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

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 observation...

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Bibliographic Details
Published in:Nature Geoscience
Main Authors: Crosta, Xavier, Etourneau, Johan, Orme, Lisa C., Dalaiden, Quentin, Campagne, Philippine, Swingedouw, Didier, Goosse, Hugues, Massé, Guillaume, Miettinen, Arto, McKay, Robert M., Dunbar, Robert B., Escutia, Carlota, Ikehara, Minoru
Other Authors: UCL - SST/ELI/ELIC - Earth & Climate
Format: Article in Journal/Newspaper
Language:English
Published: Nature Publishing Group 2021
Subjects:
General Earth and Planetary Sciences
Antarctic
Indian
Southern Ocean
The Antarctic
Antarc*
Sea ice
Online Access:http://hdl.handle.net/2078.1/244216
https://doi.org/10.1038/s41561-021-00697-1
Description
Summary: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.

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