Causes of sudden decline of the Antarctic sea ice after 2016

Abstract

Observed Antarctic sea ice had been increasing till 2015, despite the warming trend all over the world. Several hypotheses have been proposed to explain this rather controversial issue. More interestingly, this steadily increasing sea ice around Antarctica started to exhibit a sharp decrease after 2016. In this study, the aforementioned various hypotheses on the expansion of Antarctic sea ice including natural variability of the Earth climate system, surface wind, Stratospheric ozone, and Interdecadal Pacific Oscillation (IPO), are evaluated in terms of a sudden decrease of Antarctic sea ice after 2016. First, the negative IPO phase in the Pacific Ocean, an important natural climate variability and related surface cooling in the Southern Ocean through 2015 was proposed to explain increasing the Antarctic sea ice. However, no clear transition of the IPO mode was found around 2015- 2016. Next, ozone and surface wind in the Southern Ocean do not show any significant changes to explain the sharp decline of Antarctic sea ice. On the other hand, it was shown that the temperature closer to the surface of the Antarctic Ocean trends behaves similarly to the variability of the Antarctic sea ice, but not that in the upper atmosphere. This clearly indicates that variation of the Antarctic sea ice largely relates to the ocean and near-surface rather than the upper atmosphere. Because the Antarctic ice can potentially contribute to future sea level rise with unprecedented damage to human society and our environment, further study is needed for more systematic understanding of the Antarctic sea ice variation.