Abrupt climate change

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Climate change over the past 65 million years. The Paleocene / Eocene temperature maximum (PETM event) 55.5 million years ago as an exemplary abrupt climate change is clearly visible.

An abrupt climate change or an abrupt climate change , also a climate jump , is a rapid climate change to a new climate state . An abrupt climate change has serious effects on habitats in the environment, because ecosystems have to adapt to the new climatic conditions in a short time. Examples of abrupt climate changes are often described in the literature as the Dansgaard-Oeschger event or the Heinrich event . An abrupt change in climate could be observed , for example, during the Younger Dryas Period . An extreme and, according to geological scale, erratic climate change took place within the framework of the Paleocene / Eocene temperature maximum .

Climate proxies of the last 100,000 years document strong climatic jumps within decades or a few years. In order to be able to better reconstruct the dynamics and effects of abrupt climate changes in human habitat, lake or ocean sediments are particularly helpful . Atmospheric circulation also plays a major role in this.

However, the current understanding of the underlying processes is insufficient to predict these events. Should it come to this in the coming years or decades, it will be unexpected and surprising.

definition

The committee of the National Research Council defined an abrupt climate change in two ways. The first definition relates to the emergence of abrupt climate changes and the latter to its effects.

  • The physical process: A transition of the climate system into a new mode, whereby the change takes place faster than the responsible radiative forcing .
  • Effects: An abrupt climate change occurs when it occurs rapidly and unexpectedly and human and natural systems have problems to adapt.

The Intergovernmental Panel on Climate Change ( IPCC ) includes both physical processes and effects on nature and society in its definition and also mentions the order of magnitude of decades as the time frame for changes and effects: "A change in the climate system on a large scale that takes a few decades or less, which lasts for at least a few decades (or is expected to do so) and causes considerable disturbances in human and natural systems. "

causes

There are various mechanisms that can bring about an abrupt change in climate. Drastic changes in ocean currents can trigger immediate regional climate changes. The Friesland phase at the beginning of the Holocene was a very abrupt climate change, most likely caused by changes in ocean currents.

At the end of the last glacial period , ice sheets collapsed rapidly, which not only resulted in an extremely rapid and pronounced rise in sea level, but also changed atmospheric and maritime flow patterns due to the massive freshwater influx. This in turn resulted in extremely pronounced regional climate changes. In view of the unstable West Antarctic ice sheet, there is a real danger that a similarly catastrophic collapse of one or more ice sheets will not only lead to rapid and pronounced sea level rise, but also to abrupt climate changes due to global warming.

The warming of the Arctic has also led to a decrease in Arctic sea ice in recent years . This energy input does not change the temperature of the arctic sea water above freezing point as long as there is ice that can melt; because in this case the supplied energy is absorbed by melting ice via the melting enthalpy of water. From the point at which all the ice has melted, however, further energy input leads to warming of the Arctic sea. The same amount of energy that is required to melt one gram of ice - without a change in temperature - heats one gram of 0 ° C cold water to almost 80 ° C. As the sea ice disappears, the occurrence of polar amplification in the Arctic will lead to sudden warming.

Another mechanism is based on the assumption that large amounts of methane are released from methane hydrate- rich sediments and permafrost as a result of ocean warming . As a result, the global average temperature would rise because methane is a highly effective greenhouse gas . This would also contribute to warming and could thus cause a strong feedback effect in the climate system. Research suggests that this occurred during the Paleocene / Eocene temperature maximum . The global warming potential of 1 kg of methane over a period of 100 years is 25 times higher than that of 1 kg of carbon dioxide ; According to a more recent study, this factor is even 33 if interactions with atmospheric aerosols are taken into account.

A simulation by the California Institute of Technology suggests that at CO 2 levels around 1,200 ppm, the breakup of low ocean clouds could cause global temperatures to rise abruptly.

History

In the research history of climate change , details about the extent and speed of past abrupt climate changes could be found out by analyzing ice cores. These were obtained from around the 1970s, among other things, as part of the Greenland Ice Core Project or the Greenland Ice Sheet Project . Wallace Broecker was the first to recognize the sensitivity of the thermohaline circulation , which can trigger an abrupt change in climate when the current changes, and which he had done several times in the past. During a lecture at the University of New Mexico in 1991, he referred to the dangers of man-made climate change with the following words:

"The climate system is an angry beast, and we are poking at it with sticks."

"The climate system is an angry beast, and we're still irritating it."

- Wallace (Wally) Broecker : Wally's Warming Warning

This saying became a popular phrase and subsequently quoted several times.

See also

literature

  • Harunur Rashid: Abrupt climate change - mechanisms, patterns, and impacts. American Geophysical Union, Washington, DC 2011, ISBN 978-0-87590-484-9 .

