*Tonight's Arctic sea ice extent: 4.06 standard deviations below the mean.
That's the lowest in the records, which start 11/1/1978.
I'm calculating with the daily JAXA data -- daily NSIDC data is still offline. The Arctic sea ice extent value for yesterday, May 17th, was 11.145 million square-kilometers. That's a full 5.2% below last year's value on this date, in a world where the average annual decrease since 1978 has been -0.4% per year.
This year stands out starkly compared to others in this century (click to enlarge):
It stands out even more if you measure the anomaly in standard deviations from the mean. I've taken the baseline as 1981-2010. Using the standard deviation of the anomalies over this period, 2016's anomaly for May 17th, -1.22 Mkm2, is -4.06 standard deviations below the mean (click to enlarge):
That result isn't independent of the chosen baseline, but this is a reasonable baseline and it's still a notable result.
Even the notable lows of Sept 2012 didn't reach 4 stdevs below the mean....