Rapid Ross Sea Deglaciation as captured in the RICE Ice Core
Abstract
The Roosevelt Island Climate Evolution (RICE) project recovered a 763.4 m deep ice core to bedrock from Roosevelt Island, at the northern edge of the Ross Ice Shelf. The ice at Roosevelt Island is grounded 210m below sea level and accumulates in situ, with the Ross Ice Shelf flowing around the rise.
Comparison of the modern RICE isotope data with meteorological records from weather stations and reanalysis products suggest that the record is representative of the temperature variability in the Ross Sea Region, the Ross Ice Shelf and western West Antarctica. In addition, the analysis shows that the RICE record is particularly sensitive to changes in regional sea ice extent and low and mid latitude climate drivers, in particular to the combined effects of the El Niño Southern Oscillation, the Pacific Decadal Oscillation and the Southern Annular Mode. Here, we show isotope and geochemical data spanning the past 68 ka and discuss reconstructions of environmental conditions and ice dynamics. An ensemble of sensitivity modelling experiments is used to determine thresholds for the removal of ice on Roosevelt Island and correlated grounding line and ice volume changes of the Ross Ice Shelf and the West Antarctic Ice Sheet (WAIS). Our data suggest that the Ross Ice Shelf grounding line retreat during the last deglaciation was driven at least in part by the early onset of deglaciation in West Antarctica as recorded in the WAIS Divide ice core (WDC). The Ross Ice Shelf grounding line started to retreat rapidly with the initiation of an ice shelf cavity. Atmospheric circulation changes precede the onset of the Antarctic Cold Reversal (ACR) by about 200 years. We observe that RICE leads the WDC onset of the ACR by about 300 years. For RICE, the total isotopic change between values of the Last Glacial Maximum (LGM) and the early Holocene is dD = 90‰, with a 60‰ increase occurring during the transition from the ACR to the Holocene. This isotopic enrichment is 50-200% higher than existing Antarctic ice core records. LGM sea ice extent is reached again during the ACR termination and remains extensive into the early Holocene, a period of rapid atmospheric warming and circulation changes. The Holocene record is dominated by stable temperatures between 11-9.6ka, leading to cooler conditions until 6ka when temperatures start to increase until modern times.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C52A..05B
- Keywords:
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- 3337 Global climate models;
- ATMOSPHERIC PROCESSESDE: 0724 Ice cores;
- CRYOSPHEREDE: 1621 Cryospheric change;
- GLOBAL CHANGEDE: 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHY