|system||series||step||≈ age ( mya )|
The Holocene (popularly known as the Post-Ice Age) is the current period in Earth's history . In chronostratigraphy and geochronology , the Holocene is a series or epoch and, according to the decision of the International Commission on Stratigraphy (ICS), has been divided into three geological levels since 2018 (Greenlandium, Northgrippium, Meghalayum). It started about 11,700 years ago with the warming of the earth at the end of the Pleistocene .
Naming and conceptual history
The term Holocene comes from ancient Greek and means "the completely new" ( ὅλος hólos 'whole' and καινός kainós 'new'). The term was coined in 1867/1869 or as early as 1850 by the French zoologist Paul Gervais . As early as 1833 Charles Lyell had coined the term present for this period in the history of the earth . At the Third Geological Congress in London in 1885, however, the name Holocene (Germanized Holocene ) prevailed against Present . In the English-language literature, the term present in the sense of the Holocene can still be found occasionally.
An outdated name is also Alluvium (from Latin alluvio , alluvial water ), which means “age of alluvial water”. This name goes back to the British geologist William Buckland , who in 1823 divided the most recent geological history into the (pre-) deluge Diluvian (roughly equivalent to the Pleistocene ) and the post-Flood Alluvian (roughly equivalent to the Holocene).
More recently, the term also asserted itself against terms such as neo-warm period or Flandrian warm period (Flandrium). The term Flandrium was coined in 1957 by Heinzelin & Tavernier for marine transgression sediments on the Belgian coast. It was mainly used by authors who believed that the Holocene was only an interstadial of the current Ice Age and should therefore be included in the Pleistocene (e.g. West, 1977). Because of the special significance of the Holocene for the cultural history of mankind, this proposal has not been able to prevail and will not be discussed further. Due to the recent establishment of a Global Stratotype Section and Point (GSSP) and the definition of the Holocene as a separate series , this proposal is only of significance for the history of science.
There are numerous approaches from the various sub-disciplines of stratigraphy to define the beginning of the Holocene . All approaches unanimously try to capture the sharp rise in temperature at the end of the last glacial period as precisely as possible. In 2008 the International Union of Geological Sciences (IUGS) ratified the proposal of the Subcommission on Quaternary Stratigraphy and subsequently by the International Commission on Stratigraphy (ICS), a GSSP ( Global Boundary Stratotype Section and Point "global reference profile for determining the level boundaries") ) for the beginning of the Holocene.
The GSSP Pleistocene / Holocene is the ice core -2 of the North Greenland Ice Core Project (NGRIP; coordinates, 75.10 ° N, 42.32 ° W), which is archived at the University of Copenhagen . The 1492.45 m depth mark at this core was selected for the lower limit of the Holocene. In this area of the core, a decrease in the excess of deuterium from typical glacial values to typical interglacial values can be measured in an ice interval of no more than 3 years . In addition, from around this mark, the δ 18 O value increases from typically glacial values to typically interglacial values , albeit over a longer interval . These changes in the isotope values document the rapid rise in temperature at the transition from the Younger Dryas to the preboreal of the Holocene. The ice at the 1492.45 m depth mark of the NGRIP2 core and thus the official benchmark for the beginning of the Holocene were radiometrically dated to an absolute age of "11,700 years b2k" (11,700 years before 2000), with an uncertainty of 99 years.
The researchers around the " Hohenheim Tree Ring Chronology " are currently at 11,590 BC. H. (i.e. based on 1950 = 9,640 BC or 11,640 b2k), based on reaching the preboreal level.
According to varva counts in the Meerfelder Maar in the Eifel, the Holocene began around 11,590 varven years BC. H. (i.e. based on 1950; or 9,640 BC). The varve counts of the Eifelmaare or varven chronology are, however, a so-called "floating chronology", i. that is, they are based on incorporation into other chronologies, e.g. B. the dendrochronology and the Greenland ice cores (GICC05 chronology). In the meantime, however, a high degree of correspondence between all three chronologies has been achieved, the beginning of the Holocene therefore only differs by a few decades and is within the error limits. However, this can also be due to the somewhat different regional warming.
