The marine geological imprint of Antarctic ice shelves

Smith, James A; Graham, Alastair G C; Post, Alix; Hillenbrand, Claus‐Dieter; Bart, Philip J.; Powell, Ross D.

doi:10.1038/s41467-019-13496-5

Cited by 103 publications

(105 citation statements)

References 139 publications

(254 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The rapid collapse of several Antarctic ice shelves, observed recently, and the near-instantaneous acceleration of land-ice discharge into the ocean that follows the collapse, demonstrates the sensitivity of the Antarctic cryosphere to recent warming (e.g., Smith et al, 2019;Rignot et al, 2019). However, large uncertainty remains regarding the response of ice shelves to the globally rising temperatures and to the resulting changes in the atmospheric circulation.…”

Section: Introductionmentioning

confidence: 88%

Atmospheric extremes triggered the biggest calving event in more than 50 years at the Amery Ice shelf in September 2019

Francis

Mattingly

Lhermitte

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. Ice shelf instability is one of the main sources of uncertainty in Antarctica's contribution to future sea level rise. Calving events play crucial role in ice shelf weakening but remain unpredictable and their governing processes are still poorly understood. In this study, we analyze the unexpected September 2019 calving event from the Amery Ice Shelf, the largest since 1963 and which occurred almost a decade earlier than expected, to better understand the role of the atmosphere in calving. We find that atmospheric extremes provided a deterministic role in this event. The calving was triggered by the occurrence of a series of anomalously-deep and stationary explosive twin polar cyclones over the Cooperation and Davis Seas which generated strong offshore winds leading to increased sea ice removal, fracture amplification along the pre-existing rift, and ultimately calving of the massive iceberg. The observed record-anomalous atmospheric conditions were promoted by blocking ridges and Antarctic-wide anomalous poleward transport of heat and moisture. Blocking highs helped in (i) directing moist and warm air masses towards the ice shelf and in (ii) maintaining stationary the observed extreme cyclones at the front of the ice shelf for several days. Accumulation of cold air over the ice sheet, due to the blocking highs, led to the formation of an intense cold-high pressure over the ice sheet, which helped fuel sustained anomalously-deep cyclones via increased baroclinicity. Our results stress the importance of atmospheric extremes in ice shelf instability and the need to be accounted for when considering Antarctic ice shelf variability and contribution to sea level, especially given that more of these extremes are predicted under a warmer climate.

show abstract

Section: Introductionmentioning

confidence: 88%

Atmospheric extremes triggered the biggest calving event in more than 50 years at the Amery Ice shelf in September 2019

Francis

Mattingly

Lhermitte

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Ice shelves around Antarctica cover more than 1.561 million km 2 (Rignot et al, 2013;Smith et al, 2019) creating conditions of permanent limited light penetration and food depletion, which can last for millennia (Domack et al, 2005;Pudsey et al, 2006). Benthic communities living beneath the ice shelf rely on the lateral advection of food particles (Riddle et al, 2007;Gutt et al, 2011;Smith et al, 2019). Due to limited food and light, benthic communities that live under the ice shelves are more similar to those living in the deep sea (Rose et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Abundance and Distributional Patterns of Benthic Peracarid Crustaceans From the Atlantic Sector of the Southern Ocean and Weddell Sea

et al. 2020

View full text Add to dashboard Cite

Climate change is influencing some environmental variables in the Southern Ocean (SO) and this will have an effect on the marine biodiversity. Peracarid crustaceans are one of the dominant and most species-rich groups of the SO benthos. To date, our knowledge on the influence of environmental variables in shaping abundance and species composition in the SO's peracarid assemblages is limited, and with regard to ice coverage it is unknown. The aim of our study was to assess the influence of sea ice coverage, chlorophyll-a, and phytoplankton concentrations on abundance, distribution and assemblage structure of peracarids. In addition, the influence of other physical parameters on peracarid abundance was assessed, including depth, temperature, salinity, sediment type, current velocity, oxygen, iron, nitrate, silicate and phosphate. Peracarids were sampled with an epibenthic sledge (EBS) in different areas of the Atlantic sector of the SO and in the Weddell Sea. Sampling areas were characterized by different regimes of ice coverage (the ice free South Orkney Islands, the seasonally ice-covered Filchner Trough and the Eastern Antarctic Peninsula including the Prince Gustav Channel which was formerly covered by a perennial ice shelf). In total 64766 individuals of peracarids were collected and identified to order level including five orders: Amphipoda, Cumacea, Isopoda, Mysidacea, and Tanaidacea. Amphipoda was the most abundant taxon, representing 32% of the overall abundances, followed by Cumacea (31%), Isopoda (29%), Mysidacea (4%), and Tanaidacea (4%). The Filchner Trough had the highest abundance of peracarids, while the South Orkney Islands showed the lowest abundance compared to other areas. Ice coverage was the main environmental driver shaping the abundance pattern and assemblage structure of peracarids and the latter were positively correlated with ice coverage and chlorophyll-a concentration.

show abstract

“…Base GZW reflections were digitized where AG profiles exist over these features and where they were visible on SBP profiles. These were gridded using the surface splines in the tension algorithm in GMT (Smith and Wessel, 1990), converted to depth below the seafloor, and used to calculate GZW volumes. For the GZWs, volumes were calculated with sediment velocities of 1500 m s −1 but also with the higher value of 1800 m s −1 .…”

Section: Seismic Data Interpretationmentioning

confidence: 99%

“…We find no evidence for additional stillstand events in our geophysical datasets, for example, on the S4 high between Hall Basin and Robeson Channel. As our understanding of ice shelf sediments increases (see Jennings et al, 2018;Smith et al, 2019), clues to the proximity of the grounding line, the configuration of ice shelves, and the timing of stillstand/ice shelf durations will be borne out by detailed (and forthcoming) sedimentological analyses of cores from Hall Basin.…”

Section: Sedimentary Infill Of the Petermann-nares Strait Systemmentioning

confidence: 99%

“…This has implications for marine biogeochemical cycles (e.g. Hawkings et al, 2015) and ultimately organic carbon sequestration in fjord sediments, which are a known hotspot for carbon burial (Smith et al, 2015). Yet we have very few estimates of glacial erosion or sediment fluxes for either the present-day GrIS or for past configurations of the ice sheet (Hallet et al, 1996;Overeem et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, north-west Greenland

et al. 2020

View full text Add to dashboard Cite

Abstract. Petermann Fjord is a deep (>1000 m) fjord that incises the coastline of north-west Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5 and 70 m of unconsolidated glacigenic material infills in the fjord and adjacent Nares Strait, deposited as the Petermann and Nares Strait ice streams retreated through the area after the Last Glacial Maximum. We have investigated the deglacial deposits using seismic stratigraphic techniques and have correlated our results with high-resolution bathymetric data and core lithofacies. We identify six seismo-acoustic facies in more than 3500 line kilometres of sub-bottom and seismic-reflection profiles throughout the fjord, Hall Basin and Kennedy Channel. Seismo-acoustic facies relate to bedrock or till surfaces (Facies I), subglacial deposition (Facies II), deposition from meltwater plumes and icebergs in quiescent glacimarine conditions (Facies III, IV), deposition at grounded ice margins during stillstands in retreat (grounding-zone wedges; Facies V) and the redeposition of material downslope (Facies IV). These sediment units represent the total volume of glacial sediment delivered to the mapped marine environment during retreat. We calculate a glacial sediment flux for the former Petermann ice stream as 1080–1420 m3 a−1 per metre of ice stream width and an average deglacial erosion rate for the basin of 0.29–0.34 mm a−1. Our deglacial erosion rates are consistent with results from Antarctic Peninsula fjord systems but are several times lower than values for other modern GrIS catchments. This difference is attributed to fact that large volumes of surface water do not access the bed in the Petermann system, and we conclude that glacial erosion is limited to areas overridden by streaming ice in this large outlet glacier setting. Erosion rates are also presented for two phases of ice retreat and confirm that there is significant variation in rates over a glacial–deglacial transition. Our new glacial sediment fluxes and erosion rates show that the Petermann ice stream was approximately as efficient as the palaeo-Jakobshavn Isbræ at eroding, transporting and delivering sediment to its margin during early deglaciation.

show abstract

The marine geological imprint of Antarctic ice shelves

Cited by 103 publications

References 139 publications

Atmospheric extremes triggered the biggest calving event in more than 50 years at the Amery Ice shelf in September 2019

Atmospheric extremes triggered the biggest calving event in more than 50 years at the Amery Ice shelf in September 2019

Abundance and Distributional Patterns of Benthic Peracarid Crustaceans From the Atlantic Sector of the Southern Ocean and Weddell Sea

Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, north-west Greenland

Contact Info

Product

Resources

About