A review of the Australian–New Zealand sector of the Southern Ocean over the last 30 ka (Aus-INTIMATE project)

Bostock, Helen C.; Barrows, Timothy T.; Carter, L; Chase, Zanna; Cortese, Giuseppe; Dunbar, Gavin B.; Ellwood, Michael J.; Hayward, Bruce W.; Howard, William R; Neil, Helen L; Noble, Taryn L; Mackintosh, Andrew; Moss, Patrick; Moy, Andrew D.; White, Duanne; Williams, Michael; Armand, Leanne K.

doi:10.1016/j.quascirev.2012.07.018

Cited by 100 publications

(105 citation statements)

References 207 publications

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“…), classification of archive, source of core, description of archive, proxies measured within core, published interpretation of climate proxy (E/P = evaporation-precipitation balance), most recent publication, length of record, year of oldest sample (including uncertainty) (present = 1950 CE), year of youngest sample (including uncertainty), average sampling resolution according to published chronology (years sample −1 ), public archive URL, and PAGES2k identifier (where applicable). (Alloway et al, 2007;Barrell et al, 2013;Bostock et al, 2013;Reeves et al, 2013b); however, many of the compiled records extend to the present. The purpose of AUS-INTIMATE was to integrate available proxy data into climate event stratigraphies.…”

Section: Past Palaeoclimate Data Syntheses In Australasiamentioning

confidence: 99%

Low-resolution Australasian palaeoclimate records of the last 2000 years

et al. 2017

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Abstract. Non-annually resolved palaeoclimate records in the Australasian region were compiled to facilitate investigations of decadal to centennial climate variability over the past 2000 years. A total of 675 lake and wetland, geomorphic, marine, and speleothem records were identified. The majority of records are located near population centres in southeast Australia, in New Zealand, and across the maritime continent, and there are few records from the arid regions of central and western Australia. Each record was assessed against a set of a priori criteria based on temporal resolution, record length, dating methods, and confidence in the proxy-climate relationship over the Common Era. A subset of 22 records met the criteria and were endorsed for subsequent analyses. Chronological uncertainty was the primary reason why records did not meet the selection criteria. New chronologies based on Bayesian techniques were constructed for the high-quality subset to ensure a consistent approach to age modelling and quantification of age uncertainties. The primary reasons for differences between published and reconstructed age-depth models were the consideration of the non-singular distribution of ages in calibrated 14 C dates and the use of estimated autocorrelation between sampled depths as a constraint for changes in accumulation rate. Existing proxies and reconstruction techniques that successfully capture climate variability in the region show potential to address spatial gaps and expand the range of climate variables covering the last 2000 years in the Australasian region. Future palaeoclimate research and records in Australasia could be greatly improved through three main actions: (i) greater data availability through the public archiving of published records; (ii) thorough characterisation of proxy-climate relationships through site monitoring and climate sensitivity tests; and (iii) improvement of chronologies through coretop dating, inclusion of tephra layers where possible, and increased date density during the Common Era.

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Section: Past Palaeoclimate Data Syntheses In Australasiamentioning

confidence: 99%

Low-resolution Australasian palaeoclimate records of the last 2000 years

et al. 2017

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“…We use the increase in carbon of our O-LGM BGC all experiment of 317 Pg C, which falls within the estimate range of ocean carbon storage at the LGM (Ciais et al, 2011), and our simulated loss of 1290 Pg C from the PI ocean with an atmospheric pCO 2 of 185 ppm to determine the contribution of physical and biogeochemical drivers in ppm of CO 2 . (Boyle, 1992;Gebbie, 2014;Marchitto and Broecker, 2006;Tagliabue et al, 2009).…”

Section: Nutrients and Export Productionmentioning

confidence: 99%

“…Whether this was also the case for the Pacific sector remains under debate, with some evidence for increase (Bradtmiller et al, 2009;Lamy et al, 2014) and some for no change (Bostock et al, 2013;Chase et al, 2003). Meanwhile, it is widely accepted that waters south of the Antarctic Polar Front were reduced in their productivity (Bostock et al, 2013;Chase et al, 2003;Elderfield and Rickaby, 2000;Francois et al, 1997;Frank et al, 2000;Kohfeld et al, 2005;Kumar et al, 1995;Mortlock et al, 1991;Ninnemann and Charles, 1997;Shemesh et al, 1993), likely due to increased sea ice extent (Benz et al, 2016;Gersonde et al, 2005;Jaccard et al, 2013) and stratification Jaccard et al, 2005).…”

