Australia: The Land Where Time Began

A biography of the Australian continent 

The 8,200 Year Event - Links East Asian Monsoon & Climate of the North Atlantic

At 8,200 BP The North Atlantic region underwent an abrupt cooling event that affected the climate throughout the Northern Hemisphere (Cheng, 2009; Pausata et al, 2011; Thomas et al., 2007). The Greenland ice cores constrain this event, though the understanding of the timing and nature of associated teleconnections have been challenged as a result of the lack in resolution in records from other regions. It has been suggested by speleothem records from East Asia that there were monsoonal changes associated with the 8,200 year event, though the nature of these changes are still controversial (Cheng, 2009; Pausata et al, 2011).  The authors have used a stalagmite record from central China, that is sub-annually resolved, to assess changes in precipitation in East Asia during the 8.2k event. Their results demonstrate that at 8,200 BP there was a significant drying period, using δ18O and Mg/Ca measurements of the speleothem carbonate. They show that the drying event persisted for 150 years, with a central period of 70 years in which there was pronounced aridity, their chronology being based on annual layer counting. When comparing the  beginning and ending of the drying period with the record in the Greenland ice cores it is shown that the length of the event in the 2 records is indistinguishable. The conclusion reached by the authors1 is that there is an atmospheric teleconnection between the North Atlantic and monsoon system of warm climates similar to that of the present, that is effective and rapid.

Calendar-dated glacier response in the Alps2 

The authors2 present evidence for the advance of an Alpine glacier in relation to the 8.2 ka event. They based their conclusion on dendrochronological analysis of tree remains found in front of the Mont Miné Glacier in the Swiss Alps. Dozens of remains of trees that were analysed provided calendar dates of about 8175 years before A.D. 2000. The results of the analyses indicate that the onset of the 8.2 ka event terminated a retreat that had continued for about 1,000 years, with a glacier always shorter than at present.

Asian Connections

Sources & Further reading

  1. Liu, Y. H., G. M. Henderson, C. Y. Hu, A. J. Mason, N. Charnley, K. R. Johnson, and S. C. Xie. "Links between the East Asian Monsoon and North Atlantic Climate During the 8,200 Year Event." Nature Geosci 6, no. 2 (02//print 2013): 117-20.
  2. Nicolussi, Kurt, and Christian SchlŁchter. "The 8.2 Ka EventóCalendar-Dated Glacier Response in the Alps." Geology 40, no. 9 (September 1, 2012 2012): 819-22.

 

Author: M. H. Monroe
Email:  admin@austhrutime.com
Last Updated 27/02/2013

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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading