which covered an area of ​​7 million square kilometers with igneous rocks during its activity cycles . However, the events at the Permian-Triassic border and at the Triassic-Jura transition did not cause any global cooling, but on the contrary led to extremely strong warming through high emissions of greenhouse gases .

outlook

The yellowstone super volcano in Yellowstone National Park (USA) is currently the greatest hazard potential of a volcanic winter . Its eruption could lead to several decades of ice-age-like climates, which would result in global crop failures and famine. The Phlegraean Fields in the Italian region of Campania , about 20 km west of Vesuvius , are also considered to be a potential super volcano.

See also

literature

  • Keith Briffa et al .: Influence of volcanic eruptions on Northern Hemisphere summer temperature over the past 600 years. In: Nature . Volume 393, 1998, pp. 450-455. doi : 10.1038 / 30943
  • MR Rampino, S. Self, RB Stothers: Volcanic Winters. In: Annual Review of Earth and Planetary Sciences. Volume 16, 1988, pp. 73-99. doi : 10.1146 / annurev.ea.16.050188.000445
  • William J. Humphreys: Volcanic dust and other factors in the production of climatic changes, and their possible relation to ice gases. In: Journal of the Franklin Institute . 1913, pp. 131-172

Web links

Individual evidence

  1. ^ Brian J. Soden, Richard T. Wetherald, Georgiy L. Stenchikov, Alan Robock: Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor . (PDF) In: Science . 296, April 2002, pp. 727-730. doi : 10.1126 / science.296.5568.727 .
  2. ↑ Patrick McCormick et al .: Atmospheric effects of the Mt Pinatubo eruption . In: Nature . tape 373 , 1995, pp. 399-404 , doi : 10.1038 / 373399a0 .
  3. ↑ Gifford H. Miller et al .: Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice / ocean feedbacks. In Geophysical Research Letters. Volume 39, L02708, 2012, doi : 10.1029 / 2011GL050168 Volcanic
    eruptions triggered the Little Ice Age. On: scinexx.de from February 1, 2012
  4. ↑ Michael Sigl u. a .: Timing and climate forcing of volcanic eruptions for the past 2,500 years . In: Nature . No. 523 , July 2015, doi : 10.1038 / nature14565 . Press release: Volcanic eruptions that changed human history. Desert Research Institute, July 8, 2015, accessed May 22, 2019 .
  5. ↑ Robert A. Dull, John R. Southon, Steffen Kutterolf, Kevin J. Anchukaitis, Armin Freundt, David B. Wahl, Payson Sheets, Paul Amaroli, Walter Hernandez, Michael C. Wiemann, Clive Oppenheimer: Radiocarbon and geologic evidence reveal Ilopango volcano as source of the colossal 'mystery' eruption of 539/40 CE . In: Quaternary Science Reviews . tape 222 , 2019, doi : 10.1016 / j.quascirev.2019.07.037 .
  6. ^ Thomas Litt, Karl-Ernst Behre, Klaus-Dieter Meyer, Hans-Jürgen Stephan and Stefan Wansa: Ice Age and the Present . Stratigraphic terms for the Quaternary of the northern German glaciation area. In: Quaternary Science Journal . No. 56 (1/2) , 2007, ISSN  0424-7116 , p. 7–65 , doi : 10.3285 / eg.56.1-2.02 ( geo-leo.de [PDF]).
  7. ↑ DIPLOMA THESIS “Gravimetric investigations on the southern edge of the Laacher See to dissolve the subsurface structure in the edge area of ​​the volcano” ( Memento from June 16, 2012 in the Internet Archive ) Diploma thesis by Claudia Köhler 2005
  8. ↑ Ben G. Mason, David M. Pyle, Clive Oppenheimer: The size and frequency of the largest explosive eruptions on Earth . (PDF) In: Bulletin of Volcanology . 66, No. 8, December 2004, pp. 735-748. doi : 10.1007 / s00445-004-0355-9 .
  9. ↑ Julia Brugger, Georg Feulner, Stefan Petri: Baby, it's cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous . In: Geophysical Research Letters . 44, No. 1, January 2017, pp. 419-427. doi : 10.1002 / 2016GL072241 .
  10. ↑ JHFL Davies, H. Bertrand, N. Youbi, M. Ernesto, U. Schaltegger: End-Triassic mass extinction started by intrusive CAMP activity . In: Nature Communications . May 8, 2017. doi : 10.1038 / ncomms15596 .
  11. ↑ Shu-Zhong Shen, Jahandar Ramezani, Jun Chen, Chang-Qun Cao, Douglas H. Erwin, Hua Zhang, Lei Xiang, Shane D. Schoepfer, Charles M. Henderson, Quan-Feng Zheng, Samuel A. Bowring, Yue Wang , Xian-Hua Li, Xiang-Dong Wang, Dong-Xun Yuan, Yi-Chun Zhang, Lin Mu, Jun Wang, Ya-Sheng Wu: A sudden end-Permian mass extinction in South China . (PDF) In: GSA Bulletin (The Geological Society of America) . 131, September 2018, pp. 205-223. doi : 10.1130 / B31909.1 .
  12. ↑ David PG Bond, Stephen E. Grasby: On the causes of mass extinctions . In: Palaeogeography, Palaeoclimatology, Palaeoecology . 478, July 2017, pp. 3–29. doi : 10.1016 / j.palaeo.2016.11.005 .