Table 1.

Slopes and SDs of the lines of linear least squares fit for the yearly sea ice extents in the full Southern Ocean and each of the 5 sectors identified in Fig. 1, both for the 40-y record, 1979–2018, and, in parentheses, for the 36-y record, 1979–2014, before the reversal from overall sea ice increases to rapid decreases

Sector	Slope, 103 km2⋅y−1	R	Slope, % per decade
Weddell Sea	4.0 ± 3.5 (7.0 ± 3.7)	1.13 (1.88)	1.0 ± 0.8 (1.7 ± 0.9)
Indian Ocean	2.6 ± 1.8 (5.9 ± 1.8)	1.48 (3.23)	1.4 ± 0.9 (3.2 ± 1.0)
Western Pacific Ocean	2.6 ± 1.3 (3.2 ± 1.6)	1.96 (1.98)	2.3 ± 1.2 (2.8 ± 1.4)
Ross Sea	5.8 ± 2.9 (11.3 ± 3.0)	1.97 (3.75)	2.1 ± 1.1 (4.3 ± 1.1)
Bellingshausen/Amundsen Seas	−3.7 ± 1.8 (−4.9 ± 2.1)	2.02 (2.32)	−2.5 ± 1.2 (−3.2 ± 1.4)
Full Southern Ocean	11.3 ± 5.3 (22.4 ± 4.3)	2.12 (5.25)	1.0 ± 0.5 (2.0 ± 0.4)

The slopes and SDs are listed both as the areal loss each year and as the percentage of the ice cover lost each decade. The R column gives the ratio of the slope magnitude for the areal loss to its SD (calculated before rounding to the nearest 100 km²⋅y⁻¹), as a rough indicator of statistical significance, both for the 40-y record and, in parentheses, for the 36-y record. Using the 2-tailed t test mentioned in the text, statistical significance at the 95% level or above is indicated in the R column by italics and statistical significance at the 99% level or above is indicated by boldface. The trend reversals since 2014 have markedly lessened the statistical significance of the trends.