An Illustrated Guide To 2012 Record Arctic Sea Ice Melt

The Arctic sea ice minimum volume dropped sharply this year. Data from PIOMAS, Graph by L. Hamilton

By Nevin Acropolis via the Arctic Sea Ice Blog

We already knew a few weeks ago that the PIOMAS sea ice volume record had been broken, but with the latest data release by the Polar Science Center at the University of Washington we now know the minimum sea ice volume for 2012, as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS).

Here’s the graph from the PSC:

Yearly minimum sea ice volume for the 2005–2012 period (in km3):

• 2005: 9159
• 2006: 8993
• 2007: 6458
• 2008: 7072
• 2009: 6893
• 2010: 4428
• 2011: 4017
• 2012: 3263

So this year’s melting season has gone 1165 and 754 km3 below the 2010 and 2011 minimums. That’s, how shall I put it? A lot! More than at the time of the last update. Almost double the difference between the 2010 and 2011 minimums. Half the 2007 minimum.

Here is Wipneus’ version for which he calculated the “expected” 2012 values (dotted lines), based on the same date values of 1979–2011 and an exponential trend. A caveat from Wipneus: “Note that the statistical error bars are quite large.”

The minimum ended up slightly above the expected values based on statistics.

Here’s Larry Hamilton’s widely used bar graph [see top graph]:

Here’s the PIOMAS anomaly graph:

I have used my crude method of dividing PIOMAS volume numbers by Cryosphere Today area numbers to calculate the ice pack’s average thickness. Again, this is just an indication that allows us to compare with previous years:

Average thickness for September 3rd (in m):

• 2005: 2.04
• 2006: 2.13
• 2007: 2.04
• 2008: 1.98
• 2009: 1.79
• 2010: 1.28
• 2011: 1.25
• 2012: 1.27

And here’s the thickness graph from the Polar Science Center:

Let me repeat once more: we now know for sure the ice is thin. There are two lines of evidence for this: 1) observations from CryoSat-2, (definite confirmation as soon as Dr. Laxon publishes his paper), and 2) the fact that this melting season has annihilated all records on all graphs from all agencies, despite the fact that weather conditions didn’t come close to those of 2007 (more on that in the latest NSIDC monthly analysis, which I’ll report on tomorrow).