|Holocene||Subatlantic||X||450 BC Until today|
|Subboreal||VIII||3,710-450 BC Chr.|
|Atlantic||VII||7,270-3,710 BC Chr.|
|Boreal||V||8,690-7,270 BC Chr.|
|Preboreal||IV||9,610-8,690 BC Chr.|
|Younger dryas period||III||10,730-9,700 ± 99 BC Chr.|
The Holocene is defined in Chronostratigraphy as a series. The climatic stages eliminated by Axel G. Blytt and Rutger Sernander on the basis of paleobotanical data from Scandinavian moors are in principle only available in the northern hemisphere, e.g. Sometimes only detectable in Northern Europe. They are gradually falling out of use and are being replaced by the terms early, middle, and late Holocene. Even so, they are still used in many scientific publications. Absolute age data are also increasingly used.
Some authors are following the Holocene as the current epoch, the Anthropocene , since the physical system earth is now heavily influenced by humans. However, it has not yet found general recognition, especially since it is hardly relevant to applied geology. Since the beginning of the Anthropocene is set for the year 1800, this period, which only lasted 200 years, comprised geological formations that are generally adequately characterized by the term recently .
After the last glacial period (in Northern Europe about the local Vistula glacial period ) around 16,000 BC. Chr. Passed its peak, began a phase-wise global warming. Meanwhile, there were repeated abrupt climatic fluctuations, the so-called Dansgaard-Oeschger events . Compared to earlier warm periods ( Eem warm period ), the transition to the subsequent warm period took an unusually long time, and after the Alleröd period , in which the temperature had almost reached its warm period, it fell in the so-called Younger Tundra Period 10,700 BC. Back to a cold state once more.
This tundra period ended around 9640 BC. With the Friesland phase , an extremely rapid rewarming to the preboreal , the first section of the Holocene. Due to changes in ocean currents, the average temperatures in parts of the northern hemisphere rose by six degrees Celsius within only 20 to 40 years, and in Greenland by as much as 10 degrees.
This warming led u. a. to open the so-called Billinger Gate , through which the water from the Baltic Sea, which was dammed up to form an ice lake, could flow into the ocean. As a result, the water level of the Baltic Ice Reservoir sank by 26 m to sea level and, conversely, arctic fauna with Yoldia ( Portlandia arctica ) penetrated the Baltic Sea basin ( Yoldia Sea ) with the sea water .
The abrupt change in climate initially brought about a change in the flora, and consequently also the fauna. Many of the large mammals of the Ice Age disappeared in many parts of the world . This so-called Holocene mass extinction took place on the American double continent in the relatively short section from around 13,000 to 10,000 BC. Instead of. The extent to which humans or their impact on the ecosystem were the cause of the abrupt mass extinction is controversial.
Supporters of the notion that humans did not play a decisive role in this argue, among other things, as follows: New radiocarbon data would show that certain mammalian species such as B. bison ( Bos priscus that to himself Bos bison evolved), wapiti ( Cervus canadensis ) and, to a lesser extent, moose ( Alces Alces ) before and during human colonization had increased in North America in their existence, even though they successfully by man were hunted. Other species like horse ( Equus ferus ) and mammoth ( Mammuthus primigenius ) died out regionally or nationally, although z. B. the North American horses were not hunted by humans or were already declining in their numbers before humans appeared. These findings would lead to the conclusion that the radical changes in the fauna of the Holocene were not primarily caused by human influence, but were rather the result of a massive ecological upheaval due to a climate change taking place at that time . At the transition from the Pleistocene to the Holocene summer were getting warmer and more humid, so the previously water-limited steppe vegetation is - gradually but fundamentally - changed: The pastures stretched out at first, later a developed tundra of tall perennials , shrubs and forests whose The plant community was increasingly made up of plants that were inedible or even poisonous for herbivores (herbivores), such as the dwarf birch ( Betula ), and thus influenced their population and distribution. Overall, the living conditions of the affected mammals had changed so dramatically that rapid adaptations were required, which presumably not all species could make, which led to the drastic ecological restructuring observed.
Then there was a change in the way people eat, first in the Levant and later in China , Central America and other parts of the world: hunters and gatherers began to grow grain and other plants and to domesticate goats , sheep and other animals. This “ Neolithic Revolution ” gradually spread to Europe.
