Fig. 2: Ocean changes associated with the Antarctic Sea ice extent (SIE) shift.

a Monthly mean SIE anomaly in National Snow and Ice Data Center (NSIDC) observation (red line), SPEAR_ECDA (green line), SPEAR_atm_restore (black line), and SPEAR_atm_sst_restore (blue line). c Time-depth evolutions of the monthly Southern Ocean (SO) area averaged (60°S–70°S, 0°E–360°E) temperature anomalies in SPEAR_atm_sst_restore. e Same as (c) but for the salinity anomalies. g Scatter plot of the SO ocean stratification (defined as the density difference between 400 m and 0 m) averaged in time period 2014–2016 versus the Antarctic SIE difference (between 2017–2020 and 2012–2015). (b), (d), (f), and (h) are the same as (a), (c), (e), and (g) but for the Weddell Sea (55°S–74°S, 50°W–10°E). All anomalies are with respect to the 2011–2020 climatology. Units for the SIE, ocean temperature, salinity, and density are 1012m2, °C, PSU, and kgm−3, respectively.