Not too late, apparently

Antarctic ice sheets face catastrophic collapse without deep emissions cuts | Environment | The Guardian

Studies like this, which suggest that the Antarctic ice sheets will start to melt (unless deep cuts to CO2 start very quickly) but take centuries to do so can't really take into account possible geo-engineering approaches that may develop in the intervening period.  Still, seems that it's a lot "safer" to do the achievable - reduce CO2 - than bet on unproven techniques with unclear consequences.