During the melting season I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2005-2010. NSIDC has a good explanation of what sea ice extent is in their FAQ. I also look at other things like sea ice area, concentration, volume, temperature and weather forecasts, anything that can be of particular interest. Check out the Arctic sea ice graph webpage for daily updated graphs, maps and live webcam images.
June 24th 2011
This year's melting season has so far been very similar to last year's, in size, if not so much in shape. In 2010 around this time sea ice extent was dropping spectacularly fast, leaving all other years in the dust. But at the end of June the decrease suddenly had a blowout, of which it only slightly recovered towards the very end of the melting season.
This year's rate of decrease has more or less matched 2010's free fall, even if there has been a bit of a slump since the last SIE update that saw two consecutive century breaks putting 2011 comfortably in the driver's seat. 2010 has jumped into the gap and regained the lead, as 2007 is about to start its impressive streak of century breaks (18 in 40 days).
Has 2011 bumped into the limit 2010 bumped into last year or will it fire up again, just in time to try and fend off 2007's offensive? Summer solstice has passed, but the coming weeks the Sun will shine almost incessantly. With abundant clear skies anything is possible.
Sea ice extent (SIE)
Here's the IJIS SIE graph:
2010 and 2011 are still intertwined, slightly apart from the rest, but this year's slump is clearly visible. Extent decrease has been picking up over the past few days (86K reported for the 24th), but we'll have to see if and for how long it can be sustained.
The current difference between 2011 and the other years is as follows:
- 2005: -465K (-57,531)
- 2006: -230K (-59,609)
- 2007: -491K (-63,328)
- 2008: -663K (-57,526)
- 2009: -636K (-55,938)
- 2010: +110K (-74,120)
Between brackets is the average daily extent rate for the month of June. 2011's average daily extent rate for June is currently -66,348 square kilometers, still decent enough, but quite a bit less than last week (approximately 73K per day).
This year's rate on the Uni Bremen extent rate graph is also holding up well, but look at purple 2007 coming into play around this time:
For a while the trend line on the Cryosphere Today SIA anomaly graph went down hard and passed the - 1.5 million square km mark. But the slump is showing here too, and thus the anomaly has gone back up to -1.356 million square km.
It seems something of a Beaufort Gyre has started to turn (more below). Hesitantly perhaps, it's difficult to tell without the PIPS ice displacement map which has been off-line for way too long now. This means that the Beaufort Sea SIA has started to decline again, but as the ice then gets pushed into the Laptev Sea and East Siberian Sea the rapid decrease has slowed there. It seems that when there's action on one side of the Arctic, there is less of it on the other side. And things slow down when the action transitions from one part to the other. All in all a lot of back and forth lately.
Other Crysphere Today areas are showing a relatively steady decline, some of them starting to approach their minimum. We are now waiting for the Arctic Basin SIA to start dropping (like it did last year on June 28th).
Cryosphere Today area per IJIS extent (CAPIE)
The slowdown in decrease has been stronger in SIA than in SIE, meaning CAPIE rate has also slowed down considerably:
PIPS still hasn't updated their forecast maps (and three mails to three different addresses hasn't resulted in answers either). Luckily new friend Janne Tuukkanen has relieved me somewhat by re-introducing an old friend: the ice displacement forecasts from the Russian Arctic and Antarctic Research Institute (AARI). I don't how Janne did it, but he did, and it gives me something to hold on to. Much obliged, Janne!
Forecasts are updated every Thursday. Here's an animation of what AARI forecasts for the coming week (click for a larger version):
What these arrows point to is a continuation of what looks like the Beaufort Gyre spinning in the right way, pushing the ice in a clockwise motion from the Beaufort Sea towards the Siberian coast. A low pressure area between the Laptev and Kara Sea will then further churn and transport this ice towards Fram Strait. The ECMWF weather forecast maps confirm that this is likely going to happen, or at least the first few days (click for a larger version):
Clear skies, the Beaufort Gyre, compacting winds (and high SSTs) are the things that made 2007 into a record melting year, and also the reason that 2010 faltered in the curve before the final stretch. Around the start of July weather patterns altered drastically, reversing the Beaufort Gyre, spreading the ice pack and bringing clouds to the Arctic (meaning less solar energy reaching the sea water). Despite the long-term downward trend in total Arctic sea ice, these are the things that determine whether a melting season reaches a record minimum extent/area or not.
We will see in the coming week if these circumstances that are conducive to SIE/SIA decreases have an immediate impact on the ice pack, and by extension the numbers. And whether they will be prolonged into July, the month of mega-melt.
TIPS - Other blog posts and news articles concerning the Arctic and its ice:
Mauro Pelti has put up a Glacier Index List, representing his first two years of posts, 115 total posts, 108 different glaciers. Impressive.
Tamino has been playing with PIOMAS volume data: Sea Ice 3-D