A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic

• Published in: Proceedings of the National Academy of Sciences
• Main Author: Parkinson, Claire L.
• Format: Text
• Language: English
• Published: National Academy of Sciences 2019
• Subjects: Physical Sciences; Antarctic; Arctic; The Antarctic; Antarc*; Sea ice
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6642375/; http://www.ncbi.nlm.nih.gov/pubmed/31262810; https://doi.org/10.1073/pnas.1906556116

Following over 3 decades of gradual but uneven increases in sea ice coverage, the yearly average Antarctic sea ice extents reached a record high of 12.8 × 10(6) km(2) in 2014, followed by a decline so precipitous that they reached their lowest value in the 40-y 1979–2018 satellite multichannel passive-microwave record, 10.7 × 10(6) km(2), in 2017. In contrast, it took the Arctic sea ice cover a full 3 decades to register a loss that great in yearly average ice extents. Still, when considering the 40-y record as a whole, the Antarctic sea ice continues to have a positive overall trend in yearly average ice extents, although at 11,300 ± 5,300 km(2)⋅y(−1), this trend is only 50% of the trend for 1979–2014, before the precipitous decline. Four of the 5 sectors into which the Antarctic sea ice cover is divided all also have 40-y positive trends that are well reduced from their 2014–2017 values. The one anomalous sector in this regard, the Bellingshausen/Amundsen Seas, has a 40-y negative trend, with the yearly average ice extents decreasing overall in the first 3 decades, reaching a minimum in 2007, and exhibiting an overall upward trend since 2007 (i.e., reflecting a reversal in the opposite direction from the other 4 sectors and the Antarctic sea ice cover as a whole).