Glacial and Holocene terrestrial temperature variability in subtropical east Australia as inferred from branched GDGT distributions in a sediment core from Lake McKenzie

Abstract

Branched glycerol dialkyl glycerol tetraether (GDGT) distributions observed in a sediment core from Lake McKenzie were utilized to quantitatively reconstruct the pattern of mean annual air temperature (MAAT) from coastal subtropical eastern Australia between 37 and 18.3 cal ka BP and 14.0 cal ka BP to present. Both the reconstructed trend and amplitude of MAAT changes from the top of the sediment core were nearly identical to a local instrumental MAAT record from Fraser Island, providing confidence that in this sediment core branched GDGTs could be used to produce a quantitative record of past MAAT. The reconstructed trend of MAAT during 37 to 18.3 cal ka BP and timing of the Last Glacial Maximum (LGM) in the Lake McKenzie record were in agreement with previously published nearby marine climate records. The amplitude of lower-than-present MAAT during the LGM potentially provides information on the latitude of separation of the Tasman Front from the East Australian current in the subtropical western Pacific. The Lake McKenzie record shows an earlier onset of near modern day warm temperatures in the early Holocene compared to marine records and the presence of a warmer than present day period during the mid-Holocene.

Low-resolution Australasian palaeoclimate records of the last 2000 years

“…This proxy has been used to reconstruct mean annual temperature in Lake Pupuke in New Zealand (Heyng et al, 2015) and Lake Mackenzie in Australia (Woltering et al, 2014). Both temperature and aridity have been reconstructed for Onepoto maar by combining analysis of fatty acid δ 13 C, biomass-burning biomarkers, and pollen abundances calibrated to mean annual temperatures (Sikes et al, 2013).…”

“…Both temperature and aridity have been reconstructed for Onepoto maar by combining analysis of fatty acid δ 13 C, biomass-burning biomarkers, and pollen abundances calibrated to mean annual temperatures (Sikes et al, 2013). The use of GDGTs and other lipid biomarkers has great potential for reconstructing Australasian temperatures during the Common Era; however, it faces significant challenges too, including non-systematic uncertainties of ∼ 1 • C, which may obscure the magnitude of temperature change during the last 2000 years, in addition to much greater systematic uncertainties related to the origin of the biomarkers and the type of calibration used (Woltering et al, 2014).…”

Development and application of subfossil chironomid-based methods for late Quaternary climate reconstructions in eastern Australia

“…5.1; 25°26′51″S, 153°03′12″E, 90 m a.s.l) was developed using branched glycerol dialkyl glycerol tetraethers (GDGTs), which suggested a cooling of only 4.1 °C at the LGM (c. ∼18.8 ± 0.5 cal ka BP) (Woltering et al, 2014). This lower value is consistent with results from Tasmania ( Southeast Queensland lies at the northern limit of the Southern Hemisphere winter westerlies (Fig.…”

“…Fletcher and Thomas 2010), periglacial landforms (Galloway 1965), Amino Acid Racemization (AAR) from Emu eggs (Miller et al, 1997) and more recently branched glycerol dialkyl glycerol tetraether (GDGT) (Woltering et al, 2014). With the exception of pollen these proxies are relatively unconventional for the application of temperature inferences and these records have provided limited or contradicting estimates of temperature change in Australia.…”

“…The locations of marine cores PC-27 , GC-12 (Bostock et al, 2006), GC-25 (Troadson and Davies, 2001), PC-9 (Troadson and Davies, 2001) along the EAC, terrestrial temperature estimates from Lake Victoria (Miller et al, 1997), the Snowy Mountains (Galloway, 1965), and Lake Selina (Fletcher and Thomas, 2010) are displayed (b) Location of North Stradbroke Island (NSI) and Lake Mackenzie, Fraser Island (c) Location on North Stradbroke Island of Welsby Lagoon and other sites mentioned in the text, including Tortoise Lagoon Moss et al, 2013), Blue Lake , Eighteen Mile Swamp (sampling location) and Native Companion Lagoon Moss et al, 2013) xxii | P a g e Figure 5.5 The Welsby Lagoon chironomid record was split into three zones using the constrained incremental sums of squares (CONISS) function in Psimpoll (Bennett, 2002). Antarctica (Stenni et al, 2011;Pedro et al, 2012); (b) insolation curve for seasonality (Berger and Loutre, 1991); (c) δ 18 O measured from G. ruber from marine cores along the East Australian Current (EAC) and (d) temperature estimated based on branched glycerol dialkyl glycerol tetraether (GDGT) from Fraser Island (Woltering et al, 2014). The chironomid results…”