Web links

Individual evidence

  1. ↑ T. Aze, PN Pearson, AJ Dickson, MPS Badger, PR Bown, RD Pancost, SJ Gibbs, BT Huber, MJ Leng, AL Coe, AS Cohen, GL Foster: Extreme warming of tropical waters during the Paleocene-Eocene Thermal Maximum . (PDF) In: geology . 42, No. 9, July 2014, pp. 739-742. doi : 10.1130 / G35637.1 .
  2. ^ Richard E. Zeebe, Andy Ridgwell, James C. Zachos : Anthropogenic carbon release rate unprecedented during the past 66 million years . (PDF) In: Nature Geoscience . 9, No. 4, April 2016, pp. 325–329. doi : 10.1038 / ngeo2681 .
  3. ^ Brauer, A. Potsdam Institute for Climate Impact Research : Abrupt Climate Change and Sediment Archives . GFZ, Potsdam 2012, p. 52–57 , doi : 10.2312 / GFZ.syserde.02.01.10 . On-line
  4. ^ National Research Council : Abrupt Climate Change: Inevitable Surprises . National Academy Press, Washington DC 2002, ISBN 978-0-309-07434-6 , pp. 244 . On-line
  5. ^ National Research Council : Abrupt Climate Change: Inevitable Surprises . National Academy Press, Washington DC 2002, ISBN 978-0-309-07434-6 . , Page 27 - Online
  6. ^ Committee on Abrupt Climate Change, National Research Council: Definition of Abrupt Climate Change . In: Abrupt climate change: inevitable surprises . National Academy Press, Washington, DC 2002, ISBN 978-0-309-07434-6 ( chapter , table of contents ).
  7. ↑ Harunur Rashid, Leonid Polyak, Ellen Mosley-Thompson: Abrupt climate change: mechanisms, patterns, and impacts. American Geophysical Union , 2011, accessed September 17, 2013 ( ISBN 978-0-87590-484-9 ).
  8. ↑ WGII AR5 Glossary . In: Intergovernmental Panel on Climate Change, Working Group II (Ed.): Fifth Assessment Report, Report of Working Group II, Climate Change 2014: Impacts, Adaptation, and Vulnerability . 2014 ( online [PDF; accessed April 20, 2014]). WGII AR5 Glossary ( Memento of the original from April 19, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / ipcc-wg2.gov
  9. ↑ Stefan Rahmstorf : Rapid climate transitions in a coupled ocean-atmosphere model . 372nd edition. Nature , 1994, pp. 82-85 , doi : 10.1038 / 372082a0 . Online PDF
  10. ^ A b Paul Blanchon, John Shaw: Reef drowning during the last deglaciation: Evidence for catastrophic sea-level rise and ice-sheet collapse. In: GEOLOGY 23 No. 1 pp. 4-8.
  11. ↑ Leifi Physics of the Joachim Herz Foundation: Determination of the heat of fusion of ice.
  12. ↑ M. Nicolaus, C. Katlein, J. Maslanik, S. Hendrick: Changes in Arctic sea ice result in increasing light transmittance and absorption Archived from the original on August 26, 2016. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF) In: Geophysical Research Letters . 39, No. 24, December 2012. doi : 10.1029 / 2012GL053738 . Retrieved August 26, 2016. @1@ 2Template: Webachiv / IABot / core.ac.uk
  13. ↑ Alexey Portnov, Andrew J. Smith et al .: Offshore permafrost decay and massive seabed methane escape in water depths> 20 m at the South Kara Sea shelf . No. 40 . GRL, 2013, p. 3962-3967 , doi : 10.1002 / grl.50735 . Online PDF
  14. ^ Max, MD: Natural Gas Hydrate: Coastal Systems and Continental Margins . 5th edition. Springer, 2000, ISBN 978-94-011-4387-5 , pp. 415 . Online PDF
  15. ↑ James P. Kennett, Kevin G. Cannariato, Ingrid L. Hendy, Richard J. Behl: Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis . American Geophysical Union , Washington DC 2003, ISBN 0-87590-296-0 ( online ).
  16. ↑ Deborah J. Thomas, James C. Zachos, Timothy J. Bralower, Ellen Thomas, Steven Bohaty: Warming the fuel for the fire: Evidence for the thermal dissociation of methane hydrate during the Paleocene-Eocene thermal maximum . In: Geology . 30, No. 12, 2002, p. 1067. ISSN  0091-7613 . doi : 10.1130 / 0091-7613 (2002) 030 <1067: WTFFTF> 2.0.CO; 2 .
  17. ↑ P. Forster, V. Ramaswamy et al .: Changes in Atmospheric Constituents and in Radiative Forcing . Science 326 edition. Cambridge University Press, Cambridge and New York 2007, 2007, ISBN 978-0-521-88009-1 , pp. 212 . Online (PDF; 8.0 MB)
  18. ^ Drew T. Shindell , Greg Faluvegi, Dorothy M. Koch, Gavin A. Schmidt , Nadine Unger, Susanne E. Bauer: Improved attribution of climate forcing to emissions . In: Science . No. 326 . AAAS, 2009, p. 716-718 , doi : 10.1126 / science.1174760 ( online ).
  19. ^ Kyle G. Pressel, Colleen M. Kaul, Tapio Schneider: Possible climate transitions from breakup of stratocumulus decks under greenhouse warming . In: Nature Geoscience . tape 12 , no. 3 , March 2019, ISSN  1752-0908 , p. 163–167 , doi : 10.1038 / s41561-019-0310-1 ( nature.com [accessed April 27, 2019]).
  20. ^ Wallace S. Broecker, George H. Denton: The role of ocean-atmosphere reorganizations in glacial cycles . In: Geochimica et Cosmochimica Acta . 53, No. 10, October 1989, pp. 2465-2501. ISSN  0016-7037 . doi : 10.1016 / 0016-7037 (89) 90123-3 .
  21. ↑ Wally's Warming Warning: The Climate System Is an Angry Beast, and We Are Poking at It with Sticks on aquadoc.typepad.com