Australian shelf sediments reveal shifts in Miocene Southern Hemisphere westerlies

Science Advances
Jeroen GroeneveldExpedition 356 Scientists

Abstract

Global climate underwent a major reorganization when the Antarctic ice sheet expanded ~14 million years ago (Ma) (1). This event affected global atmospheric circulation, including the strength and position of the westerlies and the Intertropical Convergence Zone (ITCZ), and, therefore, precipitation patterns (2-5). We present new shallow-marine sediment records from the continental shelf of Australia (International Ocean Discovery Program Sites U1459 and U1464) providing the first empirical evidence linking high-latitude cooling around Antarctica to climate change in the (sub)tropics during the Miocene. We show that Western Australia was arid during most of the Middle Miocene. Southwest Australia became wetter during the Late Miocene, creating a climate gradient with the arid interior, whereas northwest Australia remained arid throughout. Precipitation and river runoff in southwest Australia gradually increased from 12 to 8 Ma, which we relate to a northward migration or intensification of the westerlies possibly due to increased sea ice in the Southern Ocean (5). Abrupt aridification indicates that the westerlies shifted back to a position south of Australia after 8 Ma. Our midlatitude Southern Hemisphere data are consistent w...Continue Reading

References

Sep 18, 2004·Science·Amelia E ShevenellDavid W Lea
Mar 8, 2008·Science·R Dietmar MüllerChristian Heine
Sep 18, 2013·Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences·Yi Ge ZhangRobert Deconto
Sep 5, 2014·Nature·Tapio SchneiderGerald H Haug

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Methods Mentioned

BETA
gamma
x-ray diffraction

Software Mentioned

DIFFRACplus EVA
JOIDES
Bruker DIFFRAC EVA

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