The warming was accompanied by a melting of the ice masses. After the inland ice had already released the southern Baltic Sea region at the end of the Ice Age, it divided around 6800 BC. The ice in Scandinavia until it was at the end of the Altholocene around 6000 BC. BC finally disappeared completely. The earth's crust, freed from this burden, began to recede from around 7700 BC. Until today to be lifted isostatically about 300 m . Even today, regions in Scandinavia experience uplift rates of up to 1 cm per year.
The accelerated thawing of the North American inland ice , the largest ice sheet in the northern hemisphere, led to a further rise in sea level at the beginning of the Middle Holocene (total rise compared to the minimum level during the Ice Age about 120 m). On the one hand, this was accompanied by flooding of further coastal areas, which took place in phases and ultimately formed today's coastlines ( Flemish Transgression , Dunkirk Transgression ). On the other hand, some side basins were washed over by the sea water and thus became tributaries themselves, such as Hudson Bay (between 6000 and 5500 BC). Around 5000 BC BC (possibly earlier) the Danish islands , Great Britain and Ireland were separated from mainland Europe; a process that took place through a long series of devastating storm surges, and as a result of which the Baltic Sea became a tributary of the Atlantic. The flooding of the Black Sea around 6700 BC BC was similarly dramatic and possibly led to the emergence of the Flood legends among the Near Eastern peoples ( Utnapishtim , Noach , Deukalion ).
Due to the warmer climate in Central Europe (but also in North America), the tundra vegetation of the Ice Age increasingly gave way to forest, initially with birch and pine trees , later also oaks , elms , alders and other species. At the same time, hitherto inhospitable areas further north changed from polar cold deserts to tundras.
The period from the 6th to the 2nd millennium BC Chr. Represents the temperature optimum of the Holocene ( Atlantic , also outdated Altithermum ). For the time of the optimum there is only uncertain information about the prevailing annual average temperatures. It seems clear today that the local temperatures are much more different than in the recent past. In some cases, the temperatures were several degrees Celsius above the values customary there before the start of the industrial revolution and thus before the gradual onset of global warming , but in places they were also significantly below them. Parts of the northern hemisphere in particular were more than 2 ° C warmer, including south-east Europe (between 13,000 and 11,000 years BC), the northern seas (12,000 to 10,000 years BC) and eastern China (10,000 to 6,000 years BC). Chr.). Accordingly, for example, the tree line in the Alps was at times 200 to 300 m higher, in Siberia and North America the tree line was up to 300 km further north than it is today. At the same time, the water temperatures in the northern Indian Ocean and the tropical Pacific were between 13,000 and 7,000 BC. BC by 0.5 to 2 ° C below the values before the industrial revolution, but rose in the Altithermum to 1 ° C above today's level. On a global average, a temperature of less than 0.4 ° C above the current values is assumed. The Holocene optimum was therefore not a globally uniform phenomenon, but, like every climatic phase, was regionally very different.
The most notable difference between the Altithermum and today was a significantly more humid climate in the desert areas. There is evidence of year-round rivers in the Sahara and other deserts today. The Lake Chad had at this time about the extent of the Caspian Sea . As several rock carvings from the Sahara show, there were numerous large animal species such as giraffes , elephants , rhinos and even hippos . Settlement and livestock farming were possible in these areas at that time. The same was made possible by the humid climate in the Thar (Pakistan), where the Indian summer monsoon was much more pronounced than it is today.
During the climatic peak from 4100 to 2500 BC BC, which had significantly lower temperatures than the main optimum 1, the savannah vegetation abruptly withdrew. 3200 to 3000 BC BC the climate in the desert areas became significantly drier, the desertification of the Sahara began. The inhabitants of the Sahara and other nascent desert areas had to leave their habitats and gathered in the river valleys of the Nile , Niger , Huang-Ho (China) and Indus (Pakistan) as well as in Mesopotamia on the Euphrates and Tigris . In most of these areas, the first high cultures flourished due to the need for a state organization and a significant increase in population .
Towards the end of the 4th millennium BC A worldwide drought began that lasted for several centuries. In Egypt, the failure of the Nile floods caused the Old Kingdom to collapse, followed by the First Intermediate Period . The displaced by drought from their home Amorites migrated to Mesopotamia and destroyed there, the Akkadian Empire . In the Indus valley, a weakening of the monsoons by up to 70% led to the formation of the Thar desert and the decline of the Harappa culture .
