Climate evolution at the last deglaciation: the role of the Southern Ocean

Bianchi, Cristina; Gersonde, Rainer

doi:10.1016/j.epsl.2004.10.003

Cited by 114 publications

(125 citation statements)

References 64 publications

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“…Meltwater peaks at 14 and 11 kyr BP have also been recognized close to the APF in another core (TN057-13) from the Atlantic Sector of the Southern Ocean [27]. The age scale [17] is in calendar years, with an 800 year reservoir correction. Intervals of higher and lower sediment accumulation rates have also been indicated.…”

Section: Surface Sediment and Sediment Trap Pf3: F Kerguelensis Undementioning

confidence: 99%

“…Sample treatment and preparation of slides for light microscopy documentation of diatoms followed the standard method described by [20], while the age model of core PS1654-2 is from [17], with ages converted from 14 C-radiocarbon years to calendar years, and the application of an 800 year reservoir correction.…”

Section: Methodsmentioning

confidence: 99%

“…Comparison of paleobiological proxies in piston core PS1654-2. Time series for SST, Chaetoceros spp., F. curta/cylindrus group, and F. kerguelensis relative abundances for piston core PS1654-2/ODP Site 1093 (data from [17]), and F. kerguelensis valve area and F ⁎ (piston core PS1654-2, this paper). A major meltwater event (dark gray), correlative to the ACR, and the F. kerguelensis shape shift interval (light gray) have been highlighted to facilitate comparison.…”

Section: Surface Sediment and Sediment Trap Pf3: F Kerguelensis Undementioning

confidence: 99%

“…Raw data from the World Ocean Atlas 2001 [23], gridded and interpolated with the OceanDataView software [22]. The age of each sample [17], in calendar years, with an 800 year reservoir correction, along with average area values for specific time intervals (full interglacial, termination, shape shift, full glacial), are also shown. enrichment due to lower diatom fluxes during these seasons, and consequent selective dissolution of the other, less dissolution resistant, species.…”

Section: Sediment Trapmentioning

confidence: 99%

“…An interesting application of the proxy we developed in this work is to analyze if and how the morphology of F. kerguelensis varied over glacial to interglacial transitions at the Polar Front, as this may reflect millennial-scale shifts in the position of this front, and the associated high export of biogenic silica. The core we chose for this purpose is piston core PS1654-2, collected at the Polar Front in the Atlantic Sector (close to the PF3 sediment trap location), and extensively analyzed by [17], who documented its paleotemperature evolution (derived from diatom-based transfer functions), and the presence of a major meltwater event, time-correlative to the Antarctic Cold Reversal (ACR), at ca. 13 ka.…”

Section: Introductionmentioning

confidence: 99%

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Morphometric variability in the diatom Fragilariopsis kerguelensis: Implications for Southern Ocean paleoceanography

Cortese

Gersonde

2007

Earth and Planetary Science Letters

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Diatoms play a central role in the ecosystem of the Southern Ocean, where they represent the main producers and carriers of organic carbon and dissolved silicon towards the deep ocean. Variability in space and time of the size of the most abundant species (Fragilariopsis kerguelensis) may directly impact the way this ecosystem functions, and also affect the nutrient balance of the global ocean, as important water masses (e.g. the Antarctic Intermediate Water) get their nutrient signature in this area. We used a biometric approach and analyzed the size variability of F. kerguelensis valves in sixty-four surface sediment samples from the Southern Ocean, in sediment trap samples from a mooring (Site PF3) at the Antarctic Polar Front (APF), and along a nearby piston core (PS1654-2). The average length and valve area of F. kerguelensis displayed a distinct increase in the proximity of the APF, and lower values to the north and south of it, and also changed markedly over seasonal cycles, as diatom blooms and nutrient availability waxe and wane. The last glacial to interglacial transition also witnesses important changes in the general shape and valve size of F. kerguelensis, with specimens from glacial intervals being ca. 30% larger than their interglacial counterparts (195 versus 150 μm 2 valve area). A sharp peak in average area and a very specific valve morphology correspond to the first signs of deglaciation and concurring SST (Sea Surface Temperature) increase and sea-ice retreat. The latter, together with melting icebergs, may have contributed dissolved iron to surface waters. The highest average sizes during glacial intervals are higher than what found anywhere in the Southern Ocean today. The newly proposed proxy (valve area and shape of F. kerguelensis) may thus prove useful for the reconstruction of the past position and nutrient characteristics of the APF and "opal belt", a region characterized by high production and export of biogenic silica, in a particularly sensitive and dynamic area such as the Southern Ocean.

