Australian shelf sediments reveal shifts in Miocene Southern Hemisphere westerlies

• DOI: 10.1126/sciadv.1602567
• Publication Date: 2017-05-11T13:56:58Z
• Authors: Jeroen Groeneveld; Jorijntje Henderiks; Willem Renema; Cecilia M. McHugh; David De Vleescho...; Beth A. Christensen; Craig S. Fulthorpe; Lars Reuning; Stephen J. Gallagher; Kara Bogus; Gerald Auer; Takeshige Ishiwa
• Keywords: Westerlies

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 strength and position of westerlies Intertropical Convergence Zone (ITCZ), and, therefore, precipitation patterns (2-5). We present new shallow-marine sediment records from continental shelf Australia (International Ocean Discovery Program Sites U1459 U1464) providing first empirical evidence linking high-latitude cooling around Antarctica to change in (sub)tropics during Miocene. show that Western was arid most Middle Southwest became wetter Late Miocene, creating gradient with interior, whereas northwest remained throughout. Precipitation river runoff southwest gradually increased 12 8 Ma, which we relate northward migration or intensification possibly due sea Southern (5). Abrupt aridification indicates shifted back south after Ma. Our midlatitude Hemisphere data are consistent inference expansion resulted movement westerlies. In turn, this may have pushed tropical circulation ITCZ northward, shifting main belt over large parts Southeast Asia (4).