From around 3000 BC A pronounced cold epoch, the so-called climatic peak of the Bronze Age , began in Europe . The annual mean temperature was significantly colder than today, making this period the coldest since the end of the Vistula glaciation. It lasted until about the middle of the 1st millennium BC. And then passed into a new climatic optimum , the so-called optimum of Roman times . Summer temperatures in Europe rose and could have reached values similar to those of the previous century, but were below today's. During this time, the Carthaginian general Hannibal succeeded in crossing the Alps with elephants (217 BC) and the Romans in growing wine on the British Isles .
What is striking is the connection between a renewed deterioration in the climate ( pessimum of the migration period ) and a phase of upheaval or decline of the Roman Empire . The epoch of the Great Migration began with the advance of the Huns , which in turn was triggered by a dry period in their Central Asian homeland. In north and north-west Europe, crop failures led to massive supply problems. A drought in Central Asia in the 4th century finally brought trade on the Silk Road to a standstill.
The warming in the 8th and 9th centuries is known as the Medieval Climate Anomaly . The Vikings began with the colonization of Iceland ("ice land") and Greenland ("grassland"), which then as now has "green land" on the southern coastline. At the same time there were catastrophic droughts in America and catastrophic storm surges in Europe, see list of storm surges in the North Sea . In 1362 the Frisian Islands were separated from the north German mainland by the Second Marcellus Flood .
From the middle of the 14th century, a climate change set in, which reached its peak between 1550 and 1850 in particular. This modern climate anomaly is known as the Little Ice Age . The grain no longer ripened in cold, wet summers, and famines often occurred after bad harvests. Devastating epidemics (such as the plague ) and wars (such as the Thirty Years' War ) placed an additional burden on the population. The incipient rural exodus as well as the later emigration of large sections of the population to the “ New World ” was partly caused by this climate change. During the first half of the 19th century, the Little Ice Age came to an end.
At the end of the 18th century the world population had doubled in 150 years and England brought the Industrial Revolution into the world. As a result of deforestation for the expansion of agriculture (food, cotton) and the burning of fossil fuels (initially coal, later increasingly hydrocarbons), a significant increase in atmospheric carbon dioxide (CO 2 ) can be determined as early as the 19th century . The anthropogenic CO 2 emissions, together with the methane and nitrous oxide emissions, which have also risen sharply since the beginning of industrialization, are held responsible for global warming , which is observed particularly clearly from the second half of the 20th century. In this context, it is controversial when the current interglacial will be followed by the next glacial - and whether it will come at all. Some researchers believe that global warming will disrupt the cycle of glacials and interglacials, which has been recurring for hundreds of thousands of years, and thereby prevent the onset of a new glacial. According to the state of the art, the current interglacial would last for at least 30,000 years without human influence, since the earth's low orbital eccentricity minimizes the effects of precession . In addition, the anthropogenic CO 2 emissions lead to acidification of the seas with corresponding effects on biogenic carbonate production.
In addition to this climate change and the associated rise in sea level , other anthropogenic emissions, e.g. B. nitrogen and phosphorus from fertilizers, heavy metals from metal smelting and the combustion of fossil fuels as well as artificial radionuclides , which originate from above-ground nuclear weapon tests or the technical use of nuclear fission , can be detected globally in the most recent deposits of the Young Holocene (which in principle can also be referred to as recent ) . The current extinction of species , the shift in climatic zones and the introduction of exotic species are reflected in the fossil record in different regions . Large-scale deforestation, accompanied by increased erosion, or the straightening of rivers and embankment of coastal regions lead to changes in the sedimentation dynamics of the connected storage areas.
All of this is concrete evidence that humans have become an important factor influencing geological tradition over the last 200 years. The meteorologist Paul J. Crutzen coined the term " Anthropocene " for these anthropogenically influenced and partly also purely anthropogenic sediments or the period in which they were deposited and heaped up and will be deposited and heaped up both now and in the future . In 2019, the vast majority of the 34-member Anthropocene Working Group (AWG) spoke out in favor of developing a definition by 2021 that locates the beginning of the Anthropocene around the middle of the 20th century and making it an official geological one Propose epoch.
