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

Lamping, N.; Müller, J.; Hefter, J.; Mollenhauer, G.; Haas, C.; Shi, X.; Vorrath, M-E.; Lohmann, G.; Hillenbrand, C-D. ORCID: https://orcid.org/0000-0003-0240-7317. 2021 Evaluation of lipid biomarkers as proxies for sea ice and ocean temperatures along the Antarctic continental margin [in special issue: Reconstructing Southern Ocean sea-ice dynamics on glacial-to-historical timescales] Climate of the Past, 17 (5). 2305-2326. 10.5194/cp-17-2305-2021

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Official URL: https://cp.copernicus.org/articles/17/2305/2021/

Abstract/Summary

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 IPSO25 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 IPSO25 with a phytoplankton marker (i.e. the PIPSO25 index) permits semi-quantitative sea-ice reconstructions and avoids misleading over- or underestimations of sea-ice cover. Comparisons of the PIPSO25-based sea-ice distribution patterns and TEXL86- 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 oceanic key variables properly. This is further supported by model data. We also highlight specific aspects and limitations that need to be taken into account for the interpretation of such biomarker data and discuss the potential of IPSO25 as an indicator for the former occurrence of platelet ice and/or the export of ice-shelf water.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.5194/cp-17-2305-2021
ISSN:	1814-9324
Date made live:	02 Nov 2021 12:12 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/531332

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.5194/cp-17-2305-2021

ISSN:

1814-9324

Date made live:

02 Nov 2021 12:12 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/531332