Section: Reconciling Export Productionmentioning

confidence: 99%

The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

et al. 2016

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Abstract. The ocean's ability to store large quantities of carbon, combined with the millennial longevity over which this reservoir is overturned, has implicated the ocean as a key driver of glacial-interglacial climates. However, the combination of processes that cause an accumulation of carbon within the ocean during glacial periods is still under debate. Here we present simulations of the Last Glacial Maximum (LGM) using the CSIRO Mk3L-COAL (Carbon-OceanAtmosphere-Land) earth system model to test the contribution of physical and biogeochemical processes to ocean carbon storage. For the LGM simulation, we find a significant global cooling of the surface ocean (3.2 • C) and the expansion of both minimum and maximum sea ice cover broadly consistent with proxy reconstructions. The glacial ocean stores an additional 267 Pg C in the deep ocean relative to the pre-industrial (PI) simulation due to stronger Antarctic Bottom Water formation. However, 889 Pg C is lost from the upper ocean via equilibration with a lower atmospheric CO 2 concentration and a global decrease in export production, causing a net loss of carbon relative to the PI ocean. The LGM deep ocean also experiences an oxygenation (> 100 mmol O 2 m −3 ) and deepening of the calcite saturation horizon (exceeds the ocean bottom) at odds with proxy reconstructions. With modifications to key biogeochemical processes, which include an increased export of organic matter due to a simulated release from iron limitation, a deepening of remineralisation and decreased inorganic carbon export driven by cooler temperatures, we find that the carbon content of the glacial ocean can be sufficiently increased (317 Pg C) to explain the reduction in atmospheric and terrestrial carbon at the LGM (194 ± 2 and 330 ± 400 Pg C, respectively). Assuming an LGM-PI difference of 95 ppm pCO 2 , we find that 55 ppm can be attributed to the biological pump, 28 ppm to circulation changes and the remaining 12 ppm to solubility. The biogeochemical modifications also improve model-proxy agreement in export production, carbonate chemistry and dissolved oxygen fields. Thus, we find strong evidence that variations in the oceanic biological pump exert a primary control on the climate.

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“…Our modelling of realistic temperatures required for snow bank formation at Guyra suggests a very similar range. Conversely, reconstructions of temperatures for the East Australia Current which runs along the eastern coastline of Australia, indicate that water temperature cooled only moderately at the LGM as the present day at these latitudes (within 4-6°C) (Bostock et al 2013). In addition, the extension of the Australian landmass to connect Tasmania to the mainland at lower sea-levels meant that warm water could penetrate several degrees of latitude further south before encountering Southern Ocean waters.…”

Section: Precipitation Volume and Sourcementioning

confidence: 99%

The distribution and paleoclimate implications of periglacial landforms in eastern Australia

Slee¹

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It is widely recognised that during the Late Quaternary, glaciation was limited in Australia, especially away from Tasmania. This contrasts with the widely recognised occurrence of periglacial landforms in SE Australia, particularly in Australian Alps and Tasmania.However, very little research has been undertaken into these landforms. The aim of this thesis is to investigate the extent and timing of Late Quaternary periglacial conditions in south-eastern Australia and to understand the geomorphic processes and environments associated with these landforms. This thesis presents an updated understanding of the distribution, morphology and climatic significance of periglacial landforms in eastern Australia. The thesis is divided into two sections. The first section is focused on modern 'active' periglacial landforms found primarily in the mountainous areas of Tasmania and focuses on two studies of modern freeze-thaw processes in western Tasmania. At higher elevations (1000 m) notable freeze-thaw features are active at the present time including stone banked lobes on Mt Rufus. Freeze-thaw features were identified to only 150 m above sea-level near Queenstown. However, these low elevation freeze-thaw landforms are small scale features associated with short periods where shallow ground ice forms.The second section of the thesis focuses on relict periglacial landforms that display no evidence of modern activity and most likely relate to late Quaternary cold climate conditions. It primarily focuses on the block deposits of eastern Australia, their morphology, distribution and climatic significance. Block deposits and associated landslide deposits from northern New South Wales to Tasmania were mapped. Four sites were studied in more detail and dated using surface exposure dating (SED). They yielded ages ranging from early Holocene to OIS 5 which are internally consistent within sites but vary widely between sites. These data provide evidence for repeated phases of periglacial activity during the last glacial cycle. At Guyra, several phases of mass movement were recognised with large scale landslides associated with a much earlier warm and humid climate dominating the landscape. Freeze-thaw landforms of the late Quaternary are superimposed on these older forms. The scale of last glaciation cooling is indicated by evidence for a possible nivation hollow bounded by a pronival rampart located near the town of Guyra (29°30'S). From this site a cooling range of 8-11°C is inferred, but additionally, relatively moist conditions are required for the nivation feature to form.The concept of a relatively humid glaciation also emerges from the mapping of the freezethaw landforms on a regional basis. In particular the occurrence of block deposits and screes in northern New England in patterns matching the modern precipitation gradient indicates that freeze-thaw was preferentially concentrated in a zone parallel to the coast. It is inferred that this zone represented an area of intermediate moisture landward of the divide separa...

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A review of the Australian–New Zealand sector of the Southern Ocean over the last 30 ka (Aus-INTIMATE project)

Cited by 100 publications

References 207 publications

Low-resolution Australasian palaeoclimate records of the last 2000 years

Low-resolution Australasian palaeoclimate records of the last 2000 years

The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

The distribution and paleoclimate implications of periglacial landforms in eastern Australia

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