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    Multi-decadal trends in Antarctic sea-ice extent driven by ENSO–SAM over the last 2,000 years

    Crosta, Xavier and Etourneau, Johan and Orme, Lisa C. and Dalaiden, Quentin and Campagne, Philippine and Swingedouw, Didier and Goosse, Hugues and Massé, Guillaume and Miettinen, Arto and McKay, Robert M. and Dunbar, Robert B. and Escutia, Carlota and Ikehara, Minoru (2021) Multi-decadal trends in Antarctic sea-ice extent driven by ENSO–SAM over the last 2,000 years. Nature Geoscience, 14 (3). pp. 156-160. ISSN 1752-0894

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    Antarctic sea ice has paradoxically become more extensive over the past four decades despite a warming climate. The regional expression of this trend has been linked to changes in vertical redistribution of ocean heat and large-scale wind-field shifts. However, the short length of modern observations has hindered attempts to attribute this trend to anthropogenic forcing or natural variability. Here, we present two new decadal-resolution records of sea ice and sea surface temperatures that document pervasive regional climate heterogeneity in Indian Antarctic sea-ice cover over the last 2,000 years. Data assimilation of our marine records in a climate model suggests that the reconstructed dichotomous regional conditions were driven by the multi-decadal variability of the El Niño Southern Oscillation and Southern Annular Mode (SAM). For example, during an El Niño/SAM– combination, the northward sea-ice transport was reduced while heat advection from the subtropics to the Southern Ocean increased, which resulted in reduced sea-ice extent in the Indian sector as sea ice was compacted along the Antarctic coast. Our results therefore indicate that natural variability is large in the Southern Ocean and suggest that it has played a crucial role in the recent sea-ice trends and their decadal variability in this region.

    Item Type: Article
    Additional Information: This research was funded by the ERC StG ICEPROXY project (203441), the ANR CLIMICE project, FP7 Past4Future project (243908), the RCN OCTEL project (248776/E10), the Belgian Research Action through Interdisciplinary Networks Mass2Ant project (BR/165/A2/Mass2Ant), the JSPS KAKENHI (grants 23244102 and 17H06318),the Royal Society Te Apārangi Marsden Fund (MFP-VUW1808) and the MBIE NZ Antarctic Science Platform (ANTA1801). It also benefited from the ESF Polar Climate HOLOCLIP project. D.S. benefited from the Blue-Action project (European Union’s Horizon 2020 Research and Innovation Program, grant number: 727852) and the French LEFE-IMAGO programme. Hole U1357B samples and data were provided by the International Ocean Discovery Program (IODP). Cite as: Crosta, X., Etourneau, J., Orme, L.C. et al. Multi-decadal trends in Antarctic sea-ice extent driven by ENSO–SAM over the last 2,000 years. Nat. Geosci. 14, 156–160 (2021).
    Keywords: sea ice; sea surface temperatures; Antarctic sea ice cover; multi decadal variability;
    Academic Unit: Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
    Item ID: 17528
    Identification Number:
    Depositing User: Lisa Orme
    Date Deposited: 26 Oct 2023 08:05
    Journal or Publication Title: Nature Geoscience
    Refereed: Yes
      Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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