Radiocarbon variations from the southern hemisphere, 10,350-9700 cal BP

We have made AMS measurements on a series of 10-ring samples from a subfossil Huon pine log found in western Tasmania (42degreesS, 145degreesE). The results show a pronounced rise in Delta(14)C over the first 200 years, and a decrease over the following 160 years. Tree-ring width measurements indicate that this log (catalogue SRT-447) can be cross-dated with another subfossil log (SRT-416) for which a series of high-precision radiometric C-14 measurements have previously been made. When the two tree-ring series are thus aligned, SRT-447 is the older of the two logs, and there is a 139-year overlap. We then have a Huon pine floating chronology spanning 680 years, with C-14 measurements attached. The C-14 data sets agree well within the period of overlap indicated by the tree-rings. The C-14 variations from Huon pine show excellent agreement with those from German oak and pine for the period 10,350-9670 cal BP. Aligning the Huon pine C-14 Series with that from German oak and pine allows us to examine the inter-hemispheric offset in C-14 dates in the early Holocene. (C) 2004 Elsevier B.V. All rights reserved.

Climatic variability in the southwest Pacific during the Last Termination (20-10 kyr BP)

The degree to which palaeoclimatic changes in the Southern Hemisphere co-varied with events in the high latitude Northern Hemisphere during the Last Termination is a contentious issue, with conflicting evidence for the degree of 'teleconnection' between different regions of the Southern Hemisphere. The available hypotheses are difficult to test robustly, however, because there are few detailed palaeoclimatic records in the Southern Hemisphere. Here we present climatic reconstructions from the southwestern Pacific, a key region in the Southern Hemisphere because of the potentially important role it plays in global climate change. The reconstructions for the period 20-10 kyr BP were obtained from five sites along a transect from southern New Zealand, through Australia to Indonesia, supported by 125 calibrated C-14 ages. Two periods of significant climatic change can be identified across the region at around 17 and 14.2 cal kyr BP, most probably associated with the onset of warming in the West Pacific Warm Pool and the collapse of Antarctic ice during Meltwater Pulse-1A, respectively. The severe geochronological constraints that inherently afflict age models based on radiocarbon dating and the lack of quantified climatic parameters make more detailed interpretations problematic, however. There is an urgent need to address the geochronological limitations, and to develop more precise and quantified estimates of the pronounced climate variations that clearly affected this region during the Last Termination. (c) 2005 Elsevier Ltd. All rights reserved.