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Geochronology/Neoglaciations

< Geochronology

In the image at the top, "before present" is used in the context of radiocarbon dating, where the "present" has been fixed at 1950. The apparent decreases in solar activity are called the "Maunder Minimum", "Spörer Minimum", "Wolf Minimum", and "Oort Minimum".

Changes in the 14C record, which are primarily (but not exclusively) caused by changes in solar activity, are graphed over time. Credit: Leland McInnes.

"Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes."[1]

A "climate interpretation was supported by very low δ’s in the 1690’es, a period described as extremely cold in the Icelandic annals. In 1695 Iceland was completely surrounded by sea ice, and according to other sources the sea ice reached half way to the Faeroe Islands."[2]

Little ice ages

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The Little Ice Age (LIA) appears to have lasted from about 1218 (782 b2k) to about 1878 (122 b2k).

Precisely "dated records of ice-cap growth from Arctic Canada and Iceland [show] that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430-1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. [Explosive] volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed. [The] onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required."[1]

Hypotheses

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Main resource: Hypotheses
  1. The sciences do not need to follow the humanities, religion, or the arts to be beneficial to humanity.
  2. The scientific method is not a recent occurrence.

See also

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References

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  1. ↑ 1.0 1.1 Gifford H Miller, Aslaug Geirsdottir, Yafang Zhong, Darren J Larsen, Bette L Otto-Bliesner, Marika M Holland, David Anthony Bailey, Kurt A. Refsnider, Scott J. Lehman, John R. Southon, Chance Anderson, Helgi Björnsson, and Thorvaldur Thordarson (January 2012). "Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks". Geophysical Research Letters 39 (2): L02708. doi:10.1029/2011GL050168. http://adsabs.harvard.edu/abs/2012GeoRL..39.2708M. Retrieved 2014-10-09. 
  2. ↑ Willi Dansgaard (2005). The Department of Geophysics of The Niels Bohr Institute for Astronomy Physics and Geophysics at The University of Copenhagen Denmark. ed. Frozen Annals Greenland Ice Cap Research. Copenhagen, Denmark: Niels Bohr Institute. pp. 123. ISBN 87-990078-0-0. http://www.iceandclimate.nbi.ku.dk/publications/FrozenAnnals.pdf/. Retrieved 2014-10-05. 
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