NSIDC has attempted to explain why there was record breaking Antarctic Sea Ice by claiming:

First, climate is warming over much of the Antarctic continent, as shown in several recent studies (e.g., Steig et al., 2009)

Those of us who pay attention to climate know that Steig et al, 2009 was refuted by O’Donnell et al 2010.  A very good explanation can be read at Climate Audit.

“Steig’s West Antarctic warming results from a spreading of warming in the Peninsula to the West Antarctic through choices made in their principal components. Different choices – ones more plausible in the circumstances – lead to opposite results.”