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Highly branched isoprenoids reveal onset of deglaciation followed by dynamic sea-ice conditions in the western Amundsen Sea, Antarctica

By on May 9, 2021

first_imgThe Amundsen Sea drainage sector of the West Antarctic Ice Sheet (WAIS) is widely regarded as acandidate for triggering potential WAIS collapse. The grounded ice sheet drains into the Amundsen SeaEmbayment and is thereby buttressed by its fringing ice shelves, which have thinned at an alarming rate.Satellite-based observations additionally reveal a considerable long-term decrease in sea-ice cover in theAmundsen Sea over the last two decades although the long-term significance of this trend is unclear dueto the short instrumental record since the 1970s. In this context, investigations of past sea-ice conditionsare crucial for improving our understanding of the influence that sea-ice variability has on the adjacentmarine environment as well as any role it plays in modulating ice shelf and ice sheet dynamics. In thisstudy, we apply novel organic geochemical biomarker techniques to a marine sediment core from thewestern Amundsen Sea shelf in order to provide a valuable long-term perspective on sea-ice conditionsand the retreat of the Getz Ice Shelf during the last deglaciation. We analysed a specific biomarker lipidcalled IPSO25 alongside a phytoplankton biomarker and sedimentological parameters and additionallyapplied diatom transfer functions for reconstructing palaeo sea-ice coverage. This multi-proxy data setreveals a dynamic behaviour of the Getz Ice Shelf and sea-ice cover during the deglaciation following thelast ice age, with potential linkages to inter-hemispheric seesaw climate patterns. We further apply andevaluate the recently proposed PIPSO25 approach for semi-quantitative sea-ice reconstructions anddiscuss potential limitations.last_img read more

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