DeVries Effect

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The radiocarbon age (red curve) shows fluctuations ("wiggles") compared to the calendar age.

The DeVries effect , named after the Dutch biophysicist Hessel de Vries (1916–1959), is the mismatch between the radiocarbon age of an organic material and its actual calendar age. The cause is fluctuations in the atmospheric 14 C / 12 C ratio, which means that the radiocarbon method can only achieve its full accuracy by using a calibration curve.

The radiocarbon dating method for the dating of organic material, developed mainly by Willard Frank Libby since the mid-1940s , was initially based on a monotonous, roughly linear decrease in the 14 C concentration over time. However, this led to conflicting dating results. At the end of the 1950s, Hessel de Vries found fluctuations in the 14 C / 12 C ratio, which can result, for example, from fluctuations in solar activity, the geomagnetic field or the carbon exchange between different reservoirs. This insight, which was further developed into a calibration curve by the Austrian chemist Hans E. Suess , enabled much more precise radiocarbon dating.

De Vries cycle / Suess cycle

The fluctuations in the 14 C / 12 C ratio discovered by de Vries have been repeatedly examined for periodicity since their discovery. The De Vries cycle , also named after Hessel de Vries , occasionally also Suess cycle , after Hans E. Suess , is such a periodic connection between the radiation activity of the sun and the 14 C production on earth. The mean cycle time is about 210 years, but it varies widely. In the case of irregular cycles of approx. 100–200 years, the connection between medium-term fluctuations in the 14 C content and the number of sunspots must be made . The more sunspots, the less 14 C. In the 14 C reconstruction of the Holocene solar activity, grand minima of solar activity occur several times in clusters. The approx. 200 year long intervals between individual minima of the clusters form an essential part of the deVries cycle.

There are other factors, in addition to solar activity, which have an influence on 14 C production, including the strength of the earth's magnetic field .

In 1956, Hessel de Vries found two maxima in the natural fluctuations of the 14 C / 12 C ratio around 1500 and 1700. Hans E. Suess, who further developed the radiocarbon method, then made the spectrum of atmospheric 14 C fluctuations over a period of 8000 years a periodicity of over 200 years.

Fluctuations in solar radiation are one of the climatic factors on earth, the search for a possible connection between long-period solar fluctuations and climatic fluctuations began as early as the 19th century and is ongoing. The size of the influence on the global temperature is up to a few tenths of a degree Celsius, regionally larger changes are possible.

See also

literature

  • Paul E. Damon, Alexei N. Peristykh: Radiocarbon Calibration And Application To Geophysics, Solar Physics, And Astrophysics . In: Radiocarbon . tape 42 , no. 1 , 2000, pp. 137-150 ( PDF ).

Individual evidence

  1. ↑ de Vries effect . In: John Matthews (Ed.): Encyclopedia of Environmental Change . SAGE, 2013, ISBN 978-1-4739-2819-0 .
  2. ^ Variation in Concentration of Radiocarbon with Time and Location on Earth . In: Proc. Royal Nederl. Akad. Wetenschappen . tape 61 , 1958, pp. 1-9 .
  3. ^ Heinrich Wänke, James R. Arnold: Hans E. Suess . In: Biographical Memoirs . tape 87 , 2005, pp. 354-373 ( nap.edu ).
  4. ↑ Ilya Usoskin, Kalevi Mursula: Grand minima and maxima of solar activity . In: Jean Lilensten, Thierry Dudok de Wit, Kadja Matthes (eds.): Earth's climate response to a changing Sun: A review of the current understanding by the European research group TOSCA . EOP Science, 2016, ISBN 978-2-7598-2021-4 .
  5. ^ Hans Suess: The radiocarbon record in tree rings of the last 8000 years . In: Radiocarbon . tape 22 , no. 2 , 1980, p. 200-209 , doi : 10.1017 / S0033822200009462 .
  6. ↑ José M. Vaquero, Ricardo M. Trigo: The Role of the Sun in Climate Change: A Brief History . In: Jean Lilensten, Thierry Dudok de Wit, Kadja Matthes (eds.): Earth's climate response to a changing Sun: A review of the current understanding by the European research group TOSCA . EOP Science, 2016, ISBN 978-2-7598-2021-4 .
  7. ^ Judith L. Lean: Sun-Climate Connections . In: Oxford Research Encyclopedias - Climate Science . July 2017, doi : 10.1093 / acrefore / 9780190228620.013.9 .