The Summer ice melt

Polar Arctic Melt 6-19 

thru 7-5

After the Small and persistent Arctic Cyclone of 2013 ended in June, it left the ice near the pole fairly broken up.This video is a composite of daily images from the University of Bremen, with some slight reformatting to fit into a full screen video. For a detailed (I mean really detailed!) discussion of what is happening in the far north, head over to ‪http://neven1.typepad.com/blog/ This video will be updated every weekend through the melt season.

http://neven1.typepad.com/blog/2013/07/piomas-july-2013.html#more

Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

The slow start of this year's melting season has had a dramatic effect on sea ice volume. After going steadily upwards from a very low volume at the start of the year, catching up with 2011 and 2012, this year is now well above those two lowest volume years (by 1729 and 1720 km3 respectively) and even slightly above 2010 (126 km3).

Although I knew that the bad weather for ice decrease would keep 2013 above 2011 and 2012, I didn't quite expect such a big gap. It never hurts to emphasize that PIOMAS is a model, and even though it's constrained by observations, the uniqueness of this season so far might cause some parameters to get sidetracked.

Some might say I emphasize this now because as an alarmist I'm not pleased with the results, but I don't believe this is the case (the results are bad anyhow, even if better than previous years). I emphasize that PIOMAS is a model on a regular basis, especially when PIOMAS tends to go low, because many people assume that the PIOMAS graph is showing observed data. It took me almost three years to finally be able to say last year: yes, the ice is as thin as PIOMAS says it is, because area/extent keep decreasing steadily, whereas weather patterns imply they should stall.

I always feared that PIOMAS was overestimating volume loss. For the first time I fear the opposite. That sounds like a conclusion, but it isn't, as I have more graphs to show to complete the PIOMAS update for this month.

Here is Wipneus' version with the calculated "expected" 2013 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 trend line is well above the dotted expectation, and if my eyes don't deceive me, above the confidence range as well.

Still, the anomaly from the linear trend is about to leave 2 standard deviation territory, continuing the pattern first seen in 2010:

Average thickness is still tracking as low as last year, and that's because CT sea ice area numbers are also remarkably high compared to last year. I crudely calculate the ice pack's average thickness by dividing PIOMAS (PI) volume numbers with Cryosphere Today (CT) sea ice area numbers. If they're both much higher than last year, average thickness remains just as low, of course.

Here's average thickness for June 30th in metres, with change from last month between brackets:

2005: 2.47 (+0.13)

2006: 2.44 (+0.13)

2007: 2.19 (+0.03)

2008: 2.36 (+0.07)

2009: 2.11 (-0.03)

2010: 1.91 (-0.04)

2011: 1.75 (-0.11)

2012: 1.71 (-0.12)

2013: 1.71 (-0.08)

If you want to have a look at the data yourself, you can download the spreadsheet I use and update from GoogleDrive.

Average thickness is on a par with last year. Just like all years since 2010 average thickness has now started to drop, contrary to the years prior to 2010.

The thickness graph from the Polar Science Center is again showing 2013 slightly above 2012 (just like last month) [edit: that's because the graph hasn't been updated! Will replace the graph once it's updated; N.]:

Right now I'm not sure what to make of that big gap between 2013 and previous years. If it's real, this could mean that 1) the start of the melting season is of paramount importance, and 2) 2013 is a recovery year, the first one in 5 years, volume-wise. More or less the same conclusion I drew a couple of days ago, after reviewing maps showing atmospheric circulation patterns in May and June.

But I think I'm seeing a huge melting potential out there, despite those slow start weather conditions, with holes in the interior of the ice pack and lots of discoloured, thin ice on the fringes. We mustn't forget that this melting season started with the most first-year ice on record. A bad start can postpone much of that ice to melt out, but all bad starts come to an end.

I believe there will be a rapid area/extent decrease in the coming weeks, and it remains to be seen how PIOMAS is going to interpret that. If, like I said, some of those parameters are sidetracked due to the unique pattern of this melting season so far, they just might get back on track once the melting season throws off its mask.

The coming weeks could be the most interesting we're going to see this melting season.