There are several scientific organisations that keep an eye on the Arctic sea ice cover and put out graphs to inform us of the amount of ice that is left. You can see most, if not all, of them on the ASI Graphs webpage. The minimum records on ALL of these graphs have been broken this melting season.
We already knew this would happen, so the excitement isn't commensurate with how big a thing this really is, but it's official now: the NSIDC September average sea ice extent record from 2007 has been smashed to smithereens.
Larry Hamilton's excellent bar graph:
year mo data_type region extent area
2005 9 Goddard N 5.57 4.03 2006 9 Goddard N 5.92 3.97 2007 9 Goddard N 4.30 2.78 2008 9 Goddard N 4.73 2.99 2009 9 Goddard N 5.39 3.47 2010 9 Goddard N 4.93 3.07 2011 9 NRTSI-G N 4.61 2.89 2012 9 NRTSI-G N 3.61 2.11
Like I've said a couple of weeks ago: You thought 2007 was big when it smashed the 2005 records? Well, 2012 is to 2007 what 2007 was to 2005. If my calculator doesn't deceive me, the 2007 record was a drop of 22.2% from the 2005 record. The 2012 record is a 23.6% drop from the 2007 record. (Edit: I screwed up, mistaking the 2008 number for the 2007 number. Misfratz has the right numbers in a comment below. 22.8% drop from 2005 to 2007 September average sea ice extent, and a 16% drop from 2007 to 2012 September average sea ice extent.)
As you can see the 2007 sea ice area record has also been thoroughly demolished. But the same of course goes for IJIS September average SIE (graph courtesy of Seke Rob):
So now we wait and see if the CT SIA anomaly drops below the 2007 record, and perhaps the CT Global SIA record anomaly is in the works as well (depends on the Antarctic sea ice mostly). Oh, and of course, the PIOMAS minimum volume. The record was broken a while back.
And then we'll watch the freezing season a bit. I'm working on a couple of changes. More on that later...