Claim: New Antarctic sea-ice extent due to wind and 'atmospheric warming' – what warming?

As the albedo of the Antarctic continent is slightly higher than low level clouds (unlike the Greenland Ice sheet, the high speed Antarctic winds break down the snow crystals to form an ice like substance) a decrease in low level clouds in the high latitude South Pole causes the warming of the surrounding ocean and slight cooling of the Antarctic ice sheet.
In the Northern Hemisphere as the albedo of the Greenland Ice sheet is roughly the same as the low level clouds and the Greenland Ice sheet temperature is not isolated from by a polar vortex from the surrounding ocean a reduction in low level clouds in the high latitude Northern regions causes the Greenland Ice sheet to warm.
High resolution proxy data shows the Greenland Ice sheet repeatedly warmed when the Antarctic ice sheet cooled and vice versa. This observational fact is called the polar see-saw.
This paper by Svensmark explains the polar see-saw and how changes in the solar magnetic cycle cause it.

The Antarctic climate anomaly and galactic cosmic rays The Antarctic climate anomaly and galactic cosmic rays by Henrik Svensmark
Borehole temperatures in the ice sheets spanning the past 6000 years show Antarctica repeatedly warming when Greenland cooled, and vice versa (Fig. 1) [13, 14]. North-south oscillations of greater amplitude associated with Dansgaard-Oeschger events are evident in oxygenisotope data from the Wurm-Wisconsin glaciation[15]. The phenomenon has been called the polar see-saw[15, 16], but that implies a north-south symmetry that is absent. Greenland is better coupled to global temperatures than Antarctica is, and the fulcrum of the temperature swings is near the Antarctic Circle. A more apt term for the effect is the Antarctic climate anomaly.
Attempts to account for it have included the hypothesis of a south-flowing warm ocean current crossing the Equator[17] with a built-in time lag supposedly intended to match paleoclimatic data. That there is no significant delay in the Antarctic climate anomaly is already apparent at the high-frequency end of Fig. (1). While mechanisms involving ocean currents might help to intensify or reverse the effects of climate changes, they are too slow to explain the almost instantaneous operation of the Antarctic climate anomaly.
Figure (2a) also shows that the polar warming effect of clouds is not symmetrical, being most pronounced beyond 75◦S. In the Arctic it does no more than offset the cooling effect, despite the fact that the Arctic is much cloudier than the Antarctic (Fig. (2b)). The main reason for the difference seems to be the exceptionally high albedo of Antarctica in the absence of clouds.