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Section: Surface Sediment and Sediment Trap Pf3: F Kerguelensis Undementioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Surface Sediment and Sediment Trap Pf3: F Kerguelensis Undementioning

confidence: 99%

Section: Sediment Trapmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Morphometric variability in the diatom Fragilariopsis kerguelensis: Implications for Southern Ocean paleoceanography

Cortese

Gersonde

2007

Earth and Planetary Science Letters

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Changes in the position of the Subtropical Front south of New Zealand since the last glacial period

et al. 2015

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This study fills an important gap in our understanding of past changes in the Southern Subtropical Front (S-STF) in the southwest Pacific Ocean. Paleo-sea surface temperatures (SST) were estimated from planktic foraminiferal census counts from cores straddling the modern S-STF in the Solander Trough, south of New Zealand. The estimated SST were compared for 6 time slices; glacial period (25-21 ka), Last Glacial Maximum (LGM; 21-18 ka), early deglaciation (18-16 ka), late deglacial/early Holocene period (14-8 ka), mid-Holocene period (8-4 ka), and late Holocene period (4-0 ka). The position of the S-STF was determined by two methods:(1) the location of the 10°C isotherm and (2) the location of the highest SST gradients. These new results suggest that the S-STF was not continuous between east and west of New Zealand during the glacial period. Steep SST gradients indicate that a strong S-STF rapidly shifted south during the LGM and early deglaciation. During the late deglacial and Holocene periods the position of the S-STF differs between the two methods with reduced SST gradients, suggesting a more diffuse S-STF in the Solander Trough at this time. The glacial SST data suggest that the S-STF shifted north to the west of New Zealand, while to the east there was a stronger SST gradient across the front. This was possibly the result of an increased wind stress curl, which could have been caused by stronger, or more northerly Southern Hemisphere westerly winds (SHWW), or a merging of the SHWW split jet in this region.

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First records of winter sea ice concentration in the southwest Pacific sector of the Southern Ocean

et al. 2015

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We use a Generalized Additive Model (GAM) to provide the first winter sea ice concentration record from two cores located within the southwest Pacific sector of the Southern Ocean. To compliment the application of GAM, a time series analysis on satellite records of sea ice concentration data was used to extend the standard 13.25 year time series used for paleoceanography. After comparing GAM sea ice estimates with previously published paleo sea ice data we then focus on a new paleo winter sea ice record for marine sediment core E27-23 (59°37.1'S, 155°14.3'E), allowing us to provide a more comprehensive view of winter sea ice dynamics for the southwest Pacific Ocean. The paleo winter sea ice concentration estimates provide the first suggestion that winter sea ice within the southwestern Pacific might have expanded during the Antarctic Cold Reversal. Throughout the Holocene, core E27-23 documents millennial scale variability in paleo winter sea ice coverage within the southwest Pacific. Holocene winter sea ice expansion may have resulted from the Laurentide Ice Sheet deglaciation, increased intensity of the westerly winds, as well as a northern migration of the Subtropical and/or Sub-Antarctic Fronts. Brief consideration is given to the development of a paleo summer sea ice proxy. We conclude that there is no evidence that summer sea ice ever existed at core sites SO136-111 and E27-23 over the last 220 and 52,000 years, respectively.

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Climate evolution at the last deglaciation: the role of the Southern Ocean

Cited by 114 publications

References 64 publications

Morphometric variability in the diatom Fragilariopsis kerguelensis: Implications for Southern Ocean paleoceanography

Morphometric variability in the diatom Fragilariopsis kerguelensis: Implications for Southern Ocean paleoceanography

Changes in the position of the Subtropical Front south of New Zealand since the last glacial period

First records of winter sea ice concentration in the southwest Pacific sector of the Southern Ocean

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