Last glacial sea surface temperatures and sea-ice extent in the Southern Ocean (Atlantic-Indian sector): A multiproxy approach

2003 ◽  
Vol 18 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
R. Gersonde ◽  
A. Abelmann ◽  
U. Brathauer ◽  
S. Becquey ◽  
C. Bianchi ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Sea Ice Extent ◽  
Last Glacial ◽  
Surface Temperatures ◽  
Multiproxy Approach ◽  
Indian Sector

scholarly journals Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e

2021 ◽  
Author(s):  
Matthew Chadwick ◽  
Claire S. Allen ◽  
Louise C. Sime ◽  
Xavier Crosta ◽  
Claus-Dieter Hillenbrand
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
High Variability ◽  
Sea Surface ◽  
Marine Isotope Stage ◽  
Sea Surface Temperatures ◽  
Sea Ice Extent ◽  
Mis 5E ◽  
The Antarctic ◽  
Indian Sector

Abstract. Environmental conditions during Marine Isotope Stage (MIS) 5e (130–116 ka) represent an important ‘process analogue’ for understanding the climatic responses to present and future anthropogenic warming. The response of Antarctic sea ice to global warming is particularly uncertain due to the short length of the observational record. Reconstructing Antarctic winter sea-ice extent during MIS 5e therefore provides insights into the temporal and spatial patterns of sea-ice change under warmer than present climate. This study presents new MIS 5e records from nine marine sediment cores located south of the Antarctic Polar Front, between 55 and 70° S. We investigate changes in winter sea-ice extent and sea-surface temperatures between the three Southern Ocean sectors. The Atlantic and Indian sector records have much more variable MIS 5e winter sea-ice extent and sea-surface temperatures than the Pacific sector records. High variability in the Atlantic sector winter sea-ice extent is attributed to high glacial meltwater flux in the Weddell Sea while high variability in the Indian sector winter sea-ice extent results from large latitudinal migrations of the flow bands of the Antarctic Circumpolar Current. Overall, these findings suggest that Pacific sector winter sea ice displays a low sensitivity to warmer climates. The different variability and sensitivity of Antarctic winter sea-ice extent in the three Southern Ocean sectors during MIS 5e may have significant implications for the Southern Hemisphere climatic system under future warming.

Last Glacial Maximum Antarctic sea ice linked with global mean ocean temperature: evidence from PMIP3, PMIP4 and MIROC-4m simulations

2021 ◽  
Author(s):  
Tristan Vadsaria ◽  
Sam Sherriff-Tadano ◽  
Ayako Abe-Ouchi ◽  
Takashi Obase ◽  
Wing-Le Chan ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Last Glacial Maximum ◽  
Ocean Circulation ◽  
Glacial Maximum ◽  
Ocean Temperature ◽  
Sea Ice Extent ◽  
Last Glacial ◽  
Antarctic Sea Ice ◽  
The Antarctic

<p>Southern Ocean sea ice and oceanic fronts are known to play an important role on the climate system, carbon cycles, bottom ocean circulation, and Antarctic ice sheet. However, many models of the previous Past-climate Model Intercomparison Project (PMIP) underestimated sea-ice extent (SIE) for the Last Glacial Maximum (LGM)(Roche et al., 2012; Marzocchi and Jensen, 2017), mainly because of surface bias (Flato et al., 2013) that may have an impact on mean ocean temperature (MOT). Indeed, recent studies further suggest an important link between Southern Ocean sea ice and mean ocean temperature (Ferrari et al., 2014; Bereiter et al., 2018 among others). Misrepresent the Antarctic sea-ice extent could highly impact deep ocean circulation, the heat transport and thus the MOT. In this study, we will stress the relationship between the distribution of Antarctic sea-ice extent and the MOT through the analysis of the PMIP3 and PMIP4 exercise and by using a set of MIROC models. To date, the latest version of MIROC improve its representation of the LGM Antarctic sea-ice extent, affecting the deep circulation and the MOT distribution (Sherriff-Tadano et al., under review).</p><p>Our results show that available PMIP4 models have an overall improvement in term of LGM sea-ice extent compared to PMIP3, associated to colder deep and bottom ocean temperature. Focusing on MIROC (4m) models, we show that models accounting for Southern Ocean sea-surface temperature (SST) bias correction reproduce an Antarctic sea-ice extent, 2D-distribution, and seasonal amplitude in good agreement with proxy-based data. Finally, using PMIP-MIROC analyze, we show that it exists a relationship between the maximum SIE and the MOT, modulated by the Antarctic intermediate and bottom waters.</p>

scholarly journals Sensitivity experiments to sea surface temperatures, sea-ice extent and ice-sheet reconstruction, for the Last Glacial Maximum