Although the Anthropocene concept is geoscientific, it has little practical value for today's geologists. It is of greater importance for the "Global Change research community", which is represented in large numbers in the AWG, ie those scientists who deal directly with the human-influenced changes in the Earth system. In no small part, it is also to be understood as a philosophical and political concept inspired by the environmental movement , which is intended to sensitize the public to all of the anthropogenic changes listed above, some of which could seriously endanger the continued existence of human civilization.
- Anson Mackay (Ed.): Global change in the holocene . Hodder & Stoughton, London 2005, ISBN 0-340-81214-1 .
- Neil Roberts: The Holocene . An environmental history. 2nd Edition. Oxford 1998, ISBN 0-631-18638-7 .
- Christian-Dietrich Schönwiese : climatology . 2nd Edition. Stuttgart 2003, ISBN 3-8252-1793-0 , pp. 292-304 .
- Thomas Terberger : Hunters in a changing world . Rahden (Westf.) 2004, ISBN 3-89646-435-3 .
- Heinz Wanner : Climate and People . A 12,000 year history. Haupt Verlag, Bern 2016, ISBN 978-3-258-07879-3 (introduction, also addressed to laypeople).
- Literature on the Holocene in the catalog of the German National Library
- International Chronostratigraphic Chart 2018 (PDF)
- Mike Walker, Sigfus Johnson, Sune Olander Rasmussen, Trevor Popp, Jørgen-Peder Steffensen, Phil Gibbard, Wim Hoek, John Lowe, John Andrews, Svante Björck, Les C. Cwynar, Konrad Hughen, Peter Kershaw, Bernd Kromer, Thomas Litt, David J. Lowe, Takeshi Nakagawa, Rewi Newnham and Jakob Schwander: Formal definition and dating of the GSSP (Global Stratotype Section and Point) for the base of the Holocene using the Greenland NGRIP ice core, and selected auxiliary records . In: Journal of Quaternary Science . tape 24 , no. 1 , 2008, p. 3-17 , doi : 10.1002 / jqs.1227 .
- Hans Murawski, Wilhelm Meyer: Geological dictionary . Eleventh, revised and expanded edition. Spectrum, Heidelberg 2004, ISBN 3-8274-1445-8 ( google.de ).
- Paul Gervais: Sur la répartition des mammifères fossiles entre les différents étages tertiaires qui concourent à former le sol de la France. In: Académie des Sciences et Lettres de Montpellier (ed.): Mémoires de la Section des Sciences 1850, pp. 399-413, here p. 413 .
- J. Heinzelin, R. Tavernier: Flandrien . In: P. Provost (Ed.): Lexique stratigraphique international . Vol. 1: Europe . Paris, Center National de la Recherche Scientifique 1957, p. 32 .
- Richard G. West: Pleistocene Geology and Biology with especial reference to the British Isles . 2nd Edition. Longman, London 1977, pp. 440 .
- Mike Walker, Sigfus Johnsen, Sune Olander Rasmussen, Jørgen-Peder Steffensen, Trevor Popp, Philip Gibbard, Wim Hoek, John Lowe, John Andrews, Svante Björck, Les Cwynar, Konrad Hughen, Peter Kershaw, Bernd Kromer, Thomas Litt, David J. Lowe, Takeshi Nakagawa, Rewi Newnham and Jakob Schwander: The Global Stratotype Section and Point (GSSP) for the base of the Holocene Series / Epoch (Quaternary System / Period) in the NGRIP ice core . In: Episodes . tape 31 , no. 2 . Beijing 2008, p. 264-267 .
- Neil Roberts: The Holocene: An Environmental History . 3rd ed. Wiley-Blackwell, 2014, ISBN 978-1-4051-5521-2 , pp. 159 .
- Jan Zalasiewicz, Mark Williams, Alan Smith, Tiffany L. Barry, Angela L. Coe, Paul R. Bown, Patrick Brenchley, David Cantrill, Andrew Gale, Philip Gibbard, F. John Gregory, Mark W. Hounslow, Andrew C. Kerr, Paul Pearson, Robert Knox, John Powell, Colin Waters, John Marshall, Michael Oates, Peter Rawson, Philip Stone: Are we now living in the Anthropocene . In: GSA Today . tape 18 , 2008, p. 4–8 , doi : 10.1016 / j.ancene.2014.07.002 .
- Jan Zalasiewicz, Colin N. Waters, Mark Williamsa: Human bioturbation, and the subterranean landscape of the Anthropocene . In: The Anthropocene . 2014, doi : 10.1016 / j.ancene.2014.07.002 .
