Trends in tropical climate within the late quaternary: Implications for long term ENSO and monsoon activity

Kershaw, Peter, Drake, Nick, Van der Kaars, Sander, Moss, Patrick, Armitage, Simon and White, Kevin (2007). Trends in tropical climate within the late quaternary: Implications for long term ENSO and monsoon activity. In: Norm R. Catto, Quarternary International; XVII Inqua Congress the Tropics: Heat Engine of the Quaternary. XVII International Union for Quaternary Research Congress - The Topics: Heat Engine of the Quarternary, Cairns, Australia, (206-206). 28 July-3 August 2007. doi:10.1016/j.quaint.2007.04.001


Author Kershaw, Peter
Drake, Nick
Van der Kaars, Sander
Moss, Patrick
Armitage, Simon
White, Kevin
Title of paper Trends in tropical climate within the late quaternary: Implications for long term ENSO and monsoon activity
Conference name XVII International Union for Quaternary Research Congress - The Topics: Heat Engine of the Quarternary
Conference location Cairns, Australia
Conference dates 28 July-3 August 2007
Convener Professor John Chappell
Proceedings title Quarternary International; XVII Inqua Congress the Tropics: Heat Engine of the Quaternary   Check publisher's open access policy
Place of Publication Oxford, U.K.
Publisher Pergamon
Publication Year 2007
Year available 2007
Sub-type Published abstract
DOI 10.1016/j.quaint.2007.04.001
ISSN 1040-6182
Editor Norm R. Catto
Volume 167-168
Issue Supplement 1
Start page 206
End page 206
Total pages 1
Collection year 2008
Language eng
Abstract/Summary There is increasing evidence of long term trends in tropical rainfall that are superimposed upon variation resulting from northern mid latitude and/or regional insolation forcing within the late Quaternary. Such trends have been apparent in the northern Australian region for a number of years, being evident within records of dust, fluvial and aeolian activity and lake sediment sequences. The main signals are environmental drying or increased climatic variability and vary according to location. There is some indication that they vary spatially in relation to sources of monsoon rainfall and proximity to Pacific ENSO activity that involves both atmospheric and oceanic processes. More recently, equally prominent systematic changes in climate have been recorded in low latitudes from both Africa and South America.. In the Sahara Desert there is evidence from a wide variety of sources that aridity is prevalent in glacials and humidity in interglacials. Evidence from lake sediment deposits in Dakhleh Oasis and Bir Tarfawi in Egypt suggests that the last interglacial was more humid than the present one. Lake sediments from Fezzan Basin in Libya confirm this trend. The basin contains a long palaeoclimate record that suggests interglacials from about 780 ka to 420 ka were very humid, sustaining a giant lake of about 130,000 km2. After 420 ka there is a gap in the record until the last interglacial at 100 ka when a lake of just over 1000 km2 is found in Wadi as Shati, the lowest part of the Fezzan Basin. At the base if the depression is a much smaller playa underlain by Holocene lake sediments. Thus it appears that lakes in the Fezzan have become smaller in succeeding interglacials from about 420 ka and that what little evidence there is in other parts of the Sahara Desert, as well as the Arabian Peninsula, supports this view. As a substantial portion of rainfall is produced by the African monsoon, the reduced rainfall could be due to its gradual weakening over time. Conversely, the Altiplano of South America indicates increasing moisture availability over the last two glacial cycles. Although rainfall patterns are considered to be controlled by the Southern Atlantic monsoon, the fact that the signal appears opposite to that at ODP Site 820 on the opposite side of the Pacific suggests that a long term ENSO control is also likely. Possible underlying causes of trends will be examined.
Subjects 260113 Palynology
E1
780104 Earth sciences
Q-Index Code EX
Q-Index Status Confirmed Code
Institutional Status UQ

 
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Created: Wed, 30 Apr 2008, 21:52:32 EST by Deirdre Timo on behalf of School of Geography, Planning & Env Management