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Holocene variability of the East Asian summer monsoon from Chinese cave records : a re-assessment.

Maher, Barbara A. (2008) Holocene variability of the East Asian summer monsoon from Chinese cave records : a re-assessment. Holocene, 18 (6). pp. 861-866.

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Abstract

Oxygen isotope records from stalagmites in caves in southern China, interpreted as proxy rainfall records reflecting the intensity of the East Asian summer monsoon, indicate gradual monsoon weakening for the last ~9000 years, as also documented for the Indian monsoon. Coupled with high-precision dating, the speleothem proxy records have been used to test monsoon links with orbital forcing, solar changes, iceberg discharges in the North Atlantic, ocean currents and atmospheric methane. However, these ‘benchmark’ cave records do not match other published, dated E Asian proxy rainfall record (specifically here, independently calibrated rainfall records from loess/palaeosol magnetic properties, and cave oxygen isotope intercomparisons), which show variable E Asian monsoon intensity through the entire Holocene. The strong correlation of the cave records with the extraregional Indian monsoon record yet their mismatch with these other dated Chinese rainfall records might be reconciled if the speleothem isotope variations reflect not changes in Holocene rainfall amount but in rainfall source. Declining Holocene influence of isotopically lighter, Indian monsoon-sourced moisture over China would have resulted in increasing proportions of isotopically heavier rainfall, sourced from the more oceanic E Asian monsoon. Individual speleothems may thus regionally record Holocene changes in Indian monsoon intensity and isotopic influence. Conversely, the other Chinese proxy records described here reflect changes in rainfall amount, and thus in E Asian summer monsoon intensity. For the Holocene, the E Asian and the Indian monsoon responses to orbital forcing are likely to have differed, specifically due to E Asian internal feedbacks and the seasonal contrasts between the two monsoon systems.

Item Type: Article
Journal or Publication Title: Holocene
Uncontrolled Keywords: Asian monsoon ; Holocene ; magnetic susceptibility ; Indian monsoon ; oxygen isotope records ; caves ; China.
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 23606
Deposited By: Professor Barbara A Maher
Deposited On: 10 Feb 2009 09:19
Refereed?: Yes
Published?: Published
Last Modified: 06 Aug 2013 02:28
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/23606

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