Observational Evidence for a Regime Shift in Summer Antarctic Sea Ice

• DOI: 10.1175/jcli-d-23-0479.1
• Publication Date: 2024-02-13T15:30:51Z
• Authors: Will Hobbs; Paul Spence; Amelie Meyer; Serena Schroeter; Alexander D. Fraser; Philip Reid; Tian R. Tian; Zhaohui Wang; Guillaume Liniger; Edward W. Doddridge; Philip W. Boyd
• Keywords: 01 natural sciences; 0105 earth and related environmental sciences

Abstract In recent years, the Southern Ocean has experienced extremely low sea ice cover in multiple summers. These events were preceded by a multidecadal positive trend that culminated record high coverage 2014. This abrupt transition led some authors to suggest Antarctic undergone regime shift. this study we analyze satellite and atmospheric reanalyses assess evidence for such We find standard deviation of summer doubled from 0.31 million km 2 1979–2006 0.76 2007–22. increased variance is accompanied longer season-to-season memory. The atmosphere primary driver variability, but using linear predictive model show changes cannot be explained alone. Identifying whether shift occurred difficult without complete understanding physical mechanism change. However, statistical demonstrate (i.e., autocorrelation, changed response forcing), as well spatial coherence noted previous research, are indicators based on dynamical systems theory an critical transition. Thus, our analysis further support system. Significance Statement there have been several summers with cover, including consecutive lows February 2022 2023. Since then, 2023 winter seen remarkably growth anomaly far below expected climatology. researchers question shift, observational last decade or so, variability almost doubled, much memory season season. changes, other researchers, consistent theoretical transition,