As the ASIF was down for some time, I originally posted the following comments on the current ASIB thread instead.
Every day since the 5th November 2016, Antarctic sea ice extent has been at record low levels. The NSIDC daily Antarctic sea ice extent value for March 27th came in at 3.304 million sq kms. This was a somewhat jaw-dropping 2.037 million sq kms lower than the equivalent figure from last year.
The cumulative effect of just over 20 weeks at record low levels has obviously been dragging down the rolling 365-day annual average extent figure. In fact, for the last 5 days, this average extent value has been dropping at over 5k sq kms each day.
The latest (as at 27th March) rolling 365-day average extent value has now dropped to 10.966 million sq kms. The previous record low average was 10.969 million sq kms (6th Aug 1979 - 4th Aug 1980).
To give a bit more perspective, decadal averages (calculated from the NSIDC monthly values) come out as...
1980-89 11.82 million sq kms
1990-99 12.03 million sq kms
2000-09 12.18 million sq kms
2010-16 12.46 million sq kms
Several weeks ago, on the relevant ASIF thread, I had been demonstrably cautious when I had suggested that the rolling 365-day figure would drop below 11 million sq kms by the end of March, and could likely surpass the previous record low sometime toward the end of April.
CAVEAT: Prior to the 20th Aug 1987, figures were produced on alternate days. Therefore, during that earlier record low period (1979-1980), the rolling 365-day figure actually comprised just 183 data points. The implicit assumption is, of course, that the "missing" days will, on average, tend to be halfway between the before/after dates. Some will be lower, some will be higher, but this should just about even out over the 182 "missing" days.
As LMV has just pointed out yet again (see also his comment #585, and my #583 and #587) there are good scientific reasons behind this latest twist in the Antarctic sea ice saga.