On 29/01/2017 09:24, JohnD wrote:
"N_Cook" wrote in message news
The lack of Antarctic sea-ice area is before Larsen C breaks off

Are you sure that the ice-shelf areas contribute to the overall sea ice
figures? My impression was that they didn't - I guess on the basis that
are (largely?) grounded ice fed by glaciers rather than floating sea
ice. I thought that the 'land' area boundaries of Antarctica on the
extent maps actually included the ice shelves. But ICBW and I'm sure
someone here must know for sure.

I've no knowledge on that, this is just my halfpennyworth. If the ice is
over seawater and when it breaks off it forms an ice-berg, then classed
as sea-ice I would have thought.
Penetrating radar has long since defined the boundary of the land.