1995 ◽  
Vol 21 ◽  
pp. 343-347 ◽  
Author(s):  
G. Ramstein ◽  
S. Joussaume
Keyword(s):  
Sea Ice ◽  
Last Glacial Maximum ◽  
Ice Sheet ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Sea Ice Extent ◽  
The Impact ◽  
The Last Glacial Maximum ◽  
Ice Sheet Topography ◽  
The Last Glacial

For the Last Glacial Maximum, (LGM; 21 000 BP), simulations using atmospheric general-circulation models (AGCMs) are very sensitive to the prescribed boundary conditions. Most of the recent numerical experiments have used the CLIMAP (1981) data set for ice-sheet topography, sea-ice extent and sea surface temperatures (SSTs). To demonstrate the impact of ice-sheet reconstruction on the LGM climate, we performed two simulations: one using CLIMAP (1981) ice-sheet topography, the other using the new reconstruction provided by Peltier. We show that, although the geographical structure of the annually averaged temperature is not modified, there are important seasonal and regional impacts on the temperature distribution. In a second step, to analyze the effects of cooler SSTs and sea-ice extent, we performed a simulation using CLIMAP (1981) for the ice-sheet topography, but with present SSTs. We find that the cooling due to ice sheets for the LGM climate is one-third of the global annually averaged cooling, and dial the southward shift of the North Atlantic low in winter is not due to sea-ice extent, but is an orographic effect due to the Laurenride ice sheet. This set of sensitivity experiments allows us also to discriminate between thermal and orographic forcings and to show the impact of the ice-sheet topography and cooler SSTs on the pattern of planetary waves during the LGM climate.

scholarly journals Atlantic Water advection vs glacier dynamics in northern Spitsbergen since early deglaciation

2017 ◽  
Author(s):  
Martin Bartels ◽  
Jürgen Titschack ◽  
Kirsten Fahl ◽  
Rüdiger Stein ◽  
Marit-Solveig Seidenkrantz ◽  
...  
Keyword(s):  
Sea Ice ◽  
Environmental Conditions ◽  
Late Holocene ◽  
Ice Cover ◽  
Atlantic Water ◽  
Sea Surface ◽  
Early Holocene ◽  
Sea Surface Temperatures ◽  
Surface Temperatures ◽  
Glacier Dynamics

Abstract. Atlantic Water (AW) advection plays an important role for climatic, oceanographic and environmental conditions in the eastern Arctic. Situated along the only deep connection between the Atlantic and the Arctic Ocean, the Svalbard Archipelago is an ideal location to reconstruct the past AW advection history and document its linkage with local glacier dynamics, as illustrated in the present study of a sedimentary record from Woodfjorden (northern Spitsbergen) spanning the last ~ 15 500 years. Sedimentological, micropalaeontological and geochemical analyses were used to reconstruct changes in marine environmental conditions, sea-ice cover and glacier activity. Data illustrate a partial breakup of the Svalbard–Barents–Sea Ice Sheet from Heinrich Stadial 1 onwards (until ~ 14.6 ka BP). During the Bølling-Allerød (~ 14.6–12.7 ka BP), AW penetrated as a bottom water mass into the fjord system and contributed significantly to the destabilisation of local glaciers. During the Younger Dryas (~ 12.7–11.7 ka BP), it intruded into intermediate waters while evidence for a glacier advance is lacking. A short-term deepening of the halocline occurred at the very end of this interval. During the early Holocene (~ 11.7–7.8 ka BP), mild conditions led to glacier retreat, a reduced sea-ice cover and increasing sea surface temperatures, with a brief interruption during the Preboreal Oscillation (~ 11.1–10.8 ka BP). During the late Holocene (~ 1.8–0.4 ka BP), a slightly reduced AW inflow and lower sea surface temperatures compared to the early Holocene are reconstructed. Glaciers, which previously retreated to the shallower inner parts of the Woodfjorden system, likely advanced during the late Holocene. In particular, as topographic control in concert with the reduced summer insolation partly decoupled glacier dynamics from AW advection during this recent interval.

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