Eighteen year record of circum-Antarctic landfast sea ice distribution allows detailed baseline characterisation, reveals trends and variability

• Published in: The Cryosphere
• Main Authors: Fraser, AD, Massom, RA, Handcock, MS, Reid, P, Ohshima, KI, Raphael, MN, Cartwright, J, Klekociuk, AR, Wang, Z, Porter-Smith, R
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus GmbH 2021
• Subjects: Earth Sciences; Physical geography and environmental geoscience; Glaciology; Antarctic; The Antarctic; East Antarctica; Ross Sea; West Antarctica; Bellingshausen Sea; Oates Land; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.5194/tc-15-5061-2021; http://ecite.utas.edu.au/144083

Landfast sea ice (fast ice) is an important though poorly understood component of the cryosphere on the Antarctic continental shelf, where it plays a key role in atmosphereoceanice-sheet interaction and coupled ecological and biogeochemical processes. Here, we present a first in-depth baseline analysis of variability and change in circum-Antarctic fast-ice distribution (including its relationship to bathymetry), based on a new high-resolution satellite-derived time series for the period 2000 to 2018. This reveals (a) an overall trend of −882824 km 2 yr −1 (−0.190.18 % yr −1 ) and (b) eight distinct regions in terms of fast-ice coverage and modes of formation. Of these, four exhibit positive trends over the 18-year period and four negative. Positive trends are seen in East Antarctica and in the Bellingshausen Sea, with this region claiming the largest positive trend of +1198359 km 2 yr −1 (+1.100.35 % yr −1 ). The four negative trends predominantly occur in West Antarctica, with the largest negative trend of −1206277 km 2 yr −1 (−1.780.41 % yr −1 ) occurring in the Victoria and Oates Land region in the western Ross Sea. All trends are significant. This new baseline analysis represents a significant advance in our knowledge of the current state of both the global cryosphere and the complex Antarctic coastal system, which are vulnerable to climate variability and change. It will also inform a wide range of other studies.