East Antarctic Climate and Environmental Variability over the Last 9400 Years Inferred from Marine Sediments of the Bunger Oasis

Abstract

Sediment cores around Antarctica provide a unique opportunity to cross check and supplement the climatic information recorded in ice cores. Suitable highresolution data, however, have not been available until now from East Antarctica. We present results from the longest continuous postglacial marine sediment succession (1290 cm) ever obtained from an East Antarctic basin. Twenty-one radiocarbon dates show a consistent age to depth correlation over the last 9400 calibrated years BP (cal. yr BP). For this time interval distinct changes in the silicified ice-related biotic species assemblages, accumulation rates of organic carbon, o 13 C values, and C/N ratios were detected. We demonstrate that these sediment signatures can be used as climate proxies. Our results indicate significant Holocene climatic variability with a climatic optimum between 3500 and 2500 cal. yr BP. This was followed by an abrupt and dramatic cooling that took place within less than 200 yr. Corroborating the results of other researchers we hypothesize that this climatic optimum and its termination was a circumantarctic event which would appear to be out of phase with a proposed global temperature trend (maximum) during the Holocene.:j:

Late Quaternary deglaciation and climate history of the Larsemann Hills (East Antarctica)

“…yr BP more open-water taxa are found in the Pup Lagoon core, suggesting warmer conditions. Similarly, a climate optimum is recognised in the Bunger Hills between 3500 and 2500 yr BP (Kulbe et al, 2001), in the Vestfold Hills around 4000 14 C yr BP (Roberts and McMinn, 1998) and in the Windmill Islands between 4000 and 1000 yr BP (Cremer et al, 2001(Cremer et al, , 2003a, suggesting this warm period (mid-Holocene Hypsithermal) may be a general trend in terrestrial Antarctica as reviewed by Hodgson et al (in press) and Ingó lfsson et al (1998). This period of a general warmer climate in Antarctica is detected in several proxy-climate records of Antarctica Hodgson et al, 2003) and is being considered as a potential analogue for the study of some aspects of the recent temperature rise in the Antarctic peninsula (Vaughan et al, 2003) that lead to the break up of large ice shelves (e.g.…”

Postglacial evolution of marine and lacustrine water bodies in Bunger Hills

“…The drop in TOC and δ 13 C in core PG1173 at 2.2 ka bp was previously interpreted as an abrupt cooling (Kulbe et al 2001). However, this shift clearly predates a late Holocene increase in sea ice diatoms at 1.7 ± 0.1 ka bp (Fig.…”

“…Datasets include lithological descriptions (changes in sediment colour, fabric, grain size and organic remains), total organic carbon (TOC), total nitrogen (N) and total sulfur (S) contents, stable carbon isotope ratios of TOC (δ 13 C) and mineralogical composition. For two cores (PG1173, PG1180) diatom assemblage data was presented in Kulbe et al (2001) and Verkulich et al . (2007).…”

“…). Freshwater (FW) are dominated by Amphora veneta (data from Kulbe et al 2001, Verkulich et al 2007). …”

A preliminary record of the historical seabird population in the Larsemann Hills, East Antarctica, from geochemical analyses of Mochou Lake sediments

“…After that there was a short return to stratified, open-water conditions and a reduction in near-shore winter sea-ice extent. A climate optimum in the Bunger Hills between 3500 and 2500 BP was inferred by Kulbe et al (2001). Roberts et al (2004), based on the lake sediment record from Windmill Islands, East Antarctica, suggested that from c. 2800 BP the retreat of the ice margin led to increasing meltwater inputs and freshening of the lake basin until c. 1900 BP.…”