As always, (modeled) sea ice volume has also hit its minimum in September: 6810 km3. This number is comparable to that of 2009, and well above the lowest three minima on record (2010: 4582 km3, 2011: 4302 km3, 2012: 3673 km3). This year's minimum is almost 1500 km3 higher than last year's, which itself was more than 1700 km3 higher than the 2012 record.
Like I wrote last month:
It was always clear that the Arctic could be very volatile, but this swing is huge and shows what two consecutive melting seasons with conditions that are relatively good for ice retention (2013 was cold and cloudy, 2014 cold and cloudy at the start, followed by little movement) can mean for the ice pack.
The PIOMAS sea ice volume graph produced by Wipneus shows the differences even more clearly, 2014 is right up there with 2007, 2008 and 2009:
Wipneus has also published this map in the PIOMAS thread on the Arctic Sea Ice Forum that shows the difference with 2013 (red = more volume now, blue = less volume now):
In the same thread Chris Reynolds posted this graph showing regional volume changes:
It's clear that the bulk of the volume increase, practically all of it really, has taken place in the Central Arctic. Chris has much more to say about this in his latest PIOMAS blog post on Dosbat. I highly recommend reading it.
After this small excursion, we continue the PIOMAS October 2014 update. :-)
As expected, the anomaly trend line is still above the linear trend:
Of course, on the PICT graph (the crude ice thickness measure I derive by dividing PIOMAS (PI) volume numbers with Cryosphere Today (CT) sea ice area numbers) 2014 is significantly higher than the post-2010 volume crash years:
Here's average thickness for September 30th in metres, with change from last month between brackets:
- 2005: 2.04 (-0.29)
- 2006: 2.13 (-0.06)
- 2007: 2.04 (-0.07)
- 2008: 1.96 (-0.41)
- 2009: 1.77 (-0.26)
- 2010: 1.31 (-0.18)
- 2011: 1.32 (-0.18)
- 2012: 1.41 (-0.15)
- 2013: 1.41 (-0.06)
- 2014: 1.77 (-0.18)
If you want to have a look at the data yourself, you can download the spreadsheet I use and update from GoogleDrive.
The Polar Science Center thickness graph is more or less showing the same picture:
So, what does this all mean? It means that even though things haven't returned to the pre-2007 situation - despite two melting seasons that have been excellent weather-wise for volume increases - the Arctic sea ice didn't pass a tipping point in the 2010-2012 period and is still able to make an about turn. It also means that it will take a while for this rebound to melt again (provided we see yearly decreases again) and it doesn't look likely the Arctic will be ice-free for all practical purposes before 2020. Again, read the conclusion of Chris Reynolds' latest blog post.
After the 2013 and 2014 rebounds only the linear trend looks realistic, when checking out the various graphs with different statistical fits Wipneus published on the Forum today:
According to this graph too the Arctic won't become ice-free before 2025.
I'm saying this because that's how it looks right now, but it's always good to remember that the Arctic and the word 'likely' don't get along very well. I also can't stress enough that the consequences of Arctic sea ice loss do not start when the Arctic becomes ice-free for all practical purposes. These consequences are most probably already with us, and will get worse as Arctic sea ice loss progresses, regardless of the question whether the Arctic becomes ice-free this decade, the next or between 2030 and 2040. It's all a geological blink of an eye, and much sooner than anticipated just 5 years ago.
While we speculate about all this, here and on the Forum, we keep an eye on the PIOMAS figures to see what winter will bring.