- Will Steffen, Jacques Grinevald, Paul Crutzen, John McNeill: The Anthropocene: conceptual and historical perspectives. In: Philosophical Transactions of the Royal Society A (Mathematical, Physical and Engineering Sciences) . tape 369 , 2011, pp. 842-867 , doi : 10.1098 / rsta.2010.0327 .
- A. Ganopolski, S. Rahmstorf: Rapid changes of glacial climate simulated in a coupled climate model . In: Nature . tape 409 , 2001, p. 153-158 .
- Almut Bick: The Stone Age (= Theiss Knowledge Compact ). Theiss, Stuttgart 2006, ISBN 3-8062-1996-6 .
- R. Dale Guthrie: New carbon dates link climatic change with human colonization. In: Nature 441 (2006), pp. 207-209, doi: 10.1038 / nature04604 .
- William BF Ryan and Walter C. Pitman: An abrupt drowning of the Black Sea shelf . In: Marine Geology . tape 138 , 1997, pp. 119-126 .
- Hubert H. Lamb: The Course of Postglacial Climate . In: Anthony F. Harding (Ed.): Climate Change in the Later Prehistory . Edinburgh 1982, ISBN 0-85224-425-8 , pp. 11-33 .
- Intergovernmental Panel on Climate Change : IPCC Fourth Assessment Report. Working Group I: The Physical Science Basis , Chapter 6: Paleoclimate ( ipcc.ch [PDF; 8.1 MB]).
- Michael K. Gagan: Temperature and Surface-Ocean Water Balance of the Mid-Holocene Tropical Western Pacific . In: Science . tape 279 (5353) , 1998, pp. 1014-1018 , doi : 10.1126 / science.279.5353.1014 .
- Lonnie G. Thompson et al. a .: Kilimanjaro Ice Core Records. Evidence of Holocene Climate Change in Tropical Africa . In: Science . tape 298 , 2002, pp. 589-593 , doi : 10.1126 / science.1073198 .
- Wolf Dieter Blümel: Climate Fluctuations - Determinants for the History of Culture and Settlement? In: Nova Acta Leopoldina NF 94 . No. 346 , 2006, pp. 13–36 ( uni-stuttgart.de [PDF; 3.4 MB ]).
- Jürg Luterbacher u. a .: European summer temperatures since Roman times . In: Environmental Research Letters . 2016, doi : 10.1088 / 1748-9326 / 11/2/024001 ( iop.org ).
- Benjamin Lieberman, Elizabeth Gordon: Climate Change in Human History: Prehistory to the Present . Bloomsbury, 2018, pp. 60-62 .
- J. Neumann: Climatic conditions in the Alps in the years about the year of Hannibal's crossing (218 BC) . In: Climatic Change . tape 22 , no. October 2 , 1992, doi : 10.1007 / BF00142963 .
- A. Nesbitt, B. Kemp, C. Steele, A. Lovett and S. Dorling: Impact of recent climate change and weather variability on the viability of UK viticulture - combining weather and climate records with producers' perspectives . In: Australian Journal of Grape and Wine Research . March 2016, doi : 10.1111 / ajgw.12215 .
- Christian D. Schönwiese: climatology . Stuttgart 2003, ISBN 3-8252-1793-0 , pp. 292-304 .
- Michael Buchwitz: Life in the Antropocene. (No longer available online.) In: geoberg.de. Lutz Geißler, May 17, 2005, archived from the original on September 7, 2007 ; accessed on November 3, 2018 .
- IPCC AR4, Paleoclimate, Chapter 126.96.36.199 When will the current interglacial end? In: ipcc.ch, accessed on November 3, 2018 (PDF; 8.1 MB).
- January Zalasiewicz, Paul J. Crutzen, Will Steffen: The Anthropocene. Pp. 1033-1040. In: Felix M. Gradstein, James G. Ogg, Mark D. Schmitz, Gabi M. Ogg (Eds.): The Geologic Time Scale 2012. Elsevier BV, 2012, doi: 10.1016 / B978-0-444-59425-9.00032 -9 .
- Subcommission on Quaternary Stratigraphy: Working Group on the 'Anthropocene' - Results of binding vote by AWG. May 21, 2019.