Quaternary Science Reviews 26 (2007) 1621–1637 Pollen evidence for the transition of the Eastern Australian climate system from the post-glacial to the present-day ENSO mode Timme H. Donders a,Ã , Simon G. Haberle b , Geoffrey Hope b , Friederike Wagner a , Henk Visscher a a Palaeoecology, Institute of Environmental Biology, Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584 CD, Utrecht, The Netherlands b Research School of Pacific and Asian Studies, Australian National University, Canberra, ACT 0200, Australia Received 10 April 2006; received in revised form 20 November 2006; accepted 23 November 2006 Abstract A review of Holocene climate patterns in eastern Australia is presented on the basis of a series of high-resolution pollen records across a north-to-south transect. Previously published radiocarbon data are calibrated into calendar years and fitted with an age-depth model. The resulting chronologies are used to compare past environmental changes and describe patterns of climate change on a calendar-age scale. Based on the present-day Australian climate patterns and impact of the El Nin˜o-Southern Oscillation (ENSO), the palynological data are interpreted and the prevalent climate mode throughout the Holocene reconstructed. Results show that early Holocene changes are strongly divergent and asynchronous between sites, while middle to late Holocene conditions are characterized by more arid and variable conditions and greater coupling between northern and southern sites, which is in agreement with increasing influence of ENSO. r 2006 Elsevier Ltd. All rights reserved. 1. Introduction Australian vegetation and wildlife is well adapted to climate fluctuations imposed by the El Nin˜o-Sourthern Oscillation (ENSO) system (Nichols, 1992). The high adaptation capacity implies that this region is well suited for paleoclimatic studies related to the history of ENSO dynamics. Investigating Holocene ENSO variability is particularly important because in this time interval the effects of changes in background climate, caused by orbital precession, can be studied independently of large, long- term variations in global ice cover and sea level (Markgraf and Diaz, 2000). Currently, ENSO causes significant interannual climate variability in Australia (Dodson, 2001). The early Holo- cene Australian environment was characterized by gener- ally lower variability compared to the present situation. It is therefore unlikely, that the ENSO system has continu- ously operated in the present-day mode throughout the entire Holocene (McGlone et al., 1992). More arid and variable conditions seen in Australian tropical monsoon- dominated areas after 4 14 Cka BP (3.7 cal ka BP) have been attributed to the establishment of modern-day ENSO dynamics (Shulmeister and Lees, 1995). Strongly ENSO- teleconnected regions in South-America (McGlone et al., 1992) and the Southeastern United States (Donders et al., 2005) have shown similar changes in past ENSO state. Holocene ENSO variability has likely caused synchro- nous changes across large parts of Australia, since it presently impacts a wide area. Numerous high-resolution palynological records of Holocene vegetation cover in Australia are available, which have the potential to recognize temporal and spatial patterns of past climate dynamics. In order to accurately resolve the development and role of ENSO, these records must be compared on a calendar age-scale. However, available reviews of con- tinental (Harrison, 1993; Hope et al., 2004) or regional (Kershaw, 1994; Dodson and Ono, 1997; Dodson, 1998, 2001) vegetation and climate patterns in Australian do not ARTICLE IN PRESS 0277-3791/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.quascirev.2006.11.018 Ã Corresponding author. Tel.: +31 30 253 2631; fax: +31 30 253 5096. E-mail address: t.h.donders@bio.uu.nl (T.H. Donders).