Evaluation of lipid biomarkers as proxies for sea ice and ocean temperatures along the Antarctic continental margin

• Published in: Climate of the Past
• Main Authors: N. Lamping, J. Müller, J. Hefter, G. Mollenhauer, C. Haas, X. Shi, M.-E. Vorrath, G. Lohmann, C.-D. Hillenbrand
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Environmental pollution; TD172-193.5; Environmental protection; TD169-171.8; Environmental sciences; GE1-350; Antarctic; Southern Ocean; The Antarctic; West Antarctica; Antarc*; Antarctica; Ice Shelves; Sea ice
• Online Access: https://doi.org/10.5194/cp-17-2305-2021; https://doaj.org/article/a5657180e71341ee99f34135644ffdb7

The importance of Antarctic sea ice and Southern Ocean warming has come into the focus of polar research during the last couple of decades. Especially around West Antarctica, where warm water masses approach the continent and where sea ice has declined, the distribution and evolution of sea ice play a critical role in the stability of nearby ice shelves. Organic geochemical analyses of marine seafloor surface sediments from the Antarctic continental margin allow an evaluation of the applicability of biomarker-based sea-ice and ocean temperature reconstructions in these climate-sensitive areas. We analysed highly branched isoprenoids (HBIs), such as the sea-ice proxy IPSO 25 and phytoplankton-derived HBI-trienes, as well as phytosterols and isoprenoidal glycerol dialkyl glycerol tetraethers (GDGTs), which are established tools for the assessment of primary productivity and ocean temperatures respectively. The combination of IPSO 25 with a phytoplankton marker (i.e. the PIPSO 25 index) permits semi-quantitative sea-ice reconstructions and avoids misleading over- or underestimations of sea-ice cover. Comparisons of the PIPSO 25 -based sea-ice distribution patterns and TEX <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">86</mn><mi>L</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="11pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="39f6d7bf2ebe5935ddc540125d2eae00"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-17-2305-2021-ie00001.svg" width="11pt" height="17pt" src="cp-17-2305-2021-ie00001.png"/></svg:svg> - and RI-OH ′ -derived ocean temperatures with (1) sea-ice concentrations obtained from satellite observations and (2) instrument measurements of sea surface and subsurface temperatures corroborate the general capability of these proxies to determine ...