Recent changes in Antarctic Sea Ice

In contrast to the Arctic, total sea ice extent (SIE) across the Southern Ocean has increased since the late 1970s, with the annual mean increasing at a rate of 186×10 3 km 2 per decade (1.5% per decade; p <0.01) for 1979–2013. However, this overall increase masks larger regional variations, most...

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Bibliographic Details
Published in:Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Main Authors: Turner, John, Hosking, J. Scott, Bracegirdle, Thomas J., Marshall, Gareth J., Phillips, Tony
Format: Article in Journal/Newspaper
Language:English
Published: The Royal Society 2015
Subjects:
General Physics and Astronomy
General Engineering
General Mathematics
Amundsen Sea
Antarc*
Antarctic
Bellingshausen Sea
Ross Sea
Sea ice
Southern Ocean
Online Access:http://dx.doi.org/10.1098/rsta.2014.0163
https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2014.0163
https://royalsocietypublishing.org/doi/full-xml/10.1098/rsta.2014.0163
Description
Summary:In contrast to the Arctic, total sea ice extent (SIE) across the Southern Ocean has increased since the late 1970s, with the annual mean increasing at a rate of 186×10 3 km 2 per decade (1.5% per decade; p <0.01) for 1979–2013. However, this overall increase masks larger regional variations, most notably an increase (decrease) over the Ross (Amundsen–Bellingshausen) Sea. Sea ice variability results from changes in atmospheric and oceanic conditions, although the former is thought to be more significant, since there is a high correlation between anomalies in the ice concentration and the near-surface wind field. The Southern Ocean SIE trend is dominated by the increase in the Ross Sea sector, where the SIE is significantly correlated with the depth of the Amundsen Sea Low (ASL), which has deepened since 1979. The depth of the ASL is influenced by a number of external factors, including tropical sea surface temperatures, but the low also has a large locally driven intrinsic variability, suggesting that SIE in these areas is especially variable. Many of the current generation of coupled climate models have difficulty in simulating sea ice. However, output from the better-performing IPCC CMIP5 models suggests that the recent increase in Antarctic SIE may be within the bounds of intrinsic/internal variability.

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