He shouldn't be concerened. While the Arctic is warming Antartica is mainly unaffected by global warming. The only bit warming is the West Antarctic Penninsula. That has only a small area.

Ah, Hansen is an expert in paleoclimatology and the implications for ice.

He is talking about a complete loss of ice from the entire continent of Antarctica at 450 ppm or so.

If W. Antarctica ice alone goes that's ca. 5 m (16 ft) sea level rise.

Never mind, no need for concern (